Hydroxyapatite nanoparticles as a controlled-release carrier of BMP-2: absorption and release kinetics in vitro.

Recently, nanoparticles have been extensively developed as controlled-release carriers; however, there has been little research on hydroxyapatite nanoparticles (HANPs) and their potential applications. In this study, HANPs were investigated as a controlled-release carrier of bone morphogenetic protein-2 (BMP-2), the absorption and release kinetics of which were analyzed in vitro. Different concentrations of BMP-2 solution were used to evaluate the adsorptive properties of HANPs. It was observed that the amount of BMP-2 adsorbed onto HANPs could be as high as 70 mug/mg and that adsorption rate was highly correlated with the concentration of BMP-2 solution used. After absorption, the suspension of HANPs absorbed BMP-2 (HANPs/BMP-2) was incubated at 37 degrees C for 15 days and the release kinetics of BMP-2 from HANPs/BMP-2 was determined daily. The release profile showed sustained release of BMP-2 over the period of the investigation. Collectively, these results suggest that HANPs has the potential to function as a carrier for drug delivery systems and as a scaffold material in bone tissue engineering.