Surface Modification of Silicone Rubber for Adhesion Patterning of Mesenchymal Stem Cells by Water Cluster Ion Beam

Biocompatibility of silicone rubber sheet (SR) was improved by the water cluster ion irradiation for adhesion patterning of mesenchymal stem cells (MSCs). The water cluster ions were irradiated at acceleration voltage of 6 kV and doses of 10(14) - 10(16) ions/cm(2). The effect of ion dose on changes in wettability and surface atomic bonding state was observed. Compared to the unirradiated SR, about four-time smoother surface on the irradiated one was observed. Water contact angle decreased with an increase in the ion dose up to 1x10(15) ions/cm(2). With an increase in ion dose, XPS showed decrease of atomic carbon due to lateral sputtering effect and increase of atomic oxygen due to surface oxidation. After 7 days in vitro culture, the complete adhesion pattern of the rat MSCs was obtained on the irradiated SR at dose of 1x10(15) ions/cm(2), corresponding to the low contact angle of 87 degrees. At low dose, the partial pattern on the irradiated region was observed instead.