Ag/TiO2 photocatalysts: A promising tool in combating bacterial resistance

Abstract

The photoactivation of materials is emerging as a promising strategy, as it allows pathogens to be inactivated without the selection of resistant strains. The identification and development of new drugs or photoactive agents represents an active field of research, with the aim of offering more effective therapeutic options for the control of bacterial infections. This study synthesized silver-based catalysts (Ag) (2 % and 10 % w/w%) supported on titanium dioxide (TiO₂) by the sol-gel method (2AgT/SG and 10AgT/SG). Infrared spectrometric characterization of AgT/SG catalysts revealed characteristic titanium bands and the asymmetric vibration of Ti-Ag-O. X-ray diffraction identified that these catalysts have well-defined anatase peaks representing organized crystalline phases. The differential scanning calorimetry data shows smaller endothermic peaks for the AgT/SG catalysts, indicating a low melting point. Thermogravimetric analysis showed minimal loss of mass for the catalysts. The 10AgT/SG catalyst exhibited antibacterial activity against Escherichia coli under clear light (9 W) and in the dark, due to the Ag concentration. Under black light, all catalysts activated, eliminating both E. coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) in just 10 min. This rapid bactericidal action was attributed to the massive production of reactive oxygen species (ROS), which was 1500 % higher than at the beginning of the experiment for the tested strains. These results demonstrate the potential of AgT/SG catalysts, presenting a material that overcomes the limitations of pure TiO₂ and, acts quickly, paving the way for practical applications in disinfection and infection-fighting devices.