Fabrication of Cu–Ag bimetal nanotube-based copper silicates for enhancement of antibacterial activities

A novel Cu–Ag bimetal antibacterial system is reported. In this Cu–Ag bimetal system, copper silicate nanotubes (CSNTs) and copper silicate nanotube-assembled hollow nanospheres (CSNAHSs) with high BET surface area, unique hollow structure and strong antibacterial activity, were adopted as a carrier for loading silver ions to fabricate the copper–silver bimetal antibacterial agents (designated as Ag+/CSNTs and Ag+/CSNAHSs). Additionally, the antibacterial activity of Ag+/CSNTs and Ag+/CSNAHSs was investigated against Gram-negative bacteria (Escherichia coli BL21 and Escherichia coli JM109) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). The results demonstrated that both silver-loaded copper silicates were highly effective against the four types of bacterial strains, and the Ag+/CSNAHSs showed a stronger antibacterial ability than Ag+/CSNTs due to their more silver loading contents. More importantly, a synergistic effect of copper ions and silver ions on the inhibition of the bacterial growth was observed in our bimetal antibacterial system.