electrochemistry and nanomaterials · glassy carbon modified electrodes for comparison of wine...

3rd Forum on Electrochemistry and Innovation

Electrochemistry and Nanomaterials

Universidade de Trás-os-Montes e Alto Douro

Vila Real

16, 17 of September 2013

3ª Jornadas de Electroquímica e Inovação 2013 www.e-inov.org

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PROGRAM SCHEDULE 04

ABSTRACT INDEX 06

ABSTRACTS 11

LIST OF AUTHORS 63

LIST OF PARTICIPANTS 66

SPONSORS 71


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PROGRAM

16 September

12:00-14:15 Registration

14:15-14:30 Opening Ceremony

Theme A: "Electrochemistry in nanomaterials"

Chairpersons: Carlos Pereira and Ana Bettencourt

14:30-15:30 Plenary Lesson: PATRICK UNWIN

“New Directions in Electrochemical Imaging: Structure-Activity

Investigations and Patterning at the Nanoscale”

PL1

15:30-15:45 Keynote Lecture: ANA VIANA

“Functionalization and stable self-assemble of nanoparticles on

electrode surfaces”

KN1

15:45-16:10 Coffee-Break

Chairpersons: Jorge Correia and Cristina Oliveira

16:10-17:10 Plenary Lesson: DAVID FERMIN

“Reactivity of Pd Nanoshells: Feeling the Strain”

PL2

17:10-17:40 Oral Communication: LÚCIA BRANDÃO

Platinum-free electrocatalysts for oxygen reduction

OC1

17:40-17:50 Tributo to Luísa Abrantes

17:50-18:10 Oral Communication: VIRGÍNIA FERREIRA

“Noble-metal nanoparticles modified electrodes - electrochemical and

catalytic properties”

OC2

18:10-19:30 Poster Session

19:30 Porto d´Honra and Dinner (Panoramic Restaurant)

17 September

Theme B: "Nanomaterials for electrochemical devices"

Chairpersons: Luís Proença and Dulce Geraldo

9:00-10:00 Plenary Lesson: HERMAN AGUSTÍN COSTA GARCÍA

"Nanostructures on screen printed electrodes as novel

transducers for sensors”

PL3


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10:00-10:30 Keynote Lecture: CRISTINA DELERUE-MATOS

" Nanomaterial-based electrochemical sensors: the future trends for

analytical tools”.

KN2

10:30-10:50 Oral Communication: CÉLIA SILVEIRA

" Deconvolution of cytochrome c nitrite reductase electrochemistry

using MWCNTs with different surface chemistries”

OC3

10:50-11:15 Coffee-Break

Chairpersons: Carlos Silva and Fátima Bento

11:15-11:45 Keynote Lecture: MIKHAIL ZHELUDKEVICH

"“Smart” coatings for active corrosion protection based on multi-

functional micro and nanocontainers"

KN3

11:45-12:15 Keynote Lecture: MADALINA M. BARSAN

“Nanostructured modified electrodes and application

in sensors and biosensors”

KN4

12:15-12:35 Oral Communication: LÍDIA SANTOS

“Hydrothermal synthesis of nanoparticles of WO3 and its application in

electrochromic inkjet printed thin films”

OC4

12:35-13.05 Keynote Lecture: PIER PARPOT

“Electrocatalysts based on carbon nanotubes: application to

wastewater treatments”

KN5

13:05-13:15 Best poster award and Closing Session


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ABSTRACT INDEX

Ref. Title / Presenting Author Page

PL1

New Directions in Electrochemical Imaging: Structure-Activity Investigations and Patterning at the Nanoscale

Patrick R. Unwin

11

PL2 Reactivity of Pd Nanoshells: Feeling the Strain

David J. Fermin 12

PL3

Nanostructures on screen printed electrodes as novel transducers for sensors

Agustín Costa García

13

KN1

Functionalization and stable self-assemble of nanoparticles on electrode surfaces

Ana S. Viana

14

KN2

Nanomaterial-based electrochemical sensors: the future trends for analytical tools

Cristina Delerue-Matos

15

KN3

“Smart” coatings for active corrosion protection based on multi-functional micro and nanocontainers

Mikhail Zheludkevich

16

KN4

Nanostructured modified electrodes and application in sensors and biosensors

Madalina M. Barsan

17

KN5

Electrocatalysts based on carbon nanotubes: application to wastewater treatments

P. Parpot

18

OC1 Platinum-free electrocatalysts for oxygen reduction

K. Eblagon, Lúcia Brandão 19

OC2

Noble-metal nanoparticles modified electrodes - electrochemical and catalytic properties

V.C. Ferreira

20

OC3

Deconvolution of cytochrome c nitrite reductase electrochemistry using MWCNTs with different surface chemistries

Célia M. Silveira

21

OC4

Hydrothermal synthesis of nanoparticles of WO3 and its application in electrochromic inkjet printed thin films

Lídia Santos

22


7

P1

Corrosion resistance of single wall carbon nanohorns as electrocatalyst support

Lúcia Brandão

23

P2

Development of 3D Dendritic Ni−Co Films: electrodeposition parameters and heat treatment effect

R.P. Silva S Eug nio Silva Carme im F ontemor

24

P3

Determination of plant-toxicity inductors metals at a rotating-disc bismuth film electrode by anodic stripping voltammetry

Ana. I. Matos, M. M. Rocha, M. M. M. Neto, L. L. Martins, M. P. Mourato

25

P4

Evaluation of radical scavenging activity of antioxidants by means of electrogenerated HO radical

Raquel Oliveira, D. Geraldo, F. Bento

26

P5

Screen Printed Electrodes Modified with Carboxylated Multiwall Carbon Nanotubes for the Analysis of Hydroquinone and Ascorbic Acid

Rui Gusmão, M.Fortes, R. Oliveira, D. Geraldo, F. Bento, F.Proença, C. Paiva

27

P6

Degradation of alizarin red promoted by electrogenerated HO radicals: A kinetic study

Fátima Bento, A. Vilas Boas, R. Oliveira, D. Geraldo

28

P7

A new approach to domoic acid detection

Dulce Geraldo, R. Oliveira, F. Bento, J. Gonzalez-Costas, E.Gonzalez-Romero

29

P8

Direct Methanol Micro Fuel Cell: Fabrication Process Using Microsystems Technologies

C.A. Faria, R. Sousa, L.M. Goncalves

30

P9

Trace metal interactions with CdTe/CdS quantum dots: an electrochemical study

José Paulo Pinheiro, C. Franco, R. Domingos

31

P10

Electrochemical biosensing platform using self-assembled multivalent nanoparticles

Rui Carvalho, E. Vrouwe, J.P. Pinheiro, A. Velders

32

P11

Glassy carbon modified electrodes for comparison of wine antioxidant properties

N. Dionísio, Cristina Oliveira

33

P12

Modified electrodes for electrocatalysis: electropolimerisation based on binuclear metal complexes

Sara Realista, P. Martinho, A. Melato, M.J.Calhorda

34


8

P13

Direct and catalyzed reduction of dissolved CO2 in aqueous media using a polymeric gas diffusion membrane

Rui Gusmão, C.Pereira

35

P14

Synthesis of lithium vanadium oxides nanoparticles by solution processing for electrochromic devices

A. Santos, L. Pereira

36

P15

Electrocatalytic properties of metalloporphyrins immobilized on platinum nanoparticles stably linked to gold surfaces

I. Almeida, A. S. Viana

37

P16 Functionalization of iron oxide nanoparticles for biosensors

F. Henriques, M.D. Carvalho, A.S. Viana 38

P17

Electrocatalytic Properties of Self-assembled Monolayers of Porphyrins and Chlorins Adsorbed from Phosphonic or Carboxylic Acid Groups on ITO

J. F. Cabrita, L. M. Abrantes, F. P Montforts, A. S. Viana

39

P18

‘Smart’ coatings as sensors based on nanocontainers

Frederico Maia, Alexandre C. Bastos, João Tedim, Mikhail L. Zheludkevich and Mário G.S. Ferreira

40

P19

Simultaneous Determination of Nickel and Cobalt, Using a Solid Bismuth Vibrating Electrode, by Adsorptive Cathodic Stripping Voltammetry

G. Alves , J. Magalhães, Helena M.V.M. Soares

41

P20

The role of gold nanoparticles on the sensitivity of a bi-enzymatic biosensor for carbamate pesticides determination

T.Oliveira, M. F. Barroso, S. Morais, M. Araújo, C. Freire, P. Lima-Neto, A. Correia, M.Oliveira, Cristina Delerue-Matos

42

P21

Electrochemical properties of a gold nanoparticles doped organic/inorganic hybrid matrix gel

C. Silva, S. Moreira, J. Silva, M. Costa, M. Gomes 43

P22

Immobilization of Metalloporphyrins onto Electrode Surfaces by Electropolymerization of Tailored and Conventional Monomers

Isabel M. Ornelas , C. Neves , M. Neves , A. Viana, J. Cavaleiro , J. Correia

44

P23

Influence of Zeolite Particles and Inhibitor as Additive for Concrete in the Rebar Corrosion Protection C. Vicente ,A. S. Castela, R. Neves, M. F. Montemor

45

P24 New phenolic imidazole derivatives: evaluation of antioxidant activity

A.P. Bettencourt, F. Lobo, A. Leite, C. Correia, M. Carvalho, M. Proença 46


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P25

Gold nanoparticles-based biosensor for determination of amyloid beta-peptide

P. Carneiro, J. Loureiro, S. Coelho, C. Delerue-Matos, S. Morais, M. Pereira

47

P26

Application of a DNA-based biosensor for the electrochemical investigation of the effect of free radicals and antioxidants

S. Costa, D. Cruz, M. Barroso, M. Ramalhosa, A. Duarte, C. Delerue-Matos

48

P27

Study of electrochemical properties of a protective film formed onto nickel when immersed in alkali metal solutions

Cilene Vicente, R. Duarte, A. Castela

49

P28 Development of an electrochemical aptasensor for protein detection

Sofia G. Meirinho, Luís Dias, Antonio. Peres, L. Rodrigues 50

P29

Modified Titanate Nanotubes Decorated with Nanocrystalline Bi2S3 as New Materials for Sensor Applications

J. F. Cabrita , O. C. Monteiro

51

P30

Disposable immunosensor with simple antibody orientation for label-free real-time detection of a cancer biomarker

Nádia S. Ferreira, M. Goreti F. Sales

52

P31

Smart Plastic Antibody Material for Hemoglobin Tailored by Silica Surface Imprinting and with Charged Binding Sites: Its use as Ionophore in Potentiometric Transduction

Ana P. T. Moreira, Felismina T.C. Moreira, M. Goreti F. Sales

53

P32

Carnitine tailored Sensors on Surface Molecular Imprinting based on Graphene layers

Liliana A.A.N.A. Truta, Nádia S. Ferreira, M. Goreti F. Sales

54

P33

A Biomimetic Biosensor based on Poly(o-aminophenol) film for Cardiac Biomarker detection in Point-of-Care

F. Moreira, S. Sharma, R. Dutra, J. Noronha, A. Cass, M. Sales

55

P34

Organic-Inorganic Hybrid Sol-gel Coatings to Prevent Corrosion of Galvanized Reinforcing Steel

R. B. Figueira, E. V. Pereira, C. J. R. Silva, M. M. Salta

56

P35

Characterization of ZnO Nanoparticles on Electrode Surfaces by Electrochemical Techniques

José A. Ribeiro, P. Fernandes, C. Pereira, F. Silva

57

P36 Progress on studying the effect of alloying Pd with phosphorus on the ethanol electrooxidation

S. Salomé, R. Rego, M. C. Oliveira

58


10

P37

An electrochemical impedance spectroscopy study of oxygen reduction kinetics on PdP alloys

Rosa Rego, Sónia Salomé, Maria Cristina Oliveira, J.C.S. Fernandes

59

P38

Building Biomimetic Lipid Raft Environments on Modified Gold for the Study of Bioactive Molecule-Membrane Interactions

Joaquim T. Marquês, Rodrigo F. M. de Almeida, Ana S. Viana

60


11

PL1

New Directions in Electrochemical Imaging: Structure-Activity

Investigations and Patterning at the Nanoscale

Patrick R. Unwin, Kim McKelvey, Aleix G. Güell, Stanley C. S. Lai, Anisha N. Patel, Katherine E. Meadows, Julie V. Macpherson, Robert A. Lazenby, Binoy P. Nadappuram, Barak D. B. Aaronson, Changhui Chen, Gouhui Zhang, Anatoli Cuharuc and Alexander W. Colburn

Warwick Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK

[email protected] (www.warwick.ac.uk/electrochemistry)

Electrochemical imaging methods, such as scanning electrochemical microscopy (SECM) have had a significant impact in electrochemistry and interfacial chemistry, allowing reactions and fluxes to be measured and mapped locally.1 However, despite considerable effort, such methods have largely remained stuck with a resolution at the several µm scale. At Warwick, we have recently pioneered new techniques for electrochemical imaging, notably scanning electrochemical cell microscopy (SECCM)2 and contributed to the development of related methods,3 which allow us to examine electrochemical processes, and surface reactions generally, with unprecedented spatial resolution. This talk will introduce these methods and show how they can be used to probe electrochemical reactions at individual features at electrode surfaces, including steps, terraces and single catalytic nanoparticles. A particular focus of our work is new forms of carbon such as graphene and nanotubes, where our novel methods provide considerable new insights on the intrinsic activity and allow textbook models to be examined in detail. A major outcome of our work has been the clear demonstration that the basal surface of sp2 carbon materials (graphite, graphene and nanotubes) has much higher intrinsic activity than recognised previously. A further application of these methods is in patterning and nanofabrication and it will be shown how SECCM, in particular, allows the ready creation of multidimensional nanostructures (dots, nanowires, towers, etc.) of conducting polymers. We thank the European Union FP7 programme, through an ERC award (QUANTIF) and Marie Curie Fellowships, along with EPSRC, for supporting much of this research. We also acknowledge fruitful collaborations with colleagues listed in the references below. 1. Amemiya, S.; Bard, A. J.; Fan, F. R. F.; Mirkin, M. V.; Unwin, P. R. Annu. Rev. Anal. Chem., 2008, 1, 95. 2. See for example: (a) N. Ebejer, M. Schnippering, A. W. Colburn, M. A. Edwards & P. R. Unwin, Anal. Chem., 2010, 82, 9141. (b) M. E. Snowden, A. G. Güell, S. C. S. Lai, K. McKelvey, N. Ebejer, M. A. O’Connell, A. W. Colburn, and P. R. Unwin, Anal. Chem., 2012, 84, 2483. (c) A. G. Güell, N. Ebejer, M. E. Snowden, K. McKelvey, J. V. Macpherson, and P. R. Unwin, Proc. Natl. Acad. Sci. USA, 2012, 109, 11487. (d) A. G. Güell, N. Ebejer, M. E. Snowden, J. V. Macpherson and P. R. Unwin, J. Am. Chem. Soc., 2012, 134, 7258. (e) A. N. Patel, K. McKelvey and P. R. Unwin, J. Am. Chem. Soc., 2012, 134, 20246. (f) S. C. S. Lai, A. N. Patel, K. McKelvey and P. R. Unwin, Angew. Chem. Int. Ed., 2012, 51, 5405. (g) S. C. S. Lai , P. V. Dudin , J. V. Macpherson and P. R. Unwin, J. Am. Chem. Soc., 2011, 133, 10744. (h) B. D.B. Aaronson, C.-h. Chen, H. Li, M. T.M. Koper, S. C. S. Lai and P. R. Unwin, J. Am. Chem. Soc., 2103, 35, 3873–3880. 3. (a) Y. Takahashi, A. I. Shevchuk, P. Novak, B. Babakinejad, J. Macpherson, P. R. Unwin, H. Shiku, J. Gorelik, D. Klenerman, Y. E. Korchev, and T. Matsue, Proc. Natl. Acad. Sci. USA, 2012, 109, 11540-11545. (b) Y. Takahashi, A. I. Shevchuk, P. Novak, Y. Zhang, N. Ebejer, J. V. Macpherson, P. R. Unwin, A. J. Pollard, D. Roy, C. A. Clifford, H. Shiku, T. Matsue, D. Klenerman and Y. E. Korchev, Angew. Chem. Int. Ed., 2011, 50, 9638-9642.


12

PL2

Reactivity of Pd Nanoshells: Feeling the Strain

V. Celorrio,a D. Plana,

a J. Florez,

b E. Pastor

b and David J. Fermin

a

a School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK

b Universidad de La Laguna, Dpto. de Química-Física, Avda. Astrofísico Francisco Sánchez

s/n, 38071 La Laguna (Tenerife), Spain

One of the most active areas of research in electrocatalysis is devoted to tuning the reactivity

of metal nanostructures supported on mesoporous carbon layers. Average particle size,

effective crystal orientation and chemical functional groups at nanoparticle supports are

among the parameters more widely targeted for catalyst optimisation. Tuning the composition

of binary or multimetallic nanostructures has also been investigated either in alloy or core-

shell configuration. The reactivity of these systems can be rationalized in terms of the so-

called electronic and geometric (strain) effects on the structure of d-orbitals [1-2]. A classic

example involves Pd-overlayers at Au surfaces, which have received significant attention over

the years in the context of hydrogen electrocatalysis and formic acid (HCOOH) oxidation [3].

