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Silicon nanowires

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Silicon nanowires

  1. 1. Silicon Nanowires for Biomedical Applications Ke Jiang, Ph.D 1
  2. 2. Silicon Nanowires for Bone Tissue Engineering? 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 2
  3. 3. Synthesis of SiNWsVLS Growth Mechanism1. Annealing of catalysts;2. Introduction of SiH4;3. Precipitation of SiNWs from Si/Au liquid alloy. 3
  4. 4. Cathodic Bias-Induced Calcification of SiNWs SBF = Simulated Body Fluid (pH ≈ 7.3) Ion Na+ K+ Mg2+ Ca2+ Cl- HCO3- HPO42- SO42- SBF (mM) 142.0 5.0 1.5 2.5 148.8 4.2 1.0 0.5 Blood Plasma 142.0 5.0 1.5 2.5 103.0 27.0 1.0 0.5 (mM) 4K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
  5. 5. Calcium Phosphate Coated SiNWs (CaP/SiNWs) Si Si Ca P Ca P CaP/SiNWs (synthesized by VLS method) CaP/SiNWs (synthesized by OAG method) Before coating Si (111) Si (220) After coating Graphite Si (311) CaP Graphite Au 5K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
  6. 6. Effect of Experimental Conditions on Calcification of SiNWs 1 week 2 weeks 3 weeks 4 weeks 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) Effects of Bias Conditions on Ca/Si Ratio Effects of Bias Conditions on Ca/P Ratio 6K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
  7. 7. Surface Modification of CaP/SiNW with Alendronate Alendronate  Internalized by mature osteoclasts  Inhibit resorptive function of osteoclasts  Induce apoptosis of osteoclasts Fluorescent Microscopy of FITC Labled Fluorescent Spectrum of FITC Labled Alendronate-CaP/SiNWs Alendronate-CaP/SiNWs 7K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
  8. 8. Mouse Stromal Cell (MSC) Proliferation Mouse Stromal Cells (MSCs)  derived from bone marrow;  capable of differentiation into osteoblasts, chondrocytes, and adipocytes;  treat disorders such as osteoporosis. 10 µm MSC proliferation on SiNWs, CaP/SiNWs, glucose bisphosphonate-CaP/SiNWs, alendronate-CaP/SiNWs Optical Image of MSC 8K. Jiang, D. Fan, Y. Belabassi, G. Akkaraju, J-L. Montchamp, J. L. Coffer, ACS Appl. Mater. Interface. 2009, 1, 266
  9. 9. 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. 9
  10. 10. Fabrication of SiNW/PCL Composites 10
  11. 11. Fabrication of SiNW/PCL Composites Printing Method Embedding Method 1 cm 11K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  12. 12. Acellular Calcification of SiNW/PCL Composites Embedding Method Printing Method Cnts Ca Cnts Ca 40 2.0K P P 20 1.0K Si 2 4 6 8 2 4 6 8 Energy (keV) Energy (keV) 12K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  13. 13. MSC Attachment on SiNW/PCL Composites Fabricated by the Embedding Method SiNWs SiNW/PCL-2 SiNW/PCL-4 SiNW/PCL-6 1 week 2 weeks 3 weeks 13K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  14. 14. MSC Attachment on SiNW/PCL-film Composites Fabricated by the Printing Method SiNWs SiNW/PCL PCL Film 3 days 5 days 7 days 14K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  15. 15. MSCs Viability on SiNW/PCL Composites: MTT Assay 15K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  16. 16. ALP assay: MSC Differentiation on SiNW/PCL Composites 16K. Jiang, G. Akkaraju, J. L. Coffer, J. Mater. Res. In Press.
  17. 17. SiNWs as Delivery Vehicles for Boron Neutron Capture Therapy (BNCT) 1935 H. J. Taylor; 1936 G. L. Locher. 10 5B + 1 n → [11B] → 4 He2+ + 7Li3+ + γ0.48 MeV + 2.31 MeV 0 5 2 3 Both α–particles and lithium ions have pathlengthof several micrometers; Boron-containing agents: BSH Nanomaterials as Delivery Vehicles: Dendrimer Liposome Dextran 17 17
  18. 18. SiNWs as Delivery Vehicle for BNCT 120 After Coating 100 Before Coating 80 Counts 60 40 20 0 0 200 400 600 800 1000 1200 18 DiametersK. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
  19. 19. 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 3h 6h 10 h 19K. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
  20. 20. Dissolution of BSH from SiNWs as a Function of Time Molar Ratio Time (min) 20K. Jiang, J. L. Coffer, J. G. Gillen, T. M. Brewer, Chem. Mater., 2010, 22, 279.
  21. 21. Remarks Catalyst-assisted chemical vapor deposition methods were employedto synthesize SiNWs, which were coated with calcium phosphate by anelectrochemically induced method. The alendronate modified CaP/SiNWs exhibit a cytotoxic behavior,while deliberate subtle modification of the exposed primary amine withglucose sensitively improves the cytocompatibility of the nanowire vector. SiNW/PCL composites with a variety of surface topography werefabricated and their cytocompatibility were tested in vitro. Thesecomposite materials show supportive behavior of directing mouse stromalcells attachment, proliferation, and differentiation functions. SiNWs can be used as potential delivery vehicles for boron-containingagents, therefore exhibited some properties favorable for possible use inBoron Neutron Capture Therapy. 21

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