Hyperbranched Phosphorescent Conjugated Polymer Dots with Iridium(III) Complex as the Core for Hypoxia Imaging and Photodynamic Therapy

Real-time monitoring of the contents of molecular oxygen (O₂) in tumor cells is of great significance in early diagnosis of cancer. At the same time, the photodynamic therapy (PDT) could be realized by highly toxic singlet oxygen (¹O₂) generated in situ during the O₂ sensing, making it one of the most promising methods for cancer therapy. Herein, the iridium(III) complex cored hyperbranched phosphorescent conjugated polymer dots with the negative charges for hypoxia imaging and highly efficient PDT was rationally designed and synthesized. The incomplete energy transfer between the polyfluorene and the iridium(III) complexes realized the ratiometric sensing of O₂ for the accurate measurements. Furthermore, the O₂-dependent emission lifetimes are also used in photoluminescence lifetime imaging and time-gated luminescence imaging for eliminating the autofluorescence remarkably to enhance the signal-to-noise ratio of imaging. Notably, the polymer dots designed could generate the ¹O₂ effectively in aqueous solution, and the image-guided PDT of the cancer cells was successfully realized and investigated in detail by confocal laser scanning microscope. To the best of our knowledge, this represents the first example of the iridium(III) complex cored hyperbranched conjugated polymer dots with the negative charges for both hypoxia imaging and PDT of cancer cells simultaneously.