In this contribution, we shall discuss the electrocatalytic activity of Pd nanoshells grown by

colloidal synthesis onto Au nanoparticles as a function of their effective lattice strain.

Reactivity studies are focused on CO and HCOOH electro-oxidation, as well as CO2

reduction.

Our studies based on selective area electron diffraction have shown that the effective strain of

Pd nanoshells at Au cores relaxes from 3.5 to 1% as the thickness increases from 1 to 10 nm

[4]. Recent electrochemical studies at carbon supported core-shell nanostructures indicate

that CO tolerance is significantly affected by the Pd thickness [5]. In-situ FTIR studies show a

shift of the CO oxidation towards more negative potentials as the strain of the Pd layer is

relaxed. Clear trends are also observed on the current density for the oxidation of HCOOH.

Finally, we will also demonstrate that strain exerts a strong influence on the Faradaic

efficiency for CO2 reduction in solution as revealed by differential electrochemical mass

spectrometry. The ensemble of experimental data also allows interrogating key mechanistic

aspects of these reactions.

References

1. J.K. Norskov, et al. Nat. Chem.1 (2009) 37

2. P. Strasser, et al. Nat. Chem. 2 (2010) 454; E. Santos, et al. Electrochim.Acta 55 (2010)

4346

3. L.A. Kibler, et al. Angew. Chem., Int. Ed. Engl. 44 (2005) 2080; A. Bonnefont, et. al. Cat.

Today 202 (2013) 70

4. M.G. Montes de Oca, et al. J. Phys. Chem. C 115 (2011) 10489

5. V. Celorrio, et al. J. Phys. Chem. C 116 (2012) 6275

Keywords: Core-shell nanostrucrures, Au-Pd, electrocatalysis, lattice strain effects.


13

PL3

Nanostructures on screen printed electrodes as novel

transducers for sensors

Agustín Costa García

Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of

Oviedo, Av. Julián Clavería 8, 33006 Oviedo, Spain

Our society demands new analytical tools combining requirements as suitable design, low

cost, portability, accuracy, selectivity and easy-to-use character. Adaptability to small sample

volumes is also a need. Electrochemical sensors are nowdays the type of device that better

adapts to social demand.

Conventional electrodes based on gold, platinum or carbon, are frequently used as sensor

transducers in many research papers. However, they are not very likely to become a useful

tool for commercial sensors in the clinical diagnosis field, food science or environmental

monitoring, since the contact with the sample normally invalidates them for future uses.

Screen printing techniques are making possible the mass production of screen printed

electrodes made of a several materials (gold, platinum, carbon…) and the miniaturization of

full electrochemical cells like those shown in Figure 1. They allow the design of new sensors

for wide range of fields of application.

In this communication especial attention will be paid to the description of the formation of

nanostructured screen printed electrodes, by means of several carbon materials, gold

nanoparticles in-situ generated or nanohybrides (carbon nanotubes-gold, or graphene-gold).

The application to the sensor and biosensor design will be highlighted.

Figure 1. Screen printed electrode

Keywords: Electrochemical sensors, screen printed electrodes, nanostructures, nanomaterials.

Pseudo-reference electrode

Working

electrode

Counter electrode


14

KN1

Functionalization and stable self-assemble of nanoparticles on electrode

surfaces

Ana S. Viana

CQB, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de

Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal

Surface modification by sulfur-metal interaction, involving nanoparticles, has been employed

in many applications such as biosensors, commonly prepared through a multi-step procedure.

In the last years, we have explored a one-step methodology to efficiently modify gold

surfaces, both flat [1,2] and nanostructured [3], through the use of carbon disulfide and amine

containing compounds. Their ready reaction originates a dithiocarbamate group which can be

strongly attached to a gold surface, in a bidentate N-C-S2 resonance structure [4]. This simple

approach has been performed in both organic or aqueous medium and can be regarded as an

alternative procedure to the use of thiolated self-assembled monolayers, with terminal groups

suitable for (bio)molecules attachment.

This work illustrates several examples of functionalization and surface attachment of gold,

platinum, tin oxide and magnetic iron oxide nanoparticles, with different sizes and

synthesized by chemical or hydrothermal methods. The chemical modifications range from

the covalent assemble of small pH sensitive electroactive molecules or metalloporphyrins

with catalytic activity, to the attachment of aminoacids, protein A for the specific binding of

Immuglobulin G, and enzymes (e.g. Laccase and Glucose Oxidase) aiming the preparation of

simplified biosensing interfaces. The redox behaviour of the modified electrodes is followed

by cyclic voltammetry, including the monitoring of the biological activity of enzymes.

Atomic Force Microscopy is used for the characterization of the nanoparticles before and after

modification and assemblage to the electrode surface.

[1] I. Almeida, A. C. Cascalheira, A. S. Viana, Electrochimica Acta 55 (2010) 8686.

[2] Y. Niu, A. I. Matos, L. M. Abrantes, A. S. Viana, G. Jin, Langmuir 28 (2012) 17718.

[3] I. Almeida, V. C. Ferreira, M. F. Montemor, L.M. Abrantes, A. S. Viana,

Electrochim. Acta 83 (2012) 311.

[4] H. Zhu, D. M. Coleman, C. J. Dehen, I. M. Geisler, D. Zemlyanov, J. Chmielewski, G. J.

Simpson, A. Wei, Langmuir 24 (2008) 8660.

Acknowledgments

M. de Deus Carvalho and O. Monteiro are acknowledged for providing the iron oxide and tin

oxide nanoparticles. Funding was obtained from FCT: PTDC/QUI/66612/2006 and PEst-

OE/QUI/UI0612/2013.

Keywords: Chemical modification, nanoparticles, carbon disulfide, dithiocarbamate


15

KN2

Nanomaterial-based electrochemical sensors: the future trends for

analytical tools

Cristina Delerue-Matos

REQUIMTE, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua

Dr. Bernardino de Almeida 431, 4200-072 Porto, Portugal. *[email protected]; tel: +351

228340500; fax: +351 228321159.

Electrochemical transducers play an important role in analytical chemistry. A wide variety of

electrodes has been used as support to fabricate sensor devices, including carbon paste-,

glassy carbon- and gold electrodes. Known disadvantages of conventional electrodes such as

memory effects due to difficult, time-consuming and sometimes inefficient cleaning steps can

be overcome with the more recently developed screen-printed electrodes (SPEs). These SPEs

are good alternatives because their fabrication technology is well established which allows the

mass production of reproducible, inexpensive, customized and mechanically robust

electrodes. The modification of the (working) electrode's surface with nanomaterials increases

the performance of the sensors by providing a larger and more (bio-)compatible sensing

phase. Recent progress in the synthesis of nanomaterials and fundamental understanding of

their properties has led to significant advances in nanomaterial-based sensors. Examples of

nanomaterials used in the nanostructuration of electrode surfaces are carbon-based, such as

carbon nanotubes, carbon nanofibers, and graphene, gold and magnetic nanoparticles. This

nanostructuration leads to an increase of the produced electrochemical signal which

consequently results in a higher sensitivity and a lower detection limit. Moreover, there is a

continuous effort to miniaturize the instrumentation to operate and control the sensors which

facilitates in situ measurements. All these characteristics make nanomaterial-based

electrochemical sensors attractive tools for analytical chemistry, applying different

electrochemical techniques such as voltammetry, amperometry, potentiometry and

electrochemical impedance spectroscopy.

Therefore, electrochemical sensors have recently found extensive applications in

environmental, food, pharmaceutical, and clinical laboratories and also in commercial point-

of-care devices. The number of electrochemical sensors is ever increasing, being one of the

future trends for the development of analytical tools.

Keywords: nanomaterial; electrochemistry; sensor; analytical chemistry


16

KN3

“Smart” coatings for active corrosion protection based on multi-functional

micro and nanocontainers

Mikhail Zheludkevicha, Joao Tedim

a, Mario G.S. Ferreira

a

a Department of Materials and Ceramic Engineering, CICECO, University of Aveiro,

3810-193 Aveiro, Portugal

The application of organic coatings is the most common and cost effective method for

corrosion protection and extension of service life of many metallic structures in corrosive

environments. However, the degradation processes rapidly develop once the disruption of the

protective barrier occurs. Therefore, an active protection based on the “self-healing” of

defects in coatings is necessary to attain a long-term effect.

The present paper brings a brief summary of recent works in the area of new multi-level

protective systems, based on the controlled release of anticorrosion species from “smart”

micro and nanocontainers incorporated into a polymer or hybrid coating matrix.

Nanocontainer (or nanoreservoir) is a nanosized volume filled with an active substance

confined in a porous core and/or a shell which precludes the direct contact between the active

agent and the adjacent environment.

Several types of nanoreservoirs of corrosion inhibitors, nanotraps and microcapsules with

water displacers have been recently developed, incorporated into coating systems and

assessed in terms of active corrosion protection. A multi-level self-healing approach

combining several damage prevention and restoration mechanisms within the same system,

including the entrapment of corrosive ions, corrosion inhibition and water displacement from

active defects, is here reviewed.

Keywords: self-healing, coating, corrosion, nanocontainer, inhibitor.


17

KN4

Nanostructured modified electrodes and application

in sensors and biosensors

Madalina M. Barsan, Krishna P. Prathish, Christopher M.A. Brett

Departamento de Química, Faculdade de Ciências e Tecnologia,

Universidade de Coimbra, 3004-535 Coimbra, Portugal

[email protected]

The use of carbon-based nanomaterials for electrode surface modification can lead to

promising substrates for construction of new, improved electrochemical sensors and

biosensors in which the nanostructure plays an important role. Among carbon-based

nanomaterials, graphene is an attractive material due to its excellent conductivity, feasibility

for microfabrication, high surface area, mechanical strength, optical transparency and

biocompatibility [1]. Pure graphene is a zero band gap semiconductor and chemically inert, so

that functionalization is required for its application as electrode material [2].

Functionalised graphene (G) and nitrogen doped graphene (NG) nanomaterials are excellent

candidates for electrocatalytic sensing of biomolecules and for developing biosensors, due to

their unique physicochemical and electronic properties [3]. The effect of G and NG

functionalization with acid (HNO3) or with base (KOH), on the electrochemical properties of

the modified electrodes will be shown.

Materials based on NG with the conducting polymer poly(3,4-ethylenedioxythiophene)

(PEDOT) and the redox polymer poly(neutral red) (PNR) were also synthesized and their

electrochemical features will be described.

Electrocatalysis towards important cofactors present in oxidase and dehydrogenase based

enzymes, β-nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide

(FAD+) will also be discussed, the regeneration of which is the crucial step during enzyme

reactions, and thence in biosensor performance. Applications in sensing and biosensing will

be presented.

[1]. L. Rodríguez-Pérez, M. A. Herranza, N. Martín, Chem. Commun., 49 (2013) 3721.

[2]. R. Lv, M. Terrones, Mater. Lett., 78 (2012) 209.

[3]. D. Genga, S. Yanga, Y. Zhanga, J. Yanga, J. Liua, R. Li, T. Sham, X. Sun, S. Ye, S.

Knights, Appl. Surf. Sci. 257 (2011) 9193.

Keywords: carbon nanomaterials, graphene, electrocatalysis.


18

KN5

Electrocatalysts based on carbon nanotubes: application to

wastewater treatments

M.F. Pintoa, M. Ferreira

a, I.C. Neves

a, , A.M. Fonseca

a, L. Peixoto

b, A.G. Brito

b, R.

Nogueirab, O.S.G.P. Soares

c, J.J.M. Órfão

c, M.F.R. Pereira

c, J.L. Figueiredo

c and P. Parpot

a

aDepartamento de Química, Centro de Química, Universidade do Minho, Campus Gualtar,

4710-057, Braga Portugal. bIBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering,

University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal cLaboratório de Catálise e Materiais (LCM), Laboratório Associado LSRE/LCM,

Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto,

Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

The increasing awareness of water pollution with organic compounds, such as dyes, and their

long term effects has encouraged intensive efforts towards pollution abatement.

Electrochemical oxidation may constitute an alternative route to the existing methods.

Electricity may substitute some toxic redox agents and may permit the oxidation of pollutants

in mild conditions i.e. ambient temperature and atmospheric pressure. In recent years there

has been increasing interest in multiwalled carbon nanotubes (CNTs) as heterogeneous

catalyst supports [1] owing to their high surface area and high electrical conductivity. These

peculiar characteristics qualify CNTs as adequate electrocatalysts or as catalyst support

materials for the oxidative degradation of organic pollutants in wastewater [2]. In this context

the electrochemical oxidation of some refractory compounds like oxalic and oxamic acids,

some organic dyes and pesticides was investigated on mono and bi-metallic catalysts

supported on multiwalled carbon nanotubes (CNT) aiming at the total transformation of these

compounds into carbon dioxide and water. The electrochemical performance of metallic

electrocatalysts for nitrate reduction in wastewater was also evaluated having in mind a paired

electrolytic process. The electroreactivity of the pollutants on selected electrocatalysts was

studied by cyclic voltammetry. Kinetic parameters of the reactions were also determined

using this last technique. Exhaustive electrolyses were carried out to determine the

mineralization rates and the product distribution. Finally the use of CNT and metal modified

CNT as support material for anodic biofilm in microbial fuel cells was studied.

Acknowledgements: Support for this work was provided by projects NANO/NTec-

CA/0122/2007 and F-COMP-01-0124-FEDER-022716 financed by Fundação para a Ciência

e a Tecnologia (FCT), Portugal and FEDER, in the context of Programme COMPETE

[1] P. Serp, M. Corrias, P. Kalck, Appl. Catal. A, 253 (2003) 337-358.

[2] M. Ferreira, M.F. Pinto, O.S.G.P. Soares, M.F.R. Pereira, J.J.M. Órfão, J.L. Figueiredo,

I.C. Neves, A.M. Fonseca, P. Parpot, Electrochim. Acta, 60 (2012) 278-286.

Keywords: carbon nanotubes, wastewater treatment, organic pollutant oxidation, nitrate

reduction.


19

OC1

Platinum-free electrocatalysts for oxygen reduction

Katarzyna Eblagon, Lúcia Brandão

LEPAE, Faculdade de Engenharia da Universidade do Porto, R. Dr. Roberto Frias, 4200-

465 Porto

The development of cheaper electrocatalysts for oxygen reduction reaction (ORR) and a

cathode more tolerant to methanol are very important for the development and

commercialization of direct methanol fuel cells.

In this work, ruthenium catalysts modified with selenium were prepared and

characterized. Two catalyst preparation methods were studied: reduction of the metal salt with

NaBH4 solution and reduction of the impregnated metal precursor with H2. The metal based

catalysts were modified with SeO2, using two methods: 1- pre-formed metal/carbon catalysts

were re-dispersed in xylene and SeO2 was added to the solution under reflux; and 2- the metal

precursor salt and SeO2 was co-impregnated on carbon black in a water/ethanol mixture and

reduced at 90 ° C using NaBH4. The catalysts were characterized using SEM with EDAX,

XRD, HRTEM and TG.

Results have shown that samples reduced with NaBH4 have smaller particle size and

narrower distribution of sizes. EDAX analysis of ruthenium co-precipitated with selenium

samples indicated that selenium was selectively reduced in the close proximity of ruthenium,

maybe even on the ruthenium surface. No regions with signals only from selenium were

found. XRD results show that a pure crystalline phase of hcp lattice of RuSe2 (pyrite) was not

obtained even at high annealing temperatures. Therefore it is assumed that the existing

modification is an amorphous skin of selenium on the surface of ruthenium nanoparticles.

Catalytic active layers based on different RuSe catalysts were spray dried on a

commercial gas diffusion layer. 1 cm2 electrodes were immersed in a 1.0 M H2SO4 oxygen

saturated aqueous solution and tested at room temperature, using a Ag/AgCl reference

electrode and a Dimensional Stable Anode (DSA, composed by RuO2, IrO2 and TiO2) as

counter electrode. Linear sweep voltammetry scans were performed at 2 mV s-1

from OCV up

to 0.0 V - 0.3 V vs RHE. ORR activity for different samples will be addressed and its

performance evaluated in terms of preparation method, post-annealing conditions and metal

dispersion. ORR activity of the different electrodes will be compared with activity from a

commercial electrode.

Acknowledgements:

L. Brandão is grateful to FCT for the post-doc grant (SFRH/BPD/41233/2007). The authors

acknowledge financial support through the project PTDC/CTM/108454/2008.

Keywords: oxygen reduction reaction, platinum-free electrocatalysts, chalcoge


20

OC2

Noble-metal nanoparticles modified electrodes - electrochemical and

catalytic properties

V.C. Ferreira, A.I.Melato, L.M.Abrantes

CQB, Chemistry and Biochemistry Department, Science Faculty of the University of Lisbon,

Campo Grande, 1749-016 Lisbon, Portugal

It is widely recognized that the electrochemical behaviour of electrodes can strongly

depend on its dimensions. In the past micro- and ultra-micro electrodes have shown that

problems associated namely with diffusion can be overcome and improved properties

achieved. Particles in the nanometer scale also display properties that are different from bulk

materials [1,2]. The enhancement of mass transport, signal-to-noise ratio, high effective

surface area and control over the electrode microenvironment makes them attractive for

electrochemists. When immobilized, e.g. on indium tin oxide or conducting polymers (CPs),

advantages can be taken from the electrocatalytic properties of NPs.

