A Biotinylated and Endoplasmic Reticulum-Targeted Glutathione-Responsive Zinc(II) Phthalocyanine for Targeted Photodynamic Therapy.

A biotinylated glutathione (GSH)-responsive zinc(II) phthalocyanine has been prepared and characterized. With a 2,4-dinitrobenzenesulfonyl moiety, its fluorescence emission and singlet oxygen generation were silenced in its intact state. Upon exposure to high concentration of GSH, its photosensitizing properties were restored in phosphate buffered saline and inside tumor cells. It also showed preferential uptake on HepG2 human hepatocarcinoma cells (with higher biotin receptor expression) rather than Chinese hamster ovary (CHO) cells (with lower biotin receptor expression). Upon irradiation, it caused photocytotoxicity with an IC50 value down to 0.1 μm on HepG2 cells. Moreover, it can localize in the endoplasmic reticulum (ER), causing ER stress after light irradiation.