An enzyme free self-cascade catalytic system with Au deposited bimetallic organic framework as a dual active nanozyme for glucose detection with a smartphone readout platform

A new kind of dual active biomimetic nanozyme was constructed for the establishment of an enzyme free self-cascade catalytic system. Herein, Au/FeNi-MOF nanozyme was designed and constructed by depositing Au quantum dots on a three-dimensional bimetallic organic framework via electrostatic self-assembly. By regulating the immobilization of Au quantum dots on the surface of FeNi-MOF, Au quantum dots not only exhibited stable glucose oxidase-like activity (GOx-like), but enhanced the peroxidase-like activity (POD-like) of FeNi-MOF. The obtained Au/FeNi-MOF nanozyme with both GOx-like and enhanced POD-like activities was used to mimick the cascade catalytic reaction of natural enzymes, thereby construct an enzyme free self-cascade catalytic colorimetric detection system for glucose. The detection method has a linear range of 0.02–10 mM and a detection limit as low as 15 μM with good accuracy and reproducibility. Based on the above performance, a smartphone readout platform for glucose detection was further developed. In this scheme the smartphone was used to extract and recognize the RGB values of the reaction system which were consequently converted into gray values. We recognized that evaluating glucose levels through a smartphone readout platform has the advantage of simple, convenient, and reliable, while revealing its potential application in medical monitoring.