Effects of TiO2 nanoparticles on the physicochemical and biological properties of oxidized sodium alginate/polyacrylamide-gelatin composite hydrogels fabricated by interpenetrating network approach

To enhance the applicability of alginate hydrogel in tissue engineering, we attempted to fabricate oxidized sodium alginate/polyacrylamide-gelatin (OSA/PAM-GT) composite hydrogels by interpenetrating network approach with the hydroxyapatite/D-glucono-δ-lactone (HAP/GDL) as the endogenous ionic cross-linking agent for oxidized sodium alginate (OSA) and N , N ′-methylenebisacrylamide (MBAA) as the chemical cross-linking agent for polyacrylamide (PAM), followed by their surface coverage with gelatin. Then TiO 2 nanoparticles as the reinforcing agent were added to the OSA/PAM-GT hydrogel matrix to construct organic/inorganic hybrid OSA/TiO 2 /PAM-GT composite hydrogels. In particular, the effects of the amount of TiO 2 nanoparticles on the microscopic morphology, mechanical properties , swellability, biodegradability , bio-mineralization and biocompatibility of the composite hydrogels were studied. Experimental results indicated that the addition of TiO 2 nanoparticles into the matrix of OSA/TiO 2 /PAM-GT composite hydrogels could effectively regulate the porosity, mechanical properties, swelling ratio, in vitro biodegradability and bio-mineralization of OSA/TiO 2 /PAM-GT composite. Moreo v er, OSA/TiO 2 /PAM-GT composite hydrogels had the best biocompatibility when the content of TiO 2 nanoparticles was 0.5% ( w / v ), indicating that an appropriate amount of TiO 2 nanoparticles could effectively promote cell adhesion, proliferation and differentiation. Consequently, the combined method of the interpenetrating network technology, the incorporation of TiO 2 nanoparticles with the surface coverage of gelatin could overcome the defects of alginate hydrogels to some extent, making OSA/TiO 2 /PAM-GT composite hydrogels suitable for tissue engineering applications.