'Plug and Play' nanoparticle recognition and assemblyrecognition-functionalized colloids can serve many purposes

surface modification

sensors and devices

materials

biomolecular recognitionsolution-based receptors

Noble metal nanoparticles provide a versatile building blockBrust-Schiffrin reaction provides nanoparticles of regular size and shape

NaBH4

HSS

S

S

SS

SSSSSSSS S

SS

Murray place-displacement reaction allows divergent modification

S

S

S

SS

SSSSSSSS S

SS

HSS

S

S

SS

SSSSSSSS S

SS

HS

S

S

S

SS

SSSSSSSS S

SS

HAuCl4or

PdCl2or...

20 nm Brust, M.; Walker, M.; Bethell, D.; Schiffrin, D. J.;Whyman, R. J. Chem. Soc.-Chem. Commun. 1994, 801-802.

Ingram, R. S.; Hostetler, M. J.; Murray, R. W. J. Am. Chem. Soc. 1997, 119, 9175.

but how do we bridge the gap to photolithographic techniques (100 nm)

SSSSS S

SS

HSNSSS

N

NOO

H

N

O

O

H

Au

'Bricks and Mortar' Fabrication of nanoparticle arrays

OMeN N

N N

N

HH

HH

n= 10

the bricks: randomly functionalized 2 nm Au colloids

the mortar: randomly functionalized copolymers

T. Galow, F. Ilhan, G. Cooke, V. Rotello, J. Am. Chem. Soc., 2000, 122, 3595-3598.F. Ilhan, M. Gray, V. Rotello, Macromolecules, 2001, 34, 2597-2601.

The plan:if the density of functionality on the mortar is greater than on the bricks....

Thy-Au

Polymer

then polymer should glue nanoparticles together

predicted particle-particle distance=4.4 nm

Polymer + colloid = solid

precipitation observed over 24 h from CH2Cl2

and the solid shows structure (by SAXS)!

+ black solid

.0.00

Thy-Au.polymer

Thy-Au5

10

20

25

0.5 1.5 2.0Q (nm-1)

intensity(a.u.)

maximum indicates interparticledistance =4.4±0.3 nm

this agrees perfectly withpredicted 4.4 nm particle spacing

sharp increase in scattering at small Qsuggests long range order (>20 nm)

?

A. Boal, F. Ilhan, J. DeRouchey, T. Thurn-Albrecht, T. Russell, V. Rotello, Nature, 2000,404, 746-749

sharp increase at small Q sayssomething big is here…

The solid is composed of 100 nm spherical gold aggregates!

dissolution of solid in THF allows TEM microscopy

1000 nm50 nm

solid is composed of 100±17 nm giant spherical assemblies, each with~7000 individual nanoparticles

A. Boal, F. Ilhan, J. DeRouchey, T. Thurn-Albrecht, T. Russell, V. Rotello, Nature, 2000,404, 746-749

At even lower temperatures: the Death Star!500-1000 nm arrays formed at -20°C

over 2.5 million individual particles!

50 nm

hard work has shown that the effects of polymer length, particle size, functionality,

solvent, and temperature on particle size/shape are utterly unpredictable.

what do we do??????where do we go next?

Xu, H.; Hong, R.; Lu, T.; Uzun, O.; Rotello. V. M.J. Am. Chem,. Soc., 2006, 128, 3162-3163.

One current direction in materials...magnetism!control of aggregate size/spacing=control of bulk and local magnetic properties

step 1: functionalization of superparamagnetic Fe2O3 nanoparticles

Fe2O3 particles prepared usingAlivasatos' high temperaturecupferron prep

A. Boal, K.Das, M. Gray, V. Rotello Chem. Mat.2002, 14, 2628-2636.

NN

NFe2O3

HOHO

X

Y OO

Fe2O3X

Y

stable functionalizedparticles

RT

step 2: recognition element functionalization of Fe2O3 nanoparticles

NN

NFe2O3

RTFe2O3

HO

HO

O

O

N N

OH

O

O

O

O

O

N N

OH

O

Boal, A. K.; Frankamp, B. L.; Uzun, O.; Tuominen, M. T.; Rotello, V. M. Chem.Mat. 2004,16, 3252-3256.

