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

Abstract 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 104 bacterial cells per milliliter, which is the average bacterial load of microorganisms found in real 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 Ag-Cu/TiO2, which showed MBC values of 62.5, 31.15 and 15.6 mM for the S. aureus and P. aeruginosa, E. coli and S. pneumonia species, respectively. The bactericidal effectiveness of all materials was ranked in the following order Ag/Cu > Ag > Cu > Au.