Preparation And Separation Selective Law Research Of Molecularly Imprinted Polymers

Molecular imprinting technology (MIT) was just gradually recognized since 1972. However, the extensive research about it was derived from the report about theophylline MIP published in Nature by Mosbach study group in 1993. Due to the main three features, i.e. predetermination, recongnition and practicability, MIT had aroused numerous research and development interests. With the successful applications of molecularly imprinted polymer (MIP) in many fields, such as the direct extraction of target compounds from complex system, the effective chirality resolution of the enantiomers of organic compound and the high effective solid phase extraction of template, and the direct separation of high added value active ingredient from complex system had become an important direction of the research and development of traditional Chinese medicine.In this work, two kinds of flavonoids Rutin and Quercetin were used as template molecules, ultraviolet and visible spectrophotometer was selected as testing method, maximum absorption wavelength or maximum absorption spectrophotometric was measured, and the proper functional monomers were selected, then the initiator and crosslinker were chose according to the type of functional monomers, and Rutin and Quercetin MIPs were prepared respectively. Thereafter, Rutin MIP was selected as carrier, a part of flavonoids that have the similar molecule structure with Rutin were chose, and Gaussian 03 software was applied to calculate molecular size, volume and dipole moment of template molecule and targat molecules. The relationship between adsorption selectivity law of MIP and the molecule structure factors was investigated preliminary. The research contents and results in details were as follows:1. Rutin MIP was prepared by using acrylamide and acrylic acid as functional monomers, N, N'-methylene-bis-acrylamide as cross-linker, the redox system, H2O2-Vc, as initiator, and the solution polymerization was used. The separation degree of MIP to Rutin from the mixture of Rutin and Isorhamnetin was an objective, and the influences of functional monomers, cross-linker, initiator, polymerization temperature and time on the adsorption selectivity of MIP were investigated. The optimum conditions were: the molar ratios of Rutin, acrylic acid, N, N′-methylenebiacrylamide, hydrogen peroxide to acrylamide were 0.033, 128, 35, 0.074, and hydrogen peroxide to L-ascorbic acid was 10.3, the polymerization time and temperature were 30 h and 45℃, respectively. MIP prepared at optimum conditions presented favorable adsorption of Rutin with a maximal separation degree of 5.0.2. Quercetin MIP was prepared by using acrylamide, acrylic acid and methyl methacrylate as functional monomers, N, N'-methylene-bis-acrylamide as cross-linker, the redox system, H2O2-Vc, as initiator, and the solution polymerization was used. The separation degree of MIP to Quercetin from the mixture of Quercetin and Isorhamnetin was an objective, and the influences of functional monomers, cross-linker, initiator, polymerization temperature and time on the adsorption selectivity of MIP were investigated. The optimum conditions were: the molar ratios of Quercetin, acrylic acid, methyl methacrylate, N, N′-methylenebiacrylamide, hydrogen peroxide to acrylamide were 0.067, 73, 38, 26.8, 0.054, respectively, and hydrogen peroxide to L-ascorbic acid was 16, the polymerization temperature and time were 45 oC and 24 h, respectively. The optimized MIP showed specific recognition of Quercetin from the mixture of Quercetin and Isorhamnetin with a maximal separation degree of 4.00.3. Silymarin, Naringin, Puerarin and Gallic Acid were used as target molecules. The molecular size, volume and dipole moment of the five materials were calculated by Gaussian software which was used by selecting B3LYP as basis set and STO-3G as a method. Thereafter, Rutin MIP was selected to perform adsorption experiments from the respective mixture of Rutin with the above four materials in different concentrations and different temperatures. The separation degree was regarded as index, and the adsorption selectivity of MIP to Rutin from the respective mixture of Rutin and Silymarin, Naringin, Puerarin, Gallic Acid was investigated, and the relationship between the adsorption selectivity of Rutin MIP and molecule structure was investigated preliminary. The results showed that molecule size was the main influence factor of adsorption separation degree for different flavonoids. In the equal mass concentration mixed solution, the specific adsorption of MIP to Rutin was obvious if the molecular size of target molecule was bigger than that of Rutin molecule; if the molecular size of target molecule was smaller than that of Rutin molecule, the separation degree of Rutin MIP to Rutin increased with the decrease of the size difference between target molecule and Rutin; moreover, the influence of molecule volume to separation degree was also obvious, the separation degree decreased with decreasing the molecular volume; the influence of dipole moment to separation degree had no regularity.