Antifungal behavior of silicon-incorporated diamond-like carbon by tuning surface hydrophobicity with plasma treatment

Silicon-incorporated diamond-like carbon (Si-DLC), an amorphous material containing Si atoms with sp(3)- and sp(2)-hybridized carbon, is a promising biomaterial for versatile biomedical applications due to its excellent mechanical properties, chemical inertness, biocompatibility, and antimicrobial capability. However, the antifungal properties of plasma-treated Si-DLC have not been systematically evaluated. In this study, Si-DLC coatings were deposited by chemical vapor deposition and further treated with either oxygen or fluorine plasma to render the surface anchored with different functional groups and hydrophobicity. Surface roughness was probed with atomic force microscopy, whereas bonding character and surface composition were assessed using Raman and X-ray photoelectron spectroscopy. Wettability and surface charge were investigated via water contact angle and zeta potential measurements. Antifungal assessment was performed using a Candida albicans multi-well plate screening technique and crystal violet biomass quantification. The results demonstrate that oxygen plasma-treated Si-DLC exhibited hydrophilic properties, lower negative zeta potential, and significant antifungal behavior. This material can potentially be applied on surfaces for the prevention of reduced nosocomial infections.