Influence of Chemical Composition on the Bioactivity of Spray Pyrolyzed Mesoporous Bioactive Glass

Abstract

SiO2‐CaO‐P2O5‐based mesoporous bioactive glass (MBG) is a potential material for bone implants due to its superior bioactivity. Sol‐gel is a common technique for preparing MBG. Early studies showed that for MBG, the composition and surface area have critical influences on the bioactivity of MBG. However, there is a counteractive effect if both factors are used to enhance the bioactivity of MBG: a higher Ca content (lower Si content) provides more nonbridging oxygen groups, which enhance the bioactivity, but a higher Ca content also allows a lower viscosity at high temperature. Low viscosity is not able to prevent the MBG liquid flowing into the mesopores and results in the reduction of the surface area, which deteriorates the bioactivity. Unlike sol‐gel, spray pyrolysis (SP) offers a rapid cooling rate, which can avoid the lower viscosity and resultant damage to the mesoporous structure, and the rapid cooling rate also preserves more metastable siloxane groups, which enhance the bioactivity. In this study, MBG particles with various Si:Ca ratios were synthesized using SP, and the morphology and bioactivity were investigated. Two typical morphologies, spherical mesoporous and wrinkled mesoporous, were observed. Also, a faster hydroxyl apatite formation time was observed in MBG with lower silica concentration (70 mol% SiO2).