Designed synthesis of CD@Cu-ZIF-8 composites as excellent peroxidase mimics for assaying glutathione

Abstract

Novel and highly efficient peroxidase mimics CDs@Cu-ZIF-8 are designed and prepared by a feasible solvent-free method. The introduction of copper ions enables non-active ZIF-8 nanocrystals to have good peroxidase-like activities, which can catalyse the reduction of hydrogen peroxide (H₂O₂). Furthermore, luminescent CDs are embedded into Cu-ZIF-8 nanocrystals to avoid aggregation, and particularly to construct a host–guest system with higher enzymatic catalytic activity. The synergy of CDs and the Cu-ZIF-8 matrix enhances the host–guest electron transfer, and meanwhile, accelerates the catalytic electron transfer process. Thus, CD@Cu-ZIF-8 displays superior peroxidase-like activity and glutathione (GSH) detection to pure CDs, Cu-ZIF-8 and CD@ZIF-8, and the limit of detection (LOD) reaches 0.15 μM. Considering the variety of CDs and MOFs with different metal centers and frameworks, the design strategy presented in this work will provide more opportunities to prepare CD@MOF nanozymes for being applied in the fields of biological analysis and actual biological environments.