Antimicrobial characteristics in Cu-containing Zr-based thin film metallic glass

• Thin film metallic glass (TFMG) through processing temperature control will improve the adhesion abilities.
• Amorphous Zr–Cu–Ni–Al coatings exhibit excellent antimicrobial effects.
• Smooth profile and hydrophobic property inhibit biofilm formation and bacteria growth.
• The release of copper ions from TFMG is responsible for their antimicrobial activity.

Zr-based thin film metallic glass (TFMG), exhibiting the unique properties of good glass forming ability (GFA), corrosion resistance, and biocompatibility, can be applied in various novel fields of industries. An ultra-smooth surface is obtained with the TFMG coatings, which is beneficial to modify the work surface. Thus, TFMG can be extended to medical appliances, such as surgical blades and micro-surgery scissors. The aims of this study are to fabricate the Cu-containing Zr-based TFMG onto SUS304 plates and to investigate the surface physical properties and their antimicrobial effects. The chemical compositions of Zr–Cu–Ni–Al coatings are examined by a field emission electron probe micro-analyzer (FE-EPMA). The amorphous structures of all TFMG are characterized by the X-ray diffractometry. The surface properties are analyzed by an atomic force microscope (AFM) and a water contact angle goniometer for the 304 stainless steel substrate and Zr–Cu–Ni–Al TFMG. Liquid culture methods and plate counting methods are used to assess the antimicrobial performance of specimens. The antimicrobial rate against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under the Japanese Industrial Standard JIS Z2801: 2000 is over 99%. The release of copper ion from TFMG specimen is determined by the inductively coupled plasma-mass spectrometer (ICP-MS) to evaluate the antimicrobial activity of Cu-containing Zr-based TFMG. The results show that the surface of SUS 304 stainless steel substrate can be modified with deposited Zr–Cu–Ni–Al TFMG, and their improved antimicrobial efficacy against those bacteria is attributed to their amorphous rough surface, hydrophobic properties and released copper ion. The TFMG developed in this study with adequate hardness, good adhesion ability and antimicrobial efficiencies can be used as a promising candidate to improve the surface properties of the medical appliances and also to reduce the possibility of nosocomial infection.