GENERAL SEMINAR 2009.pptx

8/14/2019 GENERAL SEMINAR 2009.pptx

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One Dimensional Assemblies of

Nanoparticles

Pratheesh V. Nair

Photosciences & Photonics Group

Chemical Sciences and Technology Division

NIIST (CSIR)

Trivandrum


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Introduction to nanoscale assemblies

One dimensional assemblies; preparation methods

Properties and applications

Future perspectives

Conclusion


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What is nano ?

Nanomater ials

Def ini t ion :- Part ic les of any matter having on e of its dimension s in the range1-100 nm

Capabilityto manipulate, control, assemble, produce

and manufacture things at atomicprecision

The prefix nano- comes from the Greek word for dwarf.

In science, nano means a measure of 10-9units.


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Importance-

Exhibit characteristic physical and chemical properties different from that

of bulk

Properties can be tailored by varying their size and shape

For any application their integration into higher order assemblies is essential

Nanoscience and nanotechnology pertain to the synthesis, characterization,

exploration, integration and utilization of materials, which are characterized by

at least one dimension in the nanometer (1 nm = 10-9m) range


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Nanoscale Building Blocks

Metal Nanostructures (Au, Ag, Cu, Pt, Pd )

Semiconductor Nanostructures (CdS, CdSe, CdTe InP, GaN)

Carbon Nanostructures (CNTs, Fullerenes, Graphene )

Quantum Dots

Quantum Rods Fullerene clusters

Carbon nanotubes

20 nm

u Nanorods

20 nm

g Nanoprisms


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Where are we now ?


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Current research on nanoparticles can be classified into two main trends

Manipulation and exploration of single NPs in devices thus reaching the

limit of miniaturization possible for electronic circuits.

Application of NPs/polymer composites as macroscale thin films

producing a new generation of currently using devices.

Angew. Chem. Int. Ed. 2006,45,5796

Nano LEDs

Quantum dot Solar cells

J. Am. Chem. Soc. 2006,128, 1385

J. Am. Chem. Soc. 2006, 128, 2115.

Bio-imaging

Paper batteries

PNAS, 2007, 104, 13574.


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How can we integrate nanomaterials into higher order structures having

well defined size, shape and function ?

they prov ide direct br idges between nanometer scale ob jects and

macroscale wo r ld

can play cr i t ical roles in the impro vement o f eff ic iencies of var ious

dev ices b ased o n n anopar tic les and their composi tes

can help in the und ers tanding of v arious b io logical processes and

quantum mechanical concepts

Top dow n

Lithography

Stamping (microcontact

printing)

Bot tom up

Self-assembly

Template assisted

Why nanoscale assemblies ?


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Nanoparticle assemblies can be classified into three categories ;

Techniques for 2D and 3D NP assemblies;

a)SolventEvaporation b)LangmuirBlodgettTransfer c)Layerbylayerassembly

a) One dimensional (1 D)

b) Two dimensional ( 2 D)

c) Three dimensional (3 D)


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Solvent Evaporation

The relatively weak attractions between nanocrystals, which are efficiently screened in

solution, become manifest as the solvent evaporates, initiating assembly of intricate,

slowly evolving structures.

J. Colloid Interface Sci.2006, 301,703.Dissipative dewetting followed byself-assembly of NPs

TEM images of nanoparticle aggregates

after solvent evaporation


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Langmuir Blodgett Transfer

Generally, a LangmuirBlodgett film contains one or more monolayers of an organic

material, deposited from the surface of a liquid onto a solid by immersing (or emersing)

the solid substrate into (or from) the liquid.

Well ordered ultra thin films

Direct detection of defects/cracks on surface

layer stability and contamination..!


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Layer by layer assembly

Layer-by-layer (LBL) assembly is a simple and versatile method for material design

with nanometer scale control over internal architecture

Device fabrication

Functional Coatings

Biomedical Applications

Scheme of the LBL film-deposition

Steps 1 and 3 represent the adsorption of polyanion

and polycation, steps 2 and 4 are washing steps.


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1-D assemblies of NPs: Preparation methods

Lineartemplate

method

Preparation methods

Selfassembly

method

Polyelectrolytes

biomolecules

InorganicNWsandtubes

Othertemplates

Magnetic

dipole moment

Electric dipole moment

Oriented attachment

Hydrogen Bonding


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Lineartemplate method

Directional organization ; critical step for the fabrication of 1 D assemblies

Soft templatesOrganic Polyelectrolytes and biomolecules

Hard templates Inorganic nanotubes and nanowires

Polyelectrolytes are polymers whose repeat ing

units bear an electrolyte group ; Dissociates in

aqueous solut ion s, making the polymers charged.

