Algal biogenic synthesis of SiO2–CaO–P2O5 system bioactive glass using Cyclotella meneghiniana and waste fish bone

Bioactive glasses containing silica and calcium phosphate are desirable in bone repair due to their ability to induce hydroxyapatite (HA) on their surface, from where a cascade of reactions culminating in bone regeneration occurs. Diatom biosilica derived from algae is a green alternative silica precursor to analytical grade reagents. Its environmentally friendly extraction process makes it suitable for the production of biocompatible silicate-based bioactive glasses. Therefore, this study aimed to prepare a bioactive glass in the system SiO 2 –CaO–P 2 O 5 biologically using the diatom Cyclotella meneghiniana as the silica source and waste catfish ( Siluriformes ) bone as the precursor for CaO and P 2 O 5 . The obtained bioactive glass was characterized for its morphology, elemental composition, mineral phase constituents, and bond properties. A standard in vitro procedure in simulated body fluid (SBF) was used to evaluate the bioactivity of the sample, while a cytocompatibility (mouse fibroblasts) test was performed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT assay). The catfish bone contained 64.535 ± 0.394 CaO and 30.818 ± 0.589 P 2 O 5 (in wt%), making it a rich source of CaO-P 2 O 5 . Analysis showed that the Ca/P ratio in the HA deposited on the glass surface was 1.65 after immersion in SBF for 14 days, which is close to that of natural bone (1.67). Besides the bioactivity displayed, the leachate from the bioactive glass was not toxic but exhibited cell viability above 95%. These performances are for a material serving as a scaffold in bone regeneration. The synthetic route where Cyclotella meneghiniana served as a silica substitute precursor is a promising green method for the production of biocompatible silicate bioactive glasses and related silica-based products.