Biofilm Properties of the Plasma Nitrided TI6AL4V Alloys with Focus on S. Aureus

Abstract

Biomedical implants are artificial components placed in the jawbone to replace lost teeth functionally and aesthetically due to accidents, caries, and various diseases. In the treatment method of biomedical implants, the healing period for patients can sometimes be prolonged. After the biomedical implant is applied to the jawbone, the lack of sufficient hydrophilic and biological properties of the implant surface can negatively impact the treatment. Particularly, it poses risks in biomedical fields as interactions between bacteria and the surface encourage implant loss. For this reason, the surface properties of biocompatible materials must be enhanced for the well-being of individuals. This study aims to enhance the surface wettability (hydrophilicity) and biofilm (cellular change) properties by controlling the surface characteristics of Ti6Al4V alloys through the application of plasma nitriding (460∘C and 535∘C for 9 h). XRD, SEM, EDS, AFM microscope, surface tension meter, and microhardness testing were employed to analyze the surface topology, metallurgical alterations, and wettability properties of plasma nitrided samples. Subsequently, Staphylococcus aureus bacterial strain was applied to the plasma nitrided samples to evaluate their biofilm behavior. It was observed that both untreated and plasma nitrided samples exhibited a hydrophilic surface. The augmentation of plasma nitriding temperature resulted in relative changes in surface wettability and surface energy while maintaining the hydrophilic character of the surfaces. Furthermore, during the 6h incubation period, sample TR1 demonstrated a higher biofilm coverage rate compared to the untreated control, but it was similar to TR2 (F = 2.481, df = 2, p > 0.05). Sample TR2 exhibited a biofilm coverage rate comparable to that of TR1 and the untreated control. The comprehensive findings indicate that plasma nitriding influences surface wettability and early-stage biofilm behavior, especially with increasing process temperature.