MnO₂/Au-Ag nanozyme-GOx cascade system for sensitive colorimetric glucose detection and test strip applications

Glucose is a vital energy source, and its accurate monitoring is crucial for the diagnosis and management of metabolic diseases. Herein, we report a simple colorimetric sensing platform for glucose detection based on MnO₂/Au-Ag nanozymes, glucose oxidase (GOx), and 3,3',5,5'-tetramethylbenzidine (TMB). In this cascade system, GOx catalyzes the oxidation of glucose to generate H₂O₂, which is subsequently decomposed by MnO₂/Au-Ag to produce reactive species that oxidize TMB, yielding a visible blue signal. The incorporation of Au-Ag nanoparticles provides additional catalytic sites and promotes interfacial electron transfer, thereby enhancing the catalytic performance of MnO₂. The platform exhibits a linear response over 0.025-0.20 mM with a detection limit of 0.012 mM. It enables reliable glucose detection in artificial sweat and 80-fold diluted serum samples. In addition, portable nitrocellulose test strips were developed for visual and smartphone-assisted glucose detection. This strategy provides a simple and portable approach for low-concentration glucose analysis and offers potential for point-of-care applications after further validation.