The synergistic effect of micro/nano-structured and Cu2+-doped hydroxyapatite particles to promote osteoblast viability and antibacterial activity

Microstructure and chemical constitution are important factors affecting the biological activity of biomaterials. This study aimed to fabricate hydroxyapatite (HAp) particles with both micro/nanohybrid structure and Cu2+ doping to promote osteogenic differentiation and antibacterial property. In the presence of inositol hexakisphosphate (IP6), micro/nano-structured and Cu2+-doped HAp (HAp-IP6-Cu) microspheres were successfully fabricated via hydrothermal method. Morphological observation showed that HAp-IP6-Cu microspheres with a diameter of 3.1-4.1 mu m were chrysanthemum-like and composed of nano-flakes approximately 50 nmin thickness. Compared with the HAp micro-rods or IP6 modified HAp(HAp-IP6) microspheres, HAp-IP6-Cu microspheres had a larger specific surface area, better hydrophilicity and stronger ability to adsorb bovine serum albumin. To evaluate the synergistic effects of micro/nanohybrid structure and Cu2+ on cell behavior, rat calvarial osteoblasts (RCOs) were cultured on HAp-IP6-Cu, HAp-IP6 and HAp layers as well as their extracts, respectively. Results demonstrated that HAp-IP6-Cu layer promoted the adhesion, proliferation and osteogenic differentiation of RCOs. The cells grew on HAp-IP6-Cu and HAp-IP6 layers exhibited greater spreading than those on HAp layer. In addition, quantitative test by the agar disk diffusion technique found that HAp-IP6-Cu microspheres were effectively against Staphylococcus aureus and Escherichia coli. These results demonstrated that HAp-IP6-Cu microspheres may be a potential candidate as a bioactive and anti-infective biomaterial for bone regeneration.