TiO₂ Nanoparticles Co-doped with Nitrogen and Fluorine as Visible-Light-Activated Antifungal Agents

Nanoparticles are widely used in photocatalytic degradation of toxic chemicals and photodynamic therapy of cells that involve light-induced generation of reactive oxygen species (ROS) followed by ROS-induced chemical/biochemical transformation. However, designing nanoparticles to capture the visible spectrum of solar light and to generate a high concentration of ROS that are effectively utilized are some of the critical issues. In particular, nanoparticle-based disinfection of pathogenic fungi under sunlight exposure is challenging due to the tough fungal cell wall. Colloidal N and F co-doped TiO₂ nanoparticles that capture the whole visible spectrum and produce ROS under light irradiation has enormous application potential for sunlight-based water purification and disinfection of food/environment. However, such potential has not been explored yet and requires extensive photocatalytic studies similar to those of the well-known TiO₂ nanoparticle. Herein we report N and F co-doped TiO₂ nanoparticles of 200-300 nm size as an antifungal agent under visible light. The colloidal form with appropriate surface chemistry offers efficient interaction of the nanoparticle with the fungal cell wall, and visible-light-induced ROS generation by nanoparticles offers fungal disinfection. Under visible-light exposure, these nanoparticles completely inhibit Fusarium oxysporum fungal growth in tomato fruit. These nanoparticles can be used for sunlight-based fungal and bacterial disinfection application.