Detection Of Carbendazim Based On Aptamer Functionalized Nanoprobe

The extensive use of pesticides carbendazim in agriculture leads to their accumulation inside the plants,which represents a serious risk to human health.Therefore,it’s significant to detect carbendazim residues for the protection of the public health.Several traditional methods are currently used for the detection of the carbendazim such as chromatographic methods and enzyme-linked immunosorbent assays(ELISA).However,they both have some shortcomings that limit their practical application.Chromatography method is not an appropriate candidate for carbendazim detection because of the high cost and low selectivity,as well as the usage of organic solvents in pre-processing process,which may pollute the environment.Although the ELISA assay has better selectivity,the detection results are easily affected by many reaction conditions.Besides,the high cost of ELISA kit could not meet the demand for low-cost and rapid detection of pesticides.Therefore,it is of great value to develop novel method for pesticides quantification with fast,low cost,high specificity and high sensitivity.Aptamers are single-stranded DNA or RNA that can bind to various target molecules with high affinity and specificity.Through the synergistic effects of hydrogen bonding,electrostatic adsorption and "pseudo base pair" stacking,the aptamer of nucleic acid can achieve high specificity recognition and binding affinity to the target.In recent years,a number of aptamers that can bind to various pesticides have been developed,providing a new idea for the specific detection of pesticides.With the development of nanotechnology,many nanomaterials have been used in pesticide measurements due to their special functions,such as gold nanoparticles,graphene oxide,quantum dots,etc.Aiming at the rapid and sensitive detection of carbendazim,this thesis mainly focuses on development of aptamer-based detection methods for carbendazim by nanoparticle-based technology.The main work as follows:1.Colorimetric Detection of Carbendazim Based on aptamers and gold nanoparticlesBy employing aptamer as recognition element and combining with gold nanoparticles as optic probes,we developed a sensitive and specific determination method for carbendazim detection,and achieved the quantitative analysis in the real sample.Utilizing the specific supramolecular interaction between aptamer absorbed on the gold nanoparticles surface and carbendazim of different concentrations,the electrostatic repulsion between Au NPs was well adjusted,leading to different extent of Au NPs aggregation,by which the carbendazim was conveniently quantified.The results showed that the method has a good linear relationship and the detection limit is 5.2 nmol/L.In addition,the established colorimetric method has also been successfully applied in the detection of carbendazim in soil and orange juice samples.Compared with traditional detection methods,this work has the advantages of simply,rapidity,high sensitivity and good selectivity,and is helpful for the construction and application of aptamer-based analytical methods in environmental monitoring.2.Detection of Carbendazim Based on Fluorescent labeled aptamers and graphene oxideGraphene oxide(GO)is considered as a promising material in biochemical detection field owing to its excellent aqueous processability,surface functionalizability,and fluorescence quenching ability.Herein,we report a simple,quick and cost-effective fluorometric carbendazim detection method by utilizing graphene oxide(GO)as a signal switch.In this strategy,in the absence of carbendazim,the FAM-labeled aptamer could be strongly adsorbed on the surface of GO and its fluorescence was almost entirely quenched.However,as carbendazim exists,it might lead to a much lower quenching efficiency after addition of GO due to FAM-labeled would combine with carbendazim not GO,thus resulting in a much higher fluorescence signal detected.It was confirmed that,after the optimization of detection conditions,carbendazim could be sensitively detected with a detection limit of 3.6 nmol/L and a good linear correlation.In addition,this fluorescence method was further applied to the detection of carbendazim in real samples.The result of which firmly demonstrated its potential application in pesticide detection.