..

0.01

0.1

1

10

0 0.05 0.1 0.15 0.2 0.25

0.1

1

10

100

Inte

nsity

(A.U

.)

Q

d=6.9 nm

d=7.9 nm

"Bricks and Mortar" assembly controls interparticle distanceshypothesis: increased interparticle distance = decreased dipolar coupling

decreased dipolar coupling=lower blocking temperature (TB)

Temperature (K)

2

4

6

8

10

12

14

0 50 100 150 200 250 300

M (

emu/

g)

hexanes

polymer assembledTB=37 K

precipitatedTB=52 K

assembly controls spacing spacing controls magnetism

ongoing studies: dendrimer and diblock copolymer assembly

Magnetic Force Microscopy (MFM) of thin films

Dendrimer plus Nanoparticle gives aggregates

TEM shows increased spacing with increasing dendrimer generation

excess of dendrimer used to control internanoparticle spacing

it works qualitatively....

1 µm

20 nm20 nm

G4

G4G0

B. Frankamp, A. Boal, V. Rotello,J. Am. Chem. Soc., in press.

Frankamp, B. L.; Boal,, A. K.; Rotello, V. M. J. Am. Chem. Soc., 2002,124, 15146-15147.

SAXS demonstrates effective control of spacingas expected, higher generations show larger effects (packing and rigidity)

G2-6 dendrimer aggregates showed liquid packing (2σ),

while G0-1 were intermediate (~1.7σ) between liquid and solid

next stop: magnetic particles!

30

40

50

60

10

100

1000

0.1 0.2 0.3 0.4q (Å-1)

Hex G1G0 G2 G4 G6

Åa.u.

Frankamp, B. L.; Boal, A. K.; Tuominan, M. T.; Rotello, V. M. J. Am. Chem.Soc., 2005, 127, 9731-9735

Nanoparticles provide at least two out of three (ain't bad!)SAM-covered nanoparticles provide regular shape

and are the right size for biomacromolecule recognition

1 nm

a

core

functionalizedmonolayer

aspirin

heparin 12-merDNA 24-mer

p53 bound to DNA

The concept: dynamic control of receptor structureself-assembly of a self-assembled system

thiol monolayers are dynamic entities

can this dynamic aspect be harnessed to create and optimize polyvalent receptors?

dynamic receptor

crosslink

imprinted receptor

just like we used to think antibodies worked!

Verma, A.; Nakade, H.; Simard, J.M.; Rotello, V. M. J.Am. Chem. Soc, 2004, 126, 10806-10807.

Can we template to something biological?

Enzyme binding and inhibition using nanoparticles

size virtually identical to nanoparticle

"halo" of cationic and hydrophobic residues surrounds active site

well established enzymatic assays using chromogenic substrates

S N

S

N

SS

non-complementarycationic control

S

S

SS

COO

COO

chymotrypsin provides good initial target

complementary anionic inhibitor

cationic

anionic

hydrophobic

uncharged5.2 nm

.

200nM

80nM

20nM

[E]=800nM

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200 1400

Time (min)

V i/V

0

Charge complementarity required for inhibition

time-dependent inhibition with anionic-functionalized nanoparticles

nanoparticle-chymotrypsin stoichiometry of 1:4 results in >90% inhibition

anionic particles do not inhibit elastase, β-galactosidase

200nM cationic mmpc

no inhibition observed with cationic control

sucAAPF-pNA substrate

200 210 220 230 240

Wavelength (nm)

cht at 23° C

cht at 80° C

cht +inhibitor

cht and and inhibitor--24hr

190 250

Slow denaturation observed with particles

circular dichroism of chymotrypsin:

-little change initially (2-step process?)

