Two-Dimensional Nanozyme Based on Iron Metal–Organic Gel/Carboxylated Graphene Oxide for Electrochemical and Colorimetric Dual-Mode Detection of Hydrogen Peroxide

Metal–organic gel (MOG) is a distinctive metal–organic hybrid material with a unique porous structure and exceptional catalytic site accessibility. The rational design of an electrochemical and colorimetric dual-mode sensor platform utilizing the peroxidase (POD)-like activity of MOG for the detection of H2O2 is crucial for clinical diagnosis. In this article, a two-dimensional composite nanozyme based on Fe-MOG and carboxylated graphene oxide (GO-COOH) was synthesized, which serves dual functions to establish electrochemical sensing and colorimetric sensing based on its excellent electrocatalytic reduction of H2O2 and POD-like activity. GO-COOH played a critical role, and the electrochemically reduced ERGO-COOH facilitated electron transfer from the metal catalytic site in Fe-MOG, enhancing the performance of electrocatalytic reduction of H2O2. Additionally, GO-COOH amplified the POD-like activity of Fe-MOG, and the Fe-MOG/GO-COOH composite participated in various ROS-mediated catalytic reactions. The developed dual-mode sensor exhibited a rapid response and high sensitivity in detecting H2O2, demonstrating excellent selectivity, reproducibility, and stability. These attributes enhanced the accuracy and reliability of the detection of H2O2 released from living cells. This MOG-based nanozymatic dual-mode sensing technology offers promising prospects for enhancing the reliability of rapid detection and holds significant potential for application in pathophysiological monitoring of living cells.