Research Of Several Electrochemical Imprinting Sensors

Modified electrode, short for chemically modified electrode, refers to the electrode whose surface has been chemically treated. In general, molecules, ions, polymers and nano-materials with special chemical properties are used to modify the electrode’s surface. After modification, the electrode will have special functions. For example, there will be great improvement in its selectivity, sensibility, stability and repeatability. Molecularly imprinted technology (MIT), also named template technology, belongs to the subject and object category of supermolecular chemistry, which stems from the simulations of antibody and antigen. In terms of its manufacturing process, it belongs to polymer chemistry. With specific target molecule (imprinted molecule or template molecule) as template, MIT can produce polymer with peculiar selectivity to the specific molecular. With MIT being applied to chemical modify electrode, sensors can be designed to identity specific molecular or ion. The reaearch constitutes the sensors of podophyllotoxin, Palladium (II) and Iridium(IV) based on the merits of Modified electrode and imprinted technology.1. This dissertation achieves the detection of substances without electrical activity through an experiment which takes podophyllotoxin, a kind of substance without electrical activity, as template, and potassium ferricyanide as probe. By discussing the preparation and application of podophyllotoxin imprinted sensor and podophyllotoxin’s electrochemical activity on the imprinted electrode, the experiment shows that the sensor has high selectivity and sensitivity to podophyllotoxin and can be used to detect real samples. Based on the experiment, this dissertation establishes a new electrochemical method, with a linear range of2.41x10-7to3.13x10-6mol/L, a limit of detecton (LOD) of2.29x10-7mol/L and a recovery between96.2%and98.8%, to detect neutral substances.2. In order to prepare palladium ion’s imprinted sensor, imprinted membrane was electropolymerized on the surface of gold nanoparticles electrically deposited on gold electrode under the potential of0.1to1.0V.In this experiment, gold nanoparticles has increased the electrode’s surface and improved its sensibility. Imprinted membrane has improved the selectivity of the electrode. This dissertation also studies the property and structure of the prepared nano-imprinted membrane. With potassium ferricyanide working as an indicator, this thesis establishes electrochemical analytical method to indirectly determine palladium ion. This method has excellent selectivity and sensitivity to palladium (II) ion. It can build up good linear relations while the concentration of palladium ion ranges from9.42x10-8to1.33x10-5mol/L. This method with a limit of detection of3.59x10-8mol/L and recovery of96.8%to100%, can be used for sample detection.3. In the research, MWCNTs-CH=CH2was taken as matrix, IrCI62-as template, ANA as functional monomer, EGDMA as cross linking agent, AIBN as initiator, N,N-DMF as porogen, to prepare MWCNTs-IIP. In addition, the synthesized MWCNTs-IIP was dispersed to p-aminobenzene sulfonic acid solution through ultrasonication by adding1-octyl-3-methylimidazolium hexafluorophosphate in the solution as conducting medium. Then the MWCNTs-MIP was modified on the surface of gold electrode through cycle voltammetry, to make an electrochemical sensor that could detect Ir(IV) on the condition of-1.5to2.5V. This sensor has a linearity range of2.60x10-7mol/L to7.01x10-5mol/L, a LOD of2.86x10-8mol/L and a recovery rate between94.7%and100%.Through a series of experiments, this dissertation argues that MIT and nanomaterials can help to improve the sensors’selectivity and sensitivity.