COMPARISON OF UV-PHOTOCATALYTIC AND INTRINSIC ANTIFUNGAL ACTIVITY OF TIO₂ NANOPARTICLES AGAINST CANDIDA TROPICALIS

Abstract

This study aimed to evaluate the antifungal activity of titanium dioxide nanoparticles (TiO₂ NPs) against Candida tropicalis ATCC 750 under dark and UV light activation conditions. Anatase-phase TiO₂ nanoparticles were applied to C. tropicalis suspensions at four concentrations (125, 250, 500, and 1000 µg/mL) and four exposure times (15, 30, 45, and 60 min). Experiments were performed under two conditions: a dark environment and UVA irradiation (365 nm, 15 cm distance). Antifungal activity was assessed by colony counting at the end of each exposure period, and both log reduction and percentage reduction values were calculated. The combination of UV irradiation and TiO₂ nanoparticles demonstrated significantly higher antifungal activity compared to the dark condition. Under UV activation, complete elimination (100% mortality, >2.48 log reduction) was achieved at 45 minutes with 1000 µg/mL TiO₂ and at 60 minutes with 500 µg/mL. In contrast, under dark conditions the maximum reduction observed was 0.84 log (85.7%) at 1000 µg/mL after 60 minutes, and complete elimination was not obtained at any concentration. The UV-only group showed a limited antifungal effect, with only 0.27 log reduction (46.7%) after 60 minutes. Overall, the photocatalytic activity of the UV-activated TiO₂ system was approximately nine times stronger than the effect of UV irradiation alone. These findings demonstrate that UV-activated TiO₂ nanoparticles exhibit strong photocatalytic antifungal activity against C. tropicalis and can achieve complete elimination at sufficiently high concentrations. Therefore, TiO₂ nanoparticles may represent a promising alternative antifungal strategy for infections caused by C. tropicalis, particularly in cases where antifungal resistance is increasing.