The surface structure, size and crystallographic orientation of the NPs and the

presence of adsorbed species play an important role on the electrochemical response of such

materials [3]. In fact, in this work it is shown that the electrochemical behaviour can be tuned

by using surfaces with distinct crystallographic orientation and/or size, by selectively

block/exposure specific surface domains within a surface.

The conducting polymers offer a suitable matrix for the immobilisation of NPs, either

by electrodeposition, electroless precipitation or by simple immersion in colloidal suspensions

[4,6]. In the last case advantage is frequently taken from the interactions between the polymer

functional groups and the particles, often of noble metals such as gold, platinum, palladium

and silver. In the particular case of thiophene and its derivatives, the presence of sulphur

atoms in the polymer structure enables specific and stable interactions through sulphur-metal

bonding. The electrocatalytic activity of CPs-NPs modified electrodes can be highly improved

as compared with pristine polymers and bulk electrodes.

Keywords: Noble-metal nanoparticles, crystallographic orientation, conducting polymers,

electrocatalytic activity.

Acknowledgments

The financial support from Fundação para a Ciência e Tecnologia, SFRH/BPD/69526/2010

and SFRH/BPD/77404/2011 is gratefully acknowledged.

References

[

1] M.-C. Daniel, D. Astruc. Chem. Rev. 104 (2004) 293.

[2] C.M. Welch, R.G. Compton, Anal. Bioanal. Chem. 384 (2006) 601.

[3] V.C. Ferreira, J. Solla-Gullón, A. Aldaz, F. Silva, L.M. Abrantes, Electrochim. Acta 56 (2011)

9568. [

4] A. Mourato, S. M. Wong, H. Siegenthaler, L. M. Abrantes , J. Solid State Electrochem. 10 (2006)

140.

[5] V.C. Ferreira, A.I. Melato, A.F. Silva, L.M. Abrantes, Electrochem. Comm. 13 (2011) 993.

[6] V.C. Ferreira, A.I. Melato, A.F. Silva, L.M. Abrantes, Electrochim. Acta 56 (2011) 3567.


21

OC3

Deconvolution of cytochrome c nitrite reductase electrochemistry using

MWCNTs with different surface chemistries

Célia M. Silveira

a, Marta Pimpão

a, Humberto A. Pedroso

a, Patrícia R.S. Rodrigues

a, José J.G.

Mouraa, Manuel F.R. Pereira

b, M. Gabriela Almeida

a,c

a REQUIMTE – Departamento de Química, CQFB, Faculdade de Ciências e Tecnologia,

Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. bLCM – Laboratório de Catálise e Materiais, Laboratório Associado LSRE/LCM,

Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R.

Dr. Roberto Frias, 4200-465 Porto, Portugal c Instituto Superior de Saúde Egas Moniz, Monte de Caparica, 2829-511 Caparica, Portugal

Carbon nanotubes (CNTs) are among the most used nanostructured materials in the field of

(bio)electrochemistry. They have demonstrated remarkable behavior in electroche-mical

studies as electrocatalysts and in facilitating protein direct electrochemistry. This has

contributed for CNTs successful use in electrochemical sensors and biosensors [1]. The

surface functionalization of the CNTs is frequently employed to improve their

biocompatibility and electroactivity. The most common method is chemical oxidation using

strong acids, which is usually associated with the introduction of reactive oxide functional

groups [2]. Typically, higher currents, lower overpotentials and enhanced electron transfer

rates are observed with the modified materials [3].

This work reports the use of multi-walled carbon nanotubes (MWCNTs) presenting different

surface chemistries as electrode modifiers for the direct electrochemistry of the multihemic

nitrite reductase (ccNiR) from Desulfovibrio desulfuricans ATCC 27774. The carbon

nanotubes dispersions were prepared in aqueous media and deposited on pyrolytic graphite

(PG) electrodes, following a layer-by-layer methodology; the resulting randomly entangled

MWCNTs bed was coated with a ccNiR film. The electrocatalytic properties of each material

were then assessed by cyclic voltammetry, either in the presence or absence of ccNiR’s

substrate. A comparison between the different oxidized MWCNTs indicated that the

combination of higher surface area, low oxygen content and less acidic functional groups

favored enzyme catalysis, highlighting the importance of surface conditions to enzyme

reactivity. Results also suggest that the CNTs containing less oxygen functionalities could

better plug into the active site of ccNiR. These nanotubes are a promising material for the

deconvolution of the complex electrochemical signals of the multihemic enzyme, allowing the

isolation of the catalytic centre response.

References:

[1] J. Wang (2005) Electroanalysis 17, 7.

[2] R.L. McCreery (2008) Chem. Rev. 108, 2646.

[3] J.J. Davis, K.S. Coleman, B.R. Azamian, C.B. Bagshaw, M.L. Green (2003) Chem. Eur. J.

9, 3732.

Keywords: multi-walled carbon nanotubes, surface oxides, direct electron transfer, nitrite

reductase.


22

OC4

Hydrothermal synthesis of nanoparticles of WO3 and its application in

electrochromic inkjet printed thin films

Lídia Santos, P. Wojcik, L. Pereira, R. Martins, E. Fortunato

CENIMAT/I3N, Departamento de Ciência de Materiais, Faculdade de Ciências e Tecnologia,

Universidade Nova de Lisboa and CEMOP/UNINOVA, Campus da Caparica, 2829-516

Caparica – Portugal

Tel. +351 212948562, Fax. +351 212948558

E-mail: [email protected], [email protected]

Although, tungsten oxide has been widely reported as a promising inorganic electrochromic

material not many studies have been made that describe the influence of shape and

nanoparticles crystallinity on the EC performance. By controlling these factors, one could

design a material with optimal EC behavior.

In this work WOx nanoparticles with different characteristics were obtained by hydrothermal

synthesis of sol-gel precursor (peroxotungstic acid) using metallic tungsten as the starting

material. It was observed that the amount of hydrochloric acid and time of the process were

the critical parameters in a synthesis of monoclinic WO3 nanoslabs and/or orthorhombic

WO3.0.33H2O nanorods.

The resulting nanocrystals were dispersed in aqueous alcoholic solution and then inkjet

printed on ITO coated flexible PET substrates. Subsequently, the sol-gel precursor was also

printed to cover the nanostructures previously deposited. This innovative approach enables to

deposit dual-phase a-WO3/WOx thin films in a low temperature two-step process, which

irrespective to nanoparticles characteristics outperform their amorphous analogues, owing to

their superior electrochemical properties. Nevertheless, dual-phase films with orthorhombic

WO3.0.33H2O nanorods presented a superior electrochromic performance which can be

explained by the higher active surface area (38 m2/g) combined with the coordinated water

molecules from this polymorph.

Keywords: Tungsten oxide, printing deposition, electrochromic, thin film.

mailto:[email protected]


23

P1

Corrosion resistance of single wall carbon nanohorns as electrocatalyst

support

Lúcia Brandão

LEPAE, Faculdade de Engenharia da Universidade do Porto, R. Dr. Roberto Frias, 4200-

465 Porto

The corrosion resistance of carbon based electrocatalyst supports in PEMFC is one of the

most important aspects besides electrode activity, and mainly at the cathode side.

Single wall carbon nanohorns (SWNH) are similar to carbon nanotubes presenting a

conic tip instead of the half fullerene cap at the top of the carbon tube; moreover they are

much cheaper to produce [1].

Previous works, developed at LEPAE, on the use of SWNH as electrocatalyst support

in fuel cells, have shown an increased performance of the SWNH based electrodes in

comparison with a carbon black support based electrode. A 60 % increase in performance was

observed for both PEMFC and DMFC at 50 ºC [1, 2]. In-situ EIS analysis indicated that the

major improvement in PEMFC performance was related to the cathode kinetics in the SWNH

sample [2]. In accordance, ex-situ linear sweep voltammograms for oxygen reduction

indicated that SWNH based electrode performs better than the carbon black one for voltages

lower than 0.65 V vs RHE [3]. Regarding methanol oxidation, ex-situ cyclic voltammetry

experiments have also indicated a higher electrochemical activity towards methanol electro-

oxidation and a higher tolerance to carbonaceous species accumulation for the SWNH based

electrode [3].

At high temperature fuel cell operation, 160 ºC, SWNH based electrodes showed a

similar peak power density to the carbon black based one despite the higher ohmic resistance.

Moreover, the SWNH based anode presented a lower charge transfer resistance than the

correspondent carbon black but similar cathode charge transfer resistance [4]. More recently,

experiments in vapour phase DMFC, at 160 ºC, also showed the improved performance of the

SWNH electrode besides presenting longer fuel cell stability during operation [3].

In this work, the corrosion resistance of SWNH and carbon black supporting Pt

electrocatalysts is addressed. An accelerated corrosion test, at 1.5 V vs NHE, was applied to

electrodes based on both the carbon supports. The corrosion extension history of each

electrode, at room temperature, was followed by electrochemical surface area measurements.

A commercial Pt electrode was also evaluated for comparison purposes.

Acknowledgements:

L. Brandão is grateful to FCT for the post-doc grant (SFRH/BPD/41233/2007) and for

financial support through the project PTDC/CTM/108454/2008.

References:

[1]- J. Mat. Sci., 46, 2011, 7198–7205; [2]- J. Nanosci. Nanotech, 11, 2011, 9016-9024; [3]-

Inter. J. Hydrogen Energy, 2012, 37 (24), 19073-19081; [4]- J. Electrochem. Soc, 158 (4),

2011, B394-B401.

Keywords: SWNH, fuel cells, carbon support, corrosion resistance.


24

P2

Development of 3D Dendritic Ni−Co Films: electrodeposition parameters

and heat treatment effect

R.P. Silvaa, . ug nio

a, T. M. Silva

a,b, M.J. Carmezim

a, c, M. F. Montemor

a,d

a

bDepartamento de Engenharia Mecânica, Instituto Superior de Engenharia de Lisboa,

Portugal c

Portugal d

Lisboa, Portugal.

Electrodeposition is a widespread technique for the production of both decorative and

functional coatings that by controlling the process parameters (applied current/potential and

deposition time) and electrolyte composition enables the fabrication of films with tailored

morphology and chemical composition.

Electrodeposition is therefore a simple, low-cost technique for the production of

nanostructured transition metal films with tridimensional architectures. These materials have

gathered increasing interest due to their applications in catalysis, energy storage and

conversion, etc. where a high specific area is a key characteristic.

In this work, co-deposition of nickel and cobalt was carried out on austenitic stainless steel

(AISI 304) substrates by imposing a square waveform current in the cathodic region. The

influence of the applied current density on the morphology and chemical composition of the

Ni−Co films was investigated by scanning electron microscopy and energy dispersive X-ray

spectroscopy and X-ray diffraction. By applying optimised deposition conditions, a stable,

fully developed, and open porous three-dimensional (3D) dendritic structure was obtained.

The electrochemical behaviour of the materials was evaluated by cyclic voltammetry and

chronopotentiometry in order to assess their application as electrodes for supercapacitors.

Selected Ni-Co films were oxidized by heat treatment at temperatures between 150 and 900

C. The influence of the temperature in the phase composition and electrochemical behaviour

of the Ni-Co films was studied.

Keywords: electrodeposition; Ni-Co alloys; dendritic structure; energy storage


25

P3

Determination of plant-toxicity inductors metals at a rotating-disc bismuth

film electrode by anodic stripping voltammetry

Ana. I. Matosa, M. M. Rocha

a, M. M. M. Neto

a, L. L. Martins

b, M. P. Mourato

b

aCentro de Ciências Moleculares e Materiais, Faculdade de Ciências, Universidade de

Lisboa, Edifício C8, Campo Grande, 1749-016 Lisboa, Portugal

Telefone: +351 21 750 0000, Fax: +351 21 750 0088, Email: [email protected] bUnidade de Investigação Química Ambiental - UIQA, Instituto Superior de Agronomia,

Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal

Telefone: +351 21 365 3426, Fax: +351 21 365 3195, Email: [email protected]

In the last decades, the growing concern with contamination of aquatic and soil life by

toxic metals as copper, cadmium, mercury and others, and their potential damaging effect on

human health, promote the development of precise and accurate analytical methods.

Stripping techniques have demonstrated to be suitable approaches to determine trace

metals in environmental samples due to their high sensitivity, excellent detection limits,

capacity to multielement determination and low cost [1,2]. Bismuth film electrodes (BiFE)

appeared as an attractive option to replace mercury electrodes. Despite similar

electrochemical characteristics in terms of potential window and ability to electrodeposit

other substances on its surface, bismuth offers others advantages as an electrode material

including low toxicity, well defined and undistorted stripping signal, excellent resolution,

good stability under hydrodynamic conditions and is less sensitive to oxygen interference than

mercury electrodes [1-3].

The purpose of this work is the simultaneous speciation of heavy metals in samples of

plant extracts, exploring the potentialities of a rotating-disc bismuth film electrode. An in situ

plated bismuth film electrode was applied for Cd and Cu determination, in acetate buffer

solution (pH 4.6), by square wave anodic stripping voltammetry (SWASV); it was

successfully used to obtain calibration curves, enabling the simultaneous determination of Cd

and Cu, reoxidized at potentials values more negative and more positive than Bi(III)

reoxidation potential, respectively. Finally, this method allowed the speciation of Cu and Cd

at low concentration levels in samples of plant nitric extracts.

Keywords: Bismuth electrodes, stripping voltammetry, speciation of heavy metals.

Acknowledgements: The authors acknowledge FCT for the financial support: PTDC/AGR-

AAM/102821/2008.

References

[1] G. M. S. Alves, J. M. C. S. Magalhães, H. M. V. M. Soares, Electroanalysis 23 (2011)

1410.

[2] E. O. Jorge, M. M. Rocha, I. T. E. Fonseca, M. M. M. Neto, Talanta 81 (2010) 556.

[3] I. Cesarino, C. Gouveia-Caridade, R. Pauliukaitè, E. T. G. Cavalheiro, C. M. A. Brett,

Electroanalysis 22 (2010) 1437.


26

P4

Evaluation of radical scavenging activity of antioxidants by means of

electrogenerated HO radical

Raquel Oliveira, Dulce Geraldo, Fátima Bento

Departamento de Química da Universidade do Minho, Campus de Gualtar, 4710-057 Braga

Hydroxyl radical is one of the most reactive radicals. The electrochemical generation of

hydroxyl radical by oxidation of water can be achieved using different anode materials. The

adsorption of HO radicals at the anode surface has a significant effect on their reactivity.

Using materials such as BDD, electrogenerated hydroxyl radicals are weekly adsorbed

whereas strongly adsorbed radicals are formed at Pt.

Although most of the available studies deal with high oxidation power anodes for the

degradation of pollutants, the use of anodes with low oxidation power can have important

applications particularly when a certain degree of selectivity is required for oxidation.

In this context electrochemically-generated hydroxyl radical was applied for the evaluation of

antioxidant scavenging activity. A set of species with antioxidant activity was oxidized by

galvanostatic electrolyses using a fairly oxidized Pt anode in conditions of O2 evolution. In

such conditions the consumption of species was not limited by mass transport but by the

oxidation kinetics of both charge transfer and reaction with HO radicals. Information

regarding the rate constant of the reaction of antioxidants with electrogenerated HO radicals

was obtained by means of the apparent rate constant variation with electrolysis current

density. Scavenger activity of the analysed antioxidants estimated by the kinetic parameter

2/, OHOR kk was ordered as follows: gallic acid, trolox > ascorbic acid > caffeic acid. The

method was applied successfully in synthetic solutions and in a green tea based beverage.

Keywords: Antioxidants, scavenging activity, HO radical generation, ascorbic acid, phenolic

compounds


27

P5

Screen Printed Electrodes Modified with Carboxylated Multiwall Carbon

Nanotubes for the Analysis of Hydroquinone and Ascorbic Acid

Rui Gusmãoa,b

, Marta Fortesa, Raquel Oliveira

a, Dulce Geraldo

a, Fátima Bento

a, Fernanda

Proençaa, Conceição Paiva

b

aCentro de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal

bInstituto de Polímeros e Compósitos/I3N, Universidade do Minho, Campus de Azurem, 4800-

058 Guimarães, Portugal

Carbon nanotubes (CNT) have demonstrated to be advantageous in electrochemical

applications such as in energy storage devices and sensors. The presence of oxygenated

carbon species, especially carboxylic acid moieties, together with metallic impurities are

identified as chief factors for the catalytic properties of CNTs. The oxygen-containing groups

are introduced randomly at the surface of CNTs by strong mineral acid treatment. These

factors can be of extreme importance for the construction of biosensors based on carbon

nanomaterials.

In this study, multiwalled carbon nanotubes (MWCNTs) were chemically shortened and

carboxylated by treatment with nitric acid for metal impurities removalusing a method

described in the literature, originating MWCNT-COOH. Ethanol suspensions of MWCNT-

COOH at different concentrations were used to modify the surfaces of commercially available

screen-printed electrodes (SPEs).

The SPEs modification with MWCNT-COOH was optimised and it was applied in order to

obtain a reproducible electrochemical response. The morphology of the MWCNT-COOH

modified SPEs was characterized by Scanning Electron Microscopy. Characterization of the

CNT film generated on the surface of the working electrode and stability studies were carried

out with potassium hexacyanoferrate. Results are compared with those obtained for

commercially available carbon SPE and SPE-MWCNT.

Effect of solution acidity on the peak current and potential of the substances was studied at

pH 3 and 7 where a correlation with the dissociation degree of carboxyl groups at the

MWCNTs on the electrode surface occurs.

