In Situ Hypoxia-Induced Supramolecular Perylene Diimide Radical Anions in Tumors for Photothermal Therapy with Improved Specificity.

Considering that hypoxia is closely associated with tumor proliferation, invasion, metastasis, and drug resistance, it is of great significance to overcome hypoxia in tumor treatment. Herein, we report a hypoxia-induced specific photothermal therapy (PTT) based on the photothermal agent of supramolecular perylene diimide radical anions. Hypoxic regions in various tumors display strong reductive ability, and in such environments the supramolecular complex of a perylene diimide derivative and cucurbit[7]uril could be reduced to supramolecular perylene diimide radical anions. Benefiting from the strong NIR absorption and good photothermal conversion performance of the in situ generated supramolecular perylene diimide radical anions, the hypoxia-induced PTT strategy exhibits excellent photothermal therapeutic efficiency as well as good specificity and biological safety. Moreover, hypoxia inducible factor expression of tumors decreases to the normal level after PTT treatment. It is anticipated that such a hypoxia-induced specific PTT strategy opens new horizons for photothermal therapy against hypoxic tumors with improved specificity and safety.