Visual colorimetric sensor array for discrimination of antioxidants in serum using MnO2 nanosheets triggered multicolor chromogenic system

Here we report a unique visual colorimetric sensor array for discrimination of antioxidants in serum based on MnO 2 nanosheets-3,3′,5,5′-tetramethylbenzidine (TMB) multicolor chromogenic system. The absorbance values of the system at 370, 450, and 650   nm provide three cross-reactive sensing elements. The presence of antioxidant will inhibit the reaction between TMB and MnO 2 nanosheets due to the presence of the competitive reaction of MnO 2 nanosheets and antioxidants. Different antioxidants containing uric acid , glutathione , ascorbic acid , cysteine, and melatonin have distinct reducing ability, producing a differential inhibition of MnO 2 nanosheets-TMB system, and therefore generating distinct colorimetric response patterns at 370, 450, and 650   nm. The obtained patterns for each antioxidant at a concentration of 20   μM were successfully discriminated using principal component analysis both in buffer and when spiked into fetal bovine serum (FBS). The identification accuracy of 45 unknown samples was found to be 100%. Remarkably, this sensor assay can visually discriminate antioxidants in diluted FBS with the naked eye.