Construction of an NIR and lysosome-targeted quinoline-BODIPY photosensitizer and its application in photodynamic therapy for human gastric carcinoma cells

In this work, a unique lysosome-targeted BODIPY photosensitizer named BOP-Lyso was designed for photodynamic therapy of cancer cells. The absorption wavelength of BOP-Lyso (10 μM) was located at 650 nm and its molar absorption coefficient was 8.2 × 10 4  cm −1 M −1 . The emission wavelength of BOP-Lyso was at 709 nm. Photosensitizer BOP-Lyso showed excellent ability to produce singlet oxygen and the singlet oxygen yield of photosensitizer BOP-Lyso was calculated to be 43.1% using methylene blue as the reference with near-infrared led light irradiation (660 nm). From MTT (a common method for determining cell survival rate, MTT: 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide) assay, BOP-Lyso had extremely low dark toxicity (cell viability > 85%) and high photo toxicity. And the IC 50 value of BOP-Lyso was 0.24 μM, which was much lower than the previously reported literature. Besides that, DCFH-DA (2′,7′-Dichlorodihydrofluorescein diacetate) was employed to capture the generation of reactive oxygen species (ROS) in PDT process. Lysosomal colocalization experiments demonstrated that photosensitizer BOP-Lyso had good co-localization capability and the colocalization coefficient was calculated to be 0.92. Furthermore, photosensitizer BOP-Lyso had also been successfully applied to AO/EB cell staining experiments and exhibited excellent results. Moreover, cancer cells (SGC-7901 cells, human gastric carcinoma cells) migration status could be effectively inhibited after NIR led light irradiation with BOP-Lyso. On the whole, taking the above series of data into account, photosensitizer BOP-Lyso would play an important role in actual PDT of cancer cells.