Aptamer/magnetic-MIP dual-recognition sandwich biosensor for rapid and recyclable determination of kanamycin in food.

Background

The rapid and precise monitoring of antibiotic residues is a cornerstone of food safety and diagnostic science. Herein, we report a high-performance dual-recognition sandwich-type fluorescent biosensor engineered by integrating Fe3O4@UiO-66-based molecularly imprinted polymers (FUMIP) with a fluorescein-labeled aptamer probe (Apt-FAM) for the ultrasensitive detection of kanamycin (KANA).

Results

Central to this design is the confined microenvironment provided by the FUMIP framework, which facilitates the selective pre-concentration of KANA through coordinated boronate affinity and hydrogen bonding. This interfacial enrichment significantly facilitates subsequent recognition by the Apt-FAM probe, forming a stable sandwich architecture that achieves a 156-fold sensitivity enhancement compared with the single-recognition control system constructed in this work. The FUMIP component exhibits a superior imprinting factor of 5.19 and an adsorption capacity of 45.11 mg/g, ensuring high-fidelity target capture even in complex matrices. The optimized biosensor enables rapid quantification within 30 min, delivering an exceptional detection limit of 0.0032 ng/mL across a broad linear range (0.01-1000 ng/mL). In comparison, the single-recognition sensor exhibits a linear range of 1-500 ng/mL with a detection limit of 0.5010 ng/mL. Furthermore, the sensor demonstrates robust reusability (70% signal retention after 20 cycles) and high practical reliability, with recoveries of 98.0%-106.2% in real food samples.

Significance

This work not only provides an advanced platform for KANA monitoring but also offers a universal strategy for the ultrasensitive detection of small-molecule contaminants by exploiting the synergy between synthetic and biological receptors.