Fluorescence ratiometric assay for discriminating GSH and Cys based on the composites of UiO-66-NH and Cu nanoclusters.

The discriminative detection of glutathione (GSH) from cysteine (Cys) remains a challenge because of their similarity in structure and chemical properties. This study reported a strategy for selective and sensitive detection of GSH based on the GSH-promoted blue fluorescence of UiO-66-NH and aggregation-enhanced emission (AEE) feature of orange emissive Cu nanoclusters (NCs). A relatively weak blue fluorescence of UiO-66-NH was converted to strong after reacting with GSH due to the rotation-restricted emission enhancement mechanism. In addition, the GSH-activated UiO-66-NH was further used as a template and reducing reagent for synthesizing orange-red AEE active Cu NCs composites (UiO-66-NH@Cu NCs). A ratiometric fluorescence response was observed after forming UiO-66-NH@Cu NCs, helping discriminate GSH over Cys. In addition, UiO-66-NH@Cu NCs were further utilized for the detection of GSH in clinical samples. The present findings provide an efficient strategy to discriminate GSH over Cys and open a new door for utilizing and functionalizing metal-organic frameworks (MOFs) for various applications.