Rational design of a stable peroxidase mimic for colorimetric detection of H₂O₂ and glucose: A synergistic CeO₂/Zeolite Y nanocomposite

Owing to the high costs and instability of natural enzymes, the development of enzyme mimics based on inorganic nanomaterials has attracted a wide concern in recent years. In this work, a stable nanocomposite composed of highly dispersed CeO₂ nanoparticles decorated on zeolite Y as support (CeO₂/Y) was synthesized by a facile wet impregnation method, and the CeO₂/Y nanocomposite was firstly proposed as an efficient peroxidase-mimicking nanozyme for accurate detection of H₂O₂ and glucose. The best catalyst was the nanocomposite with CeO₂ to zeolite Y mass ratio of 0.20 (denoted as 20CeO₂/Y), showing a better affinity and higher catalytic constant to the substrate of H₂O₂ and 3,3',5,5'-tetramethylbenzidine (TMB) than horseradish peroxidase (HRP) enzymes by the steady-state kinetic analysis. The enzyme-mimicking catalyst could be used over a wider range of pH and temperature for a long-time reuse in TMB oxidation. A facile colorimetric assay was set up for the accurate detection of H₂O₂ and glucose, with the detection limits of 0.323 μM and 35.4 μM, respectively. The CeO₂/Y-based peroxidase mimic was used to precisely detect the glucose concentration in real blood serum samples, exhibiting a great potential to be constructed as a reliable biosensor for glucose detection in some complex systems. The superior peroxidase-mimicking performance of CeO₂/Y nanocomposite is attributed to the synergistic effects of outstanding activity of highly dispersed CeO₂ nanoparticles (5-10 nm) and adsorption properties of zeolite Y with large surface area (517 m²·g^-1) and pore volume (0.329 cm³·g^-1).