Metallic composites based on Ag, Cu, Au and Ag-Cu nanoparticles with distinctive bactericidal effect on varied species

Because the spread of antimicrobial resistance is impacting current health, environmental, and technological developments, the synthesis of novel and efficient antibacterial agents is required. In this work, nanoparticles of Ag, Cu, Au and Ag-Cu were supported on TiO2 Degussa P25 by the deposition-precipitation with urea method (DPU). The antibacterial performance of these materials, well known as catalysts of reactions of environmental interest, was evaluated against four different bacterial species; which are related to airborne (S. pneumoniae and P. aeruginosa) and waterborne (E. coli and S. aureus) infections. To know the minimum concentration of each composite in relation to the viability of the above mentioned microorganisms, the minimum bactericidal concentration (MBC) technique was used. The model of this work standardized an inoculum volume of bacteria of around 10(4) bacterial cells per milliliter, which is the average bacterial load of microorganisms found in contaminated environments, the bacterial growth was followed for 24 h. The results showed that all the bacterial species were sensitive to the majority of composites, except to the Au-based composite, because most bacterial species were resistant to it. The highest bactericidal efficiency was obtained with the bimetallic composite AgCu/TiO2, which showed MBC values of 62.5 mM for both the S. aureus and P. aeruginosa species, and 31.15 and 15.6 mM for the E. coli and S. pneumonia species, respectively. The bactericidal effectiveness of all materials was ranked in the following order Ag/Cu > Ag > Cu > Au.

Automated summary

In this study, nanoparticles of Ag, Cu, Au and Ag-Cu supported on TiO2 were evaluated for their antimicrobial performance. The bimetallic composite AgCu/TiO2 showed the highest bactericidal efficiency among all materials tested, with significant MBC values against various bacterial species. Au-based composite was found to be the least effective in killing bacteria, compared to Ag/Cu, Ag, and Cu-based composites.