Construction of cathepsin B-responsive fluorescent probe and photosensitizer using a ferrocenyl boron dipyrromethene dark quencher

Dual Cathepsin B and Glutathione-Activated Dimeric and Trimeric Phthalocyanine-Based Photodynamic Molecular Beacons for Targeted Photodynamic Therapy

“…To examine the activation of 1 and 2 by cathepsin B at the cellular level, their intracellular fluorescence emission was examined using A549 human lung carcinoma cells and HepG2 human hepatocarcinoma cells. These two cell lines are commonly used for the studies of the activation effects of cathepsin B , and GSH. , A cell-permeable cathepsin B inhibitor, namely, CA-074 methyl ester (CA-074 Me), was used to selectively inactivate the intracellular cathepsin B. Both A549 and HepG2 cells were first pre-treated with CA-074 Me (25 μM) or fresh medium for 2 h. After washing, the cells were incubated with 1 or 2 (1 μM) in a serum-free medium for 1 h with or without further incubation in the medium for 4 h. The fluorescence images of these cells were captured using a confocal laser scanning microscope (Figure a,b).…”

“…Over the last decade, we have reported a series of molecular-based photosensitizers that can be activated by various stimuli, such as fibroblast activation protein, cathepsin B, acid, , and intracellular thiols. − To enhance the specificity of the photodynamic action, we have also developed two molecular-based dual activatable photosensitizers that can be fully activated in the presence of both acid and dithiothreitol. , However, these photosensitizers can still be partially activated in the presence of one of these stimuli due to the incomplete quenching. To further improve the specificity, we report herein two novel photodynamic molecular beacons (PMBs) in which two or three glutathione (GSH)-responsive 2,4-dinitrobenzenesulfonate (DNBS)-substituted zinc­(II) phthalocyanine (ZnPc) units are connected via one or two cathepsin B-cleavable Gly-Phe-Leu-Gly peptide linker(s).…”

“…To further improve the specificity, we report herein two novel photodynamic molecular beacons (PMBs) in which two or three glutathione (GSH)-responsive 2,4-dinitrobenzenesulfonate (DNBS)-substituted zinc­(II) phthalocyanine (ZnPc) units are connected via one or two cathepsin B-cleavable Gly-Phe-Leu-Gly peptide linker(s). Both GSH and cathepsin B have been found to be overproduced in cancer cells and are therefore regarded as common tumor markers. ,− Owing to the strong self-quenching of the ZnPc units and the photoinduced electron transfer (PET) effect of DNBS, these PMBs were found to be fully quenched in the native state, enabling them to achieve a remarkable response after activation both in aqueous media and inside cancer cells. To the best of our knowledge, molecular-based dual activatable photosensitizers utilizing two quenching mechanisms have not been reported so far.…”

Chlorin e6-Biotin Conjugates for Tumor-Targeting Photodynamic Therapy

“…The fluorescence of Ce6-biotin is only a little weaker than that of Ce6, probably because the modification did not alter the basic structure of Ce6. Considering its intense fluorescence emission in the infrared region, Ce6-biotin may also serve as a fluorescent probe for in vivo application [ 27 ].…”

Most recent advances on enzyme‐activatable optical probes for bioimaging

“…Considering the critical roles of cathepsin B in tumor-associated processes, a series of cathepsin Bactivatable probes have been recently reported for bioimaging or theranostics. [120][121][122][123][124] The most recently reported probes 35 and 36 are depicted in Figure 17 to elucidate the design principle, working mechanism, and performance of cathepsin Bactivatable probes.…”