Strontium-Substituted Hydroxyapatite Nanocrystals Synthesized in Ultrasonic Field: Use for Protein Adsorption

Abstract

Hydroxyapatite Ca10(PO4)6(OH)2 (HAP) is widely applied in a biomaterial because of its excellent biocompatibility and bioactivity. However, all properties of HAP, especially the adsorption properties can be tailored by modifying the composition with ionic substitutions. Among many cations that can substitute for calcium in the structure of HAP, strontium is a kind of essential trace elements in human body. It has been known as one of the cationic substitute for calcium in the HAP lattice. The strontium-substituted hydroxyapatite (Sr-HAP) is formed when strontium is doped in HAP structure. The bioactivity, biocompatibility, and adsorption properties are improved when the original lattice of HAP is destroyed. In this study, we focus on synthesis of strontium-substituted HAP nanocrystals in ultrasonic field which is a mild and simple synthesis method. The Sr-HAP with different Sr contents was synthesized. The effects of reaction temperature, sintering temperature and reaction time on protein adsorption of Sr-HAP were studied. In addition, the crystalline phase, chemical compound, surface area and morphology were characterized by XRD, FTIR, TEM and BET. The results indicate that the original lattice of HAP was destroyed and the structure of HAP doped with strontium formed. Sr-HAP with smaller crystal size, larger specific surface area and homogeneous distribution was prepared. Especially, it has great adsorption to target protein, bovine serum albumin (BSA).