(571al) Titanium Implant Coated with Hydroxyapatite Microcapsules and Poly(L-lactic acid) Releasing An Antimicrobial Agent

A titanium implant coated with hydroxyapatite (HAp) is expected to improve the osseointegration. When HAp is provided as microcapsules containing an antimicrobial agent, it must be effective in preventing infection after the implanting operation as well. This study was carried out as a fundamental study on preparing such an implant. A screw made of pure titanium of Japanese Industrial Standards (JIS) type 2 was used as a model of implants. Hollow HAp microspheres were prepared by the interfacial reaction of calcium nitrate with potassium hydrogen phosphate in a multiple emulsion at 323 K. The titanium screw was dipped into hydrofluoric acid (HF) to alter the roughness. The HAp microspheres were suspended in Hank's balanced salt solution (HBSS), and the surface-treated screw was immersed in it to be coated with the HAp microspheres. The adhering state of HAp microspheres was observed by scanning electron microscopy. The amount of HAp adhering on the titanium surface was evaluated by inductive coupled plasma emission spectroscopy. An ampicillin sodium salt (Amp) solution as an antimicrobial agent was loaded into the HAp microspheres on the titanium screw, and then the screw was covered with poly(L-lactic acid). The release profile of Amp in HBSS for several days was characterized by ultraviolet spectroscopy. The antimicrobial activity of released Amp was evaluated with Escherichia coli as an indicator strain.