Green Synthesis of Au-Doped Tin Oxide Nanoparticles Using <i>Teucrium Polium</i> Extract with Potential Applications in Photodynamic Therapy

<b><i>Objective:</i></b> The green synthesis of Tin(IV) oxide (SnO₂): Gold (Au) nanoparticles (NPs) using <i>Teucrium polium</i> medicinal plant extract was investigated, and the NPs were characterized and tested as photosensitizers to produce reactive oxygen species (ROS). <b><i>Methods:</i></b> The cytotoxic effect on C26 cells was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) technique. The results showed their toxicity in a dose-dependent manner. The green synthesis of SnO₂:Au NPs was achieved for the first time using an extract of <i>T. polium</i> medicinal plant as a reducing and stabilizing agent. The produced NPs were examined for their application in photodynamic therapy (PDT) for cancer. <b><i>Results:</i></b> Methylene blue and anthracene were used to confirm that the photosensitizer could produce ROS when excited with UVA radiation. The anticancer activity of SnO₂:Au was investigated in vitro using the C26 cell line and an MTT assay, showing that PDT with SnO₂:Au NPs could inhibit cancer cell proliferation. <b><i>Conclusions:</i></b> The significant afterglow of the SnO₂:Au NPs could cause the generation of ROS to continue several minutes after switching off the light source.