Design of novel bioactive materials through organic modification of calcium silicate

Bioactive ceramics have attractive feature for bone repair such as direct bone-bonding in the body. However their clinical application is limited to low loaded portions due to their inappropriate mechanical performances such as higher brittleness and lower flexibility than natural bone. The essential condition for artificial materials to show bioactivity is formation of bone-like apatite on their surfaces in body environment. This apatite formation is triggered by silanol (Si-OH) group on the material surfaces and release of Ca²⁺. These findings bring us an idea that novel bioactive materials with high flexibility can be designed by organic modification of calcium silicate. We synthesized organic-inorganic hybrids from organic polymers including 2-hydroxyethylmethacrylate (HEMA), starch and alginate by modification with alkoxysilane and calcium chloride. The hybrids formed apatite on their surfaces in simulated body fluid (SBF, Kokubo solution). Such a modification was also effective for providing conventional polymethylmethacrylate (PMMA)-based bone cement with bioactivity.