mposite Silica:Polypeptide Nanoparticl ibel Turksen, Brian Fong & Paul S. Russ Macromolecular Studies Group Louisiana State University NSF, ACS, LSU Coates Fund Kasetsart University Bangkok, Thailand Thursday, November 18, 2004
Jan 13, 2016
Composite Silica:Polypeptide Nanoparticles
Sibel Turksen, Brian Fong & Paul S. RussoMacromolecular Studies Group
Louisiana State University
NSF, ACS, LSU Coates Fund
Kasetsart UniversityBangkok, Thailand
Thursday, November 18, 2004
Fuzzballs
a silica interior and synthetic homopolypeptide exterior.
Homopolypeptide Shelltypically 100 nm thick
Silica (SiO2) core
typically 200 nm diameter
Optional superparamagneticinclusion
Why?The usual reasons for polymer-coated particles Stability studies, probe diffusion, standards, etc.The better reasons for polypeptide-coated
particles Should allow excellent shell thickness control. Shell is rigid spacer for assembling silica spheres. Astounding chemical versatility and functionality,
including chirality. Responsiveness and perfection of structures through
reproducible helix-coil transitions. Easily attach antibodies for recognition of cancer cells,
easily attach cancer-killing lytic peptides, too. When magnetic, good way to self-assemble all this
functionality
Our Little Corner of the World: Silica-Homopolypeptide Composite
Particles
Mostly…unstructured, random coil polymers
Co-Si-homopolypeptide composite systems Hierarchical structures Homopolypeptide shell – PBLG, PCBL (can be helix as shown, or coil?) Superparamagnetic – Fe3O4 or Co core
Silica-Stöber SynthesisHydrolysis of tetraethyl orthosilicate (TEOS)
SiOC2H5
H5C2O
OC2H5
OC2H5
C2H5OH
NH4OH
SiOOC2H5
OC2H5
OC2H5
SiH5C2O
OC2H5
OC2H5
TEOS
C2H5OHNH4OH
Si
O
O
SiOSi
OSi
O
OH
OH
OH
OHOH
OH
OHOH
OH OH
OHOH
TEOS
hydrolysis
Stöber
condensation
SEM & TEM of Silica Particles
Synthesis of Magnetite – FeSynthesis of Magnetite – Fe33OO44
FeCl3 FeCl2 NH4OH Fe3O4 NH4Cl+2 8 + 8+
Fe3O4
OH-
OH-
OH-
OH-
-OH
-OH
Fe3O4
-OH
-OH
-OH
-OH
-OH
-OH
NCH3 CH3
CH3
OMe
N+
N+
N+
N+N
+
N+
+
TMAtetramethylammonium hydroxide
Magnetic silica particles
Dark:Magnetic inclusions(~ 10nm) Gray:Glassy SiO2 matrix
TEM- Silica Coated Fe3O4
Superparamagnetic cobaltSuperparamagnetic cobalt
Co
cit –
cit –
cit –
+ NH2(CH2)3Si(OH)3Co
NH2(CH2)3Si(OH)2O –
NH2(CH2)3Si(OH)2O –
NH2(CH2)3Si(OH)2O –
+ Cit–
Co
N O
N O
N O
Stöber reaction
TEOS, APS, EtOHCo
Si
O2
OH –
OH –
OH –
OH –
+ H2O
TEM- Silica Coated Cobalt
Superparamagnetic Particles
Surface Functionalization
SiOMeMeO
(CH2)3NH2
OMe
Si
O
O
SiOSi
OSi
O
OH
O
OH
OHH
MeOH
H2O, NH3
(CH2)3NH2Si (OH)3Si
O HHO
Si
OH
Si OHOH
(CH2)3NH2
H2O, NH3, C2H5OH
Si
O
O
SiOSi
OSi
O
OH
O
OH
O
Si SiOO
(CH2)3NH2(CH2)3NH2
SiNH2(CH2)3
OH
OH
association
condensation
oligomers
adsorption on a particle
APTMS 3-aminopropyltrimethoxysilane
R = CH2CH2CO2CH2C6H5 for PBLG
R = (CH2)4NHCO2CH2C6H5 for PCBL
R
CH
CHNn
O
PCBL helix-coil transition @ 27 C in m -cresol
Homopolypeptides
PBLG best understood
homopolypeptide semiflexible
structure helix-coil transition
Synthesis of homopolypeptides
R' NH2
N
OO O
R H
R'N
N OH
O
OR
H
HCO2
R'N
NH
O
R
H
H
R'N
NH
O
R
H
HN
OO O
R HCO2
R'N
NN
O
OH
HH
HR
n
R
+
1 2 3 4
+ n
4 2 5
Summary: Particle Preparation
H2O , NH3
SiOMeMeO
(CH2)3NH2
OMe
CBL-NCA, monomer
NH2
NH2
NH2
NH2
NH2
NH2
SiOC2H5
H5C2O
OC2H5
OC2H5
O
O NH
NH
OO
O
Superparamagneticdomain
cit –
+ NH2RSi(OH)3N
SiO-
+ SiO2- N
SiO
SiOH
Cobalt particles
Is the shell covalently attached?
