Study On Electrochemical Immunosensor Based On Microelectrode For Chlorpyrifos Residues Detection

Compared with conventional methods, electrochemical immunosensors have manyadvantages, such as low cost, high sensitivity, and rapid detection, and has certain prospects forrealizing real-time monitoring. In this paper, the different sensors and interface modificationmethods for the detection of chlorpyrifos were studied in order to choose best methods for theconstructionof electrochemical immunosensor.Theresearcheswereas follows:(1) An amperometric immunosensor based on nanocomposite film for chlorpyrifosdetectionA novel immunosensor was proposed for chlorpyrifos residues, which employedglutaraldehyde (GA) as crosslinking agent to combine multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film and immobilize covalently theanti-chlorpyrifos antibody onto the surface layer of modified electrode. The modified sensorwas simple and convenient, it was detectable in the range of0.1-1.0×105ng/mL with thedetection limit of0.046ng/mL.(2) An amperometric immunosensor based on Protein A and graphene-multi-walledcarbon nanotubes-gold nanoparticle-chitosan compositefilm forchlorpyrifos detectionA kind of biosensor for chlorpyrifos detection was designed. The graphene-multi-walledcarbon nanotubes-gold nanoparticles-chitosan (GR-MWCNTs-AuNPs-CHIT) nanocompositefilm were obtained to speed up the electron transport in the liquid. ProteinAcould be combinedwith gold nanoparticles and then fixed on the electrode, which made anti-chlorpyrifos antibodyimmobilized orientedly. This method can get better performances including quickly detectingthe target concentration of high sensitivity. The method got a lower detection limit,guaranteeingtheactivity of proteins.and theprocessof preparation is nontoxic,(3) An electrochemical immunosensor for chlorpyrifos detection by using interdigitatedarray microelectrodeAn interdigitated array microelectrodes (IDAMs)-electrochemical immunosensor wasdeveloped with the signal amplification, and improvement of the sensitivity. Anti-chlorpyrifosmonoclonal antibodies were orientedly immobilized onto the microelectrode surface throughcovalent bonds to improve the effective fixed amount. The morphology changes in thepreparation were explained by atomic force microscope. Electrochemical impedance spectroscopy was choosed to characterize the fabricating of immunosensor. The immunosensorshowedthegood specificity, sensitivity and it was suitablefor the detection of chlorpyrifos.(4) An electrochemical immunosensor for chlorpyrifos detection by using microfluidicchipBased on the prominent advantages including large specific surface area and nanoscalemicrochannel, the microfluidic device could be utilized to measure the chlorpyrifos throughemploying the protein A, which can combine antibody directly with increasing amount ofchlorpyrifos antibodies. With the parameter optimized, results were obtained:10μL/min asflow velocity,100mV as the voltage,10min as pumping liquid time. The equivalent circuitwas established to analysis the test result in order to verify its validity. In addition, it had theability of improving the sensitivity and stability by using the microelectrode, thus, it played atechnicalsupportting to therapid detection ofpesticides.