Facile approach to prepare HSA-templated MnO2 nanosheets as oxidase mimic for colorimetric detection of glutathione

In this work, a simple, rapid, and highly sensitive colorimetric assay for the determination of glutathione (GSH) was developed. It employs human serum albumin (HSA)-templated MnO2 nanosheets as an artificial oxidase. HSA-templated MnO2 nanosheets can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to a blue oxTMB product with a significant increase in absorbance at 652 nm in the absence of H2O2. When GSH is introduced, the MnO2 nanosheets are reduced to Mn2+ ions, thereby inhibiting the formation of oxTMB. Based on these findings, a simple colorimetric assay was developed for the detection GSH in the range of 10 nM to 5 μM with a low detection limit of 5.6 nM. Importantly, the proposed method was successfully used for quantitative determination of GSH in biological fluids, such as human serum samples.