Integrating Bimetallic Nanoparticles with Covalent Organic Frameworks as Multifunctional Nanozyme for Colorimetric Detection of Hydrogen Peroxide and Glutathione

The controllable growth of metal nanoparticles on nanomaterials is becoming an effective strategy for developing nanocomposites with designated performance. Herein, a simple and mild strategy for the in situ growth of Pt–Pd bimetallic nanoparticles on covalent organic frameworks (COFs) to regulate the nanozyme activity was designed for colorimetric detection of hydrogen peroxide (H₂O₂) and glutathione (GSH). The COFs not only offer sufficient loading sites for the uniform dispersion of Pt–Pd bimetallic nanoparticles, but also increase the adsorption of substrate to promote the catalytic reaction. With the bimetallic synergistic effect of Pt–Pd nanoparticles, the prepared multifunctional nanozyme (Pt–Pd/COFs nanozyme) simultaneously exhibited superior peroxidase (POD)-like activity and oxidase (OXD)-like activity. Using the multifunctional nanozyme, a colorimetric sensing system was constructed for sensitive detection of H₂O₂ and GSH, with the wide linear ranges of 5–1000 µmol/L and 1–40 µmol/L, and the detection limits were 1.14 μmol/L and 0.43 μmol/L, respectively. It was successfully used for the detection of real samples in environmental water and serum, providing a simple method for disease diagnosis and environmental monitoring.