Nerve-cell attachment properties of polystyrene and silicone rubber modified by carbon negative-ion implantation

The surfaces of spin-coated polystyrene (PS) on glass and silicone rubber (SR) were modified by carbon negative ion implantation with various ion doses from 0.1 to 10 × 1015 ions/cm2 at various ion energies from 5 to 30 keV. The implantation conditions with and without a pattering mask were for investigation of cell attachment properties and for evaluation of surface physical properties of contact angle, respectively. The contact angles of modified surfaces were investigated by pure water drop as implanted and after dipping in pure water for 2 h. In case of SR, the contact angle decreases with increasing ion dose and ion energy. For the case of PS, the optimum decreasing value is about 3–5 × 1015 ions/cm2 at 10 keV implantation, and at 25 keV at 3 × 1015 ions/cm2 implantation. Nerve-cell attachment properties of modified surfaces were investigated using nerve-like cells of rat adrenal pheochromocytoma (PC12h) in vitro. As implanted at the mean implantation conditions of dose and energy which are 3 × 1015 ions/cm2 with 10 keV for PS and SR, the cells attached only on the implanted region. However, for C-implanted SR at 30 keV, the cells were abnormal in shape and of very large size.