MATERIALS ON THE NANO-SCALE FOR DIFFERENT APPLICATIONS

M. A. El-SayedGeorgia Tech.

OUTLINE1. For Catalysis.

2. For Sensing.

3. For Medicine.

NANO_PARTICLES FOR CATALYSIS

7.1 nm Cubes with {100} facets 4.8 nm Tetrahedral with {111} facets

Ahmadi, T.; Wang, Z. L.; Green, T. C.; Henglein, A.;El-Sayed, M. A., Science 1996, 272, 1924.

MORE REACTIVITY FOR ATOMS ON CORNERS AND EDGES

Narayanan, R.; El-Sayed, M. A., Nano Lett., 2004, 4(7), 1353.

Nanoparticle Shape

Tetrahedral (~76%)

Cubic (~61%)

Spherical (~85%)

Nanoparticle Size (nm) 4.8 + 0.1

7.1 + 0.2

4.9 + 0.1

Fraction of AtomsOn corners&edges

0.35

0.04

0.13

Activation Energy (kJ/mol) 14.0 + 0.6

26.4 + 1.3

22.6 + 1.2

Catalytic activity correlates with the fraction of atoms located on the corners and edges of the nanoparticles.

BY Photocatalysis in 50 nm Au Nanocage

USING CHEMICAL CONFINEMENT IN NANO-CAGES ENHANCES THE CATALYTIC ACTIVITY

(NANO-REACTORS). Application IN SOLVING Environmental

problem

BULK GOLD IS PRECIOUS BECAUSE IT DOES NOTHING (it does not tarnish i.e. it does not react with O2 )

Tutankhamun’s coffinDeath Mask of Tutankhamun~1325 B.C.

Gold nanoparticles Plasmonic Properties on the NANOSCALE CAPTURING THE PHOTON TO INDUCE The Surface Plasmon RESONANCE (SPR) Oscillation with Strong Surface-Fields?

light (520nm) Au Nanoparticle (50 nm)

+

1. The Electromagnetic field of the captured Photon is Enhanced by Thousands of Times on the surface of the nanoparticle as a Result of the Coherent Oscillation Of the Collective Excitation of the Free Electrons in the Metal Cluster.

2. THIS Enhances The Rate of their Absorption (sensing) and Scattering (SERS;imaging and thus sensing) Proprties.

3. The Strongly Absorbed Energy is Rapidly Converted Into Heat That Can Have Useful Photo-Thermal Applications in Different Fields e.g medicine.

near-field

Capturing the photon

photon

300 400 500 600 700 800 900 1000 1100 1200-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

950, 5.6870, 4.8800, 3.9720, 3.1

Normalized Optical Density

Wavelength (nm)

650, 2.4

2.4

3.9

5.6

40nm

Optical tunability of gold nanorods

Xiaohua Huang, Ivan H. El-Sayed and Mostafa A. El-Sayed, JACS, 2006, 125 (6), 1215-1220.

Gold or Silver Nanoparticles can Enhance the intensity of light of Different Colors by changing Their Size or Shape

100 nm

Solid Silver Nanocubes Gold Nanoframes (BEST SENSOR)

Gold Nanocages(BEST CATALYST)

Hollow nanoparticles

Hollow nanostructures characterized by the presence of two surfaces (and thus have two plasmon fields inside and outside the cage). The coupling between these two fields is responsible for enhancement of the overall plasmon field. They are then better sensors and BETTER ‘OPTICAL LENSES'.

The surface to volume ratio is higher for hollow nanoparticles than that for solid nanoparticles with the same outer shape and size. This together with their confining ability of the reactant and intermediates make them better catalysts (and drug carrier )

8

solid Nancubes

Mahmoud A Mahmoud

PLASMONIC FIELD ENHANCEMENT OF THE PHOTO-CURRENT FROM THE PROTON PUMP IN BACTERIO-RHODOPSIN; THE OTHER NATURAL

PHOTO-SYNTHETIC SYSTEM

CHUN-WAN YEN LI-KANG CHU

Yen, C.W.; Hayden, S.C.; Dreaden, E.C.; Szymanski, P.; El-Sayed, M.A., Tailoring Plasmonic and Electrostatic Field Effects to Maximize Solar Energy Conversion by Bacteriorhodopsin, the Other Natural Photosynthetic System. Nano Letters, 11(9), 3821-3826 (2011 CITED By Nature Materials 10, 646 (2011) .

APPLICATION OF PLASMONIC OPTICAL ENHANCEMENT

IN SOLAR ENERGY CONVERSION:

STEVEN HAYDEN

• Light-driven Proton Pump

• Electrochemical Energy (proton gradient)

• Very Low solar conversion efficiency

Bacteriorhodopsin (bR):THE OTHER PHOTO-SYNTHETiC SYSTEM IN NATURE (besides

Chlorophyll)

Blue Light Effect

BLUE LIGHT

FROM MEMBRANE INTO SOLUTION

FROM MEMBRANE

Yen, C. W.; Chu, L-K.; El-Sayed, M. A. JACS, submitted

Selection of the Nanoparticle with the best plasmonic enhancement of the M absorption

(the best enhancement of the Blue Light Effect)Maximize The overlap of

M state Absorption and SPR ExtinctionOf the nanoparticle:

1. Ag NPs: Green Spectrum, overlaps well With the Blue M absorption.

2Ag-Au alloy NPs: Orange Spectrum (Ag/Au=1/1): not as good

3. Au NPs: Red Spectrum Not good at all

THE BEST OVERLAP WITH THE M ABSORPTION IS THE EXTINCTION SPECTRUM OF THE Silver NANOPARTICLE OF 30 nm SIZE.

Plasmonic Field Strength Dependence on Nanoparticle Shape

5000 times larger current than that reported in literature (with Bias Applied)

• Charge carrier separation

• Least screening / Best stability(55k PVP)

• Highest field / Best spectral overlap (Ag Cuboidal)

• 0.2 μA/cm3 (No Bias)

Tailoring Plasmonic Electric Field Effects

APPLICATIONS IN MEDICINE

20 µm

HaCaT noncancerous

cells

HOC cancerous

cells

HSC cancerous

cells

10 µm

Ivan El-Sayed,Xiaohua Huang,M.A.El-Sayed Nanoletters ,4, 829,2005.

DETECTION OF ONE CANCER CELL USING LIGH SCATTERING FROM SELECTIVELY BOUND GOLD

NANO-PARTICLES USING A STUDENT MICROSCOPE

DIFFRACTION UNLIMITTED IMAGING

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Δ V

(mm3)

day

directtailcontrol

UNTREATED

I.V. Accumulation

direct injection

COMPARISON OF THE GROWTH RATE OF THE TREATED & THE UNTREATED

TUMOR

Dickerson, E. B.; Dreaden, E. C.; Huang, X.; El-Sayed, I. H.; Chu, HDickerson, E. B.; Dreaden, E. C.; Huang, X.; El-Sayed, I. H.; Chu, H.; Pushpanketh, S.; McDonald, J. F.; El-Sayed, M. A. Cancer Letters 2008, 269, 57.

ERIN HENDERSON

2.Confining Precious Metal(Au,Ag) Nanoparticles to the Cancer

Nucleus:CAN IT STOP CELL DIVISION

and thus stops cancer??

Lauren A. Austin Megan A. Mackey Bin Kang Chun-Wan Yen

DEFECTIVE CANCER CELL DIVISION FOR CELLS HAVING

0.4 NM GOLD IN THE NUCLEUS

Watching the Behavior of a Community of Dying Cancer Cells by binding Silver Nano-particles to their Nucleus

THANK YOU