Polystyrene sulfonate (PSS)

How they act ?

Act as a scaffold for the adsorption of metal ions with opposite charges

Ion adsorbed polyelectrolyte templates can transform to 1 D NP assemblies
http://upload.wikimedia.org/wikipedia/en/3/32/Polyelectrolyte_examples.png


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Mineralization of Single Flexible Polyelectrolyte Molecules

Minko et al, J. Am. Chem.Soc. 2002,124,10192.

Poly(2-vinylpyridine) (P2VP) was deposited on the surface of Si-wafer or mica in

different conformations from an elongated wormlike coil to compact globule.

AFM images of various conformations of P2VP

molecules on a solid substrate

Poly(2-vinylpyr idine) (P2VP)

conformational transitions from stretched wormlike coil to necklace-likeglobule, and to compact globule

the fraction of charged monomers decreases with an increase of pH and ionicstrength.


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Mineralization of PE

Electrostatic adsorption of PdCl42-

onto cationic P2VP chains

Reduction with dimethylamine

borane to get Pd NP assemblies

Cross-section profiles of Pd-nanowiresAFM images of Pd NP decorated PE chains

( single Pd nanoparticles are visible )


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Biomolecules as templates

A perfect choice for 1 D assembly of nanoparticles !!!!!

The versatility of experimental methods for the manipulation of their structure

Excellent experimental foundation for such studies developed in the life-science field

Biological templates, such as DNA, protein cages, viroid capsules, bacterial

rhapidosomes, multicellular superstructures, biolipid Cylinders, linear fibrous

biomacromolecules like fibrin, dextran and collagen have been utilized to direct

the deposition, assembly, and patterning of inorganic nanoparticles and

microstructures.


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DNA: A Programmable Nanoscale Assembly Material

Attractive Nanomaterial Properties of DNA:

Strong electrostatic and coordination interactions with metal nanoparticles

Synthetic versatility: vary length, sequence, backbone, branched

Easily modified for conjugation to molecules, nanoparticles

DNA-linked nanoparticles

100 nm

Chem. Mater.2005, 17, 1628.

Science, 2003, 302 , 1545.

DNA-wrapped CNTs

Inorg. Chem. 2000,39, 2258.


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Linear Assemblies of Nanoparticles Electrostatically Organized on DNA Scaffolds

Warner et al,Nat. Mater. 2003, 2, 272-277.

Electrostatic assembly of cationic NPs onto the anionic backbone of DNA

Wide range of structures including closely spaced linear arrays, ribbons or

bundles and branched assemblies.

linear arrays

ribbons or bundles

branched

assemblies


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Monitoring the assembly process

in solution by UV-Vis spectroscopy

Precipitation of the hybridsystem as a function of time

Linear arrays Ribbons or bundles Branched assemblies


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Au Nanocrystal Growth on Nanotubes Controlled by Conformations

and Charges of Sequenced Peptide Templates

Matsui et al, J. Am. Chem.Soc. 2003,125,5873.

Self-assembly of bis(N-R-amid o-glyc ylg lycin e)-1,7-heptane dic arbox ylatemolecules into nanowires.

Immobilization of a histidine-rich peptide on the nanowires at the binding sites.

Addition of Au salt into nanowire solution and reduction using hydrazine hydrate

bis(N-R-amido-glycylglycine)-1,7-

heptane dicarboxylate

Scheme of the Au nanowire fabrication

A-H-H-A-H-H-A-A-D


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The Influence of pH upon Au Nanocrystal Growth

Higher packing density at higher pH

43 %

78 %

pH - 8 pH - 12

packing density increases

with incubation time

i d b


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Inorganic NWs and Nanotubes

Preparation methods can be classified into three

1, Direct chemical deposition

2, Sol-gel decoration

3, Specific adsorption

Known as hard templates

most common templates are carbon nanotubes

Greater hardness and toughness ; preservation of structure and shape intact

Nature.1993

, 361,333

.

Adv. Mater., 2000, 19, 1430.

Chem. Mater., 2001, 13, 2864.

Nano Lett. 2003, 3, 723.

