Design and Construction of Enzyme–Nanozyme Integrated Catalyst as a Multifunctional Detection Platform

A new integrated catalyst, Fe3O4@Cu/GMP–GOx, was successfully constructed by assembling Cu2+ and guanosine 5-monophosphate (GMP) on magnetic nanoparticles and in situ encapsulating glucose oxidase (GOx). As the nanozyme, Fe3O4@Cu/GMP has the dual response of catalase- and laccase-like activity, which can effectively improve the cascade catalytic efficiency and amplify the colorimetric detection signal. Compared with free enzymes, Fe3O4@Cu/GMP and Fe3O4@Cu/GMP–GOx showed enhanced thermal, mechanical, and storage stability. Fe3O4@Cu/GMP can be applied to the detection of H2O2, with a linear response range of 0 to 198 μM and a limit of detection (LOD) of 0.477 μM. Fe3O4@Cu/GMP–GOx can be applied to the detection of glucose and β-arbutin and showed good selectivity and anti-interference performance. For glucose, the linear response range was 0 to 800 μM, and the LOD was 5.516 μM. For arbutin, the absorbance was linearly correlated with the concentration of arbutin in the range of 0 to 60 μM and 100 to 400 μM, and the LOD was 0.766 μM. This integrated catalyst provides a simple strategy for the application of an enzyme–nanozyme cascade system in colorimetric detection.