In Situ Synthesis of Self-Assembled Three-Dimensional Graphene–Magnetic Palladium Nanohybrids with Dual-Enzyme Activity through One-Pot Strategy and Its Application in Glucose Probe

The self-assembled three-dimensional graphene nanohybrids with in situ-formed Fe₃O₄ and Pd nanoparticles on it (3DRGO-Fe₃O₄-Pd) are first synthesized by the one-pot solvothermal method, which have intrinsic peroxidase-like and oxidase-like activity. The catalytic mechanism is analyzed by the electron spin resonance (ESR), fluorescence, and electrochemical methods. The mimic enzyme catalytic activity of 3DRGO-Fe₃O₄-Pd is much higher than those of monometallic loaded nanohybrids and their physical mixture, probably caused by synergistic effect between Pd and Fe₃O₄ nanoparticles. The 3DRGO-Fe₃O₄-Pd nanohybrids was reproducible, stable, and reusable. After 10 cycles, the catalytic activity was still higher than 90%, and the morphology and structure were basically unchanged. Based on its high peroxidase-like activity, especially the enhanced affinity toward H₂O₂, a new colorimetric detection method for reduced glutathione (GSH) and glucose has been designed using H₂O₂ as an intermediary, which provides a simple, sensitive, and selective way to detect urine glucose of diabetes with a wide linear range and low detection limit.