Synthesis And Applications Of Molecularly Imprinted Polymers Using Some Pesticides And Staphylococcus Enterotoxin B As Templates

Food safety has been much concerned for related to human health and quality of life. The most prominent problems for China are the contamination of pesticide, veterinary drug residues and microbiology factors. As a solution to the complex problem, the determination techniques play an important role in regulation the use of pesticide residues. At present, chromatography and immunity methods have been commonly used for an efficient determination of pesticide residue. However, chromatography methods requires expensive equipment, large-scale professional personnel, and the pretreatment of samples, including liquid extraction - liquid extraction and solid-phase extraction, removal of interference of impurities; General drawbacks of immunoassay techniques include the lack of suitable antibodies and their instability, which is difficult to industrial production. Using of biological molecules such as antibodies and enzyme as recognition elements, the biological sensors are limited by the stability and regeneration of biological molecules. So it is necessary to synthesis a kind of materials which can specificly recognize the target molecules with high sensitivity and stability. With the development of science and technology, molecular imprinting has been developed for preparation of the new materials.Molecularly imprinted polymers (MIPs) are polymers prepared in presence of a template that serves as a mould for the formation of template-complementary binding sites. Thus, MIPs can be created to recognize a target molecule with affinity and selectivity comparable to natural receptors and were called as"artificial antibody". And these materials can withstanding much harsher conditions than antibodies, such as high temperature, pressure, extreme pH, and organic solvents. These properties have made them extremely attractive for solving problems in the fields of preparative chemical separations, purification and sensors, or for the removal of specific molecular targets from complex mixtures.In this article, traditional precipitation polymerization was investigated in order to obtaine desired uniform microspheres. Several pesticides such as chlorpyrifos, carbaryl and cabofuran were used as templates to synthesize the molecularly imprinted polymers. Computer simulation technology was employed to investigate the interaction between them and MAA for elucidating the recognition mechanism. Results showed that the ratio between them and MAA was 1∶1, 1∶1, 1∶2. The saturation rebinding experiments and Scatchard analysis were carried out to evaluate rebinding performance. maximum number (Qmax)of binding site of MIPs is 53.91μmol/g for chlorpyrifos and 1.95μmol/g for carbaryl. Used as the recognition elements, the polymer particles were fixed on the surface of the electrode to construct the MIPs-QCM sensor. Atomic force microscopy (AFM) was employed to evaluate the obtained MIPs sensitive film coated on the electrode. The sensor developed exhibits a liner relationship between the frequency shift and carbaryl concentration in the range of 10ng/mL up to 1000ng/mL (y= 0.139 x + 2.99), and the detection limit was 12.5 ng/mL.The staphylococcus enterotoxin B (SEB) is one major cause of symptoms of food poisoning in humans. So the SEB-imprinted polyacrylamide gel beads were synthesized using suspension polymerization. Adsorption dynamic and isotherms were investigated by equilibrium adsorption experiment, and the maximum adsorption capacity of 3.86mg SEB/g imprinted beads. The problem is that the material has poor mechanical strength. In order to overcome the issue, the SEB-imprinted beads were prepared using microsphere surface-imprinting method. Two kinds of organic silane (APTMS and OTMS) were polymerized on a surface of polystyrene microspheres after the SEB template was covalently immobilized by forming imine bonds. The resulting imprinted beads were selective for SEB. The Langmuir adsorption models were applied to describe the equilibrium isotherms. The results showed that an equal class of adsorption was formed in the MIP with the maximum adsorption capacity of 3.86mg SEB/g imprinted beads. The MIP has much higher adsorption capacity for SEB than the non-imprinted polymer, and the MIP beads have a higher selectivity for the template molecule.