Construction And Electrochemical Research Of Electrochemical Sensor Based On Three-dimensional Ordered Nano-TiO₂-molecularly Imprinted Polymer

Molecular imprinted polymers(MIPs)are functional polymers with specific recognition and binding ability toward target molecules(template molecules or imprinted molecules).Nanomaterials have been widely used in electrochemical sensors due to their excellent loading capacity,biocompatibility and electrocatalytic performance.By combining nanomaterials with molecularly imprinted polymers,the sensitivity and selectivity of electrochemical sensors would be significantly enhanced due to the synergistic effect,and it would greatly improve the analytical performance of sensors.In this thesis,three novel molecularly imprinted electrochemical sensors based on the three-dimensional ordered porous nanomaterials and molecularly imprinted polymers were constructed for the electrochemical studies and detection of drug molecules.The main research results are as follows:(1)The three-dimensionally ordered macroporous nano-titanium dioxide(3DOM)modified electrode was fabricated on the indium-tin oxide(ITO)electrode surface by the template method,and applied for the detection of a food additive vanillin(VA).The morphology and electrochemical properties of the modified electrode were characterized by transmission electron microscope(TEM),scanning electron microscope(SEM),cyclic voltammograms(CV)and differential pulse voltammetry(DPV).Under the optimal conditions,the oxidation peak current of VA was found to be linearly proportional to the concentration of VA in the range from 4.0×10-8?4.0×10-5 mol/L with a low detection limit of 3.9×10-8 mol/L(S/N=3).In addition,the modified electrode was successfully used for the quantitative determination of VA in food samples.(2)A molecularly imprinted electrochemical sensor was prepared by electro-polymerization on the 3DOM/ITO electrode for the detection of homovanillic acid(HVA).The morphology and electrochemical properties of the modified electrode were characterized by SEM,Fourier transform infrared spectroscopy(FT-IR),CV,DPV and electrochemical impedance spectroscopy(EIS).Some experimental parameters such as the pH of supporting electrolyte,scanning cycles of the electro-polymerization,elution conditions of the template and incubation time,were optimized to improve the sensor performances.Under optimal conditions,the oxidation peak current of HVA was linearly related to its concentration in the range from 5.0×10-6 mol/L?7.0×10-5 mol/L with a detection limit of 5.9×10-8 mol/L(S/N=3).The imprinted electrode can be used for the determination of HVA in the urine samples with good sensitivity and anti-interference ability.(3)The metoprolol(MT)-imprinted and s-atenolol(s-ATNL)-imprinted modified electrodes were prpared by electro-polymerization,wherein MT and s-ATNL served as the template molecules,respectively,and ?-cyclodextrin(p-CD)as the functional monomer.The morphology and electrochemical properties of the modified electrodes were characterized by SEM,FT-IR,CV,DPV and EIS methods.The effects of experimental conditions such as pH of the supporting electrolyte,numbers of polymerization cycles,elution conditions of the template molecules and incubation time were discussed.Under the optimal condition,the oxidation peak currents of MT and s-ATNL were linearly dependent to the concentrations of MT and s-ATNL in the range from 5.0×10-8?2.5×10-5mol L-1 for MT and 5.0×10-8?3.5?10-5 mol L-1 for s-ATNL,with the detection limit of 1.1×10-8 mol/L(S/N=3)for MT and 4.5×10-8 mol/L(S/N=3)for s-ATNL.The imprinted modified electrodes have been successfully applied for the determinations of MT and s-ATNL in practical samples with high sensitivity and selectivity.