Photoexcitation of Ag-doped TiO2 nanoparticles with visible light for antimicrobial photodynamic therapy against Candida albicans

Abstract The emergence of antifungal resistance emphasizes the need for alternative therapies such as antimicrobial photodynamic therapy (APDT). This study evaluates the APDT efficacy of silver-doped titanium dioxide (Ag–TiO₂) nanoparticles (NPs) against Candida albicans under blue-, green-, and red-light irradiation. Ag–TiO₂ NPs were synthesized via the sol–gel method and structurally and optically characterized. Among the tested conditions, blue-light irradiation of TiO₂:Ag2 at 31.75 µg/ml, a concentration within the low range compared to previously reported studies, achieved the highest APDT total efficacy that was of 60%. The overall inhibition efficacy gradually decreased as the doping concentration increased. Additionally, in this study, cellular inactivation was observed for the first time using red-light-mediated APDT against C. albicans with doped TiO₂. Based on these findings, we conclude that Ag-doped TiO₂ nanoparticles with low doping concentrations can be effective under visible light conditions, showing potential clinical relevance.