Sol–Gel Synthesized Silica/Sodium Alginate Hybrids: Comprehensive Physico-Chemical and Biological Characterization
Antonio D’Angelo, Cecilia Mortalò, Lara Comune, Giuseppina Raffaini, Marika Fiorentino, Michelina Catauro
Abstract
The development of biomaterials with tailored properties is indispensable for biomedical applications. In this study, amorphous silica/sodium alginate (SiO2/SA) hybrids were synthesized via the sol–gel method by incorporating 2, 5, and 8% sodium alginate into the silica matrix. The hybrids were characterized to evaluate their structural, surface, thermal, moisture-responsive, and biological properties. FTIR and XRD analyses confirmed the formation of organic–inorganic networks and amorphous structures. BET measurements revealed a specific surface area of 325 m2/g for SiO2/SA2%, decreasing with higher SA content to 104.3 m2/g for SiO2/SA8%; the moisture sorption capacity followed a similar trend. Thermal analysis indicated improved stabilization of the polymer within the silica matrix. Cytotoxicity tests on HaCaT (human keratinocyte) cells line revealed moderate toxicity for the SiO2/SA2% hybrid (~40% cell viability inhibition (CVI)), while increasing the SA content reduced cytotoxicity, with a CVI of 33% for SiO2/SA5% and ~15% for SiO2/SA8%, all within non-toxic ranges according to ISO standards. The SiO2/SA5% hybrid demonstrated the best balance between functional properties and biocompatibility. These preliminary results suggest that further optimization with intermediate SA concentrations (e.g., 6–7%) could further reduce cytotoxicity while maintaining desirable properties, supporting the potential of silica/sodium alginate hybrids in future biomedical applications.