Gold nanoparticle-loaded MoS nanosheets with peroxidase-like and pyranose oxidase-like activities for bio-enzyme-free visual detection of glucose, xylose and galactose

Enzyme mimics with dual enzyme-like activities can catalyse cascade reactions with high efficiency and thus play a significant role in biochemistry since multistep cascade reactions often occur in biocatalysis. Especially, a nanozyme that simultaneously possesses peroxidase-like and pyranose oxidase (POx)-like activities is highly desired since it can be used for bio-synthetizing rare sugars and fabricating bio-enzyme-free colorimetric methods for the detection of various pyranoses. We herein prepared a novel dual-active nanozyme, which simultaneously possesses enhanced and stable peroxidase-like and POx-like activities, by loading gold nanoparticles (AuNPs) on MoS 2 nanosheets (AuNPs@MoS 2 ). The prepared AuNPs@MoS 2 nanozyme can catalyse various tandem reactions of pyranose oxidation and H 2 O 2 -mediated oxidation of TMB with high efficiency and, therefore, can be used to fabricate bio-enzyme-free colorimetric methods for the detection of various monosaccharides with a pyranyl ring, including glucose, xylose and galactose. Based on the AuNPs@MoS 2 nanozyme, we successfully developed bio-enzyme-free colorimetric methods for the detection of glucose, xylose and galactose with a visual detection limit of 0.2-0.3 mM and a spectrometry detection limit of 5.0-11 μM. The developed colorimetric glucose, xylose and galactose detection methods were successfully used to detect glucose in serum, xylose in bread and galactose in milk, respectively, with a recovery of 89-108% and a relative standard deviation (RSD, n = 5) of