| Chinese traditional herbal medicine is popular in the folk for thousands of years for its less noxious, side-effect in the treatment of various diseases. In recent decades, with the development of the society and improvement of people’s living standards, human’s concept of disease prevention and health care consciousness are gradually improve, Chinese herbal medicine becomes the first choice for health care and treatment. Epimedium belongs to berberidaceae barrenwort, which is one of the Chinese herbal medicine with long history, most potentiality and widely used in china. As the distribution centre of Epimedium, China has abundant Epimedium resources.The main effective components of Herba Epimdii are flavonoids, Icariin is an important one, followed by oxypeucedanin, anhydroicaritin, baohuoside I, etc. Modern pharmacology has demonstrated that icariin has a variety of pharmacological activities, including dispels rheumatism, make up hepatorenal, strong bones, muscles and immunity enhancement etc. However, the extraction of icariin from epimedium with the traditional methods is tedious and a bit inefficient. Based on the above situation, this paper combined with the specificity, high affinity and selectivity of molecular imprinting polymer, The molecular imprinting technology is applied to the extraction and separation of icariin from epimedium. This paper is made up of the following four chapters:The first chapter introduces the epimedium and molecular imprinting technology. Illustrating the introduction of the research, simultaneously gives a brief presentation of the background and purpose of the study.In the second chapter the icariin molecularly imprinted polymers(MIPs) were prepared by precipitation polymerization. Prior to the polymerization, computer simulation was performed to sketchily choose the suitable functional monomer and the corresponding polymerization solvents. The optimized synthesis parameters, including the functional monomer acrylamide(AM), the mixture of methanol and acetonitrile(ACN)(V: V=3:1) as the polymerization solvent, and the reaction molar ratio(1:6:80) of template molecule, functional monomer and cross-linker, were respectively obtained by the single factor analysis and the orthogonal design methods. when the polymerization condition was 10.0 mg icariin, the dosage of the polymerization solvent was 10 m L. The MIPs and non-imprinted polymer(NIPs) which were obtained under the optimal conditions were characterized by Fourier transform infrared spectrum(FTIR) and Scanning electron micrographs(SEM) respectively.In the third chapter the adsorption performance of MIPs and NIPs to template molecules were studied by dynamic, static and selective adsorption experiments. The results indicated that when the MIPs and NIPs were 40 mg, the adsorption solution was 25 m L, the adsorption capacities of MIPs and NIPs increased with the time at the beginning period of experiments and then reached the absorption equilibrium at 10 h and 8 h, respectively, which corresponding values were 609 μg g-1 and 266 μg g-1. On the other hand, under the same conditions, all of the adsorption capacity data of MIPs were obviously much higher than those of NIPs, and this indicated that the special binding sites had been formed in MIPs, which were of the high selectivity and affinity to icariin.The results of static adsorption of MIPs and NIPs illustrated that When the concentrations of icariin in methanol were 0.0140 mg m L-1 and 0.0080 mg m L-1, MIPs and NIPs reached absorption equilibrium, respectively. which corresponding values were 610 μg g-1 and 280 μg g-1. Scatchard analysis were used to investigate the adsorption mechanism of MIPs and NIPs to template. The results showed that the Scatchard plots of MIPs formed a straight line, and the linear equation was y =-380.6430 x + 273.4250(R2=0.9490). On the contrary, the plots of NIPs formed an irregular curve, This indicated that the homogeneous binding sites have been formed in MIPs, which have specific adsorption to icariin. However there were no special binding sites produced in the NIPs. The selective experiments were performed with icariin and its structural analogs bisphenol A and quercetin. Results showed that the adsorption capacity of MIPs for icariin was larger than that for quercetin and bisphenol A, and the separation factor α attained 2.17 and 2.06 respectively. The relative separation factor γ(2.05 and 2.04)indicated that the prepared icariin MIPs had good selectivity and strong separation capacity to the aim icariin molecule. Finally the adsorption behavior of MIPs to template molecules was fitted with adsorption model. The kinetic studies indicated that the Weber and Morris adsorption model could fit the experimental data well. For adsorption thermodynamics, Freundlich adsorption model was suitable to explain the adsorption behavior of icariin MIPsAt last, we made a summery to this experimental research conclusions and prospected the development direction of molecular imprinting technology in the future. |
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