Surface Antimicrobial Effects of Zr61Al7.5Ni10Cu17.5Si4 Thin Film Metallic Glasses on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Candida albicans

Zr₆₁Al_7.5Ni₁₀Cu_17.5Si₄ (ZrAlNiCuSi) thin film metallic glasses (TFMGs) can modify the surface of 304 stainless steel, and they are widely used in health care systems. We investigated modified surfaces with ZrAlNiCuSi TFMGs and their antimicrobial effects on those five microbes which are the most common nosocomial infection pathogens. The transformation of ZrAlNiCuSi bulk metallic glass into TFMG was achieved by sputtering onto stainless steel. Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Candida albicans were then isolated. The microbes were sampled on ZrAlNiCuSi TFMGs, and this was compared with stainless steel plates. After microbe-material interaction under humidity at room temperature for 3 hours, the specimens were attached to a Mueller-Hinton agar plate (Gibco, Middleton, WI, USA) and incubated at 37.0°C for 24, 48 and 96 hours. The areas of microbe growth were recorded by serial subtraction photography and then assessed using Image-Pro Plus software (Media Cybernetics, Bethesda, MD, USA). ZrAlNiCuSi TFMGs presented an amorphous rough surface and exhibited hydrophobic properties. ZrAlNiCuSi TFMGs suppressed E. coli growth on Mueller-Hinton plates for 96 hours, and there was no E. coli growth on blood agar plate enriched media and eosin-methylene blue agar selective media after 96 hours of incubation. The five microbes tested on ZrAlNiCuSi TFMGs showed a decreased growth curve after 24 hours. After 24 hours, P. aeruginosa showed a slow growth curve and A. baumannii had a sharp growth curve with TFMG interaction. ZrAlNiCuSi TFMGs prolonged the lag phase of the microbes' growth curve in S. aureus and C. albicans for 48 hours. ZrAlNiCuSi TFMGs were able to modify the surface of stainless steel, which was very hard and was found to have scratch adhesion abilities and smooth surface effects against five different microbes for at least 24 hours. This is the first description of microbe interactions with zirconium-based TFMGs. Further studies to investigate the mechanism of antimicrobial effects on ZrAlNiCuSi TFMGs are now required.