Antibacterial and corrosion resistant ANPs-TaC nanocomposite coating for biomedical applications

Abstract

To improve the antibacterial properties of metallic implants to hinder the colonization of bacteria on their surfaces, an Ag nanoparticle (ANPs)/TaC nanocomposite coating was synthesized on a titanium alloy substrate by a double cathode glow discharge approach. The nanocomposite coating was composed of AgNPs (~13 nm in diameter) embedded in a nanoscale TaC matrix, with a mean grain size of 8 nm. The nanocomposite coating exhibited a bilayer structure, composed of a compact inner layer and a cauliflower-like outer layer. The corrosion resistance of the nanocomposite coating in both a 0.9 wt% NaCl solution and Ringer's solution was studied in comparison with both uncoated Ti-6Al-4V (TC4) and an Ag-free TaC coating by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). These results showed that the incorporation of Ag nanoparticles slightly lowered the corrosion resistance of the TaC coating. The antibacterial activity of the ANPs-TaC nanocomposite coatings against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella Typhimurium (Salmonella) strains was examined based on the bacterial inhibitory zones and bacterial killing efficiency. The addition of ANPs markedly increased the antibacterial capacity of the TaC coating against all three types of microorganisms. Therefore, a unique combination of the electrochemically stable TaC phase, together with the antibacterial behavior of the ANPs, makes the ANPs-TaC nanocomposite coating an attractive choice in the design of next-generation biomedical implants.