Study On The Preparation And The Separation Selectivity Of Novel Molecularly Imprinted Polymers For The Effective Molecules Of Traditional Chinese Medicine

The separation and purification of the effective molecules of traditional Chinese medicine(TCM)are important parts of the modernization of TCM.Molecularly imprinted polymers(MIPs)are a kind of novel molecular recognition materials prepared for specific molecules,and have been widely used in the fields of drug analysis,active ingredient extraction,and chiral separation.This paper is aimed at preparing chromatographic materials with high specific recognition performance for the effective molecules of TCM.Quinine and ginsenoside Re are used as imprinting models to respectively prepare quinine-macroporous molecularly imprinted microspheres(MMIMs)and ginsenoside Re-reversible covalent MIPs by designing and improving traditional preparation techniques of MIPs.The two kinds of imprinted polymers own efficient separation selectivity for the specifie template molecule,and broaden the applieation of molecularly imprinted polymers in separation science.The specific research contents of the paper are including as follows:The first part:The monodisperse SiO2 microspheres are prepared by the Stober method,whice are uesd as colloidal particle to prepare SiO2 colloidal microspheres by the evaporation-induced self-assembly process.Study on the influence factor of the reaction time and the quantity of SiO2 microspheres for the morphological structure of SiO2 colloidal microspheres.The results show that the optimal reaction time of SiO2 microspheres is 6 h,the particles are favorable monodispersity and the size is about 340 nm.The scanning electron microscopy(SEM)shows the SiO2 colloidal microspheres are arranged with a typical face centered cubic(fce)structxure,the diameter of microspheres is mainly distributed in the range of 37-120μm.The quantity of the monodisperse is amplified to 6 times,and the particle size and structure of the prepared SiO2 colloidal micro spheres are no change much,indicating this method is suitable for large-scale preparation.In addition,the colloidal microspheres are used as chromatographic stationary phase to evaluate the chromatographic separation performance.The results show the SiO2 colloidal microsphere column with good permeability,can rapidly separate benzene derivatives at high flow rate and low background pressure.Compared with SiO2 particles(10 μm)with smaller particle structure,the SiO2 colloid microspheres show better separation selectivity.The second part:MMIMs are synthesized by combining molecular imprinted technique with colloidal crystal templating method using SiO2 colloidal microspheres as template,quinine imprinting solution as precursor.The study explored in detail the effects of the type of crosslinker in the precursor on the morphological structure and recognition performance of MMIMs.The SEM shows the MMIMs with trimethylolpropane triacrylate(TMPTA)as crosslinker possess more intact inverse opaline structure with uniform three-dimensionally ordered macroporous inside the microspheres and interpenetrating pores.Isothermal adsorption studies show that MMIMs prepared by the crosslinker TMPTA own faster binding rate and higher binding capacity than traditional bulk polymers.The binding rate faster about 7 times than bulk MIPs,and the binding capacity more 1.25 times than bulk MIPs.In addition,the separation performance were evaluated by using MMIMs as HPLC stationary phase.The results show the MMIMs prepared using TMPTA as crosslinker can effectively separate quinine and its diastereomer quinidine,and separation factor is 1.69.The study mechanism confirms that the chiral recognition mainly depends on the molecularly imprinted cavities and the ordered macroporous structure.The third part:Ginsenoside Re-reversible covalent MIPs are prepared by based on borate bond by using ginsenoside Re as imprinting molecule,4-vinylbenzeneboroxnic acid(4-VPBA)as functional monomer,ethylene glycol dimethacrylate(EDMA)as crosslinker.The synthesis conditions of ginsenoside Re-4-vinylbenzeneboronate such as reaction mode,solvent type and polymer adsorption performance are studied.The results show that the MIPs based on borate bond recognition possess fast kinetics adsorption and strong specifie binding ability for imprinted molecules in alkaline aqueous media.The adsorption proeess of MIPs conforms Freundlich model,and indicates the adsorption process of MIPs belongs to the heterogeneous adsorption process.Selective experiments show that covalent MIPs own good selectivity recognition for imprinting molecules and it’s structural analogues,and the specific recognition ability are mainly attributed to the imprinted cavities and boric acid groups in MIPs.The results of this study are expected to provide a new chromatographic separation material with high recognition performance for the separation and the purification of TCM.