| Fluoropolymers are modified in an attempt to enhance their interaction with nerve cells for the purpose of modelling biomaterial-cell interactions for eventual application in spinal cord injury repair. Poly(tetrafluoroethylene- co-hexafluoropropylene) (FEP) was modified with oxygen and nitrogen-containing functional groups and subsequently coupled with cell-adhesive peptides to mimic the laminin basal lamina environment of the peripheral nervous system. The surface chemistry of the modified surfaces were fully characterized. Hippocampal neurons were cultured on all the modified surfaces to study for neurite outgrowth and cell adhesion.; FEP surfaces were initially functionalized by reduction with sodium naphthalide followed by either hydroboration oxidation (to alcohol) or oxidation (to carboxylic acid). Functionalized surfaces were then coupled with individual peptide: YIGSR, IKVAV or RGD. The initial cell-material interaction study showed that hippocampal neurons responded to the peptide-modified surfaces in a quantitatively comparable manner to positive controls consisting of poly(L-lysine) (PLL) and laminin coated surfaces. However, qualitative differences in cell response were observed. To further study the neuron-surface interaction, a new method of surface modification was developed.; The novel mercat amination reaction was used to functionalize FEP surfaces by exposing films to a UV-activated mercury in ammonia system. Relative to hydroxyl and carboxylic acid chemistries, the mercat reaction is simpler, involving only one step and uses less reactive chemicals. The modified surfaces were defined to have amines, nitriles, hydroxyl, carboxylic acids, and carbon-carbon double bonds, which allowed for the coupling of cell-adhesive peptides. Initial cell culture studies of hippocampal neurons on these surfaces showed that the neuronal response was comparable to PLL/laminin surface even though the peptide concentrations were lower.; An in-depth study of cell-material interaction was developed to better distinguish the surfaces by neuronal response. Neurite number and length were investigated in conjunction with cell adhesion and viability. The results indicated that the hippocampal interaction was best on PLL/laminin surfaces, but was closely approximated by FEP surfaces coupled with both YIGSR and IKVAV. Surfaces with a single peptide showed significantly lesser response. The specificity of the cell-peptide interaction was demonstrated with a competitive assay. These well-defined fluoropolymer surfaces confirmed that nerve cell interaction was enhanced by the coupling of cell-adhesive peptides. |
