A Bimetallic Metal-Organic Framework-Based Aptasensor for Dual-Mode Colorimetric and Fluorescent Detection of Fumonisin B1

Fumonisin B 1 (FB 1 ) is a secondary metabolite produced by Fusarium species and is considered one of the most dangerous mycotoxins. It is widely present in maize and other agricultural commodities, posing severe threats to human health and animal husbandry. Consequently, the development of a convenient and rapid detection method is of paramount importance. In this work, a metal-organic framework (MOF)-based aptamer biosensor was constructed for the detection of FB 1 , in which aptamer-regulated nanozyme activity was employed to modulate both colorimetric and fluorescent signals. The synthesized Zr-Ce-MOF exhibits intrinsic peroxidase-like activity and fluorescence properties, enabling the catalytic oxidation of colorless o-phenylenediamine (OPD) into yellow oxidized OPD (oxOPD), thereby generating a measurable colorimetric signal. Simultaneously, the oxOPD quenches the inherent fluorescence of the MOF via a fluorescence resonance energy transfer (FRET) effect. Upon target recognition, the aptamer competitively dissociates from the MOF surface, restoring the catalytic activity of the nanozyme and resulting in an increased colorimetric signal and a decreased fluorescence signal, thereby enabling effective dual-mode detection.Under optimized conditions, the limits of detection (LODs) for FB1 were 5.97 ng/mL in colorimetric mode and 1.2 ng/mL in fluorescent mode. The recovery rates for the colorimetric and fluorescent assays ranged from 101.43% to 105.80% and 99.62% to 110.60%, respectively. This proposed dual-mode aptasensor demonstrates excellent analytical performance and provides a robust strategy for the future development of sensing platforms for agricultural contaminants and antibiotic residues.