Hierarchically porous Zr-MOFs labelled methylene blue as signal tags for electrochemical patulin aptasensor based on ZnO nano flower

Abstract

In this work, the feasibility of a novel sensitive electrochemistry aptasensor for the detection of patulin (PAT) using hierarchically porous metal organic framework@methylene blue connection aptamer as signal tags was demonstrated. The substrate electrode of the aptasensor was prepared by electrodeposited gold nanoparticles (AuNPs) on chitosan-zinc oxide nano flower-modified electrode. Subsequently, the complementary single-stranded DNA was attached to the surface of the modified electrode by Au-S bond. Signal tags self-assemble on the surface of modified electrodes by aptamer-cDNA binding, while methylene blue as mediator for electrochemical detection. Thanks to the large specific surface area provided by zinc oxide nano flower, the electrode can load more signal tags and AuNPs to achieve signal amplification. In presence of PAT, Apt preferentially binds to PAT, causing dissociation of some Apt-cDNA and releasing some signal tags leading, resulting in decreased electrical signals. Under optimal conditions, the change in electrochemical signal was proportional to the logarithm of PAT concentration, from 5 × 10−8-5 × 10-1 μg mL−1, and the detection limit was estimated to be 1.46 × 10-8 μg mL-1. The aptasensor exhibited aceptable reproducibility, renewability, long-term stability and specificity. Moreover, aptasensor was reliable in determination of PAT in spiked apple juice samples.