Study On Interfacial Reaction Of Neural Cells To Materials And Its Related Mechanism

Neuronal network is considered as one of the most complex tissues of human beings. The subject of the interface between neurons and the surface of biomaterials has of late been receiving much attention in the research fields of nerve tissue engineering and neuron chip because it has implications for repair and recruitment of the neuronal networks in vivo and in vitro. Chemically etched silicon substrates, polyelectrolyte multi-layered films by electrostatic self-assembly and patterns of biological macromolecules, were proposed as the model surfaces to study the interfacial reactions with the primary neural cells such as cortical and hippocampal neurons. The interfacial structures between cells and materials, induced effects to neural cell growth and network development by materials were studied in details using the confocal and atomic force microscopy.From the culturing results of the primary neural cells, the cells show good viability and compatibility with the designed model surfaces, including the silicon wafers with nano-scale roughness (Ra=20-70nm), hyaluronic acid based multilayered films. The neural cells can adhere and grow on the substrates, form mature dense neural networks. From the atomic force microscopic results, the interface between the neurons and silicon substrates were constructed by hierarchical structures which promoted the cell adherence and development. In addition, the neural cells were considered to change the surrounded microenvironments to improve their viability and living conditions. Meanwhile, on the multilayered films which mimicked the extracelllular matrices, the neurite outgrowth was influenced by the polycationic outmost layer and bi-layer number to certain extent. In addition, it seemed that different neurons like different polycations. The hippocampal neurons prefer poly (allylamine hydrochloride) while collagen attracts cortical neurons. Patterned neural network was fabricated using the microcontact printing of biological macromolecules. From the comparisons of different surface functional groups and different"ink", polyethylene (PEI) pattered on hydroxyl modified glass slides have achived the best performance among the tested combinations. From the immunohistochemical results, filament-like neurites runs in parallel on the PEI patterned grids. These dense neurites have relations between each other from the atomic force microscopic results. Furthermore, we found synaptic structures near the neuron body, which is the evidence of connection between axons and dendrites.In addition, a protocol of measuring membrane potential and electric field of neurons in vitro by confocal microscopy was proposed to evaluate the living status of neural cells, which was suggested to have potential applications in the study of interaction between the neural cells and materials. This is the first report of a reliable method for three-dimensional visualization of potential voltage of neurons at the best of our knowledge.