Osteoblast-like Cell Response to Titania-Ca-Modified Siloxane Biohybrids

This study examined the response of osteoblast-like cells to siloxane-based biohybrid materials obtained via the sol-gel process and modified with titania or with titania and calcium. The biohybrids' ability to form apatite and their degradation process were assessed in vitro via immersion in PBS and SBF. Characterization was performed using XRD, FT-IR, and SEM. The Siloxane-Ti biohybrid exhibited rutile crystalline phase formation, high stability, and resistance to hydrolytic degradation, but did not induce apatite growth. In contrast, the Ca-containing biohybrid showed a vitreous structure with significant surface morphology changes and increased degradability. The Ca-modification enhanced the precipitation of apatite layers, which was attributed to the presence of Ti-OH and Si-OH groups. Immersion of the Siloxane-Ti-Ca biohybrids in PBS produced a flake-like apatite-like mineral structure from the first day of immersion, while immersion in SBF led to a cauliflower-like apatite structure after 28 days. Osteoblast response was evaluated through cell adhesion, proliferation, and differentiation on the hybrid materials. The Siloxane-Ti hybrid promoted osteoblast adhesion and proliferation, whereas the Siloxane-Ti-Ca reduced cell viability and osteonectin expression at 21 days. The Siloxane-Ti hybrid also increased osteonectin expression at early stages, with osteopontin and osteocalcin expression emerging at later stages, indicating progression from early to mature stages stimulated by the hybrid material. The findings suggest that titania enhances the biocompatibility of siloxane materials and shows significant potential for bone tissue regeneration without added growth factors.