Synthesis, Recognition Characteristics And Properties Of L-3-N-Butylphthalide Molecularly Imprinted Polymers Through Precipitation Polymerization

Molecular imprinting technology can make functional monomers and template molecules initiate to be highly cross-linked polymers in the presence of cross-linking agents and initiators. The obtained polymers after removing the template molecules by chemical or solvent extraction can be molecularly imprinted polymers(MIPs) with certain hole structures and recognition sites. Molecularly imprinted polymers have predetermined recognition ability and specific recognition property for template molecules and also have advantages like simple operation, stable structure, recyclable reuse, and wide application. In recent years, molecularly imprinted polymers have been widely applied in several aspects like extracting active ingredients from Chinese herbals, enzyme catalyze simulations, solid phase extractions, sensors.L-3-n-butylphthalide is an important and bio-active phthalide derivative constituent excisting in frequently used Traditional Chinese Medicines which provide important resources for drug developments, and especially in umbelliferae plants such as Radix Angelica, Rhizoma Chuanxiong and celery. In the current study, l-3-n-butylphthalide is gaining more and more focus on biochemical, clinical and pharmaceutical researches based on its various bioactivities.In this thesis, molecular imprinting technology was adopted to synthesize l-3-n-butylphthalide molecularly imprinted polymers through precipitation polymerization and the preparation, characterization, adsorption and recognition properties of the MIPs which provide an effective method to extract and separate l-3-n-butylphthalide from Traditional Chinese Medicine complex matrices were studied in detail. The research contents and results of the thesis are as follows:In the first chapter, the development and principles of molecular imprinting technique, the preparations, synthesis methods and applications etc. of MIPs are summarized, meanwhile the research background, signification, content and innovation point of this paper are described.In the second chapter, the reagents and instruments using in the experiment as well as the experiment content of this paper are described in detail.In the third chapter, the experimental results and discussion of the paper are presented and the main points are as follows:(1) The results of molecular simulation show that in the molecularly imprinted pre-assembled system, when acetone as the solvent, the solvation energies of both l-3-n-butylphthalide and functional monomer acrylamide are the lowest, meanwhile, the complex in which the molar ratio of l-3-n-butylphthalide and acrylamide is 1: 2 has a higher stable binding energy.(2) The optimum preparation conditions of the l-3-n-butylphthalide MIPs are as follows: acetone as the porogenic solvent, acrylamide as the functional monomer, the molar ratio of template molecule to cross-linker is 1:20 and the molar ratio of template molecule to the functional monomer is 1:4. The non-imprinted polymers(NIPs) were prepared with the same procedure, but with the absence of template molecule.(3) Scanning electron micrographs show that there are cavity structures which are propitious to the re-adsorption and mass transfer of the l-3-n-butylphthalide in the MIPs. Infrared spectra show that l-3-n-butylphthalide MIPs are successfully prepared through precipitation polymerization.(4) The static adsorption experiment shows that the adsorption of the MIPs reaches saturation at a initial concentration of 0.1 mmol L-1. The dynamic adsorption experiment shows that the adsorption of the MIPs attains equilibrium shaking for 12 h. When the initial concentration of l-3-n-butylphthalide is 0.1 mmol L-1 and the adsorption time was 12 h, the equilibrium adsorption capacity of l-3-n-butylphthalide bound to MIPs is 3.561 mg g-1. The binding capacities of l-3-n-butylphthalide bound to the MIPs are higher than the NIPs under the same adsorption conditions. Scatchard analyses reveal that there are high and low affinity sites formed in the MIPs. The dissociation constants(Kd) and the apparent maximum binding capacities(Qmax) of the higher affinity binding sites were 0.008 mg m L-1 and 3.642 mg g-1 respectively, while those of the lower binding affinity sites were 0.090 mg m L-1 and 25.960 mg g-1. The selective adsorption experiment shows that l-3-n-butylphthalide MIPs have higher distribution coefficient, imprinting factor and selectivity factor for l-3-n-butylphthalide comparing with its adsorption for other two similarly structural compounds, indicating that MIPs has a high selectivity and specific recognition properties to l-3-n-butylphthalide.(5) The molecularly imprinted solid-phase extraction(MISPE) column is prepared packed with the MIPs particles. preparation of molecular imprinted solid phase extraction column filler. When methanol as the loading solvent, water was the washing solvent and ethanol-acetic acid(90:10, v/v) was the eluting solvent, the MISPE can obtain good enrichment effect as well as recovery.In the fourth chapter, the research results of the thesis are summarized, and the development directions of molecular imprinting technique in the future are also forecasted.