Apatite-forming ability of organic-inorganic hybrids fabricated from glucomannan by chemical modification with alkoxysilane and calcium salt

Abstract

So-called bioactive ceramics have attractive features such as direct bone-bonding in living body via formation of bone-like apatite layer on their surfaces. However, there is limitation on clinical applications due to their inappropriate mechanical properties such as higher Young's modulus and lower fracture toughness than natural bone. Bioactive ceramics bond to bone through bone-like apatite layer formed on their surfaces by chemical reaction with body fluid. To overcome the problem of bioactive ceramics, hybrid materials have been developed by organic modification of silanol (Si-OH) group and calcium ions, that are basic component of bioactive ceramics. In this study, we prepared organic-inorganic hybrids from glucomannan, a kind of complex polysaccharide, by modification with alkoxysilane and calcium salts. The apatite formation on the hybrids with different alkoxysilane content was examined in simulated body fluid (SBF). All the samples formed the apatite in SBF irrespective of alkoxysilane content, when they were previously treated with CaCl2 solution. The hybrids had tendency to be fractured into small pieces in SBF and release large amount of Ca2+ at low alkoxysilane content. This means that addition of alkoxysilane is effective for not only providing the hybrids with the apatite-forming ability but also improving stability in aqueous environment.