Sol-Gel Synthesized Silica/Sodium Alginate Hybrids: Comprehensive Physico-Chemical and Biological Characterization

The development of biomaterials with tunable properties is indispensable for advancing biomedical applications such as tissue engineering and drug delivery. In this study, amorphous silica/sodium alginate (SiO₂/SA) hybrid materials were synthesized via the sol–gel method by incorporating 2, 5, and 8% of sodium alginate into the silica matrix. The hybrids were extensively characterized to evaluate their structural, surface, thermal, moisture-responsive, and biological properties. FTIR and XRD analyses confirmed the successful formation of organic–inorganic networks and amorphous structures. BET measurements revealed a substantial increase in specific surface area for the 2 and 5% SA hybrids, reaching up to 325 m²/g, while the 8% SA sample showed a marked decrease due to pore blocking. Moisture sorption capacity followed a similar trend. Thermal analysis indicated improved thermal behavior and partial stabilization of the polymer within the silica matrix. Cytotoxicity tests on HaCaT cells showed increased cell viability inhibition for the 2% SA hybrid, attributed to its high surface area, while the 5 and 8% hybrids showed better biocompatibility. Overall, the SiO₂/SA 5% hybrid demonstrated the best balance between enhanced functional properties and a good biocompatibility, suggesting it as the most promising candidate for future biomedical applications.