Silica/alginate hybrid biomaterials and assessment of their covalent coupling

Abstract Organic–inorganic hybrid materials composed of co-networks of biodegradable polymer and silica have potential to combine the properties of an elastic organic polymer and inorganic silica. The nanoscale interaction of the co-networks and formation of covalent bonds between them are expected to provide tailored mechanical properties and congruent degradation. Alginate is a natural polymer commonly used in tissue engineering applications due to its good biocompatibility and biodegradability. In this work we present new alginate–silica hybrids prepared through nucleophilic ring opening reaction of 3-glycidoxypropyl trimethoxysilane (GPTMS) by carboxylic groups of alginate and incorporation of this functionalized alginate into the sol–gel process to make a hybrid. The role of the GPTMS is to provide organic/inorganic covalent coupling. The reaction of alginate with GPTMS was followed using NMR, FTIR and ToF-SIMS and the dissolution behaviour, bioactivity and mechanical properties of the resultant alginate–silica hybrid monoliths were evaluated. While mechanical strength was high with values of 110–242 MPa comparable to that of cortical bone, the amount of GPTMS coupling to the alginate was low, with the rest of the GPTMS forming diols or a separate network.