Effects of ultraviolet sterilization exposure on the structural and surface properties of graphite-/polymer-like carbon films

Existing research on the biological responses of amorphous carbon films has not adequately explored the influences of exposure to ultraviolet (UV) sterilization at 253.7 nm before cell culture. Thus, in this study, two types of amorphous carbon films, namely hydrogen-rich graphite-like carbon (GLC) and hydrogen-free polymer-like carbon (PLC) films, were deposited on Si substrates. The influences of different doses of UV sterilization exposure (at 253.7 nm) on the structures and surface properties of the amorphous carbon films were investigated. Spectroscopic ellipsometry and Raman analysis showed that there is no significant change in the optical constants and Raman spectra of GLC and PLC films. The surface properties of the amorphous carbon films, characterized by water contact angle measurements and X-ray photoelectron spectroscopy analysis, indicated that both types of films exhibited hydrophilicity and surface oxidation in response to UV sterilization. However, the effects of UV sterilization on PLC were more notable than those on GLC. Our findings highlight the need for standardization and optimization of UV sterilization conditions for specific films to promote the application of amorphous carbon film coatings in the medical domain.