Reactive oxygen species independent oxidase like nanozyme for dual-mode analysis of α-glucosidase

Designing highly sensitive and selective assay for analyzing α-glucosidase activity is of critical value for diagnosis of related diseases. Herein, we proposed a biomineralization synthetic route to construct bovine serum albumin templated hybrid nanomaterials of Au nanoclusters (Au NCs) and oxygen deficient manganese dioxide (indicated as BAM). BAM exhibits ultra-fast oxidase-like (OXD) activity that directly oxidized TMB to generate product. Unexpected, the OXD activity of BAM is not relied on the reactive oxygen species or dissolved molecular oxygen, which has rarely been reported. The superior OXD activity of BAM is derived from the strong interactions between Au NCs and MnO2-x nanosheets that contributes to the partial reduction of MnO2-x and increase of Au(Ⅰ) species. And the catalytic mechanism is related to electron transfer from TMB to MnO2-x with Au NCs as intermediates. The analysis of α-glucosidase activity has been realized by BAM and 2-O-a-D-glucopyranosyl-L-ascorbic acid (AA2G) as the catalytic substrate with dual mode. The AA2G can be hydrolyzed by α-glucosidase into AA, which can obviously inhibit the oxidation of TMB and recover the fluorescence of Au NCs. And the inhibition ratio and recovery efficacy are related the activity of α-glucosidase. Hence, the activity of α-glucosidase can be analyzed by the changes of the signal of absorbance or fluorescence. The dual-mode detection can prevent false negative/ positive results, satisfying different demands in various analytical situation.