Mixed-Valence V2O5-(Ce3+/Ce4+) Metal–Organic-Framework Nanorods for the Colorimetric and Fluorometric Detection of Glutathione

Emerging metal–organic framework (MOF)-based nanomaterials such as nanozymes have attracted interest and been applied in the detection of biomolecules like glutathione (GSH). It is still difficult to distinguish GSH from cysteine (Cys) and ascorbic acid (AA) because most antioxidants behave similarly. However, the appropriate catalytic activity, high surface area, etc., of MOF-based nanozymes can allow entry into molecular substrates, analytes, and complete contact with active nanozymes sites. Then, in this study, the colorimetric and fluorometric detection of GSH based on oxidase mimetic activity was investigated using the mixed-valence state V2O5-(Ce3+/Ce4+)-MOF nanozyme. This sensor demonstrated a suitable linear analytical response in the area of 0.1–75 and 0.1–40 μM with a detection limit of 0.048 and 0.06 μM for colorimetric and fluorometric methods, respectively. It is determined that vanadium should direct contact with the GSH molecules to trigger its activation effect of glutathione-peroxidase. In addition, it could help the preconcentration of GSH on the catalyst’s surface. When the surface states of the (Ce3+/Ce4+)-MOF covered by the generated GSSG are on the catalyst surface. Therefore, it strongly inhibits the oxidation of tetramethylbenzidine (TMB) by the oxidase-like activity of the catalyst. Therefore, it strongly inhibits the oxidation of TMB by the oxidase-like activity of the catalyst. This study’s strategy of using nanozymes with oxidase and glutathione-peroxidase-like activity to design sensors will provide a unique pathway for improving the efficiency of MOF-nanozyme-based sensors.