Bioseparations Using Electrospun Cellulose Nanofiber Adsorption Membranes

Adsorptive membranes have shown great promise for bioseparations as an alternative to packed bed chromatography. Here we evaluate adsorptive membranes (felts) made from electrospun cellulose acetate nanofibers as an ion-exchange medium for protein separations. The cellulose acetate nanofibers were hydrolyzed/deacetylated to yield regenerated cellulose nanofibers, which were then surface functionalized with either diethylaminoethyl (DEAE) anion-exchange ligand or a carboxylic acid for cation exchange adsorption. SEM imaging along with FT-IR spectroscopy were used to follow each stage of the preparation process. For comparison, a regenerated cellulose microfiber adsorption medium, a commercially available regenerated cellulose adsorptive membrane, and bleached absorbent cotton balls, were all similarly treated and evaluated. The results indicated that the functionalized nanofiber felts had higher static binding capacities and higher permeability than micro fiber and commercial membranes. Dynamic adsorption of target protein was also higher for the nanofiber felt compared to the commercial membrane. Finally, detrimental system dispersion, as determined by calculation of the Peclet number, could be limited by increasing the number of felt layers used for the nanofiber adsorption bed, without compromising low pressure drops.