Size effect-mediated differential regulation of dual enzyme-like activities of FeNi LDH for visual colorimetric detection of uric acid.

Abstract

Abnormal levels of uric acid (UA) are closely associated with gout, hyperuricemia, and various neurodegenerative diseases. Herein, MIL-88 A was used as a self-sacrificial template to controllably prepare FeNi layered double hydroxide (FeNi LDH), which combines excellent peroxidase-like (POD-like) and oxidase-like (OXD-like) activities. The morphology, particle size, and catalytic performance of the series materials were precisely optimized. The modulation effects of microstructural features including bimetallic active sites, porous sheet-like morphology, intermetallic electronic interaction and heterostructure on OXD-like and POD-like catalytic activities as well as substrate affinity were systematically investigated. It was found that reflux modification could effectively optimize the surface coordination environment of FeNi LDH and enrich highly active metal‑oxygen sites. Meanwhile, the abundant oxygen vacancies within the material could further modulate the electronic structure of the metal sites. Combined with the electronic interactions and synergistic effects between Fe and Ni bimetallic species, the catalytic activity of the material was effectively enhanced. Two visual colorimetric sensing platforms were constructed and compared for highly sensitive detection of UA. The POD method exhibited high sensitivity and excellent selectivity, while the OXD method offered rapid response and low cost without the need for natural enzymes. They are complementary in performance and independent in principle, enabling cross-validation of detection results, effectively reducing systematic errors of a single detection system, and significantly improving the accuracy and reliability of UA quantification.

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