Fabrication of poly(vinyl alcohol)–apatite hybrids through biomimetic process

Natural bone is a kind of organic–inorganic hybrid that is composed of collagen and apatite nanocrystals. Organic polymer–apatite hybrid is therefore expected as novel bone substitutes exhibiting both bone-bonding ability and mechanical performance analogous to natural bone. Biomimetic process has been paid much attention on fabrication of such hybrids, where bone-like apatite is deposited on material surfaces in a simulated body fluid (SBF, Kokubo solution) with ion concentrations nearly equal to those of human extracellular fluid at ambient conditions. Hydroxyl groups on several kinds of metal oxide gels effectively trigger heterogeneous nucleation of the apatite in body environment. This is significantly enhanced by release of calcium ions from the materials. In this study, we synthesized organic–inorganic hybrids from poly(vinyl alcohol) (PVA) by modification with silica as well as calcium nitrate. PVA has attractive features for bone substitutes such as high hydrophilicity and high flexibility. Ability of the apatite formation was examined in SBF. Apatite deposition was observed on the surfaces of the hybrids in SBF. The PVA–apatite hybrids obtained are expected as novel bone-repairing materials.