4000 3500 3000 2500 2000 1500 1000 500-2
0
2
4
6
8
10
12
14
16 (a)
sour ce: stobersIR
Figure 2aFong and Russo
stober
802
946
1628
Tra
nsm
ittan
ce /
%
Wavenumber / cm-1
4000 3500 3000 2500 2000 1500 1000 5002
4
6
8
10
12
14(b)
source: bf2cp33IR
Figure 2bFong and Russo
PBLG-coated silica
1551
1653
1736
Tra
nsm
ittan
ce /
%
Wavenumber / cm-1
4000 3500 3000 2500 2000 1500 1000 500
0
2
4
6
8
10 (c)
source: bf5ttIR p148
Figure 2cFong and Russo
DMFWashed
1391
1654
Tra
nsm
ittan
ce /
%
Wavenumber / cm-1
Almost certainly
(By the way, the polypeptide conformation is mostly -helix with some -sheet)
TGA/DTA
0 200 400 600 800 1000 1200-100
-80
-60
-40
-20
0
Fong and Russo
Figure 3
Mixed with 16K and 91K
PBLG, then isolated (2 curves)
Silica Spheres Alone
Composite Particle
PBLG
TG
/ %
T / oC
--Particles with ~ 23% by mass PBLG--Again, no evidence for binding of loose PBLG
Dynamic Light Scattering
Bigger ones may diffuse slower (solvent viscosity effects)Flat plots indicate excellent, latex-like uniformity
1.0 1.5 2.0 2.5 3.0 3.5 4.01.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Composite Particles
C18
H37
Spheres
Rh = 1750
Rh = 973
Rh = 990
Silica Spheres
Dap
p / 1
0-8 c
m2 s
-1
q2/1010 cm-2
Particle Characteristics
Silica Core Properties Radius from DLS: 97 nm Molar Mass: 4.5 x 109
Surface area: 15.6 m2/g
PBLG Shell Properties 78 nm. ~90% solvent / 10% polymer. Polymer density limited by crowding around
initiator sites.
Unfortunately, the shell thickness was not controlled by [M]/[I]. Why not?
Not all initiators are active: crowding
Challenges:
Controlling initiator density Attachment of ready-made polymers
Helix-coil Transition of PCBL
Matsuoka, M., Norisuye, T., Teramoto, A., Fujita, H. Biopolymers, 1973, 12,1515-1532
Early attempts showed NO change in the size of the particles—as if the shells were not responding.
We reasoned this might be due to overcrowding on the surface.
