The Development And Preliminary Application Of Methyl Jasmonate Electrochemical Sensors

Methyl jasmonate?Me JA?is an endogenous plant hormone that plays an important role in seed germination,root growth,flowering and fruiting,shedding and senescence,and in responding to biotic and abiotic stresses.Quantitative detection of Me JA helps to study the physiological processes and transduction pathways of Me JA,which has great practical application value in regulating agricultural production and increasing food yield etc.Because of the small amount of Me JA in plants and Me JA is easily affected by external natural conditions and interfered from internal secondary metabolites,a sensitive and specific detection method for Me JA is needed.Compared with other methods of detecting plant hormones such as capillary electrophoresis,chromatography,and mass spectrometry,electrochemical sensor method is widely concerned by people because of its advantages such as low cost,high sensitivity,good selectivity,fast response speed,simple operation?without complicated purification process?and portable?can be used in the field?etc.In this paper,two new label-free electrochemical immunosensors are prepared and used in detection of Me JA content in actual samples by introducing highly conductive carbon nanomaterials on disposable screen-printed electrodes?SPE?to amplify detection signals and immobilize antibodies.The research results are as follows:1.Construction of a new label-free electrochemical immunosensor for methyl jasmonate based on a copper-based metal organic framework functionalized graphene platformThe copper-based metal organic framework?Cu-MOFs?material was synthesized by solvothermal method.The Cu²⁺signal of Cu-MOFs as a redox probe was amplified by carboxylated graphene?GR?,and the antibody is covalently linked to the carboxyl group of graphene through the EDC/NHS coupling agent,which is the first to construct an electrochemical immunosensor for detecting Me JA.Because Cu-MOFs with high porosity and large specific surface area and GR with high conductivity and good biocompatibility produce a good synergistic effect,the sensor has obtained better analytical performance than existing methods for detecting Me JA.The results show that the immunosensor has a wide detection range:1 p M-100?M,and the limit of detection?LOD?is 0.35 p M?S/N=3?.The sensor also has good selectivity,stability and reproducibility.The standard addition method was used to detect the endogenous Me JA content of grape fruit samples in vitro through liquid phase extraction,and a satisfactory recovery rate was obtained,proving that the sensor has the potential for practical application.2.A new label-free electrochemical immunosensor modified based on carboxylated graphene-multi-walled carbon nanotube nanocomposites for the detection of methyl jasmonateCombine one-dimensional carboxylated multi-walled carbon nanotubes?MWNT?with two-dimensional carboxylated graphene?GR?to form a three-dimensional GR-MWNT nanocomposite.The stable and low-toxic ferrocene?Fc?was used as an electronic mediator and is introduced into the GR-MWNT composite material through electrostatic force.The addition of Nafion not only fixes the modified material on the surface of the SPE electrode,but also improves the stability and biocompatibility of the electrode.The GR-MWNT composite material carries a large number of carboxyl groups to provide the active sites for covalent connection with the amino group of the antibody.With the increase of Me JA concentration,the oxidation peak current of Fc gradually decreases.Under the best experimental conditions,the results show that the immunosensor has better performance than the first developed immunosensor.The detection range is 100 f M-100?M,the LOD is as low as 31.26 f M?S/N=3?,and the sensitivity,selectivity,stability and repeatability are excellent.The sensor has been successfully applied to the determination of Me JA in grape and orange fruit samples,and its detection accuracy is shown by calculating the recovery rate.The constructed electrochemical immunosensor is simple,efficient and reliable,and has broad application prospects.