Electrospun nanofibers of a phosphorylated polymer--a bioinspired approach for bone graft applications

Biomaterials based on bioinspired mineralization are expected to offer osteoconductive and osteoinductive scaffolds for bone regeneration. An important role in the mediation of in vivo biomineralization process is played by highly anionic non-collagenous phosphoproteins (NCP) bound to the collagen matrix. Inspired by this fact, synthetic analogues of the NCPs like polyvinyl phosphonic acid which provide surface nucleation sites have been employed successfully for mineralization of hard tissues. In this study, electrospun nanofibrous scaffolds of partially phosphorylated polyvinyl alcohol (PPVA) are prepared and studied for matrix mineralization and maturation of human pre-osteoblasts like MG63 cells. Partial phosphorylation was found to affect many solution properties of PVA like increase in surface tension, conductivity and semi-crystalline intermolecular hydrogen bond formations narrowing down the electrospinning window for PPVA. In vitro mineralization under SBF treatment was uniform along the length of fibers on PPVA nanofibers. Further, MG63 cells showed increased adherence and proliferation on PPVA nanofibers and the expression of alkaline phosphatase activity and cell-matrix calcium levels were about two times higher than PVA nanofibers. The study established fabrication of electrospun nanofibers of a partially phosphorylated polymer, PVA resulting in improved osteoconduction and expression of early markers of osteoinduction in MG63 cells.