Design and preparation of nanoporous Ag-Cu alloys through dealloying Mg-(Ag, Cu)-Y metallic glasses for antibacterial applications
Three-dimensional nanoporous Ag-Cu alloys with an atomic ratio of Ag to Cu varying from 0 to 1.0 were fabricated through dealloying Mg-(Ag, Cu)-Y metallic glass precursors in 0.04 M H2SO4 aqueous solution. Supersaturated Ag(Cu) solid solution in the nanoporous structure was yielded with a high Cu concentration (up to 47.4%) in fcc Ag phase after dealloying treatment. The nanoporous alloys with ultrafine ligament size (down to 20 nm), large specific surface area (up to 11.18 m2/g) and high oxidation resistance in air atmosphere were employed for inhibiting the growth of Gram-negative E. coli and Gram-positive S. aureus. In vitro characterizations reveal that the nanoporous alloy with Ag/Cu ratio of 1 : 1 exhibited the best antibacterial activities in terms of both ultralow minimal inhibitory concentration (MIC) (down to 3 and 2.5 mg/L for S. aureus and E. coli) and long-term inhibition on bacterial growth in the group of tested materials. Highly efficient and sustainable release of Cu ions from the nanoporous Ag-Cu alloy could be responsible for such excellent antibacterial activities.