Fabrication And Antibacterial Properties Of Nanoporous Cu-Ag Composites

In this paper,the nanoporous bimetallic copper-silver material(NP-CuAg)with adjustable pore/ligament size and multilayered structure was fabricated by dealloying Cu₄₀Zr₅₀Ag₁₀ amorphous alloy.In order to improve the performance,the composite(Ag/Cu_xO@NP-CuAg)of Cu_xO(x=1,2)nanowire modified by Ag nanoparticles was prepared on NP-CuAg substrate by anodizing followed by heat treatment.This work systematically studied the dealloying of Cu₄₀Zr₅₀Ag₁₀ amorphous alloy and the subsequent anodizing process.The effects of dealloying time on the microstructure of NP-CuAg and the formation mechanism of NP-CuAg were also discussed.In addition,the influences of anodizing parameters on the microstructure of Ag/Cu_xO@NP-CuAg were investigated.The relationship among dealloying and anodizing process parameters,microstructure and antibacterial properties was established.Finally,the new type nanomaterials with unique structure and excellent antibacterial properties were developed.The results showed that the stratification of the dealloyed product during the dealloying the Cu₄₀Zr₅₀Ag₁₀ amorphous alloy took place.From the SEM results,NP-CuAg with five symmetrical layers was formed by dealloying in 0.25 M HF solution for 6 h,including the internal nanoporous copper-silver layer(C-layer),nanoporous copper layer(B-layer)and outer nanoporous copper-silver layer(A-layer).By changing the dealloying time,the controllable preparation of pore and ligament size in each layer can be achieved.On the other hand,the Ag/Cu_xO@NP-CuAg composites were fabricated by anodizing NP-CuAg substrate in 0.5 M KOH solution.It was found that the Cu_xO nanowires modified by Ag nanoparticles in-situ grow uniformly on the NP-CuAg substrate.By analyzing the effects of anodizing time and the current density on the microstructure of Ag/Cu_xO(x=1,2),the optimum anodizing parameters of the preparation of Ag/Cu_xO@NP-CuAg composite were obtained.The behaviors of ionic dissolution for both the NP-CuAg and Ag/Cu_xO@NP-CuAg were similar.The dissolution of Ag⁺was relatively stable,wheras that of Cu²⁺presented an explosive trend.Moreover,the Ag/Cu_xO@NP-CuAg composite exhibited a larger ionic dissolution concentration than NP-CuAg,mainly because of its larger specific surface area and unique structure of nanowires modified by nanoparticles.All NP-CuAg and Ag/Cu_xO@NP-CuAg composite showed excellent antibacterial properties.The zone of inhibition experiments showed that the antibacterial properties of bimetallic NP-CuAg were higher than those of monometallic nanoporous Ag(NP-Ag)and nanoporous Cu(NP-Cu).The maximum inhibition zone diameter of Ag/Cu_xO@NP-CuAg composite was up to 8.3mm,while that of NP-CuAg was 4 mm,indicating that Ag/Cu_xO@NP-CuAg composite has better antibacterial properties than NP-CuAg.Through SEM analysis,it was found that both the NP-CuAg and Ag/Cu_xO@NP-CuAg could maintain their orginal morphology after antibacterial experiment,indicating good structural stability,which were conducive to a long-term application.