Imperfect hydroxyapatite bioceramics derived from golden pomfret have enhanced osteogenic properties

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⁺, Ca²⁺) 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.

Keywords: Calcium-deficient hydroxyapatite; Carbonate substitution hydroxyapatite; Cation exchange; Enhanced osteogenic property; Golden pomfret bone.

Fig. 1

Process of preparing bioceramics derived from golden pomfret.

Fig. 2

(a) XRD pattern of CHA, C-IHA and CD-IHA; (b) EDS spectra and the calculated Ca/P ratio of CHA, C-IHA and CD-IHA ; (c) Mechanism of calcium vacancy formation in the HA structure above 800 °C (analyzed by VESTA software); (d) FTIR spectra of CHA, C-IHA, and CD-IHA; (e) TG graphs of CHA, C-IHA, and CD-IHA; and (f) DTG graphs of CHA, C-IHA, and CD-IHA calculated by TG data.

Fig. 3

(a) Zeta potentials of CHA, C-IHA and CD-IHA; and (b) sources of charges in CHA, C-IHA and CD-IHA.

Fig. 4

(a) Degradation rate of CHA, C-IHA, and CD-IHA in vitro; (b) degradation mechanism of CHA, C-IHA, and CD-IHA in vitro; and (c) pH variation during the degradation of CHA, C-IHA, and CD-IHA in vitro.

Fig. 5

(a) XRD pattern of CHA, C-IHA and CD-IHA after immersion in SBF; (b) SEM images of CHA, C-IHA and CD-IHA before and after immersion in SBF; (c) FTIR spectra of CHA, C-IHA and CD-IHA after immersion in SBF; and (d) mineralization mechanism of CHA, C-IHA and CD-IHA during immersion in SBF.

Fig. 6

(a) Cell viability of L929 co-cultured with CHA, C-IHA and CD-IHA at various concentrations; (b) BMSCs co-cultured with CHA, C-IHA and CD-IHA at various concentrations; (c) Calcein-AM/PI staining result of BMSCs co-cultured with CHA, C-IHA and CD-IHA at various concentrations.

Fig. 7

(a) ALP and ARS staining image of CHA, C-IHA, CD-IHA, and control group; (b) area of ALP-active region of CHA, C-IHA, CD-IHA, and control group; (c) area of ARS-active region of CHA, C-IHA, CD-IHA, and control group.

Fig. 8

Illustration of the preparation method and action mode for golden pomfret derived hydroxyapatite.