The catalytic properties of the MWCNT-COOH-modified SPEs as well as their analytical

advantages as voltammetric detectors are discussed through the analysis of ascorbic acid (AA)

and hydroquinone (HQ).

Keywords: Carboxylated Multi-Wall Carbon Nanotubes, Hydroquinone, Ascorbic Acid,

Potassium Hexacyanoferrate, Screen Printed Electrode.


28

P6

Degradation of alizarin red promoted by electrogenerated HO radicals: A

kinetic study

Fátima Bento, Ângela Vilas Boas, Raquel Oliveira, Dulce Geraldo

Departamento de Química da Universidade do Minho, Campus de Gualtar, 4710-057 Braga

Alizarin Red (AR, 1,2-dihydroxyanthraquinone) is a dye used in textile industry since early

antiquity. Nowadays it is used in several biochemical assays in studies involving bone

growth, osteoporosis, bone marrow, calcium deposits, cellular signaling, gene expression,

tissue engineering, and mesenchymal stem cells.

Reactions of electrochemically generated hydroxyl radicals, by the oxidation of water, depend

on the reactivity of these radicals according to their adsorption degree at the anode surface. At

Pt HO radicals keep strongly adsorbed and display lower reactivity than those formed in

anodes like BDD. This effect as been already demonstrated by means of a kinetic study of

benzoic acid and p-hydroxybenzoic acid oxidation.

The study of the AR oxidation by HO radicals can bring important insight on the reactivity of

chemical functions such as aromatic rings, hydroxyl and carbonyl groups, that are common in

antioxidant molecules. Therefore, using a single molecule it is possible to investigate the

relative reactivity of these functional groups towards HO radical in identical conditions of

surface coverage, what cannot be warranted when the different molecules are considered.

The AR UV–Vis absorption spectrum displays three distinct peaks corresponding to the

anthracene ring, the carbonyl groups and quinonyl. Therefore by means of the absorbance

variation of the three UV-vis bands it was possible to evaluate the reactivity of the different

functional groups.

Keywords: Alizarin red, hydroxyl radicals, platinum, dye removal


29

P7

A new approach to domoic acid detection

Dulce Geraldoa, Raquel Oliveira

a, Fátima Bento

a, Javier Gonzalez-Costas

b, Elisa Gonzalez-

Romerob

a Departamento de Química da Universidade do Minho, Campus de Gualtar, 4710-057 Braga

b Universidad de Vigo, Vigo, Spain

The standard method for detection of marine toxins in bivalve is based on a mouse bioassay

that presents several disadvantages such as its cost, non-specificity, time analysis and of

course etic constraints. On the other hand regulation has been modified by the European

Commission 15/2011 on January 10th, 2011, replacing Regulation (EC) No 2074/2005 and

mouse bioassay will be banned from December 31, 2014. The development of new methods

for a rapid screening for detection of toxins is highly needed. Electrochemical sensors are

adequate for the development of user-friendly analytical methods that could therefore be used

in a daily base by fisherman.

In this work, we present a new strategy for the detection of domoic acid (amnesic toxin) based

on the functionalization of carbon screen printed electrodes (SPE) and SPE modified with

carbon nanotubes (CNTs). The functionalization is based in the immobilization of diazonium

ion generated by the 4-nitroaniline diazotization with sodium nitrite in hydrochloridric acid.

Although DA is not electroactive, it can be detected by means of a redox probe K4(FeCN)6,

which electrochemical response depends on the concentration of DA immobilized on a

functionalized SPE. Preliminary work has shown the possibility to carry out the

immobilization without the use of bifunctional agents, such as carbodiimides, n-

hydroxysuccinimide, that facilitates the bond between -NH2 and -COOH groups simplifying

the design of the sensor. Experimental variables such as pH, temperature and time were

optimized. Peak potential shift and enhancement of current intensity were analyzed.

Keywords: Domoic acid, toxins, carbon screen printed electrodes, SPE modified with carbon

nanotubes


30

P8

Direct Methanol Micro Fuel Cell: Fabrication Process Using Microsystems

Technologies

C.A. Faria, R Sousa, L.M. Goncalves

Algoritmi Centre, University of Minho, Guimarães, Portugal

In our days fuel cells are considered the next step for energy due to its efficiency and low

environmental impact. The electronic devices tend to decrease its size, perform more

functions, and provide more power in a smaller space. We get to a point where we need to

supply system with high power density, efficiency and low weight. It is in this context that the

fuel cell can be used. But to apply the fuel cells in electronics, transport systems and in other

applications, it is necessary that the price of this technology becomes significantly lower.

In this work we analyze the possibility of producing the fuel cell with the manufacturing

techniques used in micro fabrication and having as main raw material silicon, for being one of

the most abundant and cheaper. The possibility of being able to use silicon for fabrication of

fuel cells, will allow to place a unit power generation inside of electronic circuits and produce

smaller fuel cell modules.

A micro direct methanol fuel cell was fabricated without membrane using the silicon substrate

as the anode and cathode, applying the M M manufacturing techniques. Using a 2” wafer as

substrate, channels were fabricated by dicing. On these channels, 200nm of gold was

deposited by thermal evaporation, to create the collector contacts (a prior deposited thin layer

of titanium promotes adhesion of gold film). Cathode and anode thin-film of platinum were

deposited by e-beam, and a a thin-film of ruthenium covers the anode. After manufacture the

components, we proceeded to assembly and testing of the respective micro fuel cell. This fuel

cell is under testing. We concluded that it is possible to construct fuel cells using silicon in a

dicing process and thin-film technology.

Keywords: Fuel-Cell, DMFC, Microsystem, Energy, MEM


31

P9

Trace metal interactions with CdTe/CdS quantum dots: an

electrochemical study

José Paulo Pinheiro*,a, Cristiana Franco

b, Rute F. Domingos

b

a IBB/CBME, DQF/FCT, Universidade do Algarve, Faro, Portugal

b CQE, Instituto Superior Técnico/Universidade Técnica de Lisboa, Lisboa, Portugal

The work presented here is part of a larger project to evaluate the environmental risk of

several nanoparticles (e.g. ZnO, CdTe/CdS) towards exposure to Chlamydomonas reinhardtii.

Special emphasis is placed on quantitatively determining the role of the medium properties,

including pH, interactions with inorganic ligands and NOM on the dissolution/aggregation

behavior of the nanoparticles.

Polyacrilic acid stabilized CdS-capped CdTe quantum dots were studied. The stock solution

contains a total cadmium concentration of 0.0257 + 0.0005M, and the particle size (AFM) is

5.7±0.4 nm.

The aim of this particular study was to understand the interaction of the stabilizer (PAA) with

the cadmium ions either originated from the QD dissolution or added to the solution. The free

and bound cadmium concentrations in solution were determined by Scanned Stripping

Chronopotentiometry (SSCP) and Absence of Gradients and Nernstian Equilibrium Stripping

(AGNES),

In the first set of experiments we evaluated the effect of pH in the stability of the QD. Studies

were performed at pH 4.5, 6.0 and 8.5 in buffered medium, 10 mM ionic strength, 48h

exposure, for a NP concentration equivalent to 1.0 M of Cd.

The highest QD dissolution (i.e., percentage of Cd dissolved from the QD related to the total

Cd in the QD) was obtained at the more acidic pH (52 %). Dissolution of the QD was higher

at pH 8.5 than at pH 6.0 (24 vs. 4 %), which is the result of the increasing PAA ability to

complex the dissolved Cd leading to a further QD solubility until the equilibrium is reached.

At pH 8.5 we also observed a significant contribution of the PAA (carboxyl groups) to the

dissolved cadmium binding while below pH 6.0 that influence was negligible.

Keywords: Quantum dots, SSCP, AGNES, metal speciation, PAA


32

P10

Electrochemical biosensing platform using self-assembled multivalent

nanoparticles

Rui Carvalhoa, Elwin Vrouwe

b, J.P. Pinheiro

c, A. Velders

d

a,b

Micronit Microfluidics, Enschede, The Netherlands cUALG, CBME, Algarve, Portugal

dWUR, Wageningen, The Netherlands

Herein we report the manufacture of a novel nanoparticle based sensor to measure blood

clotting with commercial applications.

Nanoparticles are becoming extremely useful building blocks for the fabrication of

ultrasensitive optical and electrochemical nanosensors. Among these applications, the use of

Au nanoparticles as colorimetric sensors is gaining much attention owing to the possibility of

attaining high sensitivity with unsophisticated transducers. A common strategy for

biodetection with Au nanoparticles is to modify their surface with bioresponsive ligands,

which trigger the assembly or disassembly of the nanoparticles upon recognition by the target

biomolecule, for example, an enzyme.[1]

The key step of this method is to bind the bioresponsive ligands to the surface of the

nanoparticles through weak host–guest interactions; stronger multivalent interactions between

nanoparticles then lead to the formation of nanoparticle clusters. Recognition by the effector

biomolecule disrupts the multivalent network, and competition with a monovalent guest

amplifies the dispersion of the nanoparticles as the signal of the bioassay. Using linker

libraries in conjunction with multivalent β-cyclodextrin decorated gold nanoparticles will

provide with a novel sensing method for detecting relevant enzymes. Immobilization of these

aggregates in microfluidic channels, a portable enzyme sensor will be produced. By using

electrochemical techniques we can increase the sensing complexity and accuracy of the chip.

1. de la Rica, R., et al., Multivalent Nanoparticle Networks as Ultrasensitive Enzyme Sensors. Angewandte Chemie-International Edition, 2011. 50(25): p. 5703-5706.

Keywords: biosensor, nanoparticles, microfluidics, aggregation, surface plasmon resonance,

impedance, competition assay


33

P11

Glassy carbon modified electrodes for comparison of wine

antioxidant properties

Natália Dionísio, Cristina Oliveira

Departamento de Química/CQ-VR, Universidade de Trás-os-Montes e Alto Douro (UTAD),

Portugal

The ability of voltammetric techniques to evaluate the antioxidant capacity of the food

samples is well documented in the literature [1,2]. However, it was recently demonstrated that

despite the advantages of voltammetric techniques to evaluate the antioxidant capacity of food

samples, these were unable to distinguish wines containing low antioxidant capacity (e.g.

white, muscatel and tawny wines) [3].

This work reports preliminary experimental findings to improve the sensitivity of the cyclic

voltammetric technique for antioxidant determination of wines containing low concentration

of polyphenols. To achieve this purpose glassy carbon modified electrodes with carbon

Vulcan® (GCE/Vulcan®) and Ag nanoparticles supported on the carbon Vulcan

(GCE/Ag/Vulcan®) have been used. The method has been developed using gallic acid (GA)

as a phenolic acid model compound in acetate-acetic acid buffer (pH 4) and phosphate buffer

(pH 7), Figure 1. The results indicate that the electrochemical response of GA is improved

significantly at (GCE/Ag/Vulcan®) electrode compared with the unmodified electrode or even

(GCE/Vulcan®), in phosphate buffer. In acetate-acetic buffer it was demonstrated that the

sensitivity can duplicate on (GCE/Vulcan®) compared to the unmodified electrode. The new

modified electrodes were also tested on two white wines and one moscatel. It was found that

it is on (GCE/Vulcan®) and in phosphate buffer that wines differ most from each other.

Figure 1 – Cyclic voltammograms of

a glass carbon electrode (GCE) and

modified GCEs in 0.1 mM gallic acid

in phosphate buffer solution.

References

[1]- P. Kilmartin, H Zou, A Waterhouse, J. Agric. Food Chemistry, 49 (2001) 1957–1965.

[2]-, M. Aguirre, Y. Chen, M. Isaacs, B. Matsuhiro, L. Mendoza, S. Torres, Food Chemistry

121 (2010) 44–48.

[3]- M.J. Rebelo, R. Rego, M. Ferreira, M.C. Oliveira, Food Chemistry 141 (2013) 566–573.

Keywords: Polyphenols, gallic acid, antioxidant capacity, modified electrode, nanoparticles.

__ __ __ __ (GCE)

- - - - - - (GCE/Vulcan®)

___________ (GCE/Ag/Vulcan®)


34

P12

Modified electrodes for electrocatalysis: electropolimerisation based on

binuclear metal complexes

Sara Realista, Paulo Nuno Martinho, Ana Isabel Melato, Maria José Calhorda Departamento de Química e Bioquímica, CQB, Faculdade de Ciências, Universidade de

Lisboa, Campo Grande, 1749-016 Lisboa, Portugal, [email protected]

The development of modified electrodes with conducting polymers containing first

row transition metals has been a very active area of research in recent years, especially

because the metal centres are incorporated along the polymer backbone. Several applications

have been reported such as electrocatalysis, sensors and optical devices, among others [1]. A

common strategy for electrochemical synthesis of metal-containing polymers is to attach

polymerisable groups (aniline, pyrrole, etc.) onto metal complexes. Salphen-type polymers

are attractive, because extra synthetic steps can be avoided once Schiff base complexes can be

conveniently electropolymerised. Among monomers, bis(metallo)salphen are of special

interest for electropolymerisation. They behave as two connected independent salphen units

with possibility to fine tune each salphen with desirable properties. Synthesis of asymmetric

bis-salphen complexes permits the introduction of functional groups with different properties

and variation of the metal centres gives distinct redox behaviour. [2]

Here we present the synthesis of symmetric and asymmetric zinc(II), copper(II) and nickel(II)

bis-salphen complexes by reaction of 3,3’-diaminobenzidine with salicylaldehydes with

different substituents on the phenolate ring. The dinuclear complexes have been

electropolymerised on an inert substrate by potentiostatic and/or potentiodynamic modes and

their films characterized by cyclic voltammetry, atomic force microscopy and spectroscopic techniques.

1. P.H. Aubert, P. Aubert, M. Roche, P. Capedevielle, M. Maumy, G. Ricart, Chem. Mater.,

13, 2223 (2001)

2. M.F.S. Teixeira, Anal. Lett. 40, 1825 (2007)

Keywords: bis(metallo)salphen, electropolymerisation, redox behaviour, AFM Acknowledgments: We thank Fundação para Ciência e Tecnologia for financial support: PEst-OE/QUI/UI0612/2013.


35

P13

Direct and catalyzed reduction of dissolved CO2 in aqueous media using a

polymeric gas diffusion membrane

Rui Gusmãoa,b

, Carlos Pereirac

aCentro de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal

bInstituto de Polímeros e Compósitos/I3N, Universidade do Minho, Campus de Azurem, 4800-

058 Guimarães, Portugal cCentro de Investigação em Química, Faculdade de Ciências da Universidade do Porto,

4169-007 Porto, Portugal

Managing CO2 concentration is a crucial issue in aquaculture. The requirement for controlling

dissolved CO2 concentration, so that it is not too low for the nitrification processes and hence

for the quality of recirculated water, or too high, risking to induce negative effects in fish,

makes continuous, multipoint, dissolved CO2 monitoring a clear necessity. In general, the

aquaculture research associated costs for the gas-streaming infra-red techniques or fiber optic

sensors of dissolved CO2 are potentially prohibitive. Electrochemical sensors can be a cheaper

alternative for continuous, multipoint monitoring, thus contributing to the understanding of

water quality dynamics in hyperintensive aquaculture systems.

At a copper surface, the reduction of CO2 appears to be a multi-step and complex reaction

which involves shared intermediates and multiple reaction pathways. Although CO2 can be

electrochemically reduced directly on metal electrodes, either the potentials necessary are

exceedingly negative or the metal surface is rapidly poisoned by the adsorbed products or

intermediates. On the other hand, transition-metal molecular catalysts have proven to

efficiently and selectively reduce CO2 with moderate overpotentials and high Faradaic

efficiency.

In this study, we present the results of the electrochemical reduction of CO2 in aqueous media

making use of different polymeric gas diffusion membranes. Direct reduction was studied

using a Cu electrode and mediated reduction was performed either at carbon paste electrode

(CPE) or glassy carbon electrode (GCE) with Ni(cyclam) in solution.

Keywords: Carbon Dioxide, Electrochemical Reduction, Cu electrode, Ni(cyclam),

Polymeric Membrane.


36

P14

Synthesis of lithium vanadium oxides nanoparticles by solution processing

for electrochromic devices

Santos, A.C.G, Pereira, L

Materials Science Department, CENIMAT-I3N and CEMOP-UNINOVA, FCT-UNL, Campus

de Caparica, 2829-516 Caparica, Portugal

Lithium-vanadium oxide nanoparticles were prepared by solution processing using the

reaction of an aqueous hydrogen peroxide solution with lithium and vanadium alkoxides,

LiO-n-C3H7 and VO(O-i-C3H7)3. The X-ray diffraction (XRD) studies confirmed that various

phases of the Li-V oxides, having the general formula of LixV2O5 (0≤x<2.2) were obtained at

a low temperature such ~300°C. A thin film was deposited and characterized by

electrochemical impedance spectroscopy, visible spectroscopy, TGA, DSC, and DRX and

tested as an ionic conductor in an electrochromic (EC) device with the following

configuration: substrate, electrode, electrolyte, electrochromic, counter-electrode, substrate.

Besides EC devices these materials also exhibit improved properties as reversible cathodes in

lithium batteries.

Keywords: lithium-vanadium oxides; solution processing; electrochromic.


