Synthesis And Characterization Of Molecularly Imprinted Polymers Of Salvianolic Acid A

Salvianolic acid A is one of main water-soluble phenolic acids isolated from Danshen, which is dried root of Salivia miltiorrhiza Bge. In spite that its content in the plant is little, it is widely used to treat the diseases of blood vessels of the heart and cerebra and is very likely to become the ideal medicine for anti-cerebral ischemia. Because of the complexity of the plant matrices and the structural similarity to other phenolic acids, highly selective and stable materials are needed for the separation and determination of salvianolic acid A.Molecular imprinting is an emerging technique for the preparation of polymeric materials possessing high affinitive and selective properties toward a particular target compound (template molecule). The advantages that molecularly imprinted polymer (MIP) hold over natural antibodies are ease of preparation, low cost, mechanical/chemical stability. Thus, MIP is used as separation materials in extracting certain active components directly from herb.In this paper, Salvianolic acid A imprinted polymers were prepared by bulk polymerization and precipitation polymerization, respectively. Polymerization conditions for preparation MIP were researched and the binding capability and recognition mechanism were characterized. The research in this thesis includes:A series of MIP were prepared through bulk polymerization by using salvianolic acid A as the template molecule, acrylamide, methacrylic acid,2-vinylpyridine or4-vinylpyridine as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker in the porogen of acetone, ethyl acetate, acetonitrile or methanol. The adsorption ability and selectivity of the polymer were investigated by static equilibrium adsorption experiment and selectivity experiment, respectively. Scatchard analysis was employed to study the binding characteristics of MIP. The results indicated that the imprinted polymer prepared using acetone as the porogen, acrylamide as the functional monomer, and the molar ratio of functional monomer to template at6:1, exhibited the highest binding amount. Scatchard analysis revealed that two classes of binding sites were formed in the MIP, and the MIP exhibited good adsorption ability and selective ability toward salvianolic acid A.Salvianolic acid A imprinted polymer microspheres were prepared by precipitation polymerization, and synthetic conditions, surface morphologies, binding sites, adsorption properties, selectivity of MIP were studied. The result showed that the globular imprinted polymer was obtained under the optimum polymerization condition which was50mL acetonitrile as porogen,0.1mmol salvianolic acid A as template molecule,0.6mmol acrylamide as functional monomer,3mmol ethylene glycol dimethacrylate as cross-linker and10mg2,2’-Azobisisobutyronitrile as initiator. MIP displayed high adsorption capacity for Sal A in acetonitrile, which was confirmed by equilibrium binding experiments. Scatchard analysis revealed that two classes of binding sites were formed in the imprinted polymers. The adsorption efficiency and selectivity of MIP were higher compared to the non-imprinted polymers which were prepared in the same way without the addition of the template molecule.