Antibacterial activity of DLC films containing TiO2 nanoparticles

Abstract Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO 2 ) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO 2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO 2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli ( E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO 2 in DLC bulk was confirmed by Raman spectroscopy. As TiO 2 content increased, I D / I G ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO 2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO 2 concentration. As TiO 2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO 2 nanoparticles can be useful for producing coatings with antibacterial properties.