Long‐Term Performance of ZnO‐Based Thin Films and the Role of Reactive Oxygen Species against Candida albicans

ZnO‐based thin films are promising antimicrobial coatings, yet their long‐term performance and antifungal mechanisms remain poorly understood. This study evaluates the influence of film thickness and metal doping (Ti, Ag) on antifungal performance ( R ‐value according to ISO22196:2011) of ZnO thin films against Candida albicans under dark conditions. Their long‐term performance is assessed over repeated uses through direct contact (five cycles of 24 h) and leachate assays (10 cycles of 24 h). The role of reactive oxygen species (ROS) is examined through cellular responses and morphological changes. ZnO thin films exhibit a “slight” ( R = 0.7) but persistent (three cycles) effect, inducing intracellular superoxide formation. This oxidative stress is mitigated by peroxidases under nutrient‐rich conditions, causing cell wall damage and 20% cell viability. Ti incorporation has no measurable effect. In contrast, Ag doping triggered 99% ROS accumulation, exceeding cellular defenses, causing irreversible damage, and short‐lived “very good” activity ( R = 7, one cycle). Thicker films maintained activity over more cycles and leachate showed similar effects, suggesting release of antifungal compounds from films’ surface. These results show that intracellular ROS generation drives antifungal activity of ZnO‐based films, whereas film thickness determines durability. Understanding these parameters is essential to design antimicrobial coatings capable of reliable performance in real‐world applications.