Preparation And Specific Adsorption Of Protein Imprinted Polyethylene Glycol Grafted Calcium Alginate Hydrogel By Chemical Crosslinking

Recently,more attention had been paid to protein research in the field of biochemistry and medicine.Proteins separation and purification were thoroughly concerned,but the traditional separation methods had been unable to meet the social necessaries.Molecular imprinting technology was an emerging technology that had been widely developed in recent years,which could synthesize polymers with specific recognition properties for particular template molecules(such as proteins)to achieve selective separation.Proteins,with the large molecular weight and conformation complex,were susceptible to environment.Therefore,it was necessary to choose a biocompatible,network structure developed hydrogel material as the imprinted substrate.Calcium alginate had the advantages of wide source,low price and good biocompatibility.However,pure calcium alginate hydrogel suffers from insufficient mechanical strength,adsorption capacity and selectivity.In order to improve the mechanical strength of calcium alginate gel microspheres,polyethylene glycol grafted alginate hydrogel microspheres(PEG600-g-CaA)were prepared by chemical crosslinking with epichlorohydrin.With bovine serum albumin(BSA)as template,we used the obtained materials to prepare imprinted polymer and studied the adsorption behavior of microspheres.Firstly,we characterized modified materials with FTIR,13C-NMR,optical microscopy,scanning electron microscopy,thermogravimetry and differential scanning calorimetry.The effects of crosslinking structure on the swelling degree of microspheres were investigated.The results indicated that grafting reaction taking place between PEG and SA.After grafting modification,the microspheres surface changed from rough to smooth,with better thermal stability and swelling properties.We also studied the effects of BSA concentration,pH value of mixed solution on the adsorption capacity and imprinting efficiency(IE)of MIPs.The optimum preparation process was as follows:grafting ratio was 43.3%,pH value was about 4.5,the protein concentration was 2.5 mg/mL and the eluate was 0.2%wt NaOH and 5%wt SDS.We investigated the effects of environmental conditions on the adsorption properties.The results showed that the optimum conditions for the specific adsorption were as follow:the pH value of the solution was between 4.0 and 4.7 and the adsorption temperature was 25?.At the same time,we also probed into the influence of cross-linking structure on adsorption kinetics and adsorption thermodynamics.The results showed that the adsorption kinetics of MIPs with different crosslinking was similar while the equilibrium time of imprinted microspheres and non-imprinted microspheres(NIPs)was different,i.e.120 min and 60 min respectively.The results indicated that the adsorption capacity of imprinted polymer increased with the growth of BSA concentration then remained stable after BSA concentration was 4 mg/mL.Finally,we studied the specific selectivity of different crosslinking imprinted microspheres and non-imprinted microspheres for various proteins.The results showed that microspheres with appropriate crosslinking structure were beneficial to the adsorption of template proteins.The selectivity of MIPs was higher than that of NIPs,which suggested that MIPs were potential materials for protein selective separation.