In-situ synthesized porphyrinic zirconium MOF-derived multilayered nanocomposite probe for ultra-sensitive immunosensor

Aflatoxin B₁ (AFB₁) is a major concern due to its widespread contamination and potential harm. Colorimetric lateral flow immunoassays (LFIAs) incorporating gold nanoparticles (AuNPs) are widely used for on-site analyte detection. However, it remains challenging due to the limited brightness of AuNPs. Herein, we introduce an immunosensor for highly sensitive AFB₁ detection utilizing a multilayered nanocomposite probe (PCN-224@Fe₃O₄@PDA@Ab/HRP), created by sequentially modifying Fe₃O₄ nanoparticles, polydopamine layers, and horseradish peroxidase on a porphyrinic metal-organic framework, which offers magnetic separation, high signal brightness, and strong catalytic activity. Integrated with a competitive assay format, the immunosensor achieved ultrasensitive detection of AFB₁, with a detection range of 0.003-3 ng/mL and a limit of detection (LOD) of 0.0014 ng/mL. Moreover, our immunosensor exhibited satisfactory recoveries and successful detection of AFB₁ in cereal samples. Therefore, this work offers innovative strategies for designing multi-functional nanocomposite probes that enhance detection sensitivity, holding great promise in food safety monitoring.