Preparation And Performance Study Of Chlorogenic Acid Molecularly Imprinted Membrane

Chlorogenic acid(CGA)is a phenolic acid,which has been considered to be the main active ingredient of many traditional herbs by many scholars,with a wide spectrum of pharmacological properties and health protection.In this paper,a chlorogenic acid molecularly imprinted chitosan membrane was prepared by using molecularly imprinting technology(MIT)and the phase inversion method.CGA was used as the template molecule,chitosan(CS)as the film-forming material and sulfuric acid as the cross-linking agent.The adsorption capacity of the molecularly imprinted chitosan membrane was furthermore studied.Scatchard results show that there are two kinds of adsorption sites with different affinity present on the molecularly imprinted membrane(MIM),while only one kind of non-specific sites was found on the non-imprinted membrane(NIM).The adsorption isotherms indicate that the adsorption isotherm curve of chlorogenic acid binding onto the imprinted membrane agrees with the Freundlich model while that of the non-imprinted membrane conforms to the Langmuir model.The permselectivity of membranes was discussed by choosing the caffeic acid(CA)as the competitive analogue and the results indicated that MIM was a little superior to NIM in terms of permeability and selectivity,as the penetration rate of chlorogenic acid and caffeic acid was 33.54% and 31.99%,respectively.Additionally,its surface structure,chemical structure,thermal stability and hydrophilicity were analyzed in vitue of scanning electron microscopy(SEM)analysis,Fourier transform infrared spectrum(FT-IR)analysis,thermogravimetric analysis(TG)and contact angle test,respectively.Secondly,in order to improve the selectivity performance of membranes stated above,carboxymethyl chitosan(CMCS)with carboxyl groups was chosen to imprint with chlorogenic acid firstly in this paper.This is mainly because hydroxyl groups which can combine with carboxyl groups of carboxymethyl chitosan are rich in the chemical structure of chlorogenic acid.Thus,the combination capacity of the template molecules could improve.Then blend acetic acid solution of chitosan with the above mixture to form casting solution.Chlorogenic acid molecularly imprinted chitosan-carboxymethyl chitosan(CS-CMCS)membrane was prepared through phase inversion method.Furthermore,the properties of the membrane including swelling capacity,adsorption performance and selective permeability were systematically investigated and compared with chlorogenic acid molecularly imprinted chitosan membrane.The results show that chlorogenic acid molecularly imprinted chitosan-carboxymethyl chitosan membrane is more likely to swell than chlorogenic acid molecularly imprinted chitosan membrane.The selective permeability of the chlorogenic acid molecularly imprinted chitosan-carboxymethyl chitosan membrane is obviously improved,as the penetration rate of chlorogenic acid and caffeic acid was 61.51% and 45.12%,respectively.