'Plug and Play' nanoparticle recognition and assembly
recognition-functionalized colloids can serve many purposes
surface modification
materials
sensors and devices
biomolecular recognition
solution-based receptors
Noble metal nanoparticles provide a versatile building block
Brust-Schiffrin reaction provides nanoparticles of regular size and shape
HAuCl4
or
PdCl2
or...
HS
NaBH4
S S SS
S
S
S
S
S
S
S
S
SS
S S
20 nm
Brust, M.; Walker, M.; Bethell, D.; Schiffrin, D. J.;
Whyman, R. J. Chem. Soc.-Chem. Commun. 1994, 801-802.
Murray place-displacement reaction allows divergent modification
S S SS
S
S
S
S
S
S
S
S
SS
S S
HS
S S SS
S
S
S
S
S
S
S
S
SS
SS
HS
Ingram, R. S.; Hostetler, M. J.; Murray, R. W. J. Am. Chem. Soc. 1997, 119, 9175.
S S SS
S
S
S
S
S
S
S
S
SS
S S
but how do we bridge the gap to photolithographic techniques (100 nm)
'Bricks and Mortar' Fabrication of nanoparticle arrays
the bricks: randomly functionalized 2 nm Au colloids
O
H
N
O
N
O
S S S
N
HS
N
O
H
S
S S
S S
S
Au
S
S
the mortar: randomly functionalized copolymers
n= 10
H
N
N
OMe
N
H
H
N
N
H
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
+
black solid
?
and the solid shows structure (by SAXS)!
25
20
maximum indicates interparticle
distance =4.4±0.3 nm
Thy-Au.polymer
intensity
(a.u.)
this agrees perfectly with
predicted 4.4 nm particle spacing
10
Thy-Au
5
0
0.0
.
sharp
at small Q
sharpincrease
increase in
atscattering
small Q says
suggests
long
order (>20 nm)
something
bigrange
is here…
0.5
Q (nm-1)
1.5
2.0
A. Boal, F. Ilhan, J. DeRouchey, T. ThurnAlbrecht, T. Russell, V. Rotello, Nature, 2000,
404, 746-749
The solid is composed of 100 nm spherical gold aggregates!
dissolution of solid in THF allows TEM microscopy
1000 nm
50 nm
solid is composed of 100±17 nm giant spherical assemblies, each with
~7000 individual nanoparticles
A. Boal, F. Ilhan, J. DeRouchey, T. ThurnAlbrecht, 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
are utterly unpredictable.
where
do size/shape
we go next?
what do we do??????
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
X
HO
HO
N
Fe 2O3 N
N
X
Fe 2O3 O
Y
O
Y
RT
stable functionalized
particles
Fe2O3 particles prepared using
Alivasatos' high temperature
cupferron prep
A. Boal, K.Das, M. Gray, V. Rotello Chem. Mat.
2002, 14, 2628-2636.
step 2: recognition element functionalization of Fe2O3 nanoparticles
HO
O
HO
O
N
N
O
H
O
Fe 2O3 N
N
O
N
RT
Fe 2O3
O
O
O
O
N
N
O
H
Boal, A. K.; Frankamp, B. L.; Uzun, O.; Tuominen, M. T.; Rotello, V. M. Chem.
Mat. 2004,16, 3252-3256.
"Bricks and Mortar" assembly controls interparticle distances
hypothesis: increased interparticle distance = decreased dipolar coupling
decreased dipolar coupling=lower blocking temperature (TB)
..
assembly controls spacing
spacing controls magnetism
100
14
polymer assembled
TB=37 K
d=6.9 nm
10
12
precipitated
TB=52 K
10
0.1
M (emu/g)
hexanes
Intensity (A.U.)
1
d=7.9 nm
10
8
6
1
4
0.1
0.01
2
0
0.05
0.1
Q
0.15
0.2
0.25
0
50
100 150 200
Temperature (K)
ongoing studies: dendrimer and diblock copolymer assembly
Magnetic Force Microscopy (MFM) of thin films
250
300
Dendrimer plus Nanoparticle gives aggregates
TEM shows increased spacing with increasing dendrimer generation
G4
1 µm
G0
G4
20 nm
20 nm
excess of dendrimer used to control internanoparticle spacing
it works qualitatively....
B..,Frankamp,
Boal, V. Rotello,
Frankamp, B. L.; Boal,, A. K.; Rotello, V. M. J. Am. Chem. Soc
2002,124, A.
15146-15147.
J. Am. Chem. Soc., in press.
SAXS demonstrates effective control of spacing
as expected, higher generations show larger effects (packing and rigidity)
1000
60
Å
a.u.
