The heavy atom effect on thiadiazolo3,4-gquinoxaline derivatives as novel photosensitizers for photodynamic therapy

摘要

Two novel thiadiazolo[3,4-g]quinoxaline (TQ) derivatives, 6,7-bis(4-(hexyloxy)phenyl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TQs-1) and 4,9-dibromo-6,7-bis(4-(hexyloxy)phenyl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TQs-2) weresynthesized and fully characterized by ~1H-NMR, ~(13)C-NMR and HR-MS spectra. Their photo-physical and photo-chemicalproperties, including UV-Vis spectra, fluorescence spectra, photostability and singlet oxygen quantum yield werecomprehensively studied. Compared to TQs-1, TQs-2 exhibited a higher singlet oxygen quantum yield and a broaderabsorption spectrum due to the introduction of two bromine atoms. Furthermore, TQs-2 based nanoparticles (TQs-2 NPs)was obtained via a simple co-assembly strategy using a biocompatible amphiphilic polymer DSPE-mPEG2000 toencapsulate TQs-2. In vitro photodynamic therapy (PDT) experiments to three tumor cells (4T1, MCF-7 and HeLa) andnormal cells (L929) were carried out using TQs-2 NPs as photosensitizers. The results showed that TQs-2 NPs possessednegligible dark cytotoxicity to these cells at a high concentration of 50 μg mL~(-1), but exhibited high light cytotoxicity tothem, especially to three tumor cells, under a 532 nm laser illumination at the same concentration, indicating that TQs-2NPs has a promising potential for PDT applications.