Multienzyme cascades analysis of -glucosidase by oxygen deficient MoO_3-x

Background: Recently, the enzymatic cascade reactions during the cellular process are widely used for fabricating robust biosensors and they have attracted extensive attention in analyzing various clinical biomarkers. The enzymatic cascades analysis is commonly based on the peroxidase (POD)/oxidase coupled system. However, the requirement of harsh acidic environment, poor stability and interference from the oxidase further limit their analytical practicability. Herein, novel chromogenic nanomaterials with H2O2 sensitive features are urgently required to replace the POD nanozyme in enzymatic cascades based bioanalysis. Results: Herein, oxygen deficient MoO3-x with H2O2 sensitive features and near-infrared (NIR) absorption band have been ultra-fast synthesized and utilized for the enzymatic cascades analysis of alpha-Glucosidase's activity, and inhibitors screening. With the addition of 4-nitrophenyl-alpha-D-glucopyranoside, the simultaneous presence of alpha-Glucosidase and glucose oxidase (GOx) would fade their dark blue color and decrease the NIR absorption. The alpha-Glucosidase's activity can be analyzed by the absorption at 770 nm, and their limit of detection is 8 x 10-5 U/ mL, indicating the superior performance of the proposed colorimetric assay. Moreover, this proposed alpha-Glucosidase assay is further utilized for inhibitors screening. Moreover, the activity of alpha-Glucosidase can also be analyzed by the smartphone and microplate reader through the agarose-based colorimetric portable kit. Significance: This MoO3-x involved enzymatic cascades assay would facilitate for the development of bio-analysis related to H2O2 generation or consumption. Moreover, this bio-analysis strategy will contribute to the development of other H2O2 sensitive chromogenic nanomaterials for the analysis of certain biomolecules and biological enzymes.