Si NH2
OMe
MeO
OMe
APTMS
Si NH
NH2
OMe
OMe
MeO
AEAPTMS
Si
OMe
MeO
OMe
CH3
MTMS
NH2 NH2
25% amino groups
Avoiding crowding
3-(2-furoyl) quinoline-2-carboxaldehyde (ATTO-TAG™ FQ)
Silica-homopolypeptide Composite Particles
DLS of Si-PCBL particles in DMF
0 1 2 3 4 5 6 70
50
100
150
200
250
300
350
400
Si-PCBL core shell particles
Rap
p nm
q2 / 1010 cm-1
Rapp= 251.6±1.42 nm
Helix-coil transition of Co-PCBL
250.00
275.00
300.00
325.00
350.00
375.00
400.00
425.00
0 5 10 15 20 25 30 35 40 45 50 55
Temperature / °C
Ra
pp
/ n
m
1st heating
1st cooling
2nd heating
2nd cooling
3rd heating
4th heating
250.00
275.00
300.00
325.00
350.00
375.00
400.00
425.00
0 5 10 15 20 25 30 35 40 45 50 55
Temperature / °C
Ra
pp
/ n
m
1st heating
1st cooling
2nd heating
2nd cooling
3rd heating
4th heating
3rd cooling
250.00
275.00
300.00
325.00
350.00
375.00
400.00
425.00
0 5 10 15 20 25 30 35 40 45 50 55
Temperature / °C
Ra
pp
/ n
m
1st heating
1st cooling
2nd heating
2nd cooling
3rd heating
4th heating
3rd cooling
Latex
It’s Alive!
0.000 0.001 0.002 0.003 0.004 0.005 0.00660
70
80
90
100
110
120
y=7628x + 68.2R=0.99804
Rap
p / n
m
[M] / g.mL-1
Si-PCBL
0.002 0.003 0.004 0.005 0.0060.00
0.02
0.04
0.06
0.08
0.10
2/2
[M] / g.mL-1
Si-PCBL in 3 weeks
This plot showspolydispersity
Hysteresis curve
M
-M
Magnetization
Magnetizationin opposite direction
SQUID- hysteresis plot of cobalt particles
-25
-20
-15
-10
-5
0
5
10
15
20
25
-60000 -40000 -20000 0 20000 40000 60000
Applied Field (Oe)
Mag
net
izat
ion
(em
u/g
)
Silica coated cobaltLatex iron oxide
SQUID- hysteresis plot of Co-PCBL
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
-4000 -3000 -2000 -1000 0 1000 2000 3000 4000
Applied Field (Oe)
Ma
gn
eti
zati
on
(e
mu
/g)
Initial
3000 to 0 field
0 field to -3000
-3000 field to 0
0 field to 3000
Formation of colloidal crystals
Sufficiently dense suspensions assemble into colloidal crystals. With a size that matches that of visible light, diffraction results. Domains with different orientations result in different and quite pure colors.
~ 0.5 m
Colloidal Crystals (PCBL Shell)
Sufficiently dense suspensions assemble into colloidal crystals. With a size that matches that of visible light, diffraction results. Domains with different orientations result in different and quite pure colors.
~ 0.5 m
SiO2
~ 2 mm
Helical homopolypeptide shell
Why Study?Beautiful!Fun supramolecular synthesize &
characterize from nm to mm. Applies to optical devices,
better lasers, pigment-free paint, “smart colloids”, artificial muscle, separations technology
/ nm400 500 600 700
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
593 nm
568 nm
615 nm
Inte
nsi
ty
Transmittance measured on monochromator-equipped microscope
FWHM of line is ~ 16 nm, comparable to typical interference filters
Spectroscopic analysis of the crystal
Achieving population inversion gets progressively harder for shorter wavelengths; green < red.
8
3
12
12 A
B
E1
E2
A12 B12
Conclusions
Facile synthesis & excellent uniformity
Responsive shell
Hierarchical structures, conformal transitions
Potential applications —optical devices,
stationary phases for chiral separation, model
particles, artificial muscles, medical
treatments
Infinite variation with polypeptide chemistry
Future workHelix-coil transition effect on magnetizationCrosslinking particlesAsymmetric particlesApplication of different grafting techniques
Vapor deposition Grafting onto
Controlling cobalt chains-rodsInvestigation of colloidal crystalsParticles as probe diffusers
*NH
*
O
O
O
n
8
Ru
PhPCy3
PCy3
Cl
Cl
L4M RO
O
8
O
O
8
L4M R M
O
O
8
RL4
O
O
8
-dec-1-enyl-L-glutamate
benzylidene-bis(tricyclohexeylphosphine) dichlororuthenium
Crosslinking
Silica coating
N
N
N
N
N
N
N
NCA-monomer
crosslinking
Surface
Functionalization
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
HELIX COIL
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N