Microstructure and gelation behavior of hydroxyapatite-based nanocomposite sol containing chemically modified silk fibroin

Nanocomposite sol comprised of hydroxyapatite (HA) and silk fibroin (SF) was synthesized via a wet-mechanochemical route. SF particles were chemically modified using an alkali solution attempting to disentangle their surface fibrils so as to enhance the effective contact between the mineral and the organic particles. With the alkali pretreated SF involved, Vickers microhardness of the composite increases by 57% and a more enhanced three-dimensional porous network with a homogenous particle form and a uniform pore size distribution is formed through the intimate crosslinkage between HA clusters and SF fibrils. In addition, the alkali pretreatment of SF not only increased the viscosity and the rigidity of the composite sol, but also promotes its gelation process, which is favorable for healing bone defects by an injection technique.