Yang Jing-Jie, Zhao Xue-Ru, Wang Chen-Han, Hu Xi-Le, Li Jia, He Xiao-Peng
Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, School of Chemistry and Molecular Engineering, East China University of Science and Technology, 130 Meilong Rd, Shanghai 200237, China.
National Center for Drug Screening, State Key Laboratory of Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
ACS Appl Bio Mater. 2025 Sep 5. doi: 10.1021/acsabm.5c01056.
Glycosidases generally function in specific organelles to hydrolyze glycoconjugates. Thus, the in situ visualization of glycosidase activities in an organelle-targeted manner can help to better delineate their biological functions. Lysosomal β-galactosidase (β-Gal) is reported to be a biomarker for ovarian cancer and cellular senescence. Here, we developed near-infrared fluorogenic probes for the detection of β-Gal activity based on modulating the intramolecular charge transfer (ICT) of a hemicyanine dye. The constructed probe, bearing a morpholine group to target the lysosomes, enabled the visualization of lysosomal β-Gal activity in different live cells. Through a series of experiments, we rationalized that human serum albumin binding could be the main reason by which to significantly enhance the fluorescence of the probe in the acidic lysosomes where its phenol anion is protonated to quench dye fluorescence. In addition, the probe was used to image cell lines with different endogenous β-Gal expression levels and visualize lysosomal β-Gal in senescent cells. This study offers insight into the employment of ICT-based probes for fluorescence-based imaging of lysosomal enzymes.
糖苷酶通常在特定细胞器中发挥作用，水解糖缀合物。因此，以细胞器靶向方式对糖苷酶活性进行原位可视化有助于更好地阐明其生物学功能。据报道，溶酶体β-半乳糖苷酶（β-Gal）是卵巢癌和细胞衰老的生物标志物。在此，我们基于调节半菁染料的分子内电荷转移（ICT），开发了用于检测β-Gal活性的近红外荧光探针。构建的探针带有一个吗啉基团以靶向溶酶体，能够在不同活细胞中可视化溶酶体β-Gal活性。通过一系列实验，我们推断人血清白蛋白结合可能是在酸性溶酶体中显著增强探针荧光的主要原因，在酸性溶酶体中其酚阴离子被质子化以淬灭染料荧光。此外，该探针用于对具有不同内源性β-Gal表达水平的细胞系进行成像，并可视化衰老细胞中的溶酶体β-Gal。这项研究为基于ICT的探针用于溶酶体酶的荧光成像提供了见解。
