Multifunctional biomaterials that modulate oxygen levels in the tumor microenvironment.

A characteristic feature of solid tumors is their low oxygen tension, which confers resistance to radiotherapy, photodynamic therapy, and chemotherapy. Therefore, to improve treatment outcomes, it is critical to develop biomaterials capable of targeted modulation of oxygen levels in tumors. In this review, we summarize four types of oxygen-modulating biomaterials, namely, oxygen-carrying biomaterials to deliver oxygen into tumors (e.g., perfluorocarbon and hemoglobin), oxygen-generating biomaterials to promote in situ oxygen generation (e.g., MnO, catalase, and CuO), oxygen-consuming biomaterials to starve tumors (e.g., photosensitizer, glucose oxidase, and magnesium silicide), and oxygen-circulating biomaterials capable of both providing and consuming oxygen (e.g., ENBS-B). The current literature suggests that these biomaterials are useful for anticancer therapeutics. We present the key molecular mechanisms involved in modulating oxygen levels and the potential applications of these biomaterials in the context of hypoxic tumor treatment.