Study On Several Molecular / Ion Imprinted Electrochemical Sensors

Molecularly imprinted electrochemical sensors are a class of electrochemical sensors whose sensing elements are molecular imprinting polymer particles or film. The sensors effectively combine molecular imprinting technique with electrochemical method and provide a new research direction in the field of analytial chemistry. There is increasing interest in molecular imprinting polymers (MIPs) for their specific recognition property, high chemical stability inertness and easy synthesis process. After combining MIPs with electrochemical sensors, the sensors not only have high selectivity of imprinting polymers, but also have advantages of high sensitivity, low cost and rapid response. In this paper, four imprinted electrochemical sensors are prepared by different methods for researches of four analysis objects, such as the resveratrol and tanshinone with medical value, drug methamphetamine, and the harmful Pd(II) ion. And these sensors are also researched in real samples. The main contents include:1. Due to the abilities of multiwalled carbon nanotubes (MWCNTs) to promote electron-transfer and enlarge specific surface area, the recognition sites and improving sensitivity of electrochemical sensors was remarkably improved. In this work, an electrochemical sensor based on MWCNTs and RES-imprinted membrane was constructed for determination of resveratrol (RES). The RES-MIM/MWCNTs/GCE was obtained by in-suit polymerization of RES-imprinted membrane on the surface of MWCNTs modified glassy carbon electrode with RES as a template and acrylamide (AM) as a functional monomer. The surface morphology, structure and properties of the sensor were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), infrared spectroscopy and cyclic voltammetry (CV). And the detection conditions were optimized by differential pulse voltammetry (DPV). Under the optimal conditions, the sensor had high sensitivity and good anti-interference capabilities. And a good linearity was obtained for the determination of RES in the range of 0.006～20.766μmol/L with the detection limit of 0.0032μmol/L. The sensor was employed to determine RES in red wine sample with the recoveries in the range from 97.0% to 103.5% and the RSD below 4.4%.2. A molecularly imprinted electrochemical sensor for tanshinoone (TS) determination was developed via in-suit polymerization of TS-imprinted membrane on the surface of glassy carbon electrode using TSⅡA as template, methyl acrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker under the molar ratio of TSⅡA, MAA and EGDMA as 1:2:40, a mixture of chloroform and acetonitrile (1:4, v/v) as porogenic solvent. The analytical properties of sensor was researched by differential pulse voltammetry (DPV) with K.3Fe(CN)6 as a electrochemical probe. The results showed that the sensor exhibited good selectivity and high stability. A good linearity was obtained in the range of 0.4μmol/L to 220 μmol/L with a detection limit of 0.34μmol/L. The sensor had been used to detect TS in compound danshen dripping pills sample with the relative standard deviation (RSD) of less than 4.9% and the recoveries in the range from 99.3% to 106.7%.3. In order to detect the drug methamphetamine (MA), molecularly imprinted polymers (MIPs) was first fabricated by surface imprinting polymerization using 2-phenethylamine (PEA) which is the analogue of methamphetamine as template, methyl acrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, TiO2 as matrix and methanol as solvent. Then, the molecularly imprinted carbon paste electrode (MIP-CPE) for determination of MA was constructed by thorough mixing MIP and graphite powder in mass ratio of 1:4. The analytical properties of the modified carbon paste electrode were characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), and the result showed the sensor had high stability and good reproducibility. A linear ranging from 0.04μmol/L to 22.58μmol/L for the detection of MA was obtained with a detection limit of 0.037μmol/L. The sensor was also used to test MA in human serum and urine samples with the result of recoveries ranging from 99.6% to 107.5% and the RSD of less than 5.2%.4. In this work, a new Pd(Ⅱ) ion imprinted polymer particles were synthesized by precipition polymerization using ANA as functional monomer. And an ion imprinted carbon paste electrode (IIP-CPE) for was prepared using the polymer as recognition material for the determination of Pd(II). The properties of the sensor was researched by differential pulse voltammetry (DPV) in the 0.2 mol/L HAc-NaAc buffer solution (pH 3.6). The IIP-CPE showed high stability, good reproducibility, easy to update and simple operation. A linear range of the IIP-CPE was 0.028～40.8μmol/L, and the detection limit was detected to be 0.017μmol/L. The IIP-CPE was applied to determine the concentration of Pd(II) in two real samples with the result of recoveries ranging from 97.5% to 102.8% and the RSD of less than 4.8%.