Visualized Enzyme-Activated Fluorescence Probe for Accurately Detecting β-Gal in Living Cells and BALB/c Nude Mice.

Colorectal cancer was one of the major malignant tumors threatening human health and β-Gal was recognized as a principal biomarker for primary colorectal cancer. Thus, designing specific and efficient quantitative detection methods for measuring β-Gal enzyme activity was of great clinical test significance. Herein, an ultrasensitive detection method based on Turn-on fluorescence probe (CS-βGal) was reported for visualizing the detection of exogenous and endogenous β-galactosidase enzyme activity. The test method possessed a series of excellent performances, such as a significant fluorescence enhancement (about 11.3-fold), high selectivity as well as superior sensitivity. Furthermore, under the optimal experimental conditions, a relatively low limit of detection down to 0.024 U/mL was achieved for fluorescence titration experiment. It was thanks to the better biocompatibility and low cytotoxicity, CS-βGal had been triumphantly employed to visual detect endogenous and exogenous β-Gal concentration variations in living cells with noteworthy anti-interference performance. More biologically significant was the fact that the application of CS-βGal in BALB/c nude mice was also achieved successfully for monitoring endogenous β-Gal enzyme activity.