Nanomechanics of Biological, Biomedical, Biomimetic Materials
Christine Ortiz, MIT-DMSE 2004 (http://web.mit.edu/cortiz/www)
I. BIOLOGICAL TISSUES●Cartilage
(J. Seog, L. Han, L. Ng, D. Dean) ● Bone (K. Tai)
●Nacre (B. Bruet, C. King, H. Qi, R. Panas)
II. BIOMEDICAL INTERACTIONS●Protein-SAMs/PEO (M. Rixman)
●Vascular Grafts (C. Macias)●Saccharide Surfaces (J. Choi, N.
Yang)●Endotracheal Tubes (K. Brodie)●Pharmaceuticals (R. Domike)●Bone Implants (J. Vandiver)
III. BIOMIMETIC BLOCK
COPOLYMERS●Non Stimulus Responsive P(HEMA-g-EG) (D. Zhang)●Stimulus Responsive
p(MAA-g-EG) (M. Ye)
Molecular Origins of Bio(hemo)compatibility : Materials Design Issues and Challenges at the Nanoscale
CHRISTINE ORTIZ, Assistant Professor Monica Rixman, Delphine Dean, Celia Macias
Department of Materials Science and Engineering, MITWWW : http://web.mit.edu/cortiz/www
c
D. Breger, used w/permission, http://www.ldeo.columbia.edu/micro/images.section/pages/bloodclot.html
CHRISTINE ORTIZ, ASSISTANT PROFESSORMASSACHUSETTS INSTITUTE OF TECHNOLOGY
DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERINGCAMBRIDGE, MA 02139
FACTORS AFFECTING PROTEIN ADSORPTION227th ACS National Meeting Division of Polymer Chemistry
Symposium "Biomacromolecule Interactions with Synthetic Surfaces" Anaheim, CA 2004.
D
SURFACE COATING
U=-∫F(D)dD Initial protein adsorption will be determined by longer range, larger spatial length scale of averaged surface properties : many different attractive/ repulsive components lead to complicated interactions (Szleifer, I., 1997, Halperin, A., 1999Leckband, D., et al., 2000)
Secondary stages of protein adsorption depend on shorter range biomolecular adhesive binding processes that take place when the protein is in close contact with the surface (*the conformation, orientation, and mobility of the adsorbed proteins, the time scale of conformational changes, protein exchange and desorption, and interactions of adsorbed proteins with each other)
BIOMATERIAL
CHRISTINE ORTIZ, ASSISTANT PROFESSORMASSACHUSETTS INSTITUTE OF TECHNOLOGY
DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERINGCAMBRIDGE, MA 02139
Direct Measurement of Protein Interactions with End-Grafted Poly(ethylene oxide) (PEO) Macromolecules
227th ACS National Meeting Division of Polymer Chemistry Symposium "Biomacromolecule Interactions with Synthetic Surfaces" Anaheim, CA 2004.
chemically end-grafted
PEO50K “mushroom”Lcontour= 393 nm
RF=8.7 nm
F
sodium phosphate
buffer solutionIS=0.01M pH=7.4
D
lipid-bound HSA functionalized probe tip, RTIP~65 nm (SEM)
Au-coated silicon chip
covalently immobilized HSA
~10 nm
s = 62 ± 28 nm
~35-190proteins in maximum interaction area (D=0)
~2.5 PEO chains in maximum
interaction area (D=0)
Si3N4
Rixman, et al.
accepted, Langmuir 2003.
Chemical Attachment Scheme of Lipid-Bound HSA to Si3N4 Probe Tip
A. Vinkier; Heyvaert, I.; D'Hoore, A.; McKittrick, T.; C., V. H.; Engelborghs, Y.; Hellemans, I. Ultramicroscopy 1995, 57, 337. S. O. Vansteenkiste; Corneillie, S. I.; Schacht, E. H.; Chen, X.; Davies, M. C.; Moens, M.; Van Vaeck, L. Langmuir 2000, 16, 3330.
HSAHSA
Si OH
II
OO
NH2
NH2H2N
III
H3C O Si
CH3
CH3
NH2
ABDMS
Si NH2
Si NH2
Si O Si NH2
CH3
CH3
NH2
NH2
Glutaraldehyde
+
Si3N4 Probe Tip
N
Si NH2
Si NH2
Si O Si N
CH3
CH3
SiN
SiN
Si O Si N
CH3
CH3
O O
OO
O
SiN
O O
SiN
OO
I
Fluorescence micrographof HSA-functionalized
cantilever (courtesy of Irvine Lab-DMSE)
probe tip
location
-0.8
0.2
1.2
2.2
3.2
4.2
0 5 10 15 20 25 30
Distance (nm)
For
ce/ R
adiu
s (m
N/m
)
-0.05
0.05
0.15
0.25
For
ce (nN
)
HSA probe tip versus PEOsurface averageElectrostatic surface chargemodel neutral surfacevan der WaalsPEO/ HOH/ HSADolan Edwards steric
F
Au
RF (PEO)
• magnitude of force much larger
than predicted by theory
Rixman, et al., Langmuir 2003.
AVERAGE APPROACH CURVE : HSA PROBE TIP VERSUS PEO (SUBTRACTED AU INTERACTION) PBS, IS=0.01M, pH=7.4
0
0.5
1
1.5
2
2.5
3
3.5
0 10 20 30Distance (nm)
For
ce/R
adiu
s (m
N/m
)
0
0.05
0.1
0.15
0.2
0.25
0.3
For
ce (nN
)
0.15M
1.0M
0.01M
HSA versus PEO : Effect of NaCl IS Approach
CONCLUSION: Electrostatic double
layer and configurational
entropy are outweighed by
another interaction which increases
with IS →possibly due to water
interphase layer
RF (PEO)
● Salt screening : electrostatic double layer force expected↓ with ↑IS
● NaCl reduces the goodness of solvent for PEO (Armstrong, et al. 2001) : configurational entropy force expected↓ with ↑IS
Rixman, et al. 2003 unpublished data
HSA versus PEO : Effect of Solvent on ApproachIsopropanol has been shown to block hydrophobic interaction
forces(Jiang, et al 2002)
RF (PEO)
Rixman, et al. 2003 unpublished data
-7
-5
-3
-1
1
3
5
0 10 20 30
Distance (nm)
For
ce/R
adiu
s (m
N/m
)
-0.32
-0.22
-0.12
-0.02
0.09
0.19
Force (nN
)
0% Isopropanol0.5% Isopropanol5% Isopropanol100% Isopropanol0% F+sd0% F-sd0.5% F+sd0.5% F-sd5% F+sd5% F-sd100% + sd100% - sdSeries1
CHRISTINE ORTIZ, ASSISTANT PROFESSORMASSACHUSETTS INSTITUTE OF TECHNOLOGY
DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERINGCAMBRIDGE, MA 02139
ACKNOWLEDGEMENTS50th Annual Meeting of the Orthopaedic Research Society (San Francisco, CA)
Workshop on Molecular Nano-Mechanics of Extracellular Matrix of Musculoskeletal Tissues
Joonil SeogDelphine Dean Laurel Ng
Outside Collaborators: Dr. Anna Plaas, Shirley Wong-Palms (Shriners)
Funding: Dupont-MIT Alliance, Shriners of North America, NIH AR45779 (AJG), Whitaker Foundation, Cambridge-MIT Institute
Kuangshin TaiProf. Alan Grodzinsky
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