Preparation And Application Of Aptamer Electrochemical Sensor Based On Metals Loaded Carbon Nanotubes

Since the discovery of carbon nanotubes ?CNTs?, they have become a hot toptic, owing to their excellent properties, such as mechanical and electrochemical property. Compared with other general materials, carbon nanotubes show higher electrochemical activity and have larger specific surface area. In addition, metal nanoparticles also have been applied widespreadly due to their small volume, large surface and high electrocatalytic activity. Metal nanoparticles supported by carbon nanotubes have been widely used in electrochemical sensors, catalytic material and other fields owing to the combination of the superiority of the carbon nanotubes and metal nanoparticles. In this report, we modified the glassy carbon electrode with carbon nanotubes supported metal nanoparticles, and then assembled the electrode with thrombin aptamers to prepare aptamer sensors. The sensors were applied for the detection of thrombin. The prepared aptasensors show the superiority of good selectivity, high stability, wide linear range, etc. This thesis mainly includes the following four parts.The first chapter primarily introduces the overview, the properties and the preparation methods of the carbon nanotubes. The preparation and the application of the metal particles loaded carbon nanotubes are included. Then it presents the introduction, superiority of aptamer, interaction principle between aptamer and thrombin. Besides, the introduction and classification of the aptasensor, the immobilization methods of the aptamer on electrode and the application of metal nanoparticles loaded carbon nanotubes in aptasensors are totally discussed.In the second chapter, a new modified electrode electrochemical sensor was prepared by combining the quaternary amine functionalized multiwall carbon nanotubes ?Q-CNTs? and the carboxylated multiwalled carbon nanotubes loaded with Pd and Ni nanoparticles ?PdNi@CNTs?. The sensor was applied for the detection of H₂O₂ with high electrocatalytic activity, good stability and perfect repeatability.In the third chapter, a new thrombin aptasensor was developed by using methylene blue ?MB? as electrochemical indicator and the composite Q-CNTs/PdNi@CNTs as signal amplification material. A thrombin aptamer complementary DNA ?capture DNA? was immobilized on the surface of modified electrode through electrostatic interaction and then hybridized with thrombin aptamer, and the aptasensor was obtained. The aptasensor was easy to prepare and handle, and had a wide concentration range, low detection limit and high selectivity for the detection of thrombin.In the fourth chapter, we prepared a new thrombin aptasensor based on the carbon nanotbues loaded with Pd nanoparticles ?Pd@CNTs?. The thiolated thrombin aptamer was immobilized on the surface of the modified electrode and formed double-strands of DNA according to base-pairing rules. MB was used as electrochemical indicator due to its special interaction with DNA The sensor was characterized by cyclic voltammetry, ultraviolet spectroscopy, differential pulse voltammetry, etc. The aptasensor improved the detection sensitivity and had a promising application.