Iron oxides based nanozyme sensor arrays for the detection of active substances in licorice.

With the increasing applications of traditional Chinese medicines worldwide, authenticity identification and quality control are significant for them to go global. Licorice is a kind of medicinal material with various functions and wide applications. In this work, colorimetric sensor arrays based on iron oxide nanozymes were constructed to discriminate active indicators in licorice. Fe2O3, Fe3O4, and His-Fe3O4 nanoparticles were synthesized by a hydrothermal method, possessing excellent peroxidase-like activity that can catalyze the oxidation of 3,3',5,5' -tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue product. When licorice active substances were introduced in the reaction system, they showed competitive effect on peroxidase-mimicking activity of nanozymes, resulting in inhibitory effect on the oxidation of TMB. Based on this principle, four licorice active substances including glycyrrhizic acid, liquiritin, licochalcone A, and isolicoflavonol with the concentration ranging from 1 μM to 200 μM were successfully discriminated by the proposed sensor arrays. This work supplies a low cost, rapid and accurate method for multiplex discrimination of active substances to guarantee the authenticity and quality of licorice, which is also expected to be applied to distinguish other substances.