Bioinspired Bi-amino Acid Ce-MOFs Boosting Oxidase-like Activity: Dual-mode Aflatoxin Detection and Antimicrobial Activity Platform

Abstract

Bioinspired metal–organic frameworks (MOFs) have emerged as pivotal platforms for biomimetic catalytic processes due to their structural and functional mimicry of natural enzymes. However, the underlying mechanisms governing enzymatic activity regulation and substrate-specific selectivity in bioinspired MOFs remain elusive, limiting their rational design for molecular recognition. Herein, we developed a novel bioinspired oxidase (OXD)-like MOF@Arg_0.25@His_0.25 nanozyme with bi-amino acid ligand coordination as a carrier for ratiometric fluorescence-colorimetric dual-mode aflatoxins B1 (AFB1) detection. The MOF@Arg_0.25@His_0.25 exhibits significant OXD-like activity with minimal POD-like activity. We provide the concept of an energy-regulated substrate lock that modulates the transfer of electrons between the bi-amino acid-modified nanozyme and substrates to enable selective regulation of OXD-like catalysis. The unique amphiphilic properties and large specific surface area allow AFB1 adsorption capacity to attain 31.25 mg⋅g⁻¹. A dual-mode sensing platform is developed based on aptamer-modified MOF@Arg_0.25@His_0.25, attributed to its elevated OXD-like activity and notable surface adsorption characteristics. Both fluorescence quenching and chromogenic responses displayed linear inverse correlations with AFB1 concentrations over a dynamic range of 0.5–50 ng·mL⁻¹, ensuring quantitative reliability. The detection platform establishes limits of detection (LOD) for fluorescence and colorimetric assays at 1.01 ng⋅mL⁻¹ and 1.32 ng⋅mL⁻¹, respectively, thereby enabling mutual validation of the assay results. Moreover, MOF@Arg_0.25@His_0.25 demonstrates significant antimicrobial properties attributed to its enhanced OXD-like activity. This bioinspired nanozyme design paradigm establishes a versatile theranostic platform for simultaneous mycotoxin monitoring and pathogen suppression, paving the way for next-generation agro-food safety technologies.