| Electrospinning is a simple technique for preparing nanofibers with easily controlled diameters and morphology. The fibrous sponge fabricated by liquid-assisted three-dimensional electrospinning method possesses high specific surface area and interconnected, fluffy,3D nanofiber network. In this study, three-dimensional polyacrylonitrile nanofiber network was fabricated by this means after tailoring relevant parameters. In addition to the uniform interconnected porous structure it formed, its advantage was the large spacing between adjacent individual fibers compared to other electrospinning methods, which could reach greater than 15～20 μm. This dissertation aims to apply this specific nanofiber network in fields of oil absorbents and in-vitro cell culture.With the development of industrial production, water pollution resulting from oil and organic liquid spills has raised considerable concern. Using absorbent materials to deal with it has advantages of simple fast preparation processes, low costs and the possibility of collection and removal of the oil. The materials should possess high hydrophobicity, high oleophilicity, a high selectivity for oil against water, good mechanical strength and excellent oil absorption performances. In this study, the hydrophobic polyacrylonitrile nanofiber network was set as the substrate. Making use of its high specific surface area and fluffy structure, we coated graphene oxide on the nanofibers followed by the chemical reduction process to fabricate the reduced graphene oxide coated polyacrylonitrile sponge. This dissertation discusses the chemical composition, microscopic morphology and the self-assembly mechanism of this construct. The hydrophobicity, oleophilicity, selectivity for oil against water, mechanical strength and oil absorption performances were also tested. It was established that the composite had a high absorption capacity for several oils and organic liquids. After optimizing the content of reduced graphene oxide, the mass of oil the composite absorbed ranged from 80 g/g (lubricate oil) to 201 g/g (chloroform), which was over 4 to 6 times of that of commercial absorbents. In addition, this material could be recycled by simple squeezing owing to its good elasticity and absorption capability. This is the first time to combine liquid-assisted electrospinning method and graphene coating to make oil absorbing materials, providing a novel thread for separating and removing oil and organic liquid spills.Compared to 2D cell culture,3D cell culture scaffolds can mimic the microenvironment for normal cell growth, proliferation, differentiation and spreading more precisely. Due to the similar size and structure with the extracellular matrix, electrospun nanofibers were extensively applied in biomedical scaffold materials. However, there still remains the problem of too small pore sizes unfavorable for cell’s normal physiological activities. In this study, chitosan-coated polyacrylonitrile nanofiber network was prepared by the liquid-assisted electrospinning method. With the help of chitosan adhered on adjacent nanofibers, macro-pores over 100 μm in diameter were formed in the nanofiber network, allowing enough space for cell’s migration and growth. The chemical composition and microscopic morphology of the scaffold were also tested. Mouse 3T3 fibroblasts were subsequently cultured on the scaffold in vitro. After tests of cytotoxicity of the scaffold as well as the growth, migration and proliferation of 3T3 cells, it was shown that the 3D nanofiber network could mimic the cell’s natural environment, whilst improving structural support and increasing the cell-matrix surface area. Cells could successfully enter into the interior of the scaffold. Compared to 2D electrospun scaffolds, this 3D scaffold could provide better biological microenvironment for cell adherence, spreading and proliferation. |
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