37

P15

Electrocatalytic properties of metalloporphyrins immobilized on platinum

nanoparticles stably linked to gold surfaces

I. Almeida, A. S. Viana

CQB, Departamento de Química e Bioquímica, Faculdade Ciências, Universidade de Lisboa,

Campo Grande 1749-016 Lisboa, Portugal

The catalytic performance of macrocyclic organometallic compounds, such as

metalloporphyrins, towards oxygen reduction reaction (ORR) has been widely studied since

they are relatively inexpensive and stable materials to be used as cathodes in fuel cells. Self-

assembled monolayers of metalloporphyrins containing Co and Fe, as central metal ions, and

different anchor groups (disulfides [1] or phosphonic acid [2]) were adsorbed on gold and

electrochemically activated graphite electrodes, respectively, promoting the ORR reaction [1,

2]. In order to improve the catalytic response of metalloporphyrins, nanoparticles may also be

covalently attached to the electrode surface to facilitate electron transfer between porphyrin

and electrode. Recently, we employed a simple one-step methodology to functionalize flat Au

(111) electrodes through reaction between carbon disulfide, gold nanoparticles and small

electroactive compounds (e.g. epinephrine, tryptophan) or enzymes (e.g. Glucose Oxidase),

which displayed biological activity after chemical immobilization [3].

The purpose of this work is to demonstrate the potential of carbon disulfide to

establish a stable linkage between platinum nanoparticles, modified with Co and Fe

porphyrins and vitamin B12 derivatives, and Au (111) surfaces. Surface modification was

carried out in two steps in ethanolic solution. The efficiency of this immobilization method is

confirmed by the electrochemical performance of the modified electrodes on the ORR

reaction in aqueous acidic medium. The presence of nanoparticles shifts the potential of ORR

towards more positive values, and generates higher current densities, regarding pure self-

assembled monolayers of the same derivatives. This approach using carbon disulfide is

compared to the well-known surface attachment of modified nanoparticles onto pre-formed

dithiol self-assembled monolayers. AFM imaging enabled to confirm nanoparticle

modification as well as their stable attachment to the gold electrodes.

Keywords: Metalloporphyrins, carbon disulfide, nanoparticles, electrocatalyis, oxygen

reduction reaction

[1] A. S. Viana, S. Leupold, F. -P. Montforts, L.M. Abrantes Electrochim. Acta 50 (2005)

2807

[2] J. Cabrita, A. S. Viana, L. M. Abrantes, Surface Science, 605 (2011) 1412

[3] I. Almeida, V. C. Ferreira, M. F. Montemor, L.M. Abrantes, A. S. Viana Electrochim.

Acta 83 (2012) 311

Acknowledgements: FCT for financial support: PhD scholarship - SFRH /BD/70673/2010

and PEst-OE/QUI/UI0612/2013


38

P16

Functionalization of iron oxide nanoparticles for biosensors

F. Henriquesa, M.D. Carvalho

a, A.S. Viana

b

aCCMM/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de

Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal, Tel: +351 21750000; Fax:

+351217500088; E-mail: [email protected] bCQB, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de

Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal

In the last years, the interest on magnetic nanoparticles (MNPs) has been considerably

enhanced, especially due to a wide range of potential applications in biomedicine, but also in

other areas such as catalysis and biosensors. To this purpose, efficient and simple methods for

chemical modification of non-noble nanoparticles with target bio-compounds are necessary.

The in-situ formation and assemblage of dithiocarbamates on gold, with a bidentate N-C-S2

resonance structure, can be achieved through the one-pot reaction between carbon disulfide

and compounds containing amine groups, including biomolecules, and has been explored as

an alternative to thiolated self-assembled monolayers [1].

In this study, magnetite type nanoparticles with different mean sizes, and best described as

Fe3-xO4 [2], were immobilized on gold electrodes, using carbon disulfide, and their redox

behaviour was addressed by cyclic voltammetry. Using this approach, in the presence of

Laccase, known to catalyze the oxidation of phenolic compounds simultaneously with the

reduction of molecular oxygen to water, it was observed that this multi-copper enzyme could

be stably attached to the electrode. The biological activity of the Laccase modified

nanostructured electrode, was evaluated by cyclic voltammetry towards ABTS (2,2'-azino-

bis(3-ethylbenzothiazoline-6-sulphonic acid) in citrate phosphate buffer pH 4.5. Atomic force

microscopy imaging further confirmed surface modification by MNPs and also their

functionalization.

[1] I. Almeida, A. C. Cascalheira, A. S. Viana, Electrochimica Acta 55 (2010) 8686-8695

[2] M.D. Carvalho, F. Henriques, L.P. Ferreira, M. Godinho, M.M. Cruz, J. Solid State Chem.

201 (2013) 144-152

Keywords: Magnetic nanoparticles, carbon disulfide, biosensors interface, gold electrodes


39

P17

Electrocatalytic Properties of Self-assembled Monolayers of Porphyrins

and Chlorins Adsorbed from Phosphonic or

Carboxylic Acid Groups on ITO

J. F. Cabrita a,b

, L. M. Abrantes a, F. P Montforts

b, A. S. Viana

a a Centro de Química e Bioquímica, DQB, Faculdade de Ciências da Universidade de Lisboa,

Campo Grande, 1749-016 Lisboa, Portugal, Tel: +351 21 750 00 00, Fax: +351 21 750 00

88, E-mail: [email protected] bInstitut für Organische Chemie, FB 2 Biologie, Chemie der Universität Bremen, Postfach

330440, Bremen D-28334, Germany

Organophosphonic and carboxylic acid molecules have been used to form stable and

organized self-assembled monolayers (SAMs) on metal oxide substrates (e.g. ZnO [1] and

indium tin oxide (ITO) [2]), and also on noble metals (e.g Au [3]), with similar properties to

those of thiol/Au systems. When molecules with recognized catalytic activity are synthesized

with specific anchor groups, such as phosphonates or carboxylates, they can be assembled on

an electrode surface [4], enabling the study of their redox behavior in a large potential range.

In this work, the influence of different anchor moieties (–COOH e –PO3H2) of

porphyrins and chlorins on the monolayers formation onto ITO, from butanolic solutions, is

addressed. The redox properties of the modified electrodes were characterized by cyclic

voltammetry in organic medium, clearly showing the porphyrin and chlorin electrochemical

processes. UV-vis and infrared fourier transform diffuse reflectance spectroscopies and water

contact angle measurements corroborate the presence of the catalytic moieties and indicate

that phosphonic acid groups yield more organized monolayers with higher coverage than

those prepared from carboxylic acid. The electrocatalytic activity of the modified ITO

electrodes towards the reductive dehalogenation of lindane is assessed in organic medium,

and a reaction mechanism is proposed.

Acknowledgments

J. F. Cabrita acknowledges the PhD scholarship SFRH/BD/47703/2008 (Fundação para a

Ciência e Tecnologia) and PEst-OE/QUI/UI0612/2013.

References

[1] C.L. Perkins, J. Phys. Chem. C, 113 (2009) 18276.

[2] M. Chockalingam, N. Darwish, G. Le Saux, J. Justin Gooding, Langmuir, 27 (2011) 2545.

[3] J. F. Cabrita, A. S. Viana, F.-P. Montforts, L. M. Abrantes, Surface Science, 605 (2011)

1412.

[4] J. F. Cabrita, A. Viana, A. Mourato, L. M. Abrantes, Catalysis Today, 187 (2012) 70.

Keywords: self-assembled monolayers, phosphonic and carboxylic acid, porphyrins, chlorins,

lindane dehalogenation.


40

P18

Smart’ coatings as sensors based on nanocontainers

Frederico Maia, Alexandre C. Bastos, João Tedim, Mikhail L. Zheludkevich and Mário G.S.

Ferreira

CICECO-Department of Materials and Ceramics Engineering, University of Aveiro, 3810-

193 Aveiro, Portugal

[email protected]

The increase in lifetime and conservation of intrinsic properties of metallic structures is one of

the biggest challenges currently faced by many industries.

Therefore, early detection (sensing) of substrate degradation could contribute to more cost-

effective maintenance planning and preventing occurrence of accidents with catastrophic

consequences.

One important class of materials being currently used to sense changes on the substrate or in

the surroundings is application of “smart” coatings with incorporated sensing active species

able to detect and respond to those alterations. The encapsulation/immobilization of active

compounds has the advantage of limiting undesirable interactions with coating matrix,

preventing the spontaneous leaching and imparting a controlled release and consequently

response to certain triggers.

In general, encapsulated species are incorporated into coatings and following external stimuli

which promote damage or other modification on the coating, the encapsulated species respond

according to their intrinsic characteristics (sensing). In the specific case of corrosion, there is

a pH change in the cathodic/anodic areas, where encapsulated pH indicators can be useful as

sensors [1]. In a broad sense detection of mechanical impacts in coatings can also be achieved

by encapsulation of dyes that are released or activated upon mechanical action leading to the

coloration of the coating.

In this work we report the encapsulation/immobilization of sensitive compounds in inorganic

nanocontainers [2] for incorporation in sensing coatings. These nanocontainers have the

ability to respond to certain triggers caused by corrosion or mechanical impacts, thereby

acting as sensors for specific structural applications.

References:

1. Frederico Maia, João Tedim, Alexandre C. Bastos, Mikhail L. Zheludkevich and Mário

G.S. Ferreira, “Nanocontainer-based corrosion sensing coating”, submitted.

2. Frederico Maia, João Tedim, Aleksey D. Lisenkov, Andrei N. Salak, Mikhail L.

Zheludkevich and Mário G.S. Ferreira, "Silica nanocontainers for active corrosion

protection", Nanoscale 4 (2012) 1287-1298.

Keywords: nanocontainers, nanoreactors, corrosion, sensing coatings.


41

P19

Simultaneous Determination of Nickel and Cobalt, Using a Solid Bismuth

Vibrating Electrode, by Adsorptive Cathodic Stripping Voltammetry

Georgina M.S. Alves

a , Júlia M.C.S. Magalhães

a and Helena M.V.M. Soares

*a

aREQUIMTE, Departamento de Engenharia Química, Faculdade de Engenharia,

Universidade do Porto, Rua. Dr. Roberto Frias, 4200-465 Porto, Portugal *[email protected]

A simple, fast, sensitive and greener voltammetric procedure for simultaneous analysis

of nickel (Ni) and cobalt (Co) by square wave adsorptive cathodic stripping voltammetry

(SWAdCSV) using a solid bismuth vibrating electrode (SBiVE) was developed and is

presented for the first time [1]. The procedure enables to determine Ni together with Co, at

low concentration levels (gL-1

), in ammonia buffer 0.1 M (pH 9.2) and in the presence of

oxygen, and involves an adsorptive accumulation of metal-dimethylglyoxime (Ni-DMG and

Co-DMG) complexes on the electrode surface.

For Ni and Co, the detection limits, obtained with 30 s of accumulation time, were 0.6

and 1.0 gL-1

, respectively.

The method was free of metals (Cd, Cr3+

, Cr6+

, Cu, Fe and Pb up to 50 gL-1

, Al and

Mn up to 500 gL-1

; Zn up to 300 gL-1

) interferences up to the concentrations mentioned in

brackets.

The proposed method was validated for simultaneous determination of Ni and Co in

certified reference surface water and in river water samples with good results.

In conclusion, the analytical performance of the SBiVE proved to be comparable or

better than the bismuth film electrodes (BiFEs) with the advantage of allowing a faster and

simpler adsorptive methodology [it does not require the bismuth film formation (either ex-situ

or in-situ deposition), as well as the subsequent cleaning or activating procedures to

regenerate the electrode surface] than the ones previously described with BiFEs.

Keywords: Cobalt (Co), Nickel (Ni), Stripping voltammetry, Solid bismuth vibrating

electrode

ACKNOWLEDGMENTS

The authors thank to the "Fundação para a Ciência e a Tecnologia" (FCT) from Portuguese

Government for the financial support of this work with FEDER founds, by the Project PTDC/QUI-QUI/112439/2009. One of us (Georgina Alves) acknowledges a grant scholarship

(SFRH/BD/46521/2008) financed by FCT.

[1] Georgina M. S. Alves, Júlia M. C. S. Magalhães and Helena M. V. M. Soares,

Electroanalysis 25, 2013, 1247



42

P20

The role of gold nanoparticles on the sensitivity of a bi-enzymatic biosensor

for carbamate pesticides determination

Thiago Mielle B.F. Oliveiraa,b

, Maria de Fátima Barrosoa, Simone Morais

a, Mariana Araújo

d,

Cristina Freired, Pedro de Lima-Neto

b, Adriana Nunes Correia

b, Maria B.P.P. Oliveira

c,

Cristina Delerue-Matosa*

aREQUIMTE, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua

Dr. Bernardino de Almeida 431, 4200-072 Porto, Portugal. *[email protected]; tel: +351

228340500; fax: +351 228321159. bGELCORR, Universidade Federal do Ceará, Fortaleza, Brasil

c REQUIMTE, Dep. Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua

de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal d REQUIMTE, Dep. de Química e Bioquímica, Faculdade de Ciências, Universidade do

Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal

Chitosan (CS) is a natural polysaccharide with several electrochemical applications, including

in the development of biosensors. Below its pKa (6.5), it suffers a gelification process and

acts as an ideal microenvironment to electrodeposit several materials and biological elements,

due to the amino and hydroxyl groups distributed in its structure. However, because of its

insulating properties, it is necessary to enrich the polymeric matrix with conductor materials,

in order to overcome problems related to the charge-transfer resistance (Rct) and sensitivity of

the device. In this work, we developed a bi-enzymatic biosensor (LACC-TYR-AuNPs-

CS/GPE) for carbamate pesticides detection, based on graphene paste electrode (GPE)

modified by a hybrid film composed by CS, gold nanoparticles (AuNPs) and laccase (LACC)

and tyrosinase from (TYR). The experiments were carried out using 4-aminophenol (4-AMP)

as substrate in a Britton-Robinson (BR) buffer (pH 5.5). In the absence of enzymes, the

electrochemical behavior of 4-AMP is represented by a quasi-reversible process with well-

defined anodic (+0.31 V) and cathodic (+0.15 V) peaks. When pure CS was

electroimmobilized onto the GPE a decrease of the peak currents was observed due to the

insolating properties of this biopolymer. In the presence of AuNPs in the matrix (40%, v/v),

the current increased ca. 1.5 times, suggesting a better conductivity and sensitivity for

analytical applications. In the presence of LACC and TYR (2:1%, w/w), the oxidation process

of 4-AMP is catalyzed, generating a benzoquinone compound which is reduced at -0.07 V.

The results showed that in the absence of AuNPs this electrochemical signal was ca. 2 times

lower, proving the importance of the AuNPs in the biosensor configuration. The

corresponding Nyquist diagrams exhibited a large capacitive arc (Rct = 767 Ω) when pure C

was electrodeposited onto the GPE, indicating high charge-transfer resistance. Yet, when the

CS matrix was enriched with AuNPs, the charge-transfer resistance decreases sharply (Rtc =

407 Ω), corroborating the voltammetric findings. After the optimization of the square-wave

voltammetric parameters, the developed LACC-TYR-AuNPs-CS/GPE was applied to

determine trace concentrations of several carbamates in citrus fruits, with high precision and

low level of interferences.

Keywords: Chitosan; gold nanoparticles; polyphenoloxidases; bi-enzymatic biosensors;

carbamate pesticides.


43

P21

Electrochemical properties of a gold nanoparticles doped organic/inorganic

hybrid matrix gel

Carlos J. R. Silva

a, Sandra D. F. C. Moreira

a,b, J. P. B Silva

b, Manuel F. M. Costa

b,

M. J. M. Gomesb

a Centre of Chemistry, University of Minho, Braga 4710-057, Portugal

b Centre of Physics, University of Minho, Braga 4710-057, Portugal

Sol-gel method is a commonly used synthesis procedure to obtain materials that are presently

relevant in large diversity of technological fields such as in optics, electronics, coatings, etc.

Besides, this simple preparative method allows a versatile combination of involved precursors

reagents with a large variety of substances and particles that could be embedded within the

gel network so the obtained materials with judicious mechanical, thermal, optical properties

and chemical structure and composition.

The so called organic-inorganic hybrid gels are characterized as networked materials where

the inorganic silicate backbones are bonded by polymeric chains giving to this materials a

background resistivity that could be changed by the kind of substances and particles that

could be dispersed within the two main components regions. These properties show to be

relevant for the development of materials for possible application in non-volatile organic

memory devices.

In this paper were characterized the electrochemical properties OIH gel, based on a amine-

alcohol-silicate (AA(600)) matrix where gold nanoparticles (AuNPs) with different diameters

(from 4 up to 10 nm) were immobilized. Besides the enhanced plasmonic properties, derived

from the size of the embedded nanoparticle, electrochemical impedance spectroscopy (EIS)

analysis revealed that AuNPs doped OIH gels low conductivity is dependent on dispersed Au

particle sizes. Complementary current–voltage (I–V) measurements confirms that these

materials show an electrical stable window of about 5 V range and the charge transfer

mechanism is strongly dependent on the potential applied across the OIH sample.

