Preparation And Characterization Of Porous Cellulose-Based Quercetin Molecularly Imprinted Polymers And Preliminary Application Research

In this study,the porous cellulose microspheres were prepared using absorbent cotton as raw materials,and then molecularly imprinted polymers were grafted after silanization of the microspheres.Finally,porous cellulose-based quercetin molecularly imprinted polymers were prepared and systematically characterized.In this process,a method for preparing 400 ?m porous cellulose and the imprinted material was obtained,respectively.In the preliminary application research,the quercetin adsorption conditions of the imprinted material were optimized,and the selective adsorption and recycling performance were investigated.Finally,the imprinted material was used to extract quercetin from the extract of Flos Sophorae Immaturus separation.The purity of quercetin obtained by targeted separation is 68.79%,which is 4.37 times higher than the conventional solvent extraction method.The porous cellulose-based quercetin molecularly imprinted polymer prepared in this study overcomes the problem that the particle size of the material is too small and difficult to separate.At the same time,the shortcomings of large consumption of organic reagents,high energy consumption and tedious and time-consuming operations in the selective extraction and separation of natural products were solved.The purpose of stable and efficient reuse of porous cellulose-based molecularly imprinted polymers for selective targeted separation of natural products is achieved.The main research contents and results of this study are as follows:1.Optimization of the preparation method of silanized porous cellulose microspheresIn this study,absorbent cotton was used as the raw material,and porous cellulose microspheres were prepared by inverting suspension technology after alkalizing,aging,and sulfonating the absorbent cotton.Then the cellulose microspheres were pore-induced by 0.1 mol/L dilute hydrochloric acid,and then modified with silanized reagent at 60?.Finally,silanized porous cellulose microspheres with a particle size of 400?m were prepared and processed system characterization.The characteristic peaks of the silanized reagent can be seen in the infrared spectrum.The scanning electron microscope image shows that the surface of the porous cellulose microspheres modified by the silanized becomes rougher,the pore diameter becomes smaller,and the specific surface area increases.The optimized conditions of 400 ?m cellulose spheres obtained through research are:Dosage of surfactant:0.05 g/g CMTransformer oil consumption:50 mL/g CMStirring speed:560 r/minReaction temperature:80?Response time:3hUnder optimized conditions,the percentage yield of cellulose microspheres was 78.7%,and its morphology was regular and the particle size was uniform.Then the cellulose microspheres were pore-induced by dilute hydrochloric acid,and modification was performed with an excess of 3-(methacryloyloxy)propyltrimethoxysilane in an ethanol aqueous solution of glacial acetic acid.Finally,the silanized porous cellulose microspheres were prepared.The characteristic groups of the silylating agent can be seen in the FT-IR,the microporous structure is obvious,and the support can react with dilute KMnO4 to form a brown precipitate.Infrared visible characteristic groups of silylating agent2.Stable preparation method of porous cellulose-based quercetin molecularly imprinted polymerIn this study,a porous cellulose-based quercetin molecularly imprinted polymeric material with high adsorption capacity was prepared by using silanized porous cellulose as the carrier,quercetin as the template,4-vinylpyridine as the functional monomer,ethylene glycol dimethacrylate as the crosslinking agent,azobisisobutyronitrile as the initiator in combination with the traditional molecularly imprinted polymer preparation method.Through systematic characterization of the imprinted material,the characteristic peaks of the polymer in the infrared image are obvious,and a large number of imprinted polymer microspheres are grafted inside the micropores.TG analysis shows that the imprinted material is thermally stable.X-ray diffraction showed that the cellulose retained the crystalline structure of cellulose II after grafting the molecularly imprinted polymer.The optimized conditions for preparing porous cellulose microspheres are:Functional monomer:4-vinylpyridine Ethylene glycol dimethacrylate dosage:396.44 mg Silanized porous cellulose microspheres/ethylene glycol dimethacrylate=3/4(W/W)Polymerization solvent:acetonitrile/N,N-dimethylformamide=20/1(V/V)Polymerization temperature:60?Eluent:methanol/acetic acid=85/15(V/V)Ultrasonic elution time:15 minThe imprinting factor of the porous cellulose-based quercetin molecularly imprinted polymer prepared under the optimized conditions was 1.96,and the adsorption capacity was 11.73-12.25 mg/g.The preparation method is stable and reliable,and the prepared imprinted material has a regular morphology,obvious characteristics,and good thermal stability.3.Completed the preliminary application research of porous cellulose-based quercetin molecularly imprinted materialsThis study investigated the adsorption conditions,selective adsorption capacity,and cyclic adsorption performance of porous cellulose-based quercetin molecularly imprinted polymeric materials,as well as the ability of imprinted materials to target and isolate quercetin from real samples.In a quercetin solution at a concentration of 0.5 mg/mL,the adsorption conditions were optimized by single-factor optimization.The optimization conditions were as follows:Adsorption method:Elution shaker swing(30 r/min)Adsorption solvent:acetonitrile/N,N-dimethylformamide=20/1(V/V)Adsorption temperature:15?Time:8 hUnder optimized conditions,the adsorption capacity of porous cellulose-based quercetin molecularly imprinted material for quercetin was 13.19 mg/g.In the selective adsorption experiment,the imprinted material has a good selective adsorption of quercetin,and the adsorption capacity of quercetin is 3.63 times that adsorption capacity of naringenin;the imprinted material retained 83.05%of its adsorption performance after 4 cycles of adsorption and desorption,and the desorption rate was 98.6-99.7%.In the targeted separation of quercetin from Flos Sophorae Immaturus,the purity of quercetin obtained by targeted separation by using the imprinted polymeric material is 68.79%,which is 4.37 times higher than the conventional solvent extraction method.In summary,this study successfully prepared porous cellulose-based quercetin molecularly imprinted polymeric materials for targeted isolation of quercetin from natural products.A method for preparing silanized porous cellulose microsphere carrier and porous cellulose-based quercetin molecularly imprinted polymer were obtained.The optimal conditions for imprinting material to adsorb quercetin were established,and then its selective adsorption performance and recycling performance were studied.Finally,the imprinted material was applied to the targeted separation of quercetin from real samples with excellent results.The porous cellulose-based quercetin molecularly imprinted polymeric material prepared in this study has the advantages of good selective adsorption,easy recovery,and recyclability.It has opened up new materials for targeted separation of natural products,and it provides a research basis for the application of bio-based targeted separation materials in the pharmaceutical field.