Chrysanthemum-like Fe–Co LDH with peroxidase mimicking activity for visual and photothermal determination of H2O2 and glucose

Abstract

We synthesized chrysanthemum-like Fe–Co layered double hydroxide (LDH) nanostructures via a hydrothermal method. The as-prepared Fe–Co LDH demonstrates peroxidase-like activity, which catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂ to form oxidized TMB (oxTMB), resulting in a characteristic blue color. Notably, the oxTMB solution demonstrates a significant photothermal effect under 808 nm laser irradiation. This dual-responsive detection system for H₂O₂ involves both visual analysis (solution color change) and photothermal measurement (temperature variation). Moreover, the enzymatic oxidation of glucose catalyzed by glucose oxidase (GOx) generates H₂O₂ as one of its products, which enables the development of both visual and photothermal glucose detection methods. Therefore, the synthesized chrysanthemum-like Fe–Co LDH demonstrated excellent dual-mode sensing capabilities, achieving sensitive H₂O₂ detection within a linear range of 10–1000 µM, with a limit of detection (LOD) of 2.56 µM (based on 3σ/s criterion). Furthermore, this nanostructured material showed remarkable performance in glucose detection, exhibiting a similar linear range (10–1000 µM) and a comparable LOD of 2.51 µM (3σ/s), through the indirect measurement of enzymatically produced H₂O₂. The chrysanthemum-like Fe–Co LDH exhibited enhanced peroxidase-like catalytic activity, which can be attributed to the increased number of accessible active sites within its unique flower-like nanostructure. Moreover, the synthesized nanozyme demonstrates excellent potential for sensitive photothermal glucose detection in food and beverage samples, suggesting promising applications as a versatile sensing platform.