Preparation Of Ordered Macroporous Molecularly Imprinted Hybrid Materials And Targeted Separation Of Effective Ingredients From Ginkgo Leaves

Ginkgo biloba extract(EGb)has the medicinal value of antagonizing platelet activating factor,scavenging free radicals,anti-inflammatory and anti-allergic.Lactone and flavonoids are its main active ingredients.However,separation is very difficult due to the low content of each active ingredient and the presence of many structural similarities.Improving separation efficiency is of great significance for the development of new drugs and quality control.How to improve the selectivity of solid phase adsorbents is a key scientific issue.Molecularly imprinted polymers(MIPs)is a kind of solid phase adsorbent with high specific adsorption capacity for target molecules,and has potential industrial application prospects in the separation of natural products.In this paper,the two important active components of Ginkgo biloba extract,quercetin and ginkgolides B,were designed to prepare molecularly imprinted polymer materials with specific adsorption properties.MIPs prepared by bulk polymerization have the disadvantages of poor mass transfer performance and low availability of imprinted pores.The molecularly imprinted hybrid material having a three-dimensional ordered macroporous structure was prepared by combining a colloidal template technique with a surface imprinting technique.The materials can improve mass transfer performance and imprinting efficiency by improving pore structure characteristics.The main contents of this paper are as follows:(1)The thiol functionalized silica hybrid material(3DOM SiO2-SH)with three-dimensional ordered macroporous structure was prepared by using polystyrene gel crystal as template and silica sol as precursor.Then,a molecularly imprinted precursor solution was prepared using quercetin(Qe)as a template,4-vinylpyridine as a functional monomer,EDMA as a crosslinker,and acetone as a solvent.Subsequently,the molecularly imprinted precursor solution was filled into 3DOM SiO2-SH material,Finally,The material was produced by thermal polymerization in ordered macroporous to obtein OMMIPs(ordered macroporous molecularly imprinted polymers).Material composition and pore structure characteristics were characterized by FTIR,Raman,SEM,Brunauer-Emmet-Teller measurement,TGA and elemental analysis.The results show that the nano-thickness molecularly imprinted polymer film can be successfully grafted on the surface of macropores.OMMIPs have a more regular pore structure,a higher porosity and a lower swelling ratio than traditional molecularly imprinted polymers(TBMIPs).The results of thermodynamic adsorption and kinetic adsorption experiments show that OMMIPs have specific adsorption capacity for Qe,and ordered macroporous structure can significantly improve intra-particle adsorption rate and improve the availability of molecular imprinting sites.As a solid phase extraction adsorbent,OMMIPs can directly extract flavonoids from Ginkgo biloba hydrolysate and have specific adsorption capacity for Qe with a high recovery(55.1%)and purity(80.7%).(2)Ginkgolide B(GB)MDPs were successfully prepared by semi-covalent method.First,the prepolymer was synthesized with acryloyl chloride and GB,and then divinylbenzene was used as crosslinker to obtain GB-MIPs.The structure of the prepolymer was characterized by nuclear magnetic resonance and mass spectrometry.The results showed that each GB molecule can be successfully modified two acrylate units.The results of adsorption isotherm curve and specific adsorption experiments show that the imprinted polymer prepared by semi-covalent method has higher adsorption capacity and imprinting factor than non-covalently prepared imprinted polymer,and has specific adsorption capacity to GB.In this paper,Qe and GB molecularly imprinted polymers were prepared to provide new materials for the separation of flavonoids and lactones from Ginkgo biloba leaves.Moreover,the combination of colloidal template technology and surface imprinting technology to prepare OMMIPs provides a practical method for improving the utilization of template molecules and imprinted cavities.Therefore,the research results of this paper have good scientific and practical application value.