Silicon Nanowires for Biomedical Applications
Ke Jiang, Ph.D
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Silicon Nanowires for Bone Tissue Engineering?
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Biological Roles of Silicon
Improve bone calcification in rat and chick. Edith M. Carlisle in the 1970s.
Initiate bone calcification in animals and stimulates formation of collagen.
“Significant positive association” between the density of bone and silicon
uptake in men and in premenopausal women.
An essential component in bioactive glasses as bone substitutes.
Potential Biological Applications of Silicon Nanowires
Biosensor
Drug delivery
Bio-scaffold
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Synthesis of SiNWs
VLS Growth Mechanism
1. Annealing of catalysts; 2. Introduction of SiH4; 3. Precipitation of SiNWs
from Si/Au liquid alloy.
Cathodic Bias-Induced Calcification of SiNWs
SBF = Simulated Body Fluid (pH ≈ 7.3) Ion Na+ K+ Mg2+ Ca2+ Cl- HCO3
- HPO42- SO4
2-
SBF (mM) 142.0 5.0 1.5 2.5 148.8 4.2 1.0 0.5
Blood Plasma (mM)
142.0 5.0 1.5 2.5 103.0 27.0 1.0 0.5
K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266 4
Calcium Phosphate Coated SiNWs (CaP/SiNWs)
Graphite
Si (111) Si (220)
Si (311)
Au Graphite
CaP/SiNWs (synthesized by VLS method) CaP/SiNWs (synthesized by OAG method)
CaP
K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266 5
Si
P
Ca
Si P
Ca
Before coating
After coating
Effect of Experimental Conditions on Calcification of SiNWs
Effects of Bias Conditions on Ca/Si Ratio Effects of Bias Conditions on Ca/P Ratio
SEM images of calcification of SiNWs as a function of immersion time in SBF (The sample was biased at a current density of 10 mA/cm2 for 90 min)
1 week 2 weeks 3 weeks 4 weeks
K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266 6
Surface Modification of CaP/SiNW with Alendronate
Fluorescent Microscopy of FITC Labled Alendronate-CaP/SiNWs
Fluorescent Spectrum of FITC Labled Alendronate-CaP/SiNWs
K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266 7
Alendronate Internalized by mature osteoclasts Inhibit resorptive function of osteoclasts Induce apoptosis of osteoclasts
Mouse Stromal Cell (MSC) Proliferation
K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
MSC proliferation on SiNWs, CaP/SiNWs, glucose bisphosphonate-CaP/SiNWs,
alendronate-CaP/SiNWs
Mouse Stromal Cells (MSCs) derived from bone marrow;
capable of differentiation into osteoblasts, chondrocytes, and adipocytes;
treat disorders such as osteoporosis.
Optical Image of MSC
10 µm
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Silicon Nanowire/Polycaprolactone (PCL) Nanocomposites as Biocompatible Scaffolds for Bone Tissue Engineering
SiNWs usually grow on rigid substrates; Flexible materials is desired;
SiNWs incorporated in a polymer matrix;
Polycaprolactone: slow degradation rate.
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Fabrication of SiNW/PCL Composites
Fabrication of SiNW/PCL Composites
K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press. 11
Printing Method Embedding Method
1 cm
Acellular Calcification of SiNW/PCL Composites
2 4 6 8
Energy (keV)
1.0K
Cnts
P
Ca
2.0K
Si
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2 4 6 8 Energy (keV)
20
40
Cnts
P
Ca
Embedding Method Printing Method
K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
SiNWs SiNW/PCL-2 SiNW/PCL-4 SiNW/PCL-6
1 week
2 weeks
3 weeks
MSC Attachment on SiNW/PCL Composites Fabricated by the Embedding Method
13 K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
MSC Attachment on SiNW/PCL-film Composites Fabricated by the Printing Method
SiNWs SiNW/PCL PCL Film
3 days
5 days
7 days
14 K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
MSCs Viability on SiNW/PCL Composites: MTT Assay
15 K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
ALP assay: MSC Differentiation on SiNW/PCL Composites
16 K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
1935 H. J. Taylor; 1936 G. L. Locher. Both α–particles and lithium ions have pathlength of several micrometers;
Boron-containing agents:
5B + 0n → [ 5B] → 2He2+ + 3Li3+ + γ0.48 MeV + 2.31 MeV 10 1 11 4 7
17 Dendrimer Liposome Dextran
Nanomaterials as Delivery Vehicles:
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SiNWs as Delivery Vehicles for Boron Neutron Capture Therapy (BNCT)
BSH
SiNWs as Delivery Vehicle for BNCT
0
20
40
60
80
100
120
0 200 400 600 800 1000 1200
After CoatingBefore Coating
Cou
nts
DiametersK. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
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Dissolution of BSH from SiNWs as a Function of Time 0 min 5 min 10 min 15 min
20 min 25 min 30 min 40 min
50 min 60 min 80 min 100 min
120 min 3 h 6 h 10 h
19 K. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
Dissolution of BSH from SiNWs as a Function of Time
Time (min)
Mol
ar R
atio
20 K. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
Remarks
Catalyst-assisted chemical vapor deposition methods were employed to synthesize SiNWs, which were coated with calcium phosphate by an electrochemically induced method. The alendronate modified CaP/SiNWs exhibit a cytotoxic behavior, while deliberate subtle modification of the exposed primary amine with glucose sensitively improves the cytocompatibility of the nanowire vector.
SiNW/PCL composites with a variety of surface topography were fabricated and their cytocompatibility were tested in vitro. These composite materials show supportive behavior of directing mouse stromal cells attachment, proliferation, and differentiation functions. SiNWs can be used as potential delivery vehicles for boron-containing agents, therefore exhibited some properties favorable for possible use in Boron Neutron Capture Therapy.
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