Keywords: Au nanoparticles, hybrid gels, electrochemical stability, sol-gel


44

P22

Immobilization of Metalloporphyrins onto Electrode Surfaces by

Electropolymerization of Tailored and Conventional Monomers

Isabel M. Ornelas a, Cláudia M. B. Neves

b, M. Graça P. M. S. Neves

b, Ana S. Viana

a, José

A. S. Cavaleiro b, Jorge P. Correia

a

aDepartment of Chemistry and Biochemistry & CQB, University of Lisbon, 1749-016 Lisbon,

Portugal; presenting author: [email protected] bDepartment of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal

The direct borohydride fuel cell (DBFC) presents a high theoretical specific energy [1] but, as

most of this type of energy converters, its kinetics is cathode-limited. Since it works in

alkaline conditions, the use of non-precious catalysts for oxygen reduction is allowed.

Nevertheless, platinum is still the most used material for this purpose due to its high activity

for the oxygen reduction reaction, high electrical conductivity and good stability, the high

cost being the main drawback for its commercial application [2]. N-containing conducting

polymers, such as polyaniline (PAni) and polypyrrole (PPy), also display interesting activities

for the electroreduction of O2 [3]; moreover, it has been shown that the metal-nitrogen sites in

“conducting polymer like” structures are very active for the molecular oxygen reduction [4],

justifying the good performance of metalloporphyrins for such reaction [5].

This work presents a systematic study of the electrode modification by the

electropolymerization of novel metalloporphyrins compounds specially functionalized with a

pendant aniline-type moiety. Thin polymer films were synthesized from organic media in the

presence or absence of free aniline, onto vitreous carbon and platinum supports. The polymer

deposition was accomplished potentiodynamically and potentiostatically, and monitored by

microgravimetry. The morphology of the polymers was accessed by atomic force microscopy.

References:

1 - U.B. Demirci, J. Power Sources 169 (2007) 239.

2 - H. Chen, K. Scott, K. Lovell, Fuel Cells 6 (2006) 367.

3 - V.G. Khomenko, V.Z. Barzukov, A.Katashinskii, Electrochim. Acta 50 (2005) 1675.

4 – R. Bashyam, P. Zelenay, Nature 443 (2006) 63.

5 – H. Tang, H. Yin, J. Wang, N. Yang, D. Wang, Z. Tang, Angewandte Chemie 52 (2013)

5585.

Keywords: Oxygen reduction, Metalloporphyrins, Conducting polymers, DBFC.

Acknowledgements:

Fundação para a Ciência e a Tecnologia (project PTDC/QUI-QUI/121857/2010 and PEst-

OE/QUI/UI0612/2013). Thanks are also due to the University of Aveiro, ‘Fundação para a

Ciência e a Tecnologia’ (FCT) and F D R for funding the QOPNA Unit. We thank the

Portuguese National NMR network supported by funds from FCT.



45

P23

Influence of Zeolite Particles and Inhibitor as Additive for Concrete in the

Rebar Corrosion Protection

C. Vicentea,A. S. Castela

a,b, R. Neves

a, M. F. Montemor

b

aInstituto Politécnico de Setubal, ESTBarreiro, 2389-001 Barreiro, Portugal

bICEMS, Instituto Superior Técnico, Technical University of Lisbon, 1049-001, Lisboa,

Portugal

The main goal of this work was to study the influence of past additives in reinforced concrete

steel samples relatively to stability and protective behavior of the concrete and rebar corrosion

resistance. The additives used were the followings: SIKA Ferrogard 901 commercial inhibitor

containing anti-corrosion molecules, such as alkanolamines (AMAs), and spent zeolites

catalysts from FCC units (Fluid Catalytic Cracking, petrochemical industry). The

water/cement ratio used was 0.6 and a plasticizer was added to the past.

The main technique used to study the samples was Electrochemical Impedance Spectroscopy

(EIS). Reinforced concrete steel samples were constituted by a graphite rod embedded in the

samples, which was used as a reference electrode, while four steel rods also embedded were

used to simulate a rebar and as working electrodes and counter-electrode. Measurements were

performed in a three-electrode arrangement. The frequency range used was 100KHz to 5mHz

with a 10mV amplitude. The samples were kept in a dry/immersion cycles for longer periods

and measurements were regular carryout during all the process. A saturated NaCl immersion

solution was used.

Beneficial influence in the properties of concrete by zeolites or by a synergic effect with the

inhibitor seems evident, with a favorable influence in the protection of the rebar, increasing

the time for the beginning of corrosion which improves the durability of the reinforced

concrete steel samples.

Keywords: concrete; reinforced concrete steel, zeolites; corrosion inhibitor, EIS.


46

P24

New phenolic imidazole derivatives: evaluation of antioxidant activity

A.P. Bettencourt, F. Lobo, A.C. Leite, C. Correia, M.A. Carvalho, M.F. Proença

Departamento de Química, Universidade do Minho, Campus de Gualtar,

4710-057 Braga, Portugal

The damage caused by free radicals, namely reactive oxygen species (ROS), in biological

systems has been extensively studied over the last few decades. The development of several

diseases, mainly those affecting the central nervous system such as Alzheimer’s disease,

Parkinson’s disease and some tumours, are associated to oxidative stress [1-4]

. Efforts to solve

this problem mainly focus on the use of substances that can act as scavengers of free radicals,

acting as antioxidants [1-4]

. Therefore, there has been a growing interest in the synthesis and

development of novel compounds that can act as antioxidants. It is also essential to have a

simple, fast and reliable method to measure the antioxidant activity of new compounds and

several chemical and electrochemical methods have been developed for this purpose [5,6]

.

In this work a series of new phenolic imidazole derivatives was synthesized and the

antioxidant activity of all the compounds was evaluated by cyclic voltammetry. The effect of

the nature of the substituents on N1 of the imidazole ring and the number and position of

hydroxyl groups of the phenolic subunit on the oxidation peak potentials of the phenolic

imidazole derivatives was evaluated. Antioxidant activity data obtained from anodic peak

potential measurements were correlated to the ones gotten by the DPPH radical and deoxy-D-

ribose degradation assays.

Acknowledgments: To FCT and FEDER-COMPETE-QREN-EU for financial support to the

Research Centre, CQ/UM [PEst-C/QUI/UI0686/2011 (FCOMP-01-0124-FEDER-022716)].

[1] A. Contestabile, Curr. Top. Med. Chem. 2001, 1, 553.

[2] C. A. Collins, F. H. Fry, A. L. Holme, A. Yiakouvaki, A. Al-Qenaei, C. Pourzand, C.

Jacob, Org . Biomol. Chem. 2005, 3, 1541.

[3] B. Halliwell, Drugs and Aging, 2001, 18, 685.

[4] J. G. Fernández-Bolaños, Ó. López, J. Fernández-Bolaños, G. Rodríguez- Gutiérrez, Curr.

Org. Chem., 2008, 12, 442.

[5] L.M. Magalhães, M. A. Segundo, S.Reis, J. L.F.C. Lima, Anal. Chim. Acta, 2008, 613, 1.

[6] A. J. Blasco, A. G. Crevillén, M. C. González, A. Escarpa, Electroanalysis, 2007,19,

2275.


47

P25

Gold nanoparticles-based biosensor for determination of amyloid

beta-peptide

P. Carneiroa,b

, J.A. Loureiro, S.C. Coelho, C. Delerue-Matosb, S. Morais

b, M.C. Pereira

a

a LEPAE, Department of Chemical Engineering Faculty of Engineering, University of Porto,

Portugal. b REQUIMTE, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto,

Portugal. [email protected]; tel: +351 228340500; fax: +351 228321159

Alzheimer disease (AD) is a neurodegenerative pathology characterized by extracellular

deposits of amyloid β (Aβ) peptide (senile plaques). ince this disease is very difficult to

diagnose, it is clinically important to find and detect accurately biomarkers for AD by new

non-invasive methods that may facilitate the diagnostic process and identify patients at an

earlier stage [1]. Thus, the aim of the proposed research was to develop a sensitive gold

nanoparticles-based immunosensor for the detection of the main AD biomarker, i.e, amyloid

beta-peptide, in biological fluids.

Cyclic voltammetry, square-wave voltammetry and electrochemical impedance spectroscopy

were selected for the biosensor characterization. The proposed immunosensor was

constructed in four steps: 1) formation of a self-assembled monolayer (SAM); 2)

electrodeposition of gold nanoparticles (AuNPs); 3) antibody immobilization; 4) analysis of

the signal resulting from the antibody-antigen interaction.

Firstly, several SAMs and experimental conditions were tested, namely, cystamine,

cystamine+mercaptoethanol, mercaptopropionic acid and mercaptopropionic

acid+mercaptoethanol at different concentrations and immersion times. The best results were

attained using 5 mmol/L mercaptopropionic acid and a time of immersion of 2 h.

Concerning the synthesis of AuNPs, the Turkevich method was used. Hydrodynamic size and

potential zeta values were characterized by dynamic light scattering and laser doppler

velocimetry, respectively. AuNPs exhibited a 37 nm mean hydrodynamic diameter and a -38

mV zeta potential. Electrochemical deposition of the AuNPs on the previously SAM modified

electrode was carried out at - 0.2 V for 500 s.

For the antibody immobilization, several concentrations and incubation times were evaluated.

The antibody was functionalized in order to support its correct orientation, with minimal

steric hindrance to interact favorably with its target antigen. The best results were obtained

using a 1 µg/mL concentration of antibody and an incubation time of 7.5 h. The antibody-

antigen interaction was firstly characterized using an ELISA test in order to estimate the

necessary time (5 min.) to promote the reaction between the antibody and the antigen. The

developed gold nanoparticles-based immunosensor allows accurate and reproducible

detection of the amyloid-beta peptide at low levels.

Acknowledgements: This work was supported by project PTDC/QUI-BIQ/102827/2008. [1] Hampel, H., Shen, Y., Walsh, D., Aisen, P., Shaw, L., Zetterburg, H., Trojanowski, J. and Blennow, K. (2010), Experimental Neurology, 223, 334-346.

Keywords: Alzheimer’s disease; Amyloid-beta peptide; Immunosensor; Gold nanoparticles;

Self-assembled monolayer.


48

P26

Application of a DNA-based biosensor for the electrochemical investigation

of the effect of free radicals and antioxidants

Sofia Costaa, Diana Cruz

a, M. Fátima Barroso

a, M. J. Ramalhosa

a, Abel J. Duarte

a, C.

Delerue-Matosa

aREQUIMTE, Instituto Superior de Engenharia do Porto, Rua Dr. António Bernardino de

Almeida, 431, 4200-072 Porto, Portugal

Reactive oxygen and nitrogen species (ROS and RNOS) such as hydrogen peroxide (H2O2),

hydroxyl radical (HO·) and nitric oxide (

·NO) are formed in vivo during aerobic metabolism.

Although cells have developed various enzymatic and nonenzymatic systems to control ROS

and RNOS production, a certain fraction escapes the cellular defense and may cause

permanent or transient damage to proteins, lipids, and nucleic acids (1).

Some food and beverage compounds have an important external contribution to body

defenses against oxidative insult. It provides cell specific antioxidants that are able to

scavenge multiple types of free radicals contributing to maintain cellular health.

In this work, an electrochemical DNA-based biosensor was developed in order to assess the

total antioxidant capacity (TAC) of foodstuffs.

The performance of this biosensor consisted in four steps: i) deoxyadenylic acid

oligonucleotide (dA) immobilization onto carbon paste electrodes (CPE); ii) Damage of the

dA by the immersion of the bioelectrode on the free radicals (H2O2, HO· and

·NO) iii)

Protective effect promoted by antioxidants, in the presence of free radicals, onto de dA-CPE

iv) Detection and measurement of the oxidation peak current of the dA using square wave

voltammetry (SWV).

References

(1) Richter, C., Park, J-W., Ames, B.N. (1988) Proc. Nati. Acad. Sci. 85, 6465-6467.

Acknowledgments

M.F. Barroso is grateful for the post-doc fellowship (SFRH/BPD/78845/2011) financed by

POPH–QREN–Tipologia 4.1–Formação Avançada, subsidized by Fundo Social Europeu and

Ministério da Ciência, Tecnologia e Ensino Superior. This work has been supported by FCT

through grant no. PEst-C/EQB/LA0006/2011 and project PP-IJUP-2011-276.

Keywords: DNA; free radicals, antioxidants; biosensors.


49

P27

Study of electrochemical properties of a protective film formed onto nickel

when immersed in alkali metal solutions

Cilene Vicentea, R. G. Duarte

a,b, A. S. Castela

a,b

aInstituto Politécnico de Setubal, ESTBarreiro, 2389-001 Barreiro, Portugal

bICEMS, Instituto Superior Técnico, Technical University of Lisbon, 1049-001, Lisboa,

Portugal

Nickel and nickel alloys are important materials for the design of vessels in different process

industries. Nickel electrode is also used in different energy-producing cells in which aqueous

or no aqueous solutions are used as electrolytes. Nickel and its alloys exhibit excellent

corrosion resistance in aqueous aggressive environments, which are attributed to the ability of

nickel to form a stable passive film on its surface [1].

The nature and the mechanism of formation of the passive film depend, among other factors,

on the composition and pH of the electrolyte. In alkaline environments, NiO was proved to be

the main constituent of the passive film on Ni surface [2]. Passivity is a crucial factor in

determining the capability of metals to resist corrosion. Investigation of the electrochemistry

of a passivity metal can reveal not only the structure and composition, but also the corrosion

behavior of the film [3].

The corrosion resistance was investigated by electrochemical techniques, specifically

electrochemical impedance spectroscopy (EIS) and polarization curves. The frequency range

used was from 100 KHz to 5 mHz and were 7.13 reading per decade of frequency. The

impedance results were treated using the software ZView. The polarization curves were

obtained in the range -0.5 to 1.0 V at scan rate of 10 mV/s. The equipment used the G-300

Gamry Instruments. Several alkaline halide solutions were used and Chemical

characterization of the films was performed by SEM. Influence of the electrolyte composition

in passive film properties were detected.

Keywords: EIS; nickel; passive film; alkaline metal solutions

Reference

1. Abd El Aal, E.E., Breakdown of passive film on nickel in borate solutions containing

halide anions. Corrosion Science, 2003. 45(4): p. 759-775.

2. Abd El-Haleem, S.M. and S. Abd El-Wanees, Chloride induced pitting corrosion of

nickel in alkaline solutions and its inhibition by organic amines. Materials Chemistry

and Physics, 2011. 128(3): p. 418-426.

3. Guiñón-Pina, V., A. Igual-Muñoz, and J. García-Antón, Influence of temperature and

applied potential on the electrochemical behaviour of nickel in LiBr solutions by

means of electrochemical impedance spectroscopy. Corrosion Science, 2009. 51(10):

p. 2406-2415.


50

P28

Development of an electrochemical aptasensor for protein detection

Sofia G. Meirinhoa, Luís Dias

b, Antonio M. Peres

b, Lígia R. Rodrigues

a

aCentre of biological Engineering, University of Minho

bLaboratory of Separation and Reaction Engineering, Escola Superior Agrária, Polytechnic

Institute of Bragança

The development of aptamer-based electrochemical biosensors as an emerging technology has

made the detection of small and macromolecular analytes easier, faster, and more suited for

early detection of protein biomarkers. Biomarkers are produced by body organs or tumors and

measure antigens on cell surfaces. When detected in high amounts in blood, they can be

suggestive of tumor activity 1,2

. These markers are more often used to evaluate treatment

effects or to assess the potential for metastatic disease in patients with established disease.

Osteopontin (OPN) is a protein found in all body fluids, and constitutes a possible biomarker

because its overexpression has been related with breast cancer evolution and metastasis 3–5

.

Currently, biomarkers are commonly used for the development of diagnostic methods,

allowing the detection of the disease in its initial stages. An electrochemical aptasensor for the

detection of OPN was developed using an RNA aptamer immobilized on a gold screen-

printed electrode (Au/SPE). The immobilized biotin-modified aptamer on Au/SPE constitutes

the biorecognition element for the target protein and the electrochemical signal generated

from the interaction aptamer-target protein was evaluated by cyclic voltammetry (CV). A

decrease in the current as a consequence of protein binding to the aptamer was observed

through the analysis of the electron flow produced by a redox reaction between ferri- and

ferrocyanide. The electrochemical aptasensor herein developed presents a high specificity for

OPN as compared with other proteins commonly found in the biological fluids.

Keywords: Osteopontin; aptamer; aptasensor; screen-printed electrode; cyclic voltammetry

Acknowledgment: This work was financially supported by Fundação para a Ciência e a

Tecnologia (FCT) through the PhD grant SRFH/ BD/65021/2009.

Reference: 1. Karley, D., Grupta, D. & Tiwari, A. Biomarkers: The Future of Medical Science to Detect

Cancer. Journal of Molecular Biomarkers & Diagnosis 2, 2–5 (2011).

2. Rodrigues, L. R., Teixeira, J. A., Schmitt, F. L., Paulsson, M. & Lindmark-Mansson, H.

The Role of Osteopontin in Tumor Progression and Metastasis in Breast Cancer. Cancer

Epidemiology, Biomarkers & Prevention 16, 1087–1097 (2007).

3. Rodrigues, L. R., Lopes, N., Sousa, B., Vieira, D. & Milanezi, F. Significance of

Osteopontin Expression in Human Invasive Breast Tumour Stroma. The Open Breast Cancer

Journal 1, 1–9 (2009).

4. Macrì, A. et al. Role of osteopontin in breast cancer patients. Tumori 95, 48–52 (2009).

5. Ahmed, M. & Kundu, G. C. Osteopontin selectively regulates p70S6K / mTOR

phosphorylation leading to NF-κB dependent AP-1-mediated ICAM-1 expression in breast cancer

cells. Molecular Cancer 9, 1–13 (2010).


