SELECTIVE NEURITE OUTGROWTH ON SILVER NEGATIVE ION (Ag-)-IMPLANTED POLYSTYRENE SURFACES

The negative ion implantation technique was applied to modify polymer surfaces of culture dishes for neuronal cells, PC12h. The silver negative ion (Ag-)-implantation was carried out at an ion energy of 20 keV and a dose of 3 ×1015 ions/cm2 with non-treated polystyrene (NTPS), tissue culture polystyrene (TCPS), and collagen-coated TCPS-Iwaki (CCPS). Ag--implanted surfaces of Ag/NTPS, Ag/TCPS, and Ag/CCPS were studied with respect to contact angle and/or chemical composition. The numerical values of contact angles on Ag/NTPS and Ag/TCPS were similar within experimental error, indicating the resemblance in their hydrophobicity and hydrophilicity. The PC12h cells, however, were attached only to the Ag--implanted region of NTPS, but not to the non-implanted NTPS region. Moreover, the neurite outgrowth was also observed to extend specifically along the Ag--implanted region of NTPS but not on the non-implanted NTPS region,although neurites extended towards all directions on collagen-coated TCPS as a control surface. There was no remarkable difference in neurite outgrowth among Ag--implanted regions of TCPS and CCPS. Thus Ag/NTPS region was affirmed to promote highly selective attachment, growth, and differentiation of PC 12h cells, although its mechanism is still unknown.