Comparing two antibacterial treatments for bioceramic coatings at short culture times

Abstract

Plasma-sprayed hydroxyapatite coatings were employed industrially for decades to improve osteointegration of articular implants, but many studies have warned about the problems inherent to this procedure (mechanical properties, harmful phases). Consequently, a combination of hydroxyapatite with TiO2 sprayed by high velocity oxy-fuel spray was considered in this study. As infection after joint replacement surgery is one of the most critical concerns when considering implant performance, it is necessary to study possible ways to reduce or eliminate it. Two coating treatments were chosen for this study: addition of a percentage of ZnO and immersion in gentamicin for 24 h. Furthermore, three bacteria were considered: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The evolution of bacteria viability in solution was measured at 0, 2, and 4 h; and plate assays were performed to study antibacterial effects by diffusion. The results show an important antibacterial effect of the as-sprayed coating, attributed to the presence of -OH radicals on the surface. The presence of ZnO did not have any additional influence on bacteria viability, but gentamicin-treated samples showed an improvement in antibacterial behavior for Gram-negative bacteria in solution, as well as a bactericidal effect in diffusion conditions.