Table 1.

A summary of the representative materials, strengths, and shortcomings of different approaches for oxygen-supplementing PDT. ROS, reactive oxygen species.

Strategy	Representative Materials	Strengths	Shortcomings
Increasing oxygen utilization efficiency using micro-/nanomotors	Poly(ethylene glycol) block polystyrene, Fe3O4 nanoparticle-loaded hemoglobin	Deep tumor penetration through movement	Maximum efficiency limited by oxygen concentration
Living organism oxygen generators	Chlorella, Cyanobacteria, Spirulina, and thylakoid membrane of green plants	Synchronous activation of oxygen supply and ROS generation, abundance of water in the human body beneficial for oxygen generation	Harsh tumor microenvironment harming organism activity; micrometer size limiting deep tumor penetration; light wavelengths in visible light range
Light-driven water splitting	Tungsten nitride, carbon nanodot, graphdiyne oxide, iron disulfide, cobalt phytate, C3N4	Synchronous activation of oxygen supply and ROS generation, abundance of water in the human body for oxygen production	Safety concern due to presence of metal ions
Modification of tumor blood circulation	Heparin, warm water bath	Concurrent improvement of light delivery	Weak effect on tumor regions distant from blood vessels
Tumor H2O2 decomposition	Metal-based materials, catalase	Inherent tumor specificity	Efficiency limited by H2O2 concentration
Oxygen delivery	Hemoglobin, perfluorocarbon, metal–organic frameworks	High efficiency	Lack of inherent tumor specificity