Surface-functionalized electrospun carbon nanofiber mats as an innovative type of protein adsorption/purification medium with high capacity and high throughput.

Due to recent advances in the production of biotherapeutics, high capacity, high throughput adsorption media for efficient and economic separation of these medically important products are in great demand. One option that has been evaluated extensively is membrane/mat adsorption. While these media allow for rapid adsorption (due to the decreased internal diffusion) and high throughput processing (due to the open porous structure), they often suffer from low capacity and poor enrichment factors. Herein, we report the fabrication, characterization, and protein adsorption evaluation of an innovative type of membrane/mat adsorption media based on electrospun carbon nanofibers. By surface-functionalization of these nanofibers with a weak acid cation-exchange ligand, the capacity was doubled for binding a model protein (i.e., lysozyme) compared to commercial products; and the capacity value was over 200 mg lysozyme per gram of adsorption media. Meanwhile, the thin nanofibers (having diameters of ~300 nm) along with open pores among nanofibers in the mats (having sizes of ~10-15 μm) allowed for higher operating flow rates and lower pressure drops. Furthermore, the incorporation of higher ligand density and the addition of a non-ionic surfactant (i.e., Triton X-305) into the adsorption buffer eliminated the non-specific binding of a competing protein (bovine serum albumin). In combination, this study suggested that electrospun carbon nanofiber adsorption media would provide a promising alternative to packed resin beds for bioseparations.