J. Phys. Chem. C. 2003, 107, 2453.

Chem. Eur. J., 2003, 9, 1898.

Nano L ett. 2004, 4, 225.

Science 2004, 304, 1787.

Adv. Mater., 2004, 16, 929.

Nano Lett. 2002, 2, 1253.


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Aligning Au Nanorods by Using Carbon Nanotubes as Templates

Liz-Marzan et al, Angew. Chem. Int. Ed. 2005,44,4375.

uniform electrostatic assembly of Au nanorods on MWNTs

rods form strings with end-to-end contacts

uniaxial plasmon coupling

TEM images of Au assembled on

MWNTs (average diameter 30 nm) Surface plasmon coupling in Au nanorods


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Brust. M and co workers, Adv. Mater. 2001,13,1800.

Template ; a corrugated thin film of amorphous carbon withtopographical features of nanometer dimensions.

PTFE lines on a

glass substrate

Vapour deposition

of carbon filmCarbon

replica

Au NP

solution

Evaporation Self-assembly of

Au NPs in rows

Templated Gold Nanowire Self-Assembly on Carbon Substrates

AFM image of PTFElines on glass substrate

TEM image of self-assembled

lines of Au NPs on carbon

replica

Au nanowire obtained after

heat treatment

Template Free Self Assembly method


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Template- Free, Self - Assembly method

1. Templates may affect the properties of nanoparticle assemblies.

2. Removal of templates is not easy.

3. Morphological or structural alterations to the NP chains.

Demerits of template assisted synthesis

Magnetic Dipole Moments

The magnetic NPs can self-assemble into one-dimensional chains onsubstrates and in colloid dispersions through magnetic dipolarinteraction without the help of an applied magnetic field.


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Chain formation and anisotropy of magnetic NPs have been well-known in nature

TEM image of a magnetotactic bacterium,

Desulfovibrio magneticus strain RS-1, showing

a chain of bullet-shaped magnetosomes aligned

along the Earth's magnetic field.

agnetotactic bacterium a biological compass

Tokyo University of Agricultur e and Technology

Magnetosomes ineukaryotic algaeNP chains in frontaltissues of Chinook salmonMagnetoSpirillum MS-1)


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Self-Assembly of iron oxide nanoparticles through magnetic dipole interactions

Zhang et al, J. Phys. Chem. C. 2008,112,15151.

Magnetic dipole interactions in weakly ferromagnetic nanoparticles

Under an applied magnetic field, the nanostructures can be oriented aligning

with the external magnetic field.

TEM images of aligned nanoparticles

Electric Dipole Moments


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Electric Dipole Moments

prevalent in semiconductor nanoparticles due to either the presence of an

anisotropic crystal lattice or surface defects.

Strong electrostatic or steric repulsion from stabilizers overcompensates

electric-dipole attractions between NPs.

Repulsive forces electrostatic interactions

VT= VA+ VR

VA= -A/(12 D2) - attractive forces

VR= 2 a 2exp(-D) - repulsive forces

DLVO Theory

Attractive forces van der Waals

interactions and dipoledipole interactions


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How to overcome the repulsion..? Partial removal of the stabilizer !!!

Organization of CdTe NPs into nanowires upon partial removal of the of organic stabilizer

Kotov and co workers, Science, 2002, 297, 237.

CdTe quantum dot to nanowire transformation in phosphate buffer solution

Rogach and co workers, J. Phys. Chem. C. 2007,111,18927.


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Hydrazine

Ligand removal

CdTe QDS CdTe nanowire

Hydrazine induced one dimensional organization of CdTe QDs

Hydrazine is a Bronsted base and can gently react to remove the capping ligands from the

nanocrystal surface.

Hydrazine is a reducing agent, preventing oxidation of QD surface and repairing any

oxidized tellurium surface sites.

Pratheesh V. Nair and K. George Thomas J. Phys. Chem. Lett. 2010

O i t d A ti


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Oriented Aggregation

Oriented aggregation is a special case of aggregation that provides an important

route by which nanocrystals grow and unique, often symmetry-defying, crystal

morphologies are produced.

Oriented attachment may occur by

collisions of aligned nanocrystals in suspension

or

rotation of misaligned NPs in contact toward low-energy interface configurations

Oriented

attachment

1 D

growth

misaligned NPs aligned NPsNanowires

Formation of Ag nanowires from Ag NPs through oriented attachment


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Formation of Ag nanowires from Ag NPs through oriented attachment

Liz-Marzan et al, J. Mater. Chem. 2004,14,607.

