Mn 3 O 4 microspheres as an oxidase mimic for rapid detection of glutathione.

Exploiting a rapid and sensitive method for biomarker detection has important implications in the early diagnosis of diseases. Here, we synthesized Mn 3 O 4 microspheres which worked as a nanozyme to exhibit outstanding oxidase-like activity for rapid colorimetric determination of glutathione (GSH). The Mn 3 O 4 microspheres of about 800 nm in size could be prepared through a hydrothermal method, and we found that the as-prepared Mn 3 O 4 microspheres could quickly oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to its oxidized form (TMBox) in the absence of H 2 O 2 . After adding glutathione (GSH), TMBox was able to be changed into to its original form and resulted in the corresponding decrease in absorbance value at 652 nm. The Mn 3 O 4 -TMB system had good linearity with GSH concatenation in the range of 5-60 μM, and the limit of detection was 0.889 μM. Furthermore, this assay possessed high selectivity specificity, which made it possible to detect GSH in human serum samples. Thus, the obtained assay based on the oxidase mimic of Mn 3 O 4 would enlarge and exploit the application fields of nanozymes in bio-analysis.