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.