Colorimetric detection of glutathione through tuning the oxidase-like activity of MnCO<sub>3</sub> nanoparticles

Abstract

<p indent="0mm">Nano-oxidases are a kind of nanomaterials with catalytic properties similar to natural oxidases. Regulating the catalytic activity of oxidase-like mimics is of great significance in biosensing as well as clinical diagnosis and treatment. In this article, MnCO₃ nanoparticles (NPs) with oxidase-like activity were prepared by one-pot hydrothermal method, and were able to catalyze the production of reactive oxygen species from dissolved oxygen and transform colorless substrate 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxTMB with a characteristic absorption peak at <sc>652 nm.</sc> Further studies showed that the catalytic oxidation of TMB by MnCO₃ NPs could be inhibited by the addition of glutathione (GSH), and thus the production of oxTMB as well as the absorbance at <sc>652 nm</sc> decreased, which showed a linear relationship with the concentration of GSH in a certain range. Based on this mechanism, a new colorimetric method for GSH detection based on regulating the oxidase-like activity of MnCO₃ NPs was established and successfully applied to the determination of GSH in serum. With the assistance of smartphone, a portable analysis method for GSH detection was also developed with the application potential for point-of-care testing and disease diagnosis.