Recently, exploitation of nanozymes for signal amplification has aroused extensive research interesting in the fields of analytical chemistry and nanoscience. Herein, we introduced a new sensing strategy based on the ascorbic acid (AA) precisely regulated Ag3PO4 nanozyme for signal amplification. AA can reduce the partial Ag+ on the surface of Ag3PO4 nano-particles to form Ag° particles and result in the formation of Ag°/Ag3PO4 heterostructure. Due to surface plasmon resonance (SPR), the Ag° particles in heterostructure can act as the co-catalysts to enhance the electron-hole separation and the interfacial charge transfer, leading to a highly efficient oxidase mimicking activity for catalyzing the oxidation of the substrate of 3,3,5,5-tetramethylbenzidine (TMB) under visible light. Impressively, the activity enhancement of Ag3PO4 nano-peroxidase was linearly depended on the AA concentrations. Based on this feature, we employed it for multiple biological detections. For example, L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) was designed for α-glucosidase substrate, which can be hydrolyzed by α-glucosidase and lead to AA release. Further, the signal of α-glucosidase activity can be efficiently enlarged by Ag3PO4 nanozyme. Taking advantages of the powerful signal amplification by Ag3PO4 nanozymes, we developed the multiple sensing assays for monitoring AA in rat brain microdialysates, detection of α-glucosidase activity and its inhibitors (anti-diabetic drugs). The assay allowed the ultrasensitive colorimetric detection of α-glucosidase inhibitor with an ultra-low detection limit of 10 nM, and a naked-eye detection of the inhibitor concentration as low as 1 μM. The sensing strategy based on AA precisely regulated Ag3PO4 nano-peroxidase provides a promising candidate platform for highly stable and efficient cascaded signal amplification in biosensing field.
Keywords: Inhibitor screening; Nanozymes; Photo-nanoperoxidase; α-glucosidase.
Copyright © 2018. Published by Elsevier B.V.