Ultrafine Platinum Nanoparticles Supported on Covalent Organic Frameworks As Stable and Reusable Oxidase-Like Catalysts for Cellular Glutathione Detection

Nanozymes have been widely developed as supplements of natural enzymes owing to their relatively low cost, high mass production, easy storage, good stability, and reusability. By controlling the particle size, nanozymes' catalytic activities can distinctly be improved. The porous materials such as covalent organic frameworks (COFs) are definitely considered as promising supports for in situ preparation of high-dispersity and small-size nanozymes. Herein, we designed and synthesized COF-supported ultrafine platinum nanoparticles (Pt NPs/COF-300-AR) by controlling the growth of Pt NPs by using uniformly distributed nitrogen atoms of well-organized framework structures of 3D COFs. Pt NPs/COF-300-AR nanohybrids catalyzed the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) solution to turn blue, displaying excellent oxidase-like activity, good stability, and high reusability, which should be owed to the uniform size and high dispersity of ultrafine Pt NPs. By virtue of those advantages, the TMB-Pt NPs/COF-300-AR colorimetric platform was successfully applied to cellular glutathione detection. Similarly, other COFs with good acid resistance and abundant functional groups can also be used as the supports of a nanozyme, which will greatly expand the members of the nanoenzyme family.