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Fabricating Graphene Paper and Determining Its Electrical and Mechanical Properties and Using It for Proliferation and Differentiation of Neural Stem Cells

Akbar Shirazian, Soheil | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47119 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Akhavan, Omid
  7. Abstract:
  8. Nowadays, tissue engineering and stem cells-based therapies have outlined a promising prospect in neural networks regeneration. But it usually requires biocompatible and conductive scaffolds for culturing neural stem cells and directing their differentiation toward the neurons. Graphene due to its unique physical and chemical properties has attracted much interest in tissue engineering. For this purpose, in this study biocompatible graphene oxide foams have been used for neural stem cell culturing. For the first time, graphene oxide foam were fabricated by precipitation of chemically exfoliated graphene oxide sheets in an aqueous suspension onto the PET substrate at ~80 oC under UV irradiation and then rolled around one of the edges to act as a 3-dimesional cylindrical-like scaffold. By using scanning electron microscopy, the thickness of these foams (with linear density of ~10 GO sheets/µm) was measured around 10-50 µm. Atomic force microscopy confirmed the presence of monolayer graphene oxide sheets with the thickness of 1.4 nm in graphene oxide suspension. X-Ray photoelectron spectroscopy confirmed that the UV irradiation resulted in partial reduction of the layers during fabrication process. Also Raman spectroscopy demonstrated the presence of multilayer graphene oxide sheets (≥3 layers) in the foam structure. The Young’s modulus of the foams was obtained about 1.7 GPa. In the best case, by using tensile test. Furthermore, Four probe method found that the electrical sheet resistance of the GOFs was low enough (17-24 Ω/sq) to produce the electrical simulation currents (~20 mA) used in differentiation of the neural stem cells into the neurons (rather than glial cells). Contact angle test also showed that rolling the GOFs resulted in formation of cross-section with superhydrophilic characteristic, inducing effective proliferation and differentiation of the hNSCs throughout the pores and interfaces of the scaffold. Moreover, Fluorescence imaging revealed that stimulating the hNSCs resulted in coaxial-like growth of the neural fibers and inducing differentiation of the neural stem cells in to the neurons
  9. Keywords:
  10. Mechanical Properties ; Electrical Properties ; Three Dimensional Scaffolds ; Electrical Stimulation ; Graphene Oxide Foam ; Neural Stem Cells ; Neuronal Differentiation

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