Construction Differential And Ratiometric Molecularly Imprinted Electrochemical Sensors

Molecularly imprinted polymers（MIPs）based electrochemical sensors offer the advantages of high sensitivity,good selectivity and simple frabraction processes,being widely used in various fields.Besides the specific recognition MIPs to template molecules,other substances in the solution are adsorbed on the surface of MIPs via non-specifical adsorption mechanism,resulting in interference in the determination of the target analyte by MIPs based sensors.Hence,the anti-interference ability of MIPs based sensors is needed to improve further.In thesis,the non-specific adsorption signal of MIPs is corrected by a differential strategy,which uses the signal from non-molecularly imprinted polymers（NIPs）electrochemical sensor as a reference.When the specific recognition of MIPs to template molecules is obtained,the selectivity of the MIPs based sensors is much improved.The ratiometric strategy with excellent self-correction ability to the variation in external factors.The combination of differential and ratiometric strategies can enhance further the accuracy and stability of the MIPs based sensors.The main contents are outlined below.1.Ratiomitric and differential MIPs electrochemical sensor for quercetinNickel cobalt sulfide（NiCo₂S₄）was synthesized and used to modify glassy carbon electrode（GCE）.Thionin（THi）was electropolymerized on Ni Co₂S₄/GCE.The MIPs membrane for quercetin（Qu）was electropolymerized on the surface of P_THi/Ni Co₂S₄/GCE by usingβ-cyclodextrin as functional monomer.In the electrochemical determination,the ratiometric sensor is constructed with the current of PTHi as the reference signal.Because the preparation conditions of NIPs and MIPs membranes are similar,the differential response between MIP_Qu/P_Thi/Ni Co₂S₄/GCE and NIP/P_Thi/Ni Co₂S₄/GCE is mainly from the specific recognition of MIPs to Qu,improving the anti-interference ability of MIPs ratiometric electrochemical sensor.The linear range of Qu detection of the prepared method is 0.05～12.5μM,with thelimit of detection（LOD）of 0.013μM.2.MIPs differential electrochemical sensors for simultaneous determination of4-acetaminophenol and sulfadiazine as well as ratiometric detectionBy using pyrrole as monomer,acetaminophenol（AP）or sulfadiazine（SMR）as the templates,MIPs for AP or SMR were prepared by electropolymerization on the surface of Ni₂P/GCE.The imprinting factors of MIP_AP/Ni₂P/GCE and MIP_SMR/Ni₂P/GCE are 6.13 and5.82,respectively,which is not high enough for high selectively determination AP and SMR.To improve the selectivity of the MIPs sensors,we proposed a differential strategy to reduce the non-specific adsorption of MIP_AP/Ni₂P/GCE and MIP_SMR/Ni₂P/GCE.As MIP_AP/Ni₂P/GCE and MIP_SMR/Ni₂P/GCE are prepared under similar conditions,they have very similar non-specific adsorption behavour to various interferents.On the other hand,the current peaks for the determination AP and SMR are well separated.Hence,MIP_SMR/Ni₂P/GCE can be used as the NIPs for AP detection to eliminate the non-specific adsorption of the interferents.Similarly,MIP_Ap/Ni₂P/GCE can be used as the NIPs for SMR detection to eliminate the non-specific adsorption of the interferents.The couple of MIP_AP/Ni₂P/GCE and MIP_SMR/Ni₂P/GCE can be used to determine simultaneously AP and SMR in differential mode.The detection ranges of the sensors are 0.05～20μM,and the LOD of the AP and SMR are 0.011 and 0.019μM,respectively.On the other hand,the MIP_SMR/Ni₂P/GCE can be used as the internal standard in ratiometric and differential MIPs for the determination of AP.