Comparative study of hydroxyapatite, fluor-hydroxyapatite and Si-substituted hydroxyapatite nanoparticles on osteogenic, osteoclastic and antibacterial ability

Abstract

This study compared the effects of hydroxyapatite (HA), fluor-hydroxyapatite (FHA) and Si-substituted hydroxyapatite (SiHA) on osteogenic differentiation, osteoclastic activity and antibacterial properties. HA, FHA and SiHA were prepared via a sol–gel reaction and characterized by scanning electron microscopic analysis (SEM), transmission electron microscopic analysis (TEM), and X-ray photoelectron spectrometry. Cell proliferation was evaluated using an MTT assay and cytoskeletal morphology was observed by fluorescence microscopy. Osteogenic differentiation was evaluated using alkaline phosphatase activity and Alizarin red staining. Quantitative real-time PCR was used to evaluate the mRNA expression of runt-related transcription factor 2 (Runx2) and osteopontin (OPN). New bone formation was tested using μCT, haematoxylin and eosin staining and TRAP staining. The antibacterial actions against Porphyromonas gingivalis (P. g) were evaluated through plate counting and live-dead bacterial staining. The results demonstrated that HA, FHA and SiHA can promote proliferation of bone mesenchymal stem cells (BMSCs). ALP activity in FHA extract with a concentration of 625 μg mL⁻¹ was the highest after 14 days osteogenic induction; similar results were observed for Runx2 and OPN mRNA expression. HA, FHA and SiHA decreased trabecular space in bone defects, but FHA reduced osteoclastic activity and inhibited P. g growth. In conclusion, FHA can promote osteogenic activity, reduce osteoclastic activity and enhance antibacterial effects.