Oxygen plasma surface modification enhances immobilization of simvastatin acid

Simivastatin acid (SVA) has been reported to stimulate bone formation with increased expression of BMP-2. Therefore, immobilization of SVA onto dental implants is expected to promote osteogenesis at the bone tissue/implant interface. The aim of this study was to evaluate the immobilization behavior of SVA onto titanium (Ti), O-2-plasma treated titanium (Ti + O-2), thin-film coatings of hexamethyldisiloxane (HMDSO), and O-2-Plasma treated HMDSO (HMDSO + O-2) by using the quartz crystal microbalance-dissipation (QCM-D) technique. HMDSO surfaces were activated by the introduction of an OH group and/or O-2-functional groups by O-2-plasma treatment. In contrast, titanium surfaces showed no appreciable compositional changes by O-2-Plasma treatment. The QCM-D technique enabled evaluation even at the adsorption behavior of a substance with a low molecular weight such as simvastatin. The largest amount of SVA was adsorbed on O-2-plasma treated HMDSO surfaces compared to untreated titanium, HMDSO-coated titanium, and O-2-Plasma treated titanium. These findings suggested that the adsorption of SVA was enhanced on more hydrophilic surfaces concomitant with the presence of an OH group and/or O-2-functional group resulting from the O-2-Plasma treatment, and that an organic film of HMDSO followed by O-2-plasma treatment is a promising method for the adsorption of SVA in dental implant systems.