Papers by Author: Rei Araki

Abstract: Silicone rubber substrates were irradiated at an acceleration voltage of 7 kV and a dose of 1×1015 ions/cm2 by the simultaneous use of oxygen cluster and monomer ion beams, and then soaked in CaCl2 solution. Apatite-forming ability of the substrates was examined using a metastable calcium phosphate solution that had 1.5 times the ion concentrations of a normal simulated body fluid (1.5SBF). After the irradiation, the silicon oxide clusters (SiOx) were formed at the silicone rubber surface. The hydrophilicity of the substrates was remarkably improved by the irradiation. The irradiated silicone rubber substrates formed apatite in 1.5SBF, whereas unirradiated ones did not form it. These results suggest that the functional groups such as Si–OH and/or COOH groups induced apatite nucleation in 1.5SBF.

Abstract: Polyethylene (PE) substrates were irradiated at a dose of 1×1015 ions·cm−2 by the simultaneous use of oxygen (O2) cluster and monomer ion beams. The acceleration voltage for the ion beams was 7 kV. Unirradiated and irradiated PE substrates were soaked in simulated body fluid with ion concentrations 1.5 times of those of human blood plasma (1.5SBF) for 7 days. The irradiated PE substrate formed apatite on its surface, whereas unirradiated one did not form it. This is attributed to the formation of functional groups effective for apatite nucleation, such as COOH groups, on the substrate surface by the simultaneous use of O2 cluster and monomer ion beams. In addition, the apatite-forming ability of the irradiated substrate was improved by the subsequent CaCl2 treatment. This suggests that Ca2+ ions present on the substrate surface accelerated the apatite deposition. We can conclude that apatite-forming ability can be induced on surface of polyethylene by the simultaneous use of O2 cluster and monomer ion beams.