UV-Light-Activated (Gd,Y)VO4:Eu3+Nanoparticles for Radiotherapy Enhancement

Cancerous cells could be resistant to radiotherapy (RT) and require enhanced doses of irradiation exceeding the tolerance of patients. Nanoparticles containing high-Z elements and possessing high X-ray absorption have been recently proposed as nano radio enhancers. Here, we investigate the mechanisms of generation of hydroxyl radicals (•OH) under X-ray irradiation of water solutions containing ultraviolet (UV)-light-pretreated (Gd,Y)VO4:Eu3+nanoparticles. The contributions of two mechanisms in the observed effect are analyzed. It has been concluded that UV-light pretreatment leads to the capture of photoinduced holes and the formation of hydrogen peroxide (H2O2) via photoinduced electron interaction with oxygen molecules, which provide a long-lasting •OH generation effect after the termination of UV irradiation. X-ray irradiation of UV-light-pretreated (Gd,Y)VO4:Eu3+nanoparticles stimulates both hole release and H2O2radiolysis, enhancing sufficiently the effect of •OH generation.