Preparation And Binding Characteristics Of Molecularly Imprinted Polymers For The Numb-taste Components Of Zanthoxylum

Molecular Imprinting Technology(MIT)is a novel technique for producing polymer materials with high affinity and selectivity for target compound(template),the polymer materials is called molecular imprinting polymers.Molecular Imprinting Technique has been widely used in separation,purification,catalytic sensor and so on,and has a broad prospect.The numb-taste components of Zanthoxylum is the main composition of hemp taste.It has many physiological functions,such as anesthesia,excitement,bacteriostat,dispel the wind prescription,insecticide and so on.The numb-taste components of Zanthoxylum is widely used in food,medicine and cosmetics.Traditional extraction method for numb-taste components of Zanthoxylum mainly adopts chromatography,but there are many defects,such as separation time too long,high cost and separation scale is small,limited to using experimental research.Molecular imprinting technology provides a new method for the separation and purification of the numb-taste components of Zanthoxylum.In this paper,the substance with the resemblemolecular structure for the numb-taste components of Zanthoxylum is synthesized.Using the dummy template as the template molecule,molecular imprinting polymers(MIPs)were synthesized by precipitation polymerization method,silica molecular imprinting polymers(SMIP)were synthesized by surface molecularly imprinting method,and the identification characteristics of MIPs and SMIP were studied.Solid phase extraction is prepared with the SMIP as packing material,the relatively pure numb-taste components of Zanthoxylum can be obtained by it.The main studies are as follows:1.Synthesis and confirmation of the structural analogue(LM1 and LM2)for the numb-taste components of Zanthoxylum.Two kinds of the structural analogue for the numb-taste components of Zanthoxylum are compounded by chemical methods.The structure is characterized by IR spectra,UV spectra,H-NMR spectra,and C-NMR spectra.The grade of purity is confirmed by HPLC and GC-MS.In the certain concentration range from 1.0 mg/m L to10 mg/m L,the two substance doesn’t show obvious hemp taste.2.Preparation of molecularly imprinted polymer by bulk polymerization.(1)Using the dummy template(LM2)as the template molecule,methylacrylic acid(MAA),2-vinylpyridine(2-Vpy),acrylamide(AM)as the function monomers,ethylene glycol dimethacrylate(EDMA)as the cross-linker,acetonitrile as the pore-foaming agent,2,2-azobisisobutyronitrile(AIBN)as the initiator,15 kinds of MIPs is prepared by bulk polymerization,a best kind of MIPs is chose out from the several kinds of MIPs.(2)The adsorption dynamic curve of MIPs displayed that the adsorption of the numb-taste components of Zanthoxylum on MIPs could reach equilibrium within 10 h and the recognition factor(α)was 2.53.The adsorption isothermal curves of MIPs and NIPs showed that the adsorption quantity of the numb-taste components of Zanthoxylum in the cavity formed by MIPs was higher than that of NIPs.In the certain concentration range from 0.05 mg/m L to 0.3 mg/m L,two kinds of the binding sites were observed between the imprinted polymer and the numb-taste components of Zanthoxylum.Their dissociation constants(Kd)were 6.544×10-2 mg/m L and 3.087×10-1 mg/m L,and the apparent maximum absorption capacity(Qmax)were17.487 mg/g and 45.019 mg/g,respectively.3.Preparation of silica molecularly imprinted polymer by surface molecularly imprinting method.(1)With the dummy template(LM2)as the template molecule,2-vinylpyridine(2-Vpy)as the function monomers,ethylene glycol dimethacrylate(EDMA)as the cross-linker,acetonitrile as the pore-foaming agent,2,2-azobisisobutyronitrile(AIBN)as the initiator,SMIP is prepared by surface molecularly imprinting method.The result of the optimal experiment are as follows: on the basis of 1 mmol 2-Vpy,the molar ratio of n(LM2):n(2-Vpy):n(EDMA)is 1:4:20.8,the amount of acetonitrile is 82 m L a,the amount of acylation silica is 830 mg,the polymerization reaction is sustained for 4 hours at 50 degree centigrade,then the polymerization reaction is sustained for 20 hours at 60 degree centigrade.(2)The adsorption dynamic curve of SMIP displayed that the adsorption of the numb-taste components of Zanthoxylum on SMIP could reach equilibrium within 210 min and the recognition factor(α)was 2.91,the dynamic adsorption process was in accord with pseudo-first order kinetic model.The adsorption isothermal curves of SMIP and SNIP showed that the adsorption quantity of the numb-taste components of Zanthoxylum in the cavity formed by SMIP was higher than that of SNIP.The process of isothermal adsorption was in accord with Freundlich isotherm,it is adsorption theory of multi-molecular layers.In the certain concentration range from 0.05 mg/m L to 0.35 mg/m L,two kinds of the binding sites were observed between the imprinted polymer and the numb-taste components of Zanthoxylum.Their dissociation constants(Kd)were 1.972×10-3 mg/m L and 2.824×10-2 mg/m L,and the apparent maximum absorption capacity(Qmax)were 14.433 mg/g and 31.378 mg/g,respectively.Using the dummy template(LM2)as the template molecule,SMIP can achieve good effect of imprinting.4.Separation of the numb-taste components of Zanthoxylum in Zanthorylum bungeanum oleoresin by molecularly imprinted solid phase extraction.A kind of solid-phase extraction column packed with prepared SMIP was used as solid-phase material to extract the numb-taste components of Zanthoxylum from Zanthorylum bungeanum oleoresin.The result of the study showed that the solid-phase extraction column have the specific recognition selectivity for the numb-taste components of Zanthoxylum,the relatively pure numb-taste components of Zanthoxylum can be obtained.