Characterization, cytotoxicity and cell proliferation of two Hydroxyapatite products from Lates calcarifer fish bones via thermal calcination

Abstract This study investigates the sustainable extraction of nano-Hydroxyapatite (nano-HAp) from Lates calcarifer fish bones, a by-product of the seafood industry, through thermal calcination. Nano-HAp was synthesized at two temperatures (650 °C and 700 °C), resulting in rod-like (42 nm) and spherical (98 nm) particles, respectively. Both samples were identified as B-carbonated HAp, with Ca/P molar ratios of 1.842 for HAp 650-4 h and 1.856 for HAp 700-4 h, confirming the presence of B-type HAp, which has higher Ca/P ratios than the standard HAp found in bones and teeth (1.67). Cytotoxicity tests showed that both samples exceeded the ISO 10993-5:2009 standard, with L929 cell viability above 70% at concentrations up to 2 mg mL −1 . Notably, the study emphasizes that the size and morphology of nano-HAp play a critical role in its biological activity. Larger spherical particles (HAp 700-4 h) enhanced the proliferation of human bone marrow-derived mesenchymal stem cells (hBMSCs) more effectively than smaller rod-like particles (HAp 650-4 h), suggesting their greater potential for tissue engineering and bone regeneration applications. This work demonstrates the promising biocompatibility of fish bone-derived nano-HAp and its potential for sustainable biomedical applications.