Diamond-like carbon films doped with ZrO2 nanoparticles: Improving antimicrobial properties

Abstract

Diamond-like carbon films doped with zirconium oxide nanoparticles were developed as a nanocomposite, seeking better antibacterial properties for medical applications. Monoclinic zirconium oxide nanoparticles were heated and sonicated at 700 W to obtain a suspension with a particle size with low polydispersity in hexane as a solvent. There were no appreciable changes, neither in the surface organic functional groups nor in the crystalline structure with the heating process. The suspension was introduced into a reaction chamber to generate a carbon plasma in a deposition process. Ti6Al4V was used as a substrate in order to obtain acceptable adherence values close to 22 N. Diamond-like carbon films doped with zirconium oxide nanoparticles were obtained via PECVD and an additional cathode technique. The bactericidal and fungicidal properties of the films were evaluated by direct and non-direct contact. Non-contact results showed films with good bactericidal properties, close to 95 % after 6 h and 36 % after 18 h. Fungicidal properties were at 65 % and 50 %, respectively, under the same test conditions. These results suggested that the nanoparticles helped to maintain quasi-constant damage in C. albicans, in contrast to E. coli, where the properties decreased considerably. So, the death mechanism caused by zirconium oxide nanoparticles is more effective long-term against C. albicans than E. coli. When there is direct contact, the nanoparticle agglomerates acted as a poison in the cell, causing degeneration in geometry and continuity of the cells.