Nanomaterials relieving hypoxia for enhanced tumor therapy

Hypoxia is a hallmark of solid tumors and it significantly contributes to the development of key biological features of tumors, including the microenvironment, migration, invasion, metastasis, pathological angiogenesis, drug resistance, immunosuppression, and poor prognosis. Hypoxia hampers the efficacy of current anti-tumor approaches, including radiotherapy, chemotherapy, immunotherapy, and photodynamic therapy. This has fueled the development of nanomaterials to reoxygenate the tumor's microenvironment by delivering exogenous O2 or generating O2 in situ as therapeutic approaches per se or to improve the efficacy of current anti-tumor approaches. Herein, we review the recent research progress of nanomaterials for O2 delivery and generation in situ. Their potential transition to the clinics is also discussed.