MOF-based nanocomposites coupled with RecJf exonuclease-assisted target recycling amplification: Dual signal amplification for ultrasensitive detection of vanillin

A "signal off" electrochemical aptasensor based on metal-organic framework (MOF) - based nanocomposites and RecJf exonuclease-assisted target recycling was constructed for ultrasensitive detection of vanillin (VAN). In this work, benefited from the high catalytic activity of the synthesized gold nanoparticle/iron-based MOF/polyetherimide-reduced graphene oxide (AuNPs/NH2-MOF-235(Fe)/PEI-rGO) and the AuNPs/Ce-MOF nanocomposites toward thionine (Thi), the electrochemical signal was amplified. And the target recycling assisted by RecJf exonuclease were triggered with the presence of VAN, which induced the strongly reduced electrochemical signal. On account of dual amplification strategies, the performance of the aptasensor was significantly improved to achieve ultrasensitive detection of VAN. Under optimal conditions, the linear relationship was fitted for VAN with a linear range of 2 pM - 0.2 mM and the detection limit of 1.14 pM (S/N = 3). Furthermore, this assay for VAN has excellent specificity, long-term stability, and satisfactory results of the detection in the real samples. In summary, the aptasensor could be further used for the specific quantitative determination of other targets in foods.