Application Of Electrochemical Sensor Based On Molecularly Imprinted Polymer In Detection Of Biological Small Molecule

Molecular imprinting technology (MIT) has become an important method for preparation of artificially synthetic materials which can imitate the specific binding process of biomolecules. With the development of molecular imprinting technology, molecular imprinting sensors based on molecular imprinted polymers (MIPs) are receiving increasing attention. This thesis focuses on the construction of novel MIP sensors on graphene modified glassy carbon electrode by electropolymerization and the developed MIPs electrochemical sensors have been applied for the determination of some kinds of biomolecules. The work mainly includes three parts:(1)The MIP electrochemical sensor of dopamine (DA) was prepared on the surface of r-GO modified glassy carbon electrode (r-GO/GCE) by electropolymerization, wherein DA was used as the template and β-cyclodextrin (β-CD) was used as the monomer. The developed MIP sensor could be applied for the detection of DA with high sensitivity and selectivity. SEM was used to characterize the morphology of the MIP electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to characterize the electrochemical properties of the MIP electrode. Multiple factors including the thickness of imprinted film, template extraction, supporting electrolyte and other factors which have influence on the electrochemical response of DA were optimized in the experiment. Under the optimized experimental conditions, the MIP sensor could be employed for the quantitative determination of DA. The linear response range was 5×10-7 mol/L to 1×10-5 mol/L with a correlation coefficient of 0.996 and the detection limit was 1.03×10-7 mol/L (S/N=3). The MIP sensor was successfully applied for the determination of DA in rat brain tissue and the result was satisfactory.(2) The novel MIP electrochemical sensor was constructed by electrochemical polymerization of β-CD on the r-GO/GCE electrode for rapid and sensitive determination of (-)-epigallocatechin-gallate (EGCG). The fabricated MIP sensor was characterized by SEM, CV and DPV techniques. Under optimal experimental conditions, the MIP sensor exhibited the excellent ability of specific binding of EGCG determined by multiple binding sites and imprinted cavities. The linear response range for EGCG by the sensor was 1×10-8 mol/L～1×10-5 mol/L and the detection limit was 8.78×10-9 mol/L (S/N=3). The developed MIP electrochemical ensor was successfully applied for the determination of EGCG content in the extract of tea with relative standard deviation (RSD) of 3.5%(n=5).(3)The MIP electrochemical sensor was prepared by electropolymerizing β-CD on the r-GO/GCE while D-Methotrexate (D-Mtx) was used as the template molecule. The electrochemical methods including CV, EIS and DPV were utilized to characterize the electrochemical properties and specific recognition ability of the MIP film for D-Mtx. The determination of D-Mtx was conducted by using DPV method, and the linear range was 3×10-8 mol/L～1×10-5 mol/L. The detection limit reached 1.47×10-8 mol/L (S/N=3).Under the optimized conditions, the MIP sensor was employed for the determination of D-Mtx in real samples successfully.