Rational design of a stable peroxidase mimic for colorimetric detection of H

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).