-complete conversion to random coil over 24 hr

complete denaturation over 24 h

Hong, R.; Fischer, N. O.; Verma, A.; Goodman, C. M.; Emrick, T. S.; Rotello, V. M. J. Am. Chem. Soc., 2004, 126, 739-743.

Hong, R.; Emrick, T.; Rotello, V.J. Am. Chem. Soc., 2004, 126, 13572-13573.

You, C-C.; De, M.; Rotello, V. M. J. Am. Chem. Soc., 2005, 127, 12873-12881.

450 nM

75 nM

µ

Nanoparticles provide highly effective gene delivery agents

Cationic nanoparticles transfect mammalian cells

Green fluorescent protein (GFP) plasmid transfection of 273T cells

internalizednanoparticles

how efficient is the transfection?

what controls this efficiency?

Amphiphilic particles work betteroptimal transfection observed with ~70% cationic coverage

S N

S

N

SS

%cationic coverage

0

10

20

30

40

50

100 85 68 63 58

Milli

Units

β-ga

lact

osid

ase

Activ

ity

S N

S

N

SS

increasing chain length increases efficiency

S N

S

N

SS

S N

S

N

SS 0

200

400

600

800

1 2 3 PEI

Milli

Units

β-g

alac

tosid

ase

Activ

ity/m

g to

tal p

rote

in

MMPC

1

2

3

all of the systems are betterthan PEI, a popular commercialtransfection agent!

next step:-more complex monolayers-uptake and localization tags

K. Sandhu, J. Simard, C. McIntosh, S. Smith,V. Rotello, Bioconjugate. Chem., 2002, 13, 3-6.

Hong, R.; Han, G.; Kim, B.; Forbes, N. S.; Rotello, V. M J. Am. Chem. Soc.,2006, 128, 1078-1079.

Han, G.; You, C.-C.; Kim, B.-J.; Forbes, N. S.; Martin, C. T.;Rotello, V. M., Angew. Chem. 2006, 45, 3165-3169.

A brief summary (of a long talk!)

Nanoparticles provide:

Building blocks for nanomaterials-bricks and mortar assembly-orthogonal surface modification-controlled interparticle spacing with dendrimers

Scaffolds for biomolecular recognition -monolayers are self-templating-large surface area-tunable preorganization

Efficient delivery vectors-with tunable glutathione release

Alumni: grad studentsBing NieEric BreinlingerMichael GreavesAngelika NiemzRobert DeansAlex CuelloTrent GalowFaysal IlhanEunhee JeoungMark GrayAndy BoalHugues d’ CremiersKulmeet SandhuKanad DasKate GoodmanKate McKuskerHugues d’ Cremiers

Kanad DasKevin BardonJoe SimardRay ThibaultJoe CarrollOktay UzunNick FischerNandani ChariY-M LegrandJoe WorrallJoe FernandezBen FrankampRui Hong

Alumni: postdocsGilles ClavierAllan GoodmanAlam SyedUlf Drechsler

Acknowledgments:

Amitav SanyalTyler NorstenRoy ShenharBelma Erdogan

Current: postdocsChang-Cheng You“Pops” ArumugamYuval Ofir

Current: gradsHiroshi NakadeAyush VermaAli Bayir Hao XuGang HanSudhanshu SrivastavaBrian JordanRochelle ArvisoMrinmoy DeBappaditya SamantaPartha GhoshTongxiang LiuBasar GiderSarit AgastiOscar MirandaMichael PollierApiwat ChampoosorDap Patra

CollaboratorsGraeme CookeTodd EmrickSallie SmithJoe JerryNeil ForbesTom RussellJacques PenelleMark TuominenCraig Martin

FundingNIHNSFNSF CHM-NSECNSF MRSECKeck FoundationONR