Hybrid agarose gel for bone substitutes

Over the last decades, different materials have been investigated to overcome some flaws of bone substitutes. Even though various materials have been proposed for this conception, the in vivo assessments have still highlighted a lack of bioactivity and integration. In this context, this work focuses on the development of hybrid gel with surface properties specifically designed to promote bone regeneration by a sustained local delivery of active agents. We propose a new approach using modified-silica with high specific surface area and superior hydrophilicity dispersed in agarose hydrogel. In this optic, silica particles were dispersed in agarose solutions before the gelation of the composite upon cooling. The dispersion of the silica particles in the agarose gel was determined via scanning electronic microscopy. The degradation of the silica/agarose gels was also studied over a period of 12 weeks. Finally, the influence of the addition of silica on the permeability of the agarose gel was assessed via a diffusion test. The results showed that modified-silica particles exhibit a wide size distribution (500 nm and 10 µm) and can form clusters with higher size after their dispersion in agarose (up to 100 µm). The hybrid gel was stable over 12 weeks in aqueous solution. Moreover, no difference in permeability was noted between the hybrid gel and agarose hydrogel, allowing molecules up to 3 nm in diameter to diffuse freely within 1 mm thick agarose gels in less than 24 h. The present results indicate that hybrid agarose gel could represent an attractive matrix to disperse silica for scaffold applications.