Evidence of an aggregative mechanism during the formation of silver nanowires in DMF

HRTEM images showing the various steps during the formation of Ag

nanowires from individual Ag nanoparticles

Formation of Ag nanowires by solvent reduction in DMF, in the presence of

poly(vinylpyrrolidone) (PVP) at high temperature

Self Assembly of ZnO: From Nanodots to Nanorods


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Self-Assembly of ZnO: From Nanodots to Nanorods

Weller et al, Angew. Chem. Int. Ed. 2002,41,1188.

Formation of high-quality single crystalline ZnO nanorods from spherical ZnO

nanoparticles through oriented attachment.

lattice planes go straight through the contact areas

particles are epitaxially fused together

bottlenecks between the adjacent particles are still visible

individual nanoparticles aligned nanoparticles nanorods

Hydrogen Bonding
http://en.wikipedia.org/wiki/File:3D_model_hydrogen_bonds_in_water.jpg


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Hydrogen Bonding

A hydrogen bond is the attractive force between the hydrogen

attached to an electronegative atom of one molecule and an

electronegative atom of a different molecule.

Hydrogen-Bonding-Assisted Self-Assembly of polymers

J. Am. Chem. Soc. 2009,131, 13594 Langmuir, 2008, 24, 7727.

U i i l Pl C li th h L it di l S lf A bl f G ld N d
http://pubs.acs.org/action/showImage?doi=10.1021/ja905240w&iName=master.img-001.jpg&type=masterhttp://en.wikipedia.org/wiki/File:3D_model_hydrogen_bonds_in_water.jpg


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Uniaxial Plasmon Coupling through Longitudinal Self-Assembly of Gold Nanorods

George Thomas and co workers, J. Phys. Chem. B. 2004,108,13066.

Absorption spectra of gold nanorods

recorded immediately after the

addition of MPA

Properties and applications


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p pp

1D NP assemblies exhibit many collective properties, which are evidently

different from single NPs.

Drastic effects on the optical response from surface plasmon absorption is

found when metallic NPs form rods, chains or sheets

Time-dependent optical studies to elucidate the mechanism of chain self-assembly

Decrease in intensity of surface plasmon band at 520 nm and formation of a shoulder at

higher wavelength

Adv. Mater. 2005,17, 2553.


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One-Dimensional Energy Transfer in CdTe Nanoparticle Chains

Presence of Frster resonance energy transfer (FRET) between QDs in the chain.

Red shift of 36 nm

J. Phys. Chem. B. 2004,108,6927.

Nanochains of CdTe QDs formed from

individual particles through dipole -

dipole interaction


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Gas sensors

Absorption of H2 led to the expansionof the crystalline lattice of Pd.

Gap between Pd NPs in an array

decreased, leading to higher electron

transfer.

On venting the H2, a reversible affect

was observed.

Hydrogen Sensors and Switches from

Electrodeposited Palladium nanowire Arrays

Science, 2001,293, 2227

Sensors for biomolecules


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George Thomas and co workers, J. Am. Chem. Soc. 2005,127,6516.

Selective Detection of Cysteine and Glutathione Using Gold Nanorods

1 D A bl f P id F i li d A NP A A h T d M I S i


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1-D Assembly of Peptide-Functionalized Au NPs: An Approach Toward Mercury Ion Sensing

Mandal, T. K. and co workers, J. Phys. Chem. C. 2007,111,1248.

Detection limit4 ppm

Future Perspectives


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p

Development of preparation methods for large-scale production as well as

precise positioning of 1D NP arrays.

Better understanding of the formation mechanism of template-free NP

chains.

Control of interparticle distances in NP chains, so that distance-dependent

photonic and electronic transfer along the NP chains could be realized.

Production of NP chains consisting of multiple components, for example,

1D hybrid chains of metal and semiconductor NPs.

Conclusions


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Controlled organisation of nanoparticles is an essential step for the

fabrication of nanomaterial based devices.

One dimensional organisation of NPs can be achieved either by template

assisted synthesis or by self assembly method.

The collective properties of 1D NP assemblies are evidently different from

single NPs.

1 D NP assemblies can be used as sensors for gases, bimolecules and toxic

metal ions.

There are plenty of unknown phenomena awaiting exploration and there are

also many problems requiring resolution.


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GENERAL SEMINAR 2009.pptx