Preparation And Applications Of Electro-polymerization Molecularly Imprinted Electrochemical Sensor

Molecularly imprinted polymers (MIPs) have a lot of advantages, such as selective recognition, good stability, resistance to acid base environment, and can be recycled, and so on. In theory, MIPs of almost every molecular can be synthesized. The use of biosensor has difficulties in preservation, proper conditions and limited object, and MIPs sensor overcomes the aforementioned drawbacks, so it becomes one of the research hotspots in electrochemical sensor. Comparing with other preparation techniques, the advantage of electro-polymerization is that the thickness and the density of the polymer layer can be monitored and regulated easily.In this paper, with the electro-polymerization, we preprared molecularly imprinted polymers modified electrode. The imprinted sensors showed high recognition ability, and were successfully applied to the determination in real samples.The main contents of this thesis are summarized there steps:(1) Using [Fe(CN)6]3as an electrochemically active probe, fabrication of molecularly imprinted poly-o-phenylenediamine film on a columnar-structured platinum electrode applied to the determination ofβ-agonistFabrication of molecularly imprinted poly-o-phenylenediamine film on a columnar-structured platinum electrode applied to the determination ofβ-agonist. Surfactant sodium dodecyl sulfonate, which was used in the electro-polymerization reaction of o-PD, prevented the hydrolysis degradation of poly-o-phenylenediamine (PoPD) and enhanced the stability of the PoPD film in the anionic micellar media. Besides, surfactant enhanced the conductivity of the PoPD film, making electrochemical response signal of active probe more sensitive. The sensor surface morphology was characterized by scanning electron microscopy. The preparing process of sensor was characterized by eleetrochemical quartz crystal microbalance. The electrochemical performance of the sensor was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. Under the optimal experimental conditions, with [Fe(CN)6]3-/4-electrochemical probe, applied to the determination of β-agonists, good linear relationship and a detection limit of1.68×10-9M were obtained. The imprinted electrode exhibited excellent selectivity, short response time and good stability and reproducibility for the determination of the imprinted molecules. The proposed sensor was successfully applied to detect β-agonists in real human serum samples.(2) Using [Fe(CN)6]3-/4-as an electrochemically active probe, fabrication of Ni2+-sol-gel molecularly imprinted modified electrode was prepared to the determination of ractopamineA Ni2+-sol-gel molecularly imprinted modified electrode was fabricated on columnar-structured platinum electrodes via taking ractopamine as template,3-methypropyl trimethoxy silane as functional monomer. The characterization of molecularly imprinted modified electrode was investigated via electrochemical methods. Under the optimal experimental conditions, with [Fe(CN)6]3-/4-electrochemical probe, applied to the determination of ractopamine,good linear relationship and a low detection limit of1.68×10-9M were obtained. Salbutamol, clenbuterol, terbutaline didn’t interrupt the determination of ractopamine. The imprinted electrode exhibited excellent selectivity, short response time.(3)Using [Fe(CN)6]3-/4-as an electrochemically active probe, fabrication of Fe3+-sol-gel molecularly imprinted modified electrode was prepared to the determination of T-2Fabrication of Fe+-sol-gel molecularly imprinted modified electrode was prepared to the determination of T-2. In this study, iron ions (Fe3+) were introduced to increase the chelation of the metal ions and templates for preparing molecularly imprinted polymers (MIPs). With the increased chelation of the metal ions and templates, the selectivity and sensitivity of the MIPs were effectively improved. To obtain the optimal conditions, experimental parameters such as the dosage of Fe3+, polymerization segments, elution time and incubation time were optimized. The performance of the imprinted film was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Under the optimal experimental conditions, electrochemical response of the imprinted sensor and T-2 concentration was obtained good linear relationship rangeing from1.12×10-9～2.12×10-6M with a detection limit of3.39×10-9M. Ochratoxin A, salbutamol, ractopamine and ascorbic acid, didn’t interrupt the determination of T-2. The imprinted electrode exhibited excellent selectivity, short response time and good stability and reproducibility.