Rare earth-doped titanium dioxide for enhanced reactive oxygen species generation in photodynamic anti-tumor therapy of scaffolds

Photodynamic therapy, as a minimally invasive treatment, selectively and optically damaged skin tumor cells through the generation of reactive oxygen species (ROS). However, its antitumor efficacy is limited by the rapid recombination of electron-hole pair in photosensitizers. In this work, a rare-earth lanthanide-doped titanium dioxide nanosystem was successfully developed via a co-coprecipitation method. In this nanosystem, lanthanide doping induced lattice distortion and generated oxygen vacancy defects, effectively suppressing electron-hole pair recombination. Furthermore, the unique electronic structure of the lanthanide dopant modulated the band positions and Fermi level of titanium dioxide, thereby narrowing the bandgap and broadening its optical absorption spectrum. Subsequently, the nanosystem was incorporated into a poly-L-lactic acid scaffold by selective laser sintering. Photoelectrochemical and ROS analyses revealed significant enhancement in electron–hole pair separation and a marked increase in ROS generation. Density functional theory calculations further confirmed that the reduced bandgap contributed to the improved photocatalytic performance of titanium dioxide. In vitro cell experiments demonstrated that this photodynamic therapy platform achieved an 82.4 % inhibition rate of skin tumour growth. Overall, this work presents a feasible strategy to enhance the therapeutic efficacy of tumour photodynamic therapy.