Design Of Nanochannel Gated Electrochemiluminescence Sensor Chip And Its Applications In Mycotoxins Detection

Mycotoxins are common secondary metabolites of various fungi and widely present in various food products and feeds.Contaminated food poses a serious health threat to humans and animals.Therefore,the development of a fast,sensitive,low-cost,portable sensor chip is of great significance for the detection of mycotoxins.Based on the classic luminol-H₂O₂electrochemiluminescence（ECL）system,this thesis uses a variety of nano-materials to enhance the ECL signal,and combines the switchable gating characteristics of Au-AAO membrane nanochannel to construct novel ECL sensors,which have been successfully applied to the sensitive detection of fungal toxins,such as T-2 toxin,vomitoxin（DON）and ochratoxin A（OTA）.The specific work content is as follows:1.In this work,a reusable ECL sensor based on nanochannel gating has been successfully developed and applied to the rapid detection of T-2 toxin.Firstly,luminol/Au NPs were prepared using the good catalytic activity of Au NPs as ECL luminescence materials,combined with the aptamer-modified Au-AAO film as the sensing interface,placed between two chambers filled with different solutions as a switchable gating.When the target is present,the specific binding of the toxin to the aptamer can change the actual pore size of the Au-AAO membrane,thereby affecting the ECL signal of the luminescent material.The sensor has the advantages of high sensitivity,selectivity,low cost,and reusability.It has a good linear relationship in the toxin concentration range of 10 pg·m L^-1to 100μg·m L^-1,and the detection limit is 3.14 pg·m L^-1.It has been successfully applied to the detection of beer samples.2.This work has developed an ECL sensor chip based on Au-AAO membrane and bipolar electrode dual signal suppression,which has been successfully applied to the rapid detection of DON toxins.By using laser etching technology to process the required bipolar electrode structure on the ITO substrate and combining it with a 3D-printed microreactor,the sensing chip was prepared by simultaneously modifying the adapter molecule on the surface of the Au-AAO membrane and the cathode area of the bipolar electrode.The presence of toxin molecules can be detected through the combination of two approaches:regulating the nanopore switch status of the Au-AAO membrane to facilitate the flow of quencher AA and increasing the space resistance in the cathode area of the bipolar electrode,both of which inhibit the decrease of ECL signal output in the anode signal output area.The sensor chip has a good linear relationship with ECL intensity in the range of toxin concentration from 5pg·m L^-1to 10μg·m L^-1,and the detection limit was 1.67 pg·m L^-1,which could achieve specific and sensitive detection of toxins.3.This work has successfully developed an ECL sensor chip based on Au-AAO membrane and bipolar electrode dual signal enhancement,which has been applied to the detection of OTA toxins.The sensing chip was prepared using laser etching technology and3D printing technology.The adapter molecule was covalently modified on the surface of the Au-AAO membrane,and oxidized graphene was modified and adsorbed with the adapter molecule in the cathode area of the bipolar electrode.The binding between the target toxin and the adapter molecule will open the nanochannel,causing the coreactant to flow in.At the same time,the binding between the adapter molecule and the cathode area will cause it to detach from the electrode surface,reducing the electrode impedance.Through these two appraoches,the ECL signal is simultaneously enhanced.The sensor chip has a good linear relationship with the ECL intensity in the range of toxin concentration from 1 pg·m L^-1to 500ng·m L^-1,and the detection limit was 0.34 pg·m L^-1,which could achieve sensitive detection of toxins.