Magnetic-controlled assembly of aptamer-functionalized MOF-based molecularly imprinted polymers for fluorescence/colorimetric dual-mode sensing of ochratoxin A.

Abstract

Polydopamine-based molecularly imprinted polymers suffer from over-crosslinking, which buries recognition sites and limits performance. To overcome this, we developed a magnetic-controlled assembly strategy to fabricate a fluorescence/colorimetric dual-mode sensor for ochratoxin A (OTA). By utilizing a weak magnetic field, we induced the ordered and directional deposition of dopamine onto aptamer-functionalized metal-organic framework (MOF). This magnetic modulation produces a core-shell structure with highly accessible recognition sites, significantly enhancing binding affinity compared to conventional disordered polymerization. The detection mechanism relies on a synergistic gatekeeper effect whereby specific OTA capture physically shields the MOF from degradation, enabling the fluorescence and colorimetric readouts. This preservation of the MOF structure inhibits the release of fluorescent ligands while retaining catalytic activity for 3,3',5,5'-tetramethylbenzidine oxidation, thereby enabling the self-validating dual-mode detection. The platform demonstrated the detection limits of 6 pg mL-1 (fluorescence) and 10 pg mL-1 (colorimetric), thereby offering a highly efficient and generalizable pathway for multimodal biosensors.

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