Silver nanoparticle-loaded hydroxyapatite coating: structure, antibacterial properties, and capacity for osteogenic induction in vitro

Postoperative implant-associated infection remains a serious complication in dental and orthopedic surgery. Here we describe an efficient method of synthesizing a silver nanoparticle-loaded hydroxyapatite coating (AgNP-HAC) for implants with different morphologies, including net-plate (SHAC), oriented nanorod arrays (RHAC), and oriented nanoplate arrays (PHAC). The fabrication process included the following steps: (i) sol-gel preparation of bioglass coatings (BGC; CaO-SiO2-P2O5); (ii) transformation of the BGC to an HAC in a simulated body fluid under hydrothermal conditions; and (iii) preparation of the AgNP-HAC by a facile Ag mirror reaction. The results indicated that AgNP-SHAC, -RHAC, and -PHAC had antibacterial activity against Staphylococcus aureus and Escherichia coli. The AgNP-HAC surfaces were superior to a conventional titanium alloy in terms of stimulating spreading, proliferation, and attachment and inducing osteogenic differentiation in human bone marrow stromal cells; among the different types of coating, AgNP-RHAC and -PHAC elicited a superior biological response to AgNP-SHAC. Taken together, these findings suggest that the incorporation of Ag into HA coatings with different morphologies can yield a safe and highly effective surface for metallic implants.