Preparation And Study Of Molecularly Imprinted Electrochemical Sensors Based On Polycyclodextrin

Molecularly imprinted polymers(MIPs)are becoming an important class of synthetic materials which have the ability of molecular recognition like natural receptors.The development of molceularly imprinted polymeric membranes has attracted more and more attention and has broad application prospects in electrochemical sensor.In this paper,combined chiral recognition of β-cyclodextrins(β-CD)and excellent conductivity of graphene(GNS)with molecular imprinting technology,some novel electrochemieal sensors are constructed successfully based on the molecular imprinting polymeric membranes.The main results are as follows:(1)A sensor was fabricated by preparing a molecular imprinted membrane of Bisphenol A(BPA)on a graphene nanosheets(GNS)modified glassy carbon electrode(GCE)with β-CD as a functional monomer.The morphology of the film was characterized by SEM methods.Cyclic voltammetry(CV)and differential pulse voltammetry(DPV)methods were used to characterize the electrochemical behaviors of BPA at the modified electrode.The influence of some factors on the electrochemical response of the senor to BPA was investigated,such as thickness of the film,time of eluting and adsorbing of BPA,pH of the adsorption solution as well as the concentration ratio of the template to the functional monomer.Under the optimized condition a linear relationship between current and the concentration of BPA in samples was found in the range of 7.5×10-8～6.25×10-5 mol/L with a detection limit of 7.39×10-8 mol/L.(2)A sensor was fabricated by preparing a molecular imprinted membrane of L-Tryptophan(L-Trp)on a GNS modified GCE with β-CD as a functional monomer.The morphology of the film was characterized by SEM methods.The electrochemical behavior of L-Trp)on the MIP/GNS/GCE was studied.The influence of some factors on the enantiomeric recognition ability of this molecular imprinted membrane was investigated,such as thickness of the film,time of eluting and adsorbing of Trp,pH of the adsorption solution as well as the concentration ratio of the template to the functional monomer.Under the optimized condition a linear relationship between current and the concentration of L-Trp in samples was found in the range of 5×10-7～2.5×10-5 mol/L with a detection limit of 5×10-8 mol/L,and the ratio of current response of L-Trp to D-Trp of 3.5 showed good enantiomeric recognition ability.(3)A sensor was fabricated by preparing a molecular imprinted membrane of L-tyrosine(L-Tyr)on a GNS modified GCE with β-CD as a functional monomer.On regular electrodes Tyr and Trp cannot be separated,but on the MIP/GNS/GCE by differential pulse voltammetry,oxidation peak potential of Trp and Tyr are 0.63 V and 0.53 V,respectively.This method realizes selective determination to Trp and Tyr.This method could be used to detect Trp and Tyr in samples and the result is satisfactory.