Synthesis And Performance Of Polymer-grafted Ionic Exchangers Via Grafting-from And Grafting-to Methods

Chromatography material as the key component and the foundation of protein chromatography has been widely studied.In recent years,different kinds of polymergrafted chromatography medium have showed their own superiority.However,the effect of grafting technique on the properties of chromatography medium is not clear.In this work,Sepharose FF-based cation-exchange gels grafted with 3-sulfonic acid propyl methacrylate potash(SPM)was fabricated by grafting-from and grafting-to technique.The properties of Sep-g-SPM and Sep-pSPM ion-exchangers were characterized systematically and the adsorption behaviors of lysozyme and γ-globulin on ion-exchange gels were studied.We also studied the interaction between polymer chains and protein via QCM.In this work,“grafting-from” means that the monomer SPM “grew” in the Sepharose FF gel pore from the induced group of the gel to get the polymer chain.The polymer-grafted medium was named Sep-g-SPM.While,“grafting-to” means that the pre-synthesized polymer SPM was covalently coupled in the Sepharose FF pore,and the medium was named Sep-pSPM.It was proved that Sep-g-SPM provided controllable introduction of polymer chain with the regular distribution of the ligand,and thus had larger accessible pore radius and smaller depths of polymer layers than Sep-pSPM.The result of protein adsorption revealed that high-capacity adsorption of lysozyme and γ-globulin could be achieved simultaneously in the Sep-g-SPM cation exchanger with an ionic capacity(IC)of 308 mmol/L in this work,which was 362.9 mg/mL and 256.9 mg/mL,respectively.The highest adsorption capacity of lysozyme on Sep-pSPM could achieve 462.4 mg/mL.So,the adsorption capacity of lysozyme on ion-exchangers had little relationship to grafting technique in this work.Compared with Sep-g-SPM cation exchangers,Sep-pSPM cation exchangers brought about irregular chain distribution and different architecture of polymer layer.It led to more serious repulsive interaction to γ-globulin,and thus Sep-pSPM cation exchangers had lower adsorption capacities for γ-globulin than Sep-g-SPM cation exchangers with the similar ICs.Moreover,uptake results of protein indicated that the facilitated transport of adsorbed γ-globulin occurred only in Sep-pSPM cation exchangers and was dependent on the architecture of polymer layers.The results of QCM experiments showed that the polymer-grafted layer adsorbed protein continuously over time.At the same time,the polymer layer structure of the interface also changed.The concentration of ions in the solution had regulatory effect on the adsorption of protein,and both Sep-g-SPM and Sep-pSPM medium exhibited better salinity tolerance.This study provided a basis for the development of ion-exchangers and the study of protein adsorption mechanism in polymer grafting media.