Oxidase-like Nanozyme Activity of Manganese Metal–Organic Framework Nanosheets for Colorimetric and Fluorescence Sensing of l-Cysteine

The utilization of ultrathin Mn-metal–organic framework (Mn-UMOF) nanosheets for oxidase-like nanozyme activity has been demonstrated. The Mn-UMOF exhibited superior nanozyme activity to oxidize chromogenic TMB and ABTS than the bulk Mn-BMOF. Based on this fact, a platform for the colorimetric sensing of l-cysteine (l-cys) has been established over the detection of other amino acids and natural compounds such as urea and glucose. In addition, the Mn-UMOF has the capability of catalyzing the oxidation of amplex red to the fluorescent first oxidized product, which has been used to develop a fluorescence turn-off sensor for the selective sensing of l-cys.