Ratiometric fluorescence method based on silver nanoclusters for sensitive detection of β-galactosidase activity

Abstract

β-Galactosidase (β-Gal), alternatively referred to as lactase, is intricately associated with cellular aging and the progression of ovarian and breast cancers due to its aberrant activity. Therefore, the accurate detection of this enzyme holds substantial importance for early disease diagnosis. In this work, a sensitive ratiometric fluorescent sensing system utilizing silver nanoclusters (AgNCs) was developed for the first time to measure β-Gal activity. Specifically, β-Gal catalyzed the hydrolysis of its substrate 3-indoxyl-β-D-galactopyranoside, leading to the production of hydrogen peroxide (H2O2) and an indoxyl oxidation product that emitted blue fluorescence at 478 nm. The generated H2O2 effectively quenched the fluorescence of AgNCs at 627 nm. Thus, the fluorescence intensity ratio F478/F627 can be used for the detection of β-Gal activity. The results demonstrated that the ratio of F478/F627 exhibited excellent linear correlations with β-Gal activity within the ranges of 0.2-10.0 U/L and 10.0-50.0 U/L, achieving a detection limit of 0.031 U/L. Furthermore, the ratiometric fluorescent method was effectively utilized to measure β-Gal levels in human serum samples, highlighting its substantial potential for clinical diagnostics.