51

P29

Modified Titanate Nanotubes Decorated with Nanocrystalline Bi2S3 as New

Materials for Sensor Applications

J. F. Cabrita a, O. C. Monteiro

a a Centro de Química e Bioquímica, DQB, Faculdade de Ciências da Universidade de Lisboa,

Campo Grande, 1749-016 Lisboa, Portugal, Tel: +351 21 750 00 00,

Fax: +351 21 750 00 88, E-mail: [email protected]

Nanostructured materials have become one of the most important research subjects

and have established a remarkable development in a wide assortment of scientific fields [1].

Despite all known successes, the control of the materials’ intrinsic properties is still difficult

and challenging. The synthesis of nanocomposite materials has been one of the most fruitful

methods for solving this issue: by synergetically combining several materials it is possible to

prepare new materials with improved and innovated properties [2,3].

Titanate nanotubes (TNTs) combining the properties of conventional TiO2

nanoparticles with the properties of layered titanates, have received increasing attention

because of their wide potential applications, including sensor [4]. The open mesoporous

morphology together with the absence of micropores and the high specific surface area should

facilitate transport of reagents during the process. Simultaneously, for the nanoscale coupled

semiconductors it can be expected that the TNTs electro-activity will be significantly

improved by the enhancement of charge separation and minimization or inhibition of charge-

carrier recombination. The synthesis of TNTs and posterior sensitization with Bi2S3

nanocrystalline semiconductor particles was investigated in this work. The TNTs and

Bi2S3/TNTs nanocomposite powders were prepared and characterized, by TEM, SAED, SEM,

DRX and DRS. The evaluation of the electrochemical properties of Bi2S3/TNTs

nanocomposites were carefully analyzed and their performance attested for the ascorbic acid

electrocatalytic oxidation.

Acknowledgments

This work was financially supported by FCT under the projects

PTDC/CTM/NAN/113021/2009 and PEst-OE/QUI/UI0612/2013.

References

[1] D.V. Bavykin, F.C. Walsh, “Titanate and titania nanotubes: synthesis, properties and

applications”, R C, Cambridge, 2010.

[2] E.K. Ylhainen, M.R. Nunes, A.J. Silvestre, O.C. Monteiro, J. Mater. Sci. 47 (2012) 4305.

[3] V. Bem, M.C. Neves, M.R. Nunes, A.J. Silvestre, O.C. Monteiro, J. Photochem.

Photobiol. A 232 (2012) 50.

[4] Y.P. Dong, L. Huang, J. Zhang, X.F. Chu, Q.F. Zhang, Electrochimica Acta, 74 (2012)

189.

Keywords: Nanostructured materials, titanate nanotubes, nanocrystalline Bi2S3, ascorbic acid,

electrocatalysis.


52

P30

Disposable immunosensor with simple antibody orientation for label-free

real-time detection of a cancer biomarker

Nádia S. Ferreira, M. Goreti F. Sales

BioMark/ISEP, School of Engineering, Polytechnic Institute of Porto, R. Dr. António

Bernardino de Almeida, 431, 4200-072, Portugal. Tel: +351228340544;

E-mail: [email protected]; [email protected]

Oxidative Stress is the imbalance between oxidant-producing systems and antioxidant defense

mechanisms, resulting in an excessive production of reactive oxygen species. This condition

is widely recognized as a central feature of many biological processes and diseases, such as

cancer. The oxidized nucleotide 8-hydroxy-2’-deoxyguanosine (8OHdG) is among the several

indicators used for screening oxidative cell damage. The methods presently used to quantify

this biomarker involve complex, expensive and non-portable techniques.

As an alternative, this work reports a novel immunosensor for this purpose. It was assembled

by employing a novel strategy for suitable antibody orientation, aiming its subsequent

application in the determination of 8OHdG in point-of-care. The Anti-8OHdG was bound to

an amine modified gold support through its Fc region, by effective covalent binding to the

carboxylic function. Non-oriented approaches of antibody binding to the platform were tested

in parallel, in order to show that the presented proposal favored antibody/antigen affinity.

The immunosensor design was evaluated by Quartz-Crystal microbalance with Dissipation,

Atomic Force Microscopy, Electrochemical Impedance Spectroscopy (EIS) and Square-Wave

Voltammetry. EIS was also a suitable technique to follow the analytical behavior of the

device against 8OHdG. The affinity binding between 8OHdG and the antibody immobilized

in the gold modified platform increased the charged transfer resistance across the

electrochemical sep-up. The observed behavior was linear from 0.02 to 7.0 ng/mL 8OHdG.

Interference from Glucose, Urea and Creatinine was found negligible. An attempt of

application to synthetic samples was also successfully conducted.

Overall, the presented approach enabled the production of suitably oriented antibodies over a

gold platform by means of a much simpler process than other oriented-antibody binding

approaches described in the literature, as far as we know, and was successful in terms of

analytical features and sample application.

Keywords: Immunosensor; Oriented antibody binding; Cancer biomarker; 8-hydroxy-2’-

deoxyguanosine.




53

P31

Smart Plastic Antibody Material for Hemoglobin Tailored by Silica Surface

Imprinting and with Charged Binding Sites: Its use as Ionophore in

Potentiometric Transduction

Ana P. T. Moreira, Felismina T.C. Moreira, M. Goreti F. Sales



E-mail: [email protected] ; [email protected]

Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in

gas transport. Hb-associated disturbances are related to several diseases, such thalassemia,

anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer.

Overall, it is of great importance to know the concentration of Hb in the blood in many

health-related conditions.

There are many methods described in the literature for determining Hb. Most of these rely on

antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place

between these biomolecules. However, the use of antibodies for Hb determination in routine

clinical use is very expensive, due to the high cost of the material, the need for special

handling and storage, and the non-reusability. These constraints may be limited by replacing

natural antibodies by plastic receptors, obtained by molecular imprinting procedures.

Thus, this work describes a novel smart plastic antibody material (SPAM) by surface

imprinting technique for the detection of Hb and its application to design small, portable and

low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica

nanoparticles and allowing its subsequent interaction with different vinyl monomers, of

different chemical functions and ionic charges. Control materials were designed in parallel to

assess the ability of establishing stereochemical recognition of Hb and the effect of the

kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed

the surface modification of the silica material used for imprint.

All materials were mixed with PVC/plasticizer and applied as selective membranes in

potentiometric transduction. Suitable emf variations were detected only for selective

membranes having a SPAM material and a charged lipophilic anionic additive. All control

materials were unable to produce a potentiometric response.

Overall, good features were obtained for SPAM-based selective membranes carrying an

anionic lipophilic additive. In H P buffer of pH 5, limits of detection were 43.8μg/mL for

a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity

was also observed against other coexisting biomolecules. The analytical application was

conducted successfully, showing accurate and precise results.

Keywords: Surface molecular imprint; Hemoglobin; Potentiometry; Ion-selective electrodes.




54

P32

Carnitine tailored Sensors on Surface Molecular Imprinting based on

Graphene layers

Liliana A.A.N.A. Truta, Nádia S. Ferreira, M. Goreti F. Sales



E-mail: [email protected]; [email protected]

A new biosensor based on surface molecularly imprinted polymer (MIP) on graphene layers

was successfully developed. It consists in a 3D polymeric network created on top of surface

and around the target template, Carnitine (CRT), a potential biomarker of ovary cancer. The

polymeric structure was obtained after radical polymerization of

(vinylbenzyl)trimethylammonium chloride, 4-styrenesulfonic acid and vinyl pivalate,

including in the reaction mixture ethylene glycol dimethacrylate as cross-linker and

ammonium persulphate as initiator. Non-imprinted polymer (NIP) material was also

produced, by excluding the template from the procedure.

The imprinted graphene structures were further used for the selective determination of CRT

by potentiometric transduction. For this purpose, a selective membrane was prepared by using

the MIP material as ionophore, and dispersing it in a plasticized poly(vinylchloride) matrix,

that included (or not) a suitable amount of charged lipophilic additive. The membranes were

casted over a solid conductive support, made of graphite or of conductive glass. Control

membranes were also produced by replacing MIP by NIP material.

The potentiometric performance of the above electrodes was assessed against CRT solutions

of increasing concentrations. Graphite supports displayed the best analytical features, with

average slope and detection limit of 40.51 mVdecade-1

and 3.55x10-6

molL-1

, respectively.

The effect of pH upon the potentiometric response was evaluated for different buffer solutions

(within 2-9) and the best performance for this sensor was obtained with HEPES (4-(2-

hydroxyethyl)-1-piperazineethanesulfonic acid) buffer of pH 5.2. The interference effect of

albumin, ascorbic acid, glucose, creatinine and urea in the performance of the electrochemical

unit was tested for concentrations up to their normal physiologic levels in urine and good

selectivity was observed. The application of the devices to the analysis of spiked samples

showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%), with relative errors below

-20%.

Overall, the combination of the MIP sensory material with a suitable selective membrane and

electrode design showed to be a promising tool for point-of-care applications.

Keywords: Carnitine; Surface Molecularly imprinted sensors; Graphene; Solid conductive

supports; Potentiometry.




55

P33

A Biomimetic Biosensor based on Poly(o-aminophenol) film for Cardiac

Biomarker detection in Point-of-Care

Felismina T.C. Moreiraa,b,c

, Sanjiv Sharmad, Rosa A. F. Dutra

e, João P. C. Noronha

c, Anthony

E. G. Cassd, M. Goreti F. Sales

a

aBioMark/ISEP, School of Engineering, Polytechnic Institute of Porto, R. Dr. António

Bernardino de Almeida, 431, 4200-072, Portuga. Tel: +351228340544; Email:

[email protected] bINESC-TEC (coordinated by INESC Porto), Faculdade de Ciências da Universidade do

Porto, Rua do Campo Alegre, Porto, Portugal. cREQUIMTE/FCT-UNL, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa,

2829-516 Caparica, Portugal. dDepartment of Chemistry & Institute of Biomedical Engineering, Imperial College, London,

UK. ePROCAPE, LAPED, Universidade Federal de Pernambuco, Recife, Brazil.

Acute coronary syndrome (ACS) is a spectrum of acute myocardial ischemia spanning from

unstable angina to acute myocardial infarction (AMI). Patients under AMI require from

emergency medical assistance a quick diagnosis, but symptoms of chest pain, pressure,

shortness of breath, and/or nausea are common to acute myocardial ischemia conditions.

Myoglobin (Myo) is a nonspecific biomarker that appears in the peripheral circulation as

early as 1 to 2 hours after cardiac damage. Quick and low-cost methods for Myo

detection/determination in point-of-care are therefore appreciated.

This work describes for this purpose an electropolymerized molecular imprinting (EMI)

polymer film for Myo detection in ischemic episodes. The EMI is composed with Myo and

aminophenol (AP) monomer deposited on gold screen printed electrode surface (Au-SPE).

Myo was removed from the polymeric matrix was with proteinase K. A non-imprinted

material (NI) was synthesized by following the same procedure without having a template.

This material was used as a negative control. Atomic Force Microscopy and RAMAN

Spectroscopy analysis confirmed the surface modification of the working area in the Au-SPE.

The ability of the biomaterial EMI and its negative control NI to rebind Myo on the Au-SPE

support was followed electrochemically. Electrochemical Impedance Spectroscopy (EIS) and

Square Wave Voltammetry (SWV) were used for this purpose. The NI/Au-SPE was unable to

interact with Myo in a predicted way, showing a similar-to-random behavior. EMI/Au-SPE

devices displayed an opposite behavior, showing linear responses to Myo down to 3.5 g/mL

or 0.58 g/mL in EIS or SWV assays, respectively. The corresponding detection limits were

1.5 µg/mL or 0.28 µg/mL. EMI also showed negligible interference from troponin T, bovine

serum albumin and urea under SWV assays, showing promising results for point-of-care

applications when applied to spiked biological fluids.

Keywords: Myoglobin; Screen-Printed Electrodes; Molecular Imprinting; Electro

polymerization.


56

P34

Organic-Inorganic Hybrid Sol-gel Coatings to Prevent Corrosion of

Galvanized Reinforcing Steel

R. B. Figueiraa, E. V. Pereira

a, C. J. R. Silva

b, M. M. Salta

a

aLNEC – Laboratório Nacional de Engenharia Civil,

Av. do Brasil 101, 1700-066 Lisboa, Portugal,

bCentro de Química, Universidade do Minho, Braga, Portugal.

The use of hot dip galvanized steel (HDGS) has been recognized as one effective measure to

increase the service life of reinforced concrete structures exposed to carbonation or to

chlorides ions. Immediately after concreting, with the hydration of the fresh concrete,

passivating surface layers made of calcium hydroxyzincate are formed, consuming between 5

and 10 µm of zinc. Simultaneous hydrogen evolution may also develop, leading to the loss of

adherence between steel and concrete [1].

This work describes the studies developed for applying a sol-gel method to produce organic-

inorganic hybrid (OIH) coatings over HDGS and evaluates their efficiency as a pretreatment

to reduce the formation of excessive amounts of zinc oxides as well as H2 evolution. OIH

matrices were synthesized by using a functionalized metal alkoxide as precursor (3-

isocyanatopropyltriethoxysilane) that was made to react with five oligopolymers (Jeffamines)

with different molecular weight in a 2:1 molar ratio. The inclusion of Cr(III) as corrosion

inhibitor within the OIH coating was also tested [2]. All coatings were produced over HDGS

samples by dip-coating method.

OIH coatings performance was evaluated by electrochemical and surface analysis techniques

(SEM/EDS and GD-OES). For electrochemical studies, galvanic current and polarization

resistance measurements were performed over a 70 days period in electrochemical cells

specially designed to be embedded in cement based materials.

It was concluded that, when compared non-coated HDGS samples, all the OIH sol-gel

coatings produced reduce the corrosion activity during the initial stages of contact of the

HDGS with the high alkaline environment of the cement based materials studied.

Furthermore, all the hybrid sol-gel coatings allowed the formation of calcium hydroxyzincate

corrosion protective layers on the surface of the steel.

Keywords: Organic-inorganic Hybrids, Sol-gel, Galvanized Steel, Corrosion.

[1] Yeomans, S. R., Galvanized steel reinforcement in Concrete, Elsevier: Amsterdam, 2004,

chapter 1.

[2] R. B. Figueira, C.J.R. Silva, E.V. Pereira, M. M. Salta, Proceedings from Electrochemistry

2012 - Fundamental and Engineering Needs for Sustainable Development, München,

September 17 – 19th.

[3] R. B. Figueira, E. V. Pereira, C. J. R. Silva,

M. M. Salta, Proceedings from XVIII Meeting

of the Portuguese Electrochemical Society, Porto, 24th-27

th of March 2013.

Acknowledgements: The authors thanks the FCT for research the PhD grant

SFRH/BD/62601/2009 and the financial support by Centro de Química [project F-COMP-01-

0124-FEDER-022716 (ref. FCT Pest-C/Qui/UI0686/2011)-FEDER-COMPETE].


57

P35

Characterization of ZnO Nanoparticles on Electrode Surfaces by

Electrochemical Techniques

José A. Ribeiro, Paula M.V. Fernandes, Carlos M. Pereira*, Fernando Silva

Faculdade de Ciências da Universidade do Porto, Departamento de Química e Bioquímica,

Centro de Investigação em Química – Linha 4

Rua do Campo Alegre 687 – 4169-007 Porto – Portugal

*[email protected]

ZnO nanostructures have a wide range of high technology applications such as surface

acoustic wave filters, photonic crystals, photodetectors, light emitting diodes, photodiodes,

gas sensors, optical modulator waveguides, solar cells and varistors [1]. ZnO nanoparticles

are also receiving a lot of attention because of its antibacterial property and its bactericidal

efficacy has been reported to increase as the particle size decreases [2].

The synthesis and characterization of nanoparticles are two essential aspects to any study

given that their reactivity and properties are defined by their composition, size and

morphology. Scanning electron microscopy (SEM), transmission electron microscopy (TEM),

atomic force microscopy (AFM), scanning tunnelling microscopy (STM) and X-ray

diffraction (XRD) are usually employed for the characterization of nanoparticles [3].

However, these techniques have some limitations which are particularly unfavourable when

examining nanoparticle-modified electrodes. Thus, the inefficiency in cost and time and the

sample preparation restrictions prevent the analysis of modified electrodes immediately

before or after each experiment [3].

The aim of this work is to provide a simple and time-efficient in situ characterization method

for ZnO nanoparticles on electrode surfaces using electrochemical techniques. The approach

proposed is based on routine electrochemical experiments.

Keywords: ZnO, Nanoparticles, Electrochemical techniques.

References

[1] S. Baruah, J. Dutta, Sci. Technol. Adv. Mater. 10 (2009) 1.

[2] G. Applerot, A. Lipovsky, R. Dror, N. Perkas, Y. Nitzan, R. Lubart, A. Gedanken, Adv.

Funct. Mater. 19 (2009) 842.

[3] Y. Wang, E. Laborda, C. Salter, A. Crossley, R.G. Compton, Analyst 137 (2012) 4693.


