Preparation Of Electrochemical Sensor For Bisphenol A And Tolazoline Based On Molecular Imprinting Technique And Electropolymerization Film

Molecularly imprinted polymer(MIP) is a new kind of macromolecular material with high molecular recognition characteristic. Furthermore, synthetic MIPs are highly stable and able to bear high temperature, acid or alkaline condition, and organic solution. The MIPs made in traditional ways, however, are usually thick and recognition sites are buried deep inside the particles, which introduce difficulties for electrochemical sensing application, such as bad reversibility and reproducibility, long analysis time intervals and low sensitivity, etc. To overcome some of the difficulties associated with traditional MIPs matrices, electrochemical sensors for the detection of bisphenol A and tolazoline are constructed successfully in the thesis by coupling self-assembly, electropolymerization with molecular imprinting technology.The details are as follows:1. Electrochemical Sensor for Bisphenol A Based on Molecular Imprinting Technique and Electropolymerization MembraneBy using the approach of self-assembly and electropolymerization, molecularly imprinted polymer membrane for Bisphenol A has been synthesized with Bisphenol A as template molecule,o-Aminothiophenol as functional monomer. Based on which, an electrochemical sensor was constructed and its response to BPA was evaluated by cyclic voltammetry. The peak current intensity was linear to Bisphenol A in the range from 6.0×10-7 to 5.5×10-5 mol·L-1 with a detection limit of 2.0×10-7 mol/Land the RSD< 5%(n=9). The response time of stable current was about 2 min. The proposed sensor also exhibited good selectivity, reproducibility and stability. The AC impedance technology and chronoamperometry were employed to study the electrochemical Characteristic of the membrane. The sensor was successfully applied to the determination of BPA in several sample.2. Preparation and Characterization of Tolazoline Sensor Based on Molecularly Imprinted PolymerA novel electrochemical sensor for the detection of tolazoline based on molecularly imprinted polymer of electropolymerized o-aminothiophenol onto gold electrode was constructed. Its response to tolazoline was evaluated by differential pulse voltammmograms(DPV). Under the optimized conditions, the response current of the proposed sensor decreased linearly in two concentration ranges of tolazoline from 0.4 to 5μg-mL-1 (r=0.9986) and from 5 to 120μg·mL-1(r=0.9953) with a detection limit of 0.18μg·mL-1. The RSD was about 2.47%and the response time was closed to 3 min. Moreover, the studied imprinted sensor exhibited high selectivity and long-term stability. The sensor was successfully applied to the determination of tolazoline in human urine samples.3. Electrochemical Tolazoline Sensor Based on Gold Nanoparticles and Imprinted Poly-o-aminothiophenol FilmAmperometric detection of tolazoline (TL) was carried out on a gold nanoparticles (AuNPs)/poly-o-aminothiophenol (PoAT)-modified electrode by a molecular imprinting technique and electropolymerization method. The modification procedure was characterized via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The recognition between the imprinted sensor and target molecule was observed by measuring the variation of amperometric response of the oxidation-reduction probe, K3Fe(CN)6 on electrode. Under the optimal experimental conditions, the peak currents were proportional to the concentrations of tolazoline in two ranges of 0.05 to 5.0μg·mL-1 and 5.0 to 240,μg·mL-1 with the detection limit of 0.016μg·mL-1. Meanwhile the prepared sensor showed sensitive and selective binding sites for tolazoline. The enhancement of sensitivity was attributed to the presence of AuNPs which decreased the electron-transfer impedance.