Diameter of titanium nanotubes influences anti-bacterial efficacy

Abstract

Bacterial infection of in-dwelling medical devices is a growing problem that cannot betreated by traditional antibiotics due to the increasing prevalence of antimicrobialresistance and biofilm formation. Here, due to changes in surface parameters, it isproposed that bacterial adhesion can be prevented through nanosurface modificationsof the medical device alone. Toward this goal, titanium was created to possessnanotubular surface topographies of highly controlled diameters of 20, 40, 60, or80 nm, sometimes followed by heat treatment to control chemistry and crystallinity,through a novel anodization process. For the first time it was found that throughthe control of Ti surface parameters including chemistry, crystallinity, nanotubesize, and hydrophilicity, significantly changed responses of both Staphylococcusepidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and othermedical device related infections) were measured. Specifically, heat treatment of80 nm diameter titanium tubes produced the most robust antimicrobial effectof all surface treatment parameters tested. This study provides the first steptoward understanding the surface properties of nano-structured titanium thatimprove tissue growth (as has been previously observed with nanotubular titanium),while simultaneously reducing infection without the use of pharmaceutical drugs.