Peroxidase-like Nanozyme Composite-based Colorimetric Determination of Glutathione and Cysteine

Simple, low-cost, and fast determination of cysteine and glutathione with high sensitivity is an essential problem to evaluate the physiological processes in living organisms. Artificial nanozymes have provided considerable opportunities in biosensing. In this work, using a graphene-based ternary nanozyme, we present a simple but efficient colorimetric method for the determination of cysteine and glutathione. The nanozyme exhibits excellent and stable catalytic performance toward H2O2 and catalyzes the 3,3′,5,5′-tetramethylbenzidine chromogenic reaction. However, this reaction is significantly suppressed by cysteine and glutathione. Thus, a sensitive colorimetric method is presented based upon this inhibition. Excellent performance with low detection limits, good selectivity, and rapid analysis suggests potential bioanalytical applications for the determination of cysteine and glutathione.