Abstract
Imperfect hydroxyapatite (IHA) bioceramics, which contain defects such as calcium deficiency, carbonate substitution, and metal cation substitution, exhibit improved osteogenic properties. In this study, we used a two-step calcination-hydrothermal process to manufacture two types of golden pomfret bone-derived imperfect hydroxyapatite bioceramics (G-IHA): carbonated calcium-deficient hydroxyapatite (CD-IHA) and carbonated hydroxyapatite (C-IHA). Their composition, surface morphology, zeta potential, degradation capacity, mineralization and osteogenic properties were systematically investigated. The results revealed that G-IHA with a higher defect content, including A-type carbonate substitution and Ca vacancies, had negatively charged surface. As a result, G-IHA surfaces are more favourable to ion exchange and interaction with cations (e.g., Na(+), Ca(2+)) in the microenvironment, which results in improved degradation and mineralization. Specifically, after 28 days of degradation, G-IHA showed significantly higher weight losses (CD-IHA and C-IHA were 17% and 13%, respectively) than commercial hydroxyapatite (CHA; 7%). In addition, G-IHA have a higher better bone-like apatite formation ability, and a higher degree of osteogenic differentiation than CHA. Notably, carbonated calcium-deficient imperfect hydroxyapatite (CD-IHA) exhibited the highest bioactivity and osteogenic capacity as evidenced by its increased alkaline phosphatase activity and improved bone matrix mineralization capacity. In conclusion, this study revealed that imperfect hydroxyapatite bioceramics derived from golden pomfret bone have the potential to enhance osteogenic properties and be employed in clinical settings as bone substitute materials.