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A fluorescence “off–on–off” sensing platform based on bimetallic gold/silver nanoclusters for ascorbate oxidase activity monitoring

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Abstract

Herein, papain-protected bimetallic gold/silver nanoclusters (Au/Ag NCs) were successfully synthesized and applied for the detection of ascorbate oxidase (AAO). The doping of papain-protected Au nanoclusters with Ag enhanced the fluorescence intensity with an intense red fluorescence peak at 617 nm, and the red-emitting Au/Ag nanoclusters were further used to monitor the AAO activity. The fluorescence of Au/Ag NCs could be quenched by hydrogen peroxide (H2O2) due to the generation of hydroxyl radicals (˙OH) from the reaction of Ag/Au nanoclusters and H2O2. However, the addition of ascorbic acid (AA) effectively reacted with the free radicals and caused the fluorescence recovery of the Au/Ag NCs. Furthermore, AAO could catalyze the oxidation of AA to form dehydro-ascorbate (DHA). As a result, there was not enough AA to consume the hydroxyl radicals, which resulted in a decrease in the fluorescence of the papain-capped Au/Ag NCs. Therefore, the AAO activity can be monitored by measuring the fluorescence intensity of the red-emitting Au/Ag NCs. Moreover, the developed method for AAO detection displayed a good linear relationship from 5 to 80 mU mL−1 and the detection limit was 1.72 mU mL−1. Thus, a simple and selective method for the determination of the AAO activity was constructed and satisfactory results were obtained in real sample detection.

Graphical abstract: A fluorescence “off–on–off” sensing platform based on bimetallic gold/silver nanoclusters for ascorbate oxidase activity monitoring

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Supplementary files

Article information


Submitted
22 Oct 2019
Accepted
28 Nov 2019
First published
29 Nov 2019

Analyst, 2020, Advance Article
Article type
Paper

A fluorescence “off–on–off” sensing platform based on bimetallic gold/silver nanoclusters for ascorbate oxidase activity monitoring

M. Wang, M. Wang, G. Wang and X. Su, Analyst, 2020, Advance Article , DOI: 10.1039/C9AN02108F

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