Study On Molecularly Imprinted Polymeric Composite Microspheres With Magnetic Susceptibility

Molecular Imprinting Technique (MIT) is a technique originated from bionic to prepare polymers with recognition specificity to template molecules by manual method. Molecular Imprinting Polymers (MIPs) have exhibited extensive application prospect in separation, purification, immunoassay, enzyme mimic, biomimic sensor, and other fields.In this thesis, the principle of MIT, the preparation methods of molecularly imprinted polymeric microspheres (MIPMs, SMIPs), and the application of MIPs, as well as the specialty and methods of protein template imprinting were expatiated. The preparation methods and the applications of magnetic composite microspheres (MCMs) were reviewed in detail. Amino acid molecules imprinted polymeric composite microspheres with magnetic susceptibility (MS-SMIPs) were prepared by suspension polymerization (SP) and inverse emulsion-suspension polymerization (IESP), respectively. Protein molecules imprinted soft-wet gel composite microspheres with magnetic susceptibility (MS-PIGMs) were prepared by inverse suspension polymerization (ISP) and seeded inverse suspension polymerization (SISP), respectively. The resulting MS-SMIPs and MS-PIGMs were characterized by scanning electron microscope (SEM), thermogravimetric analyzer (TG), vibrating sample magnetometer (VSM), infrared spectrum (FTIR), high performance liquid chromatography (HPLC), and so on.It was showed that SP method was easier than IESP method being used to prepare MS-SMIPs, but SP method didn't suitable for high viscosity monomers to be used to prepare MS-SMIPs. The compatibility of Fe3O4 particles with monomers and polymers was solved through pre-encapsulation of Fe3O4 particles by inverse emulsion in IESP method, the difficulty for SP method to disperse high viscosity monomers to turn into droplets was overcome as well, and precipitation didn't occur easily in aqueous recognition system, for the resulting MS-SMIPs had a large quantity of air cores inside, hence had low density themselves. Theresulting MS-PIGMs by ISP method could adjust their crosslinked network and gel pore size themselves, being helpful to elution and adsorption of proteins. MS-PIGMs prepared by SISP method realized microbead surface imprinting of protein molecules, so the problem of low utilization ratio of template proteins caused by residual of templates in "protein entrapment imprinting" method was solved, while the rate of mass transfer and diffusion of proteins inside MS-PIGMs were improved.The results showed that the resulting MS-SMIPs were all good spheroid form, and had certain magnetic responsibility. Stirring rate, amount of dispersant and Fe3O4, and other factors all could affect the size and morphology of the resulting MS-SMIPs obviously. Tyrosine imprinted MS-SMIPs and tryptophan imprinted MS-SMIPs had higher molecular recognition specificity to their templates, respectively. Phenylalanine imprinted MS-SMIPs had no obviously molecular recognition specificity in contrast. The resulting MS-PIGMs were all spheroid form, and had large quantity of regularly distributed pores, which close in dry condition. Dispersant, initiator, Fe3O4, and other factors could all affect the morphology of the resulting MS-PIGMs. MS-PIGMs all had certain magnetic responsibility, and had higher molecular recognition specificity to their templates. The recognition of MS-PIGMs to their template proteins was due to the synergic action of a large number of hydrogen bonds caused by a very close surface contact between a template protein and the imprinted cavity.