58

P36

Progress on studying the effect of alloying Pd with phosphorus

on the ethanol electrooxidation

S. Salomé, R. Rego, M. C. Oliveira

Departamento de Química/CQ-VR,

Universidade de Trás-os-Montes e Alto Douro (UTAD), Portugal

Ethanol alcohol fuel cells have received much attention for portable applications due to their

advantages over analogous devices feed with hydrogen. Much effort has been devoted to

employ Pd-alloys on the ethanol electrooxidation reaction (EOR), looking for a synergetic

effect between Pd and the alloying element. However, the alloying element has been restricted

to another metal element, giving rise to bimetallic and even trimetallic alloys [1].

In this work, the electrocatalytic behavior of Pd alloyed to a non-metal element (phosphorus)

towards EOR in the alkaline medium is investigated. The PdP alloy is prepared by electroless

deposition onto a carbon paper substrate previously activated by the electrodeposition of Pd

nucleus [2]. The effect of this procedure on the PdP alloy morphology and electrocatalytic

activity is analyzed using increasing Pd loadings. Comparison of the electrocatalytic activity

of PdP alloy and Pd electroless is evaluated from cyclic voltammetry, chronoamperometry

and electrochemical impedance spectroscopy, Figure 1. The long-term stability of the

electrodes is ascertained from 250 successive cycles recorded in 0.5 M EtOH + 0.5 M NaOH

and SEM/EDS analysis of the surface electrodes.

-0.6 -0.3 0.0 0.3 0.6

0.0

0.4

0.8

1.2

1.6

j/ m

A.c

m-2

E vs (Ag/AgCl)/ V

Pd

PdP c

a)

b)

Figure 1 – a) Cyclic voltammetry and b) Nyquist plot of ethanol oxidation on Pd electroless

and Pd-P alloy at -0.30 V in 0.5 M EtOH + 0.5 M NaOH solution.

[1] M.C. Oliveira, R. Rego, L.S. Fernandes, P.B. Tavares, Journal of Power Sources, 2011,

196, 6092–6098; [2] S. Salomé, R. Rego, A. Querejeta, F. Alcaide, M. Cristina Oliveira,

Electrochimica Acta (in press). DOI: 10.1016/j.electacta.2013.04.159

Keywords: DEFCs, Methanol, Ethanol, PdP alloy

Acknowledgments: FCT and COMPETE projects PTDC/QUI-QUI/110855/2009 and UI 686 -

2011-2012,PEst-C/QUI/UI0686/2011.

0 200 400 600 800 1000

0

200

400

600

800

1000

-Z "

/

Oh

m

Z ´ / Ohm

PdP

Pd


59

P37

An electrochemical impedance spectroscopy study of oxygen reduction

kinetics on PdP alloys

Rosa Regoa, Sónia Salomé

a, Maria Cristina Oliveira

a, J. C. S. Fernandes

b

aDepartamento de Química/CQ-VR, Universidade de Trás-os-Montes e Alto Douro, 5001-801

Vila Real bICEMS / DEQ, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais

1049-001 Lisboa, Portugal [email protected]

To make proton exchange membrane fuel cells (PEMFCs) competitive to applications in the

transportation, stationary, and portable/micro power generation, new effective low cost

electrocatalysts must be developed. Palladium alloys (Pd-Co, Ni, Cr and Cu) have been

introduced as cathode electrocatalysts for the oxygen reduction reaction (ORR) in acid medium

[1, 2]. It has also been shown that Pd and PdP exhibit interesting activity for the ORR reaction in

acid medium [3].

In the present study, electrochemical impedance spectroscopy (EIS) has been used to evaluate the

electrochemical performance of porous PdP-gas diffusion electrodes (GDE) for ORR in PEMFCs.

PdP-GDEs have been prepared by electroless deposition as described previously [3]. The aim of

this study is to understand the effect of catalyst coverage of the carbon paper support on the

electrochemical activity and resistance of PdP-GDE electrodes.

The catalysts have been studied in sulfuric and perchloric media and in the presence or absence of

methanol and/or nafion and their behavior have been compared with that exhibited by a platinum

electrocatalyst. The results indicate that, although the carbon paper support PdP coverage does not

influence the ohmic resistance, the charge transfer resistance is significantly affected. In addition,

the Nyquist plot (Figure 1) presents a single time constant that may be associated with a one-step

electron transfer reaction, from O2 to H2O formation.

0 500 1000 1500 2000 2500

0

500

1000

1500

2000

2500

0 500

0

500

Z'' /

ohm

Z' /ohm

0.1 M H2SO

4

0.1 M H2SO

4 + 0.5 M MeOH

0.1 M H2SO

4 + Nafion

0.1 M HClO4

Z''

/ohm

Z' /ohm

Figure 1. Nyquist plot of the ORR on PdP (load of 0.50 mg cm-2

) in O2-saturated solutions at 0.55 V.

[1] K. Oishi, O. Savadogo, Electrochimica Acta 98 (2013) 225; [2] D. C. Martínez-Casillas, G.

Vásquez-Huerta, J. F. Pérez-Robles, O. Solorza-Feria, Journal of Power Sources 196 (2011) 4468; [3]

R. Rego, A. M. Ferraria, A. M. Botelho do Rego, M. C. Oliveira, Electrochimica Acta 87 (2013) 73

Keywords: PdP-GDE, ORR, EIS

Acknowledgments: FCT and COMPETE projects PTDC/QUI-QUI/110855/2009 and UI 686 - 2011-2012,PEst-C/QUI/UI0686/2011.



60

P38

Building Biomimetic Lipid Raft Environments on Modified Gold for the

Study of Bioactive Molecule-Membrane Interactions

Joaquim T. Marquês, Rodrigo F. M. de Almeida, Ana S. Viana,

Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa

Campo Grande, Ed. C8

[email protected]

In search for improved biomimetic platforms, supported lipid bilayers (SLB) prepared on gold

currently occupy an important position whether in the development of lipid-based biosensor

interfaces or in the study of biomembrane-related cellular processes. Of special relevance is

lipid composition, in particular those combinations of lipids that lead to the formation of lipid

rafts, which are rarely employed on most of the reported studies of SLB on gold. In a previous

work we have shown, using a ternary lipid mixture (DOPC/DPPC/Cholesterol 2:2:1), that the

formation of a raft-containing lipid bilayer directly on gold is only possible in very strict

bilayer assembling conditions due to the hydrophobic nature of gold [1]. However, such

conditions may not be suitable for many experiments. Furthermore, modification of the metal

surface may be required to preserve the bioactivity of a membrane-inserted protein. We used

the same lipid mixture to find the suitable conditions for SLB formation and its properties on

modified gold surfaces with hydrophilic self-assembled monolayers (SAM) of 11-

mercaptoundecanoic acid (MUA) or cysteine (Cys). The interaction of ternary lipid vesicles

with the two SAMs was similar, as evaluated by surface plasmon resonance and quartz crystal

microbalance. For both SAMs the presence of a planar lipid bilayer was confirmed by atomic

force microscopy in buffer solution, Domains with nanometer differences, typical of lipid

rafts, were clearly observed. The thickness of the lipid films estimated by ellipsometry is that

expected for a lipid bilayer.

Due to their tight packing MUA SAMs block the access of electroactive molecules to the

substrate, whereas shorter monolayers such as Cys might be suitable for the development of

lipid-based biosensor interfaces with electrochemical transduction. Therefore we used Cys-

modified electrodes to form raft-containing SLBs and study the interactions with a redox

active molecule, epinephrine. Cycilc voltammetry in buffer solution revealed that epinephrine

interacts differently with the SLB depending on lipid composition. Interestingly, fluorescence

spectroscopy revealed a rather weak interaction of epinephrine with lipid bilayers in

suspension, underlining the suitability of the platform cys-SLB to study and detect

membrane-associated processes with high sensitivity.

This work was financed by FCT: Ph.D. fellowship: SFRH/BD/64442/2009, grant PEst-

OE/QUI/UI0612/2013, and IF2012 initiative (POPH, Fundo Social Europeu).

[1] J. T. Marquês, R. F. M. de Almeida, A. S. Viana Soft Matter, 8 (2012) 2007-2016.

Keywords: Planar lipid bilayers; lipid rafts; chemically modified gold; atomic force

microscopy.


61


62

AUTHOR LIST

Aaronson, B. D. B. PL1

Abrantes, L. M. OC2, P17

Almeida, I. P15

Almeida, M. G. OC3

Almeida, R. F. M. P38

Alves, G. M. S. P19

Araújo, M. P20

Barroso, M. F. P20, P26

Barsan, M. M. KN4

Bastos, A. C. P18

Bento, F. P4, P5, P6, P7

Bettencourt, A. P. P24

Brandão, L. OC1, P1

Brett, C. M. A. KN4

Brito, A. G. KN5

Cabrita, J. F. P17, P29

Calhorda, M. J. P12

Carmezim, M. J. P2

Carneiro, P. P25

Carvalho, M. A. P24

Carvalho, M. D. P16

Carvalho, R. P10

Cass, A. E. G. P33

Castela, A. S. P23, P27

Cavaleiro, J. A. S. P22

Celorrio, V. PL2

Chen, C. PL1

Coelho, S. C. P25

Colburn, A. W. PL1

Correia, C. P24

Correia, A. N. P20

Correia, J. P. P22

Costa García, A. PL3

Costa, M. F. M. P21

Costa, S. P26

Cruz, D. P26

Cuharuc, A. PL1

Delerue-Matos, C. KN2, P20, P25, P26

Dias, L. P28

Dionísio, N. P11

Domingos, R. F. P9

Duarte, A. J. P26

Duarte, R. G. P27

Dutra, R. A. F. P33

Eblagon, K. OC1

Eug nio S P2

Faria, C. A. P8

Fermín, D. J. PL2

Fernandes, J. C. S. P37

Fernandes, P. M. V. P35

Ferreira, M. KN5

Ferreira, M. G. S. KN3, P18

Ferreira, N. S. P30, P32

Ferreira, V.C. OC2

Figueira, R. B. P34

Figueiredo, J. L. KN5

Florez, J. PL2

Fonseca, A. M. KN5

Fortes, M. P5

Fortunato, E. OC4

Franco, C. P9

Freire, C. P20

Geraldo, D. P4, P5, P6, P7

Gomes, M. J. M. P21

Gonçalves, L. M. P8


64

Gonzalez-Costas, J. P7

Gonzalez-Romero, E. P7

Güell, A. G. PL1

Gusmão, R. P5, P13

Henriques, F. P16

Lai, S. C. S. PL1

Lazenby, R. A. PL1

Leite, A. C. P24

Lima-Neto, P. P20

Lobo, F. P24

Loureiro, J. A. P25

Macpherson, J. V. PL1

Magalhães, J. M. C. S. P19

Maia, F. P18

Marquês, J. T P38

Martinho, P. N. P12

Martins, L. L. P3

Martins, R. OC4

Matos, A. I. P3

McKelvey, K. PL1

Meadows, K. E. PL1

Meirinho, S. G. P28

Melato, A. I. OC2, P12

Monteiro, O. C. P29

Montemor, M. F. P2, P23

Montforts, F. P. P17

Morais, S. P20, P25

Moreira, A. P. T. P31

Moreira, F. T. C. P31, P33

Moreira, S. D. F. C. P21

Moura, J. J. G. OC3

Mourato, M. P. P3

Nadappuram, B. P. PL1

Neto, M. M. M. P3

Neves, C. M. B. P22

Neves, I. C. KN5

Neves, M. G. P. M. S. P22

Neves, R. P23

Nogueira, R. KN5

Noronha, J. P. C. P33

Nunes Correia, A. P20

Oliveira, M. B. P. P. P20

Oliveira, M. C. P11, P36, P37

Oliveira, R. P4, P5, P6, P7

Oliveira, T. M. B. F. P20

Órfão, J.J.M. KN5

Ornelas, I. M. P22

Paiva, C. P5

Parpot, P. KN5

Pastor, E. PL2

Patel, A. N. P15

Pedroso, H. A. OC3

Peixoto, L. KN5

Pereira, C. M. P13, P35

Pereira, E. V. P34

Pereira, L. OC4, P14

Pereira, M. C. P25

Pereira, M. F. R. KN5, OC3

Peres, A. M. P28

Pimpão, M. OC3

Pinheiro, J. P. P9, P10

Pinto, M. F. KN5

Plana, D. PL2

Prathish, K. P. KN4

Proença, M. F. P5, P24

Ramalhosa, M. J. P26


65

Realista, S. P12

Rego, R. P36, P37

Ribeiro, J. A. P35

Rocha, M. M. P3

Rodrigues, L. R. P28

Rodrigues, P. R. S. OC3

Sales, M. G. F. P30, P31, P32, P33

Salomé, S. P36, P37

Salta, M. M. P34

Santos, A. C. G. P14

Santos, L. OC4

Sharma, S. P33

Silva, C. J. R. P21, P34

Silva, F. P35

Silva, J. P. B P21

Silva, R. P. P2

Silva, T. M. P2

Silveira, C. M. OC3

Soares, H. M. V. M. P19

Soares, O. S. G. P. KN5

Sousa, R. P8

Tedim, J. KN3, P18

Truta, L. A. A. N. A. P32

Unwin, P. R. PL1

Velders, A. P10

Viana, A. S. KN1, P15, P16, P17,

P22, P38

Vicente, C. P23, P27

Vilas Boas, A. P6

Vrouweb, E. P10

Wojcik, P. OC4

Zhang, G. PL1

Zheludkevich, M. L. KN3, P18

LIST OF PARTICIPANTS

Almeida Inês Faculdade de Ciências da Universidade de Lisboa

Lisboa [email protected]

Baião Vanessa Faculdade de Ciências da Universidade de Lisboa


Bastos Alexandre Universidade de Aveiro

Aveiro [email protected]

Barsan Madalina Faculdade de Ciências e Tecnologia Universidade de Coimbra

Coimbra [email protected]

Bento Fátima Universidade do Minho

Braga [email protected]

Bermudez Verónica Universidade de Trás-os-Montes e Alto Douro

Vila Real [email protected]

Bettencourt Ana Universidade do Minho


Brandão Lúcia FEUP

Universidade do Porto

Porto [email protected]

Cabrita Joana Faculdade de Ciências da Universidade de Lisboa


Carneiro Pedro FEUP

Universidade do Porto


Carvalho Rui Micronit Microfluidics

Enschede (Holanda)

[email protected]

Correia Jorge Faculdade de Ciências da Universidade de Lisboa


Costa Sofia REQUINTE Instituto Superior de Engenharia do Porto



67

Cruz Diana REQUINTE

Instituto Superior de Engenharia do Porto


Faria Carlos Universidade do Minho MicroNanotechnol. and Biomedical Applications

Guimarães [email protected]

Fermin David University of Bristol Bristol [email protected]

Fernandes João Salvador

Instituto Superior Técnico


Fernandes Mariana Universidade de Trás-os-Montes e Alto Douro


Ferreira Nádia Instituto Superior de Engenharia do Porto


Ferreira Virgínia Faculdade de Ciências da Universidade de Lisboa


García Agustín University of Oviedo

Oviedo [email protected]

Geraldo Maria Dulce

Universidade do Minho


Gonçalves Luís Universidade do Minho MicroNanotechnol. and Biomedical Applications

Guimarães [email protected]

Gusmão Rui Universidade do Minho


Henriques Filipa Isabel

Faculdade de Ciências da Universidade de Lisboa


Maia Frederico Universidade de Aveiro


Marquês Joaquim Faculdade de Ciências da Universidade de Lisboa



68

Matos Ana Faculdade de Ciências da Universidade de Lisboa


Matos Cristina Delerue

REQUINTE

Instituto Superior de Engenharia do Porto

[email protected]

Meirinho Sofia Universidade do Minho

Departamento de Eng. Biologica


Melato Ana Faculdade de Ciências da Universidade de Lisboa


Monteiro Olinda Faculdade de Ciências da Universidade de Lisboa


Moreira Ana Instituto Superior de Engenharia do Porto


Oliveira Maria Cristina

Universidade de Trás-os-Montes e Alto Douro


Oliveira Raquel Universidade do Minho


Ornelas Isabel Faculdade de Ciências da Universidade de Lisboa


Pereira Carlos Faculdade de Ciências da Universidade do Porto


Pinheiro Jose Paulo Universidade do Algarve

Faro [email protected]

Proença Luis ISCS Egas Moniz Almada [email protected]

Realista Sara Faculdade de Ciências da Universidade de Lisboa



69

Rego Rosa Universidade de Trás-os-Montes e Alto Douro


Ribeiro José Faculdade de Ciências da Universidade do Porto


Santos Ana Catarina

CENIMAT - I3N FCT - Universidade Nova de Lisboa

Lisboa anacatarinasantos123@gmail.

com

Santos Lídia CENIMAT - I3N FCT - Universidade Nova de Lisboa


Salomé Sónia Universidade de Trás-os-Montes e Alto Douro


Silva Carlos Universidade do Minho


Silva Rui Pedro Instituto Superior Técnico


Silveira Célia REQUIMTE - FCT Universidade Nova de Lisboa


Soares Helena ICETA / REQUIMTE/FEUPUniversidade do Porto


Truta Liliana Instituto Superior de Engenharia do Porto

PORTO [email protected]

Unwin

Patrick University of Warwick

Warwick [email protected]

Vaz Pereira Elsa LNEC Lisboa [email protected]

Viana Ana Faculdade de Ciências da Universidade de Lisboa


Vicente Cilene Instituto Politécnico de Setúbal

Setúbal [email protected]

Zheludkevich

Mikhail

CICECO Universidade de Aveiro



70


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