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 PC12h cells

although its mechanism is still unknown.