50
40
30
100
Hex G0 G1 G2 G4 G6
10
0.1
0.2
0.3
0.4
q (Å-1)
G2-6 dendrimer aggregates showed liquid packing (2σ),
while G0-1 were intermediate (~1.7σ) between liquid and solid
next stop: magnetic particles!
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
core
a
1 nm
functionalized
monolayer
aspirin
heparin 12-mer
DNA 24-mer
p53 bound to DNA
The concept: dynamic control of receptor structure
self-assembly of a self-assembled system
thiol monolayers are dynamic entities
can this dynamic aspect be harnessed to create and optimize polyvalent receptors?
crosslink
dynamic receptor
just like we used to think antibodies worked!
imprinted receptor
Can we template to something biological?
Verma, A.; Nakade, H.; Simard, J.M.; Rotello, V. M. J.
Am. Chem. Soc, 2004, 126, 10806-10807.
Enzyme binding and inhibition using nanoparticles
chymotrypsin provides good initial target
S
S
COO
S
S
COO
complementary anionic inhibitor
S
S
cationic
anionic
hydrophobic
uncharged
5.2 nm
N
S
S
N
non-complementary
cationic control
size virtually identical to nanoparticle
"halo" of cationic and hydrophobic residues surrounds active site
well established enzymatic assays using chromogenic substrates
Charge complementarity required for inhibition
no inhibition observed with cationic control
1.2
200nM cationic mmpc
1
.
Vi/V0
0.8
20nM
0.6
80nM
0.4
[E]=800nM
0.2
200nM
sucAAPF-pNA substrate
0
0
200
400
600
800
1000
1200
1400
Time (min)
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
Slow denaturation observed with particles
complete denaturation over 24 h
cht at 23° C
circular dichroism of chymotrypsin:
cht at 80° C
-little change initially (2-step process?)
-complete conversion to random
coil over 24 hr
cht +inhibitor
cht and and inhibitor--24hr
190
200
210
220
Wavelength
230
(nm)
240
250
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.
75 nM
450 nM
µ
Nanoparticles provide highly effective gene delivery agents
Cationic nanoparticles transfect mammalian cells
Green fluorescent protein (GFP) plasmid transfection of 273T cells
internalized
nanoparticles
how efficient is the transfection?
what controls this efficiency?
Amphiphilic particles work better
optimal transfection observed with ~70% cationic coverage
MilliUnits β-galactosidase Activity
50
S
S
N
S
S
N
40
30
20
10
0
100
85
68
%cationic
63
58
coverage
increasing chain length increases efficiency
1
S
N
S
S
N
S
2
S
N
S
S
N
S
3
S
N
S
MilliUnits β-galactosidase Activity/mg total protein
S
800
all of the systems are better
than PEI, a popular commercial
transfection agent!
600
next step:
-more complex monolayers
-uptake and localization tags
400
200
0
S
N
1
2
3
MMPC
PEI
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
Acknowledgments:
Alumni: postdocs
Gilles Clavier
Allan Goodman
Alam Syed
Ulf Drechsler
Amitav Sanyal
Tyler Norsten
Roy Shenhar
Belma Erdogan
Current: postdocs
Chang-Cheng You
“Pops” Arumugam
Yuval Ofir
Alumni: grad students
Current: grads
Bing Nie
Eric Breinlinger
Michael Greaves
Angelika Niemz
Robert Deans
Alex Cuello
Trent Galow
Faysal Ilhan
Eunhee Jeoung
Mark Gray
Andy Boal
Hugues d’ Cremiers
Kulmeet Sandhu
Kanad Das
Kate Goodman
Kate McKusker
Hugues d’ Cremiers
Hiroshi Nakade
Ayush Verma
Ali Bayir
Hao Xu
Gang Han
Sudhanshu Srivastava
Brian Jordan
Rochelle Arviso
Mrinmoy De
Bappaditya Samanta
Partha Ghosh
Tongxiang Liu
Basar Gider
Sarit Agasti
Oscar Miranda
Michael Pollier
Apiwat Champoosor
Dap Patra
Kanad Das
Kevin Bardon
Joe Simard
Ray Thibault
Joe Carroll
Oktay Uzun
Nick Fischer
Nandani Chari
Y-M Legrand
Joe Worrall
Joe Fernandez
Ben Frankamp
Rui Hong
Collaborators
Graeme Cooke
Todd Emrick
Sallie Smith
Joe Jerry
Neil Forbes
Tom Russell
Jacques Penelle
Mark Tuominen
Craig Martin
Funding
NIH
NSF
NSF CHM-NSEC
NSF MRSEC
Keck Foundation
ONR