Oxidation facilitated antimicrobial ability of laser micro-textured titanium alloy against gram-positive Staphylococcus aureus for biomedical applications

Micro-textures were engineered on titanium samples by a rapid, highly repeatable, and cost effective nanosecond laser texturing process. The controlled and repeatable micro-texture was effective in the reduction of adhesion and proliferation of Staphylococcus aureus. However, the adhesion and proliferation of human bone marrow mesenchymal stem cells were found unaffected. The authors observed time-delayed saturation of oxidation on laser micro-textured Ti6Al4V as compared to pristine material yielding a super-hydrophobic surface (contact angle of ∼158.2°). An in-house setup was designed to expose a three-dimensionally laser micro-textured Ti6Al4V sample to S. aureus-spiked nutrient broth for 24 h in a closed loop continuous flow system. The authors observed a 50% reduction of S. aureus adhesion and proliferation over the laser micro-textured surface compared to pristine samples. In vitro tests confirmed that blood coagulation remains largely unaffected, while protein adsorption was decreased by fourfold on the micro-textured surfaces, a desirable property for surgical tools. Nanosecond laser micro-textured surfaces were effective in reducing S. aureus adhesion and its proliferation due to phase evolution, oxidative transformation of Ti6Al4V, and reduction of surface potential. In addition, laser based micro-texturing is a nontoxic, environment friendly green process that is also a cost effective alternative to conventional surface modification techniques such as mechanical micromachining and chemical treatments.