Biowaste-based hydroxyapatite for bone repair: synthesis from Anadara granosa and Achatina fulica: preliminary study

Bone regeneration is a critical area in tissue engineering because of the increasing incidence of bone defects resulting from trauma, degenerative diseases, and congenital disorders. The focus of this study is the synthesis of hydroxyapatite (HAp) from two natural calcium-rich biowastes: Anadara granosa (blood cockle) and Achatina fulica (snail). The shells were calcined at 900 °C to form calcium oxide (CaO) and then converted into HAp via the wet precipitation method using a Ca/P molar ratio of 1.67. The synthesized HAp powders were evaluated for their chemical properties and biological performance. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of phosphate and hydroxyl functional groups, and among the samples, An 100 showed the highest crystallinity. MC3T3-E1 cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay at 24, 48, and 72 hours. At 72 hours, An 100, An 75, and An 50 maintained a viability above 70%, indicating good biocompatibility. In contrast, An 25 and Ac 100 exhibited significant cytotoxicity (p < 0.05). Only the noncytotoxic concentrations were used for the in vitro scratch wound-healing assay, where An 100 demonstrated the most rapid wound closure, indicating increased osteoblast migration. Furthermore, in this study, the elemental composition and structural integrity of Hap was analyzed to understand the factors affecting its stability and performance in biological environments. These findings suggest that naturally derived HAp is a promising, sustainable, and effective biomaterial for bone tissue engineering and has favorable effects on cell viability and migration.