Preparation And Characterization Of Paper-Based Hydrophobic Interaction Chromatography Membrane

In the field of bioseparation,hydrophobic interaction membrane chromatography has attracted increasing attention due to a number of advantages of this technique,namely,low pressure drop,high flux,less recovery liquid volume(needed for elution)and easy to scale-up compared to column chromatography.The aim of the present study is to develop cellulose-based hydrophobic interaction chromatography membrane.Poly(N-isopropylacrylamide) (PNIPAM)grafted filter papers were prepared by UV-induced grafting polymerization to make the membrane.For PNIPAM grafted membrane, protein loading(adsorption)and releasing(desorption)is controlled by the temperature of the mobile phase since the hydrophobicity of PNIPAM is temperature-dependent.Filter paper was selected as base material due to its high hydraulic permeability,low cost and compatible with proteins. 1.N-Isopropylacrylamide(NIPAM)was introduced onto the surface of filter paper to form a layer of PNIPAM by UV-induced surface photograft polymerization.Factors that influence the grafting degree of the polymer on filter papers were studied.The morphology of the polymer grafted papers was investigated by SEM.It was found that the grafting degree could be controlled mainly by monomer concentration employed in the polymerization.The porous structure of the filter paper remained after the grafting even at high grafting amount(around 40%based on dry fiber mass) of PNIPAM.Protein adsorption/desorption performance of the paper-based membranes was investigated using BSA as model proteins.2.The styrenic terminated PNIPAM macromonomer with a molecular weight 2,000 and 8,000,respectively,were prepared by esterification between carboxylic end-ed olig(NIPAM)and chloromethyl styrene.The structure of the obtained macromonomer was characterzed by ~1H-NMR and UV spectra.3.Copolymers of NIPAM with four types of acrylate,namely,methyl methacrylate(MMA),ethyl acrylate(EA),butyl acrylate(BA)and butyl methacrylate(BMA),were prepared respectively through solution free radical polymerization.Thermo-sensitivity of aqueous solutions of the copolymers obtained was investigated by turbidity observation and dynamic light scattering measurement.It was found that the structure and content of acrylic comonomer strongly affects the LCST of the copolymers,i.e.the larger the carbon number in the ester moiety of the acrylate the lower the LCST,and the alkyl group located at the ester moiety is more effective in lowering the LCST than the alkyl binding at the a position of the acrylate.Conclusively,water soluble thermo-sensitive copolymer with a designed low LCST can be obtained by copolymerization of NIPAM with acrylate.It is expected that paper-based membrane with a lowered LCST of grafted NIPAM-containing polymer can be prepared by additionally incorporating hydrophobic acrylate to the monomer feed during grafting polymerization.