Oxygen switches: Refueling for cancer radiotherapy

Abstract

Radiotherapy remains the major therapeutic intervention for tumor patients. However, the hypoxic tumor microenvironment leads to treatment resistance. Recently, a burgeoning number of nano-radiosensitizers designed to increase the oxygen concentration in tumors were reported. These nano radiosensitizers served as oxygen carriers, oxygen generators, and even sustained oxygen pumps, attracting increased research interest. In this review, we focus on the novel oxygen-enrich nano radiosensitizers, which we call oxygen switches, and highlight their influence in radiotherapy through different strategies. Physical strategies-based oxygen switches carried O2 into the tumor via their high oxygen capacity. The chemical reactions to generate O2in situ were triggered by chemical strategies-based oxygen switches. Biological strategies-based oxygen switches regulated tumor metabolism, remodeled tumor vasculature, and even introduced microorganisms-mediated photosynthesis for long-lasting hypoxia alleviating. Moreover, the challenges and perspectives of oxygen switches-mediated oxygen-enrich radiotherapy were discussed.

Cascade strategy for glucose oxidase-based synergistic cancer therapy using nanomaterials

“…247 Furthermore, some nanosensitizers can reshape the inherent properties of the TME by mitigating hypoxia or consuming GSH, thus boosting the RT-mediated conversion of O 2 into ROS and curtailing the radiation resistance of tumor cells. 42,248 Therefore, given the H 2 O 2 -increased effect of GOx, which offers abundant substrates for catalyzed ROS and O 2 supply, introducing GOx or GOx-like nanozymes with nanosensitizers to realize cascade-amplified RT may be a feasible alternative. In light of the above, Pan et al 242 fabricated a GOx-based nanoreactor camouflaged with a cancer cell membrane (TiO 2 @MnO 2 -GOx@C), presenting a paradigm for GOx-enhanced RT.…”