NIR-II light-activated two-photon squaric acid dye with Type I photodynamics for antitumor therapy

Abstract Photodynamic therapy (PDT) for hypoxic tumors has attracted wide attention owing to its noninvasiveness, easy maneuverability, and instantaneity. However, hypoxia in penetration depth of conventional ultraviolet light greatly weakened performance. To solve these problems, under NIR-II irradiation, squaric acid nanoparticles (SQ NPs) with superior reactive oxygen, especially, hydroxyl radicals (•OH) production performance were first utilized tumor therapy. SQ NPs intense capture capability, NIR emission, excellent photobleaching resistance show continuous •OH generation capabilities laser excitation. Through the PDT performance, growth was effectively inhibited, survival rate mice improved. This work highlights application photoexcitation deep tissue type I photodynamic tumors, which will facilitate development depth.