Modified hydroxyapatite nanoparticles reinforced nanocomposite hydrogels based on gelatin/oxidized alginate via Schiff base reaction

Abstract

The aim of this study is to prepare nanocomposite hydrogel based on gelatin/oxidized alginate, and evaluate its reinforcement by incorporation of nanohydroxyapatite (nHA) for use in bone tissue engineering applications. We used Schiff-base reaction as a click chemistry to prepare nanocomposite hydrogels. Additionally, the nHA was modified using sodium alendronate as a bisphosphonate through formation of coordinate bonds (chelate formation) to prepare bisphosphonate-modified hydroxyapatite (nHABP). The presence of bisphosphonate in the network can improve the cytocompatibility of the scaffolds and suppress the nanoparticles aggregation by inducing steric repulsion. Improved mechanical and rheological properties in the samples containing nHABP is due to the enhanced dispersion of modified nanoparticles as a result of the additional interaction between amine groups in the nHABP and aldehyde groups in the polymeric matrix. We demonstrated how the presence of bisphosphonate ligand in the oxidized alginate-gelatin network can improve nanoparticles dispersion via Schiff-base reaction.