In Vitro Bactericidal Efficacy of Nanostructured Ti6Al4V Surfaces is Bacterial Load Dependent.

The demand for medical implants globally has increased significantly due to an aging population amongst other reasons. Despite the overall increase in the survivorship of Ti6Al4V implants, implant infection rates are increasing due to factors such as diabetes, obesity, and bacterial resistance to antibiotics. Two commonly found bacteria implicated in implant infections are and . Based on prior work that showed nanostructured surfaces might have potential in passively killing these bacterial species, we developed a hierarchical, hydrothermally etched, nanostructured titanium surface. To evaluate the antibacterial efficacy of this surface, etched and as-received surfaces were inoculated with or at concentrations ranging from 10 to 10 colony-forming units per disc. Live/dead staining revealed there was a 60% decrease in viability for and greater than a 98% decrease for on etched surfaces at the lowest inoculum of 10 CFU/disc, when compared to the control surface. Bactericidal efficiency decreased with increasing bacterial concentrations in a stepwise manner, with decreases in bacterial viability noted for above 10 CFU/disc and above 10 CFU/disc for . Surprisingly, biofilm depth analysis revealed a decrease in bacterial viability in the 2 μm layer furthest from the nanostructured surface. The nanostructured Ti6Al4V surface developed here holds the potential to reduce the rate of implant infections.