Ultra Electron-Donating Segment-Dependence of NIR-II Absorbing Aza-boron-dipyrromethenes for Photothermal-Photodynamic Phototherapy of Breast Cancer

Since breast cancer often occurs in the upper quadrant, the use of the second near-infrared (NIR-II) light that penetrates deeper tissues and matches phototherapy agents is a prerequisite for true phototherapy treatment. NIR-II absorbing organic functional dye is an ideal choice for effective antitumor phototherapy. Herein, we developed a series of aza-BODIPYs (NN-azaBDPs) with 1,4-dimethyl-1,2,3,4-tetrahydroquinoxaline (NN) as an ultra electron-donating group at 3,5-sites. CF3-NN bearing the D–A–A′ system absorbs at 990 nm and emits at 1240 nm in the NIR-II region. CF3-NN nanoparticles have fluorescence imaging capabilities in the NIR-II region and significant photothermal conversion efficiency (77.8%), and the twisted structure of the NN segment creates a basis for the generation of reactive oxygen species. NN-azaBDPs provide a platform for photothermal-photodynamic combined therapy for breast cancer.