Carbon Nanotube Biopolymer based Biosensor for the Electrochemical

Detection of Neurotransmitters

Sudheesh K. Shukla, Avia Lavon, Offir Shmulevich, Hadar Ben-Yoav*

Department of Biomedical Engineering,

Ben-Gurion University of the Negev, Beer Sheva, 8410501, Israel * Tel: (+972) 8-6479717; E-mail: benyoav@bgu.ac.il

Acknowledgment: The authors thanks the Ilse Katz Institute for Nanoscale Science & Technology for their help in material characterization tests.

Conclusions and future work

Carbon nanotube (optimized %)-chitosan composites is a promising electrochemical interface for the neurotransmitter

detection have 0.16 µA current with the electron transfer rate of 1.339 cm s-1 and diffusion co-efficient of 1.18 x 10-14 cm2s-1.

Surface characterization validating the controlled distribution and encapsulation of optimized CNT ratio in chitosan matrix

and enhancing the roughness of the CNT-CHIT composite and differentiating the potential of interfering species.

The result exploring the understanding of CNT-CHIT interface for its better utilization in electrochemical micro-systems for

the molecular detection different analytes.

Future work involves validating the developed NTs sensor in in vitro and in vivo settings with living cells and brain tissue.

Challenge

Accurate detection of NTs is

prevented by co-exiting

interfering species (e.g. uric

acid).

Motivation

Neurotransmitters (NTs), are the biochemical messengers that transfer biological signal

from the brain to the whole body and govern their metabolic and physiological functions.

Deficiency of neurotransmitters can cause severe brain disorder, such as Schizophrenia

and Parkinson's disease with symptoms of coma, depression and sleepiness.

Our Research Aim

Development of a carbon nanotubes-

biopolymer and its integration in

microfabricated devices for the selective and

sensitive detection of redox-active NTs.

Nanobioelectronics Laboratory (NBEL)

Material Synthesis and Integration Approach of the Electrochemical Biosensor

Carbon Nanotube -0

.1 0.0

0.1

0.2

0.3

0.4

0.5

0.6

-1.2

-0.9

-0.6

-0.3

0.0

0.3

0.6

0.9

1.2

Cu

rre

nt

(A

)

Potential (V)

Chitosan

Optical and Electrochemical Characterization

D

Scanning electron microscope (SEM) characterization of (a) chitosan, (b) CNT, (c)

CNT-CHIT composite. Energy dispersive X-ray spectroscopy of (d) chitosan and (e)

CNT-CHIT composite. SEM results reveals the surface morphology of chitosan and

encapsulation of CNT in chitosan to relay the organized conductance of materials. The EDS

result supporting the incorporation of CNT with chitosan by increasing counting percentages

of element in CNT-CHIT composite than chitosan alone.

X-ray diffraction

(XRD) pattern of

chitosan and CNT-

CHIT composite.

XRD study supporting

the crystalline

behaviour of CNT-

chitosan thank

chitosan alone.

0.1 0.2 0.3 0.4 0.5 0.6

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

Cu

rre

nt

(A

)

Potential (V) Vs Ag/AgCl

Bare Au electrode

CHIT modified Au electrode

1% CNT-CHIT modified Au electrode

1.50 % CNT-CHIT modified Au electrode

1.75% CNT-CHIT modified Au electrode

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

-1.2x100

-9.0x10-1

-6.0x10-1

-3.0x10-1

0.0

3.0x10-1

6.0x10-1

9.0x10-1

1.2x100

5 mVs-1

10 000 mVs-1

Cu

rre

nt

(A

)

Potential (V) Vs Ag/AgCl

References

o E. Kim et al., Adv. Funct. Mater. 2015, 25, 2156-2165.

o M.A. Mohammed, A.K. Attia, H.M. Elwy, Electroanalysis, 2016, 28,

Early view.

o A. Joshi, S.N. Chava, D. Mandal, T.C. Nagaiah, Electroanalysis,

2016,

28, Early view .

Scheme for the fabrication of electrochemical sensor approach based on carbon nanotube-chitosan (CNT-CHIT) composites for the detection of neurotransmitters.

Dopamine Biosensor

Introduction

(a) (b)

20 30 40 50 60

Chitosan-CNT

Inte

nsi

ty (

a.u

.)

2(degree)

Chitosan

Atomic force microscopy (AFM) of (a) chitosan and (b) CNT-CHIT composite. AFM studies reporting the

surface information, roughness and size distribution of the materials.

(a) (b)

(d)

(e)

(c)

Cyclic voltammograms of comparative CV response of bare Au electrode, chitosan

modified and different ratio of CNT (1%, 1.5% and 1.75%) -CHIT modified Au

electrode. CVs show the high current response with the highest loading of CNT due to

its conducting behavior.

Cyclic voltammograms of 1.75% CNT-CHIT composite/Au in 5 mM [Fe(CN)6]3-/4- on

increasing scan rate from 5 mVs-1 to 10 000 mVs-1. Results shows the stability of the CNT-

chitosan composite materials over the Au electrode. CNT-CHIT composite materials showed

the promising electron transfer rate and diffusion coefficient .

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

20

25

30

35

40

45

50

Cu

rre

nt

(A

)

Potential (V) vs Ag/AgCl

a

j

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

20

25

30

35

40

45

50

55

60

(f)

(e)

(d)

(c)

Cu

rre

nt

(A

)

Potential (V) vs Ag/AgCl

(a) PBS

(b) PBS+Uric Acid

(c) 1 +dopamine+Uric Acid

(d) 5 +dopamine+Uric Acid

(e) 10 +dopamine+Uric Acid

(f) 25 +dopamine+Uric Acid

(a)

(b)

Detection of

dopamine using

differential pulse

voltammetry (DPV)

of CNT-CHIT

electrode in

phosphate buffer

(0.1 M, pH 7.4)

containing various

level of dopamine

concentration (0

µM, 0.1µM, 0.5µM,

1µM, 5 µM, 10 µM,

25 µM, 50 µM, 100

µM, 200 µM).

Detection of dopamine using DPV of CNT-CHIT electrode in phosphate buffer (0.1 M, pH

7.4) containing various level of dopamine (c to f) the presence of respecting interference

uric acid.

0 50 100 150 200

20

25

30

35

40

45

50

55

60

(b)

y= 1.369 x + 28.18

R2= 0.7854

Cu

rre

nt

(A

)

[DA] in M

y=0.140 x+24.89

R2=0.9453

(a)

Current peak response vs

dopamine concentration in the

presence (b) and the absence (a)

of uric acid. The resulted

sensitivity and limit of detection in

the absence of uric acid were 1.369

µA/µM and 0.1 µM, respectively.

The resulted sensitivity and limit of

detection in the presence of uric

acid were 0.140 µA/µM and 5 µM,

respectively. These variations in

sensing performance are due to the

interference of the uric acid.