A visible and sensitive assay for the quantitative detection of β-glucosidase (β-glu) activity based on Au@CeO2 core-shell nanoparticles (Au@CeO2 NPs) is described. As a hydrolytic enzyme, β-glu can promote the hydrolysis of β-arbutin to hydroquinone (HQ), which can trigger the decomposition of the CeO2 shell. With the single-particle enumeration (SPE) strategy coupled with dark field optical microscopy (DFM), an obvious color alteration of single Au@CeO2 NPs during the etching process can be observed in real-time. By statistically calculating the number of the etched nanoparticles, the β-glu activity level can be quantified accurately. This assay displays a broad linear range from 0.5 to 50 mU⋅mL-1 and low detection limit of 0.12 mU⋅mL-1. In addition, this method was successfully used to determine β-glu in real samples and acquires satisfactory recoveries in the range of 97.1-102.0%. This study provides a visualization analysis method for β-glu, which may be helpful for monitoring other targets in the future.
Keywords: Au@CeO2 nanoparticles (NPs); Dark field optical microscopy; Optical sensor; Single-particle enumeration (SPE); β-glucosidase (β-glu) activity.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.