Dual-signal aptasensor based on Zr-MOF for ultrasensitive detection of AFB1 in corn

A dual-signal aptasensor for ultra-sensitive detection of AFB1 was developed based on the inherent electrochemical and fluorescence properties of Zr-MOF, leading to improved detection accuracy and reduced false-positive problems caused by individual signals. Using a large number of Zr (IV) metal sites on the surface of Zr-MOF, the signal recognition probe was constructed based on Lewis acid-base theory by forming a stable Zr-O-P ligand bond with the modified -PO43- at the end of the aptamer, and improving the binding stability and immobilization efficiency. The signal recognition probe Zr-MOF/Apt was constructed using this method and bound to cDNA which was anchored to the surface of highly porous gold electrode via the principle of base complementary pairing. When AFB1 presented, due to the aptamer binding it specifically, the signal probe fell off from the electrode surface into the electrolyte, resulting in a decrease in the electrochemical signal on the electrode, and at the same time, the fluorescence signal was increased in the electrolyte. The performance of the dual-signal aptasensor was confirmed by electrochemical and fluorescence signals and exhibited excellent detection performance under optimal conditions (linear range of 0.001–30 ng mL−1 and detection limit of 0.6 pg mL−1 for the electrochemical signal, 0.8 pg mL−1 for the fluorescence signal). It also showed good stability, selectivity, and reproducibility. The spiked recoveries in corn samples ranged from 95.0 % to 120.0 %.