Noncalcined Bioactive Glass/Fish Scale Gelatin Hybrids Prepared by Sol-Gel Processing for Enhanced In Vitro...

Fish-derived biomaterials have attracted increasing interest for biomedical applications due to their biocompatibility and sustainability. In this study, fish scale gelatin was extracted through sequential acid-alkaline treatment followed by heat extraction at 75 °C and utilized to fabricate a composite scaffold with bioactive glass (BG). BG sol was synthesized from tetraethyl orthosilicate, triethyl phosphate, calcium nitrate, nitric acid, ethanol, and deionized water using a sol-gel method. The BG sol was blended with fish scale gelatin solution and stirred for 2 days to form a wet gel, which was subsequently oven-dried for 6 h to obtain fish scale gelatin/bioactive glass (FSG/BG) composites. The materials were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Thermal analyses showed that the extracted gelatin exhibited behavior comparable to commercial gelatin. FTIR spectra confirmed the formation of Si-O-Si networks and the presence of characteristic protein functional groups in the composite. The compressive strength of the FSG/BG scaffold (7.63 MPa) was higher than that of pure BG (6.51 MPa), indicating improved structural integrity. In vitro bioactivity was evaluated by immersing BG and FSG/BG discs in simulated body fluid (SBF) at 37.5 ± 0.5 °C for up to 16 days. Hydroxyapatite formation on the scaffold surface and Ca²⁺ concentration changes confirmed the favorable apatite-forming ability and bioactivity of the FSG/BG composite, suggesting its potential for bone tissue engineering applications.