Biocompatibility and electrochemical evaluation of ZrO2 thin films deposited by reactive magnetron sputtering on MgZnCa alloy

Abstract

Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics; nevertheless, its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved. ZrO2-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability. In this work, the degradation, cytotoxicity, and antibacterial performance of ZrO2 thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated. Short-term degradation of ZrO2-coated and uncoated samples was assessed considering electrochemical techniques and H2 evolution (gas chromatography). Additionally, long term degradation was assessed by mass-loss measurements. The results showed that a 380 nm ZrO2 coating reduces the degradation rate and H2 evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term. The ZrO2 coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface, in comparison to the bare alloy. Finally, the ZrO2 coating prevents the adhesion and biofilm formation of S. aureus.