In Situ Photocatalysis of TiO-Porphyrin-Encapsulated Nanosystem for Highly Efficient Oxidative Damage against Hypoxic Tumors.

Reactive oxygen species (ROS)-mediated cell apoptosis has been a significant strategy for tumor oxidative damage, while tumor hypoxia is a major bottleneck for efficiency. Here, a novel TiO-porphyrin nanosystem (FA-TiOPs) is designed by encapsulating TiO-porphyrin (TiOP) in folate-liposome. The nanosysytem can photocatalyze HO and tumor-overexpressed HO in situ generating sufficient ROS. TiOP can photosplit water to produce ·OH radical, HO, and O. Generated O not only conquers the hypoxia of tumor environment but also can be further excited by TiOP to O for killing tumor cells. Density functional theory calculations indicate that high energy in excited state (S) of TiOP and narrow gap energy between S and the triplet excited state (T) might contribute to the efficient photocatalytic action. Moreover, the generated and overexpressed HO in tumors can also be photocatalyzed to generate O especially in acid condition, helpful to specific anticancer effect while harmless to normal tissues. This research might pave a new way to bypass the hypoxia-triggered problem for cancer therapy.