A covalent organic framework–MnO 2 nanosheet system for determination of glutathione

Covalent organic frameworks (COFs) are usually synthesized by virtue of Schiff base reaction between amino and aldehyde groups. Owing to their electron-rich property, COFs are widely applied to detect electron-deficient nitroaromatic explosives through photoinduced electron transfer mechanism. However, except for these cases, the COFs-based chemosensors are rarely reported for the analysis of electron-rich biomolecules. In this work, a fluorescent platform constructed by COFs and MnO 2 nanosheets is developed for sensitive detection of glutathione (GSH). It is found that the fluorescence of COFs can be effectively quenched by MnO 2 nanosheets. The quenching mechanisms involving inner filter effect and static quenching effect are discussed in detail. Due to the reducing ability of GSH, it can trigger the reduction of MnO 2 to Mn 2+ , accompanying with the fluorescence recovery of COFs. The linear range of GSH is achieved from 0.5 to 100 µM with a detection limit of 0.28 µM. This method is further applied for GSH detection in human serum samples with satisfactory results.