Pollen-stigma biomimetic framework: a CuCo₂O₄ nanozyme-based electrochemical aptasensor for ultrasensitive aflatoxin...

Inspired by the highly specific recognition and signal amplification of pollen germination on a stigma, we propose a biomimetic electrochemical sensing strategy for ultrasensitive aflatoxin B1 (AFB1) detection. In this pollen-mimetic system, CuCo₂O₄ nanoflowers serve as "pollen-mimetic grains", with their bimetallic Cu/Co centers functioning as an internal "energy conversion system" for robust signal output. AFB1 acts as the "stigmatic secretion", triggering the release of CuCo₂O₄ nanoprobes from the aptamer complex via target-induced strand displacement. The released nanoprobes are subsequently captured by a hairpin probe on the electrode, which mimics the "stigmatic receptor", through specific DNA hybridization. Finally, the captured CuCo₂O₄ nanozyme catalyzes the oxidation of TMB, mimicking "pollen germination and tube growth" to amplify the recognition event into a measurable electrochemical signal. Under optimized conditions, this biomimetic sensor achieves a wide linear range (10^-11 to 10^-4 mg mL^-1) and an ultralow detection limit of 2.59 fg mL^-1, with excellent reproducibility, stability, and selectivity. Recovery rates in real food samples range from 97.61% to 101.53%. This pollen-stigma biomimetic framework not only provides a highly sensitive platform for AFB1 detection but also establishes a new paradigm for designing high signal-to-noise ratio biosensors for complex matrices.