Magnetic supported gold-copper bimetallic organic framework nanocomposite as a novel nanozyme for ultra-fast point-of-care colorimetric assay of glutathione

Herein, the turn-off colorimetric system based on magnetic supported gold-copper bimetallic organic framework (Fe3O4@Au/Cu-MOF) nanozyme catalytic reaction has developed for the high sensitivity spectrophotometric determination of glutathione (GSH). Fe3O4 is embedded into Cu-MOF to reduse aggregation, exposing more active metal sites. The uniform size, high dispersity of Au and the 2D Cu-MOF structure with coordinatively unsaturated metal sites enhances the host–guest electron transfer. The intrinsic catalytic activity of each site was enhanced due to the synergistic interaction between the three metals. Meanwhile, the Fe3O4@Au/Cu-MOF was recyclable, maintaining a relative activity of more than 87.4% after 10 cycles, and the catalytic activity remained stable at pH 3–11 and temperature ranging from 5 to 70 °C. Fe3O4@Au/Cu-MOF nanocomposites displayed higher peroxidase activity than their individual components, which can be utilized in catalysis to oxidise the peroxidase substrate 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) into a green-colored product in the presence of H2O2. After the introduction of GSH, the green color ABTS•+ was gradually fading owing to the free radical scavenging effect. The novel colorimetric sensing platform demonstrated excellent performance for GSH detection in real samples with a detection limits of 0.033 μmol/L, the detection time of only 3 min. The suggested bioassay is user-friendly, economical, and applicable to both food analysis and medical diagnostics.