The Construction Of Electrochemical Sensor Based On Molecular Imprinted Polymer Modified Graphene Nanocomposites And Its Application

Molecularly imprinted electrochemical sensor combined the molecularly imprinted polymer for the target identification and electrochemical sensing technology for the advantages of high sensitivity,good selectivity,simple equipment.Molecularly imprinted film was synthesized on a special carrier surface,which can greatly increase the exposed surface imprinting sites,speed up the recognition site and the target molecules between mass transfer effect,avoid the shortcoming of molecularly imprinted recognition sites embedded by the traditional method.It has increasingly attracted the attention of the researchers.Based on the advantage of electrochemical sensor and the surface molecular imprinting,this work utilized different functional graphene modified electrodes as carrier,o-phenylendiamine(o-PD)as functional monomer.Through the control of polymerization conditions,the molecularly imprinted film modified were prepared on the modified electrode surface.The sensor realized the molecularly imprinted polymer and electrochemical sensor integration;The target recognition and sensing properties of the sensor were discussed;This paper discussed the application of sensor in the actual samples.The results obtained for the new molecularly imprinted electrochemical sensors provided methodology reference and basis.Specific contents are described as follows:1.Molecularly imprinted electrochemical sensor for daidzein recognition based on poly(sodium 4-styrenesulfonate)functionalized grapheneThe PSS-GR was prepared through the non-covalent interaction between PSS and graphene oxide with hydrazine hydrate as reductant.The UV-vis,IR,SEM and TEM were used to character the PSS-GR.The PSS-GR/GCE was prepared by drop-coating PSS-GR onto the surface of glassy carbon electrode.The negatively charged poly(sodium 4-styrenesulfonate)units and benzene rings of PSS-GR can attract positive charged o-PD and provide ?-? stacking effect of o-PD and daidzein,which makes the compact imprinted film and more imprinted sites.The ratio of the functional monomer and the template,the cycles of electropolymerization,therebinding time were discussed.The target recognition performance and mass transfer process of daidzein were researched in the presence of [Fe(CN)6]3-/[Fe(CN)6]4-as a probe for signal transduction.The results showed that the sensor can completely combine daidzein on the surface of the electrode in 11 minutes to saturation;Immersing in 0.1 mol/L NaOH solution for 15 min can completely remove the target molecules.Compared with the similar structure analogues(puerarin and quercetin,genistein,chrysin),the calculated imprinted ratio of daidzein was 5.25(MIP/NIP).Under the optimized conditions,the decrease of the peak current was linear with the concentration of daidzein in the range of 1×10-9~2×10-8 mol/L.The detection limit was calculated as 8×10-10 mol/L(S/N=3).That showed faster mass transfer process and better recognition.The modified electrode was successfully applied to determine daidzein in human serum sample and pueraria with satisfied recovery.2.Molecularly imprinted electrochemical sensor for 2,4-dichlorophenol detection based on poly(sodium 4-styrenesulfonate)functionalized graphene.Based on the last chapter,according to the non-covalent interaction between PSS-GR and 2,4-DCP,the molecularly imprinted film was prepared with o-PD as functional monomer and 2,4-DCP as template by electropolymerization using cyclic voltammetry.The ratio of the functional monomer and the template,the cycles of electropolymerization,the rebinding time were discussed.The target recognition performance and mass transfer process of 2,4-DCP were researched in the presence of[Fe(CN)6]3-/[Fe(CN)6]4-as a probe for signal transduction.The results showed that the sensor can complete combine 2,4-DCP on the surface of the electrode in 14 minutes to saturation;Immersing in 0.1 mol/L NaOH solution for 10 min can complete remove the target molecules.Compared with other analogues(2-chlorophenol,2,4,6-trichlorophenol,pentachlorophenol,ortho-aminophenol and pyrocatechol),the calculated imprinted ration of 2,4-DCP was 7.83.The relative current intensity of ferro/ferricyanide decreased linearly with increasing concentration of 2,4-DCP in the range of 5×10-9~8×10-8 mol/L with a detection limit of 1×10-9 mol/L(S/N=3).Finally,the modified electrode was successfully applied to determine 2,4-DCP in water sample(the lake,tap water,rain).3.Molecularly imprinted electrochemical sensor for 2,4-dichlorophenol recognitionbased on polydopamine functionalized reduced oxide grapheneThe PDA-rGO was obtained from the reduction of graphene oxide by one-step oxidative polymerization of dopamine.The UV-vis,IR,XRD,SEM and TEM were used to character the PDA-rGO.The PDA-rGO/GCE was prepared by drop-coating PDA-rGO onto the surface of glassy carbon electrode.The MIP film was prepared by electropolymerization of o-phenylenediamine(o-PD)as monomer with template2,4-dichlorophenol(2,4-DCP)by hydrogen bond.The target recognition performance and mass transfer process of 2,4-DCP were researched in the presence of[Fe(CN)6]3-/[Fe(CN)6]4-as a probe for signal transduction.The results showed that the sensor can completely combine 2,4-DCP on the surface of the electrode in 6 minutes to saturation;Immersing in 0.1 mol/L ethanol solution for 8 min can completely remove the target molecules.Compared with other analogues,the MIP sensor had a high affinity of 2,4-DCP about 3.67?4.02?4.63?5.77 and 25 times than them and calculated imprinted ration of 2,4-DCP was 15.5.Finally,the modified electrode was successfully applied to determine 2,4-DCP in water sample.