title: Nanofiber adsorbents for high productivity continuous downstream processing.
abstract: An ever increasing focus is being placed on the manufacturing costs of biotherapeutics. The drive towards continuous processing offers one opportunity to address these costs through the advantages it offers. Continuous operation presents opportunities for real-time process monitoring and automated control with potential benefits including predictable product specification, reduced labour costs, and integration with other continuous processes. Specifically to chromatographic operations continuous processing presents an opportunity to use expensive media more efficiently while reducing their size and therefore cost. Here for the first time we show how a new adsorbent material (cellulosic nanofibers) having advantageous convective mass transfer properties can be combined with a high frequency simulated moving bed (SMB) design to provide superior productivity in a simple bioseparation. Electrospun polymeric nanofiber adsorbents offer an alternative ligand support surface for bioseparations. Their non-woven fiber structure with diameters in the sub-micron range creates a remarkably high surface area material that allows for rapid convective flow operations. A proof of concept study demonstrated the performance of an anion exchange nanofiber adsorbent based on criteria including flow and mass transfer properties, binding capacity, reproducibility and life-cycle performance. Binding capacities of the DEAE adsorbents were demonstrated to be 10mg/mL, this is indeed only a fraction of what is achievable from porous bead resins but in combination with a very high flowrate, the productivity of the nanofiber system is shown to be significant. Suitable packing into a flow distribution device has allowed for reproducible bind-elute operations at flowrates of 2,400 cm/h, many times greater than those used in typical beaded systems. These characteristics make them ideal candidates for operation in continuous chromatography systems. A SMB system was developed and optimised to demonstrate the productivity of nanofiber adsorbents through rapid bind-elute cycle times of 7s which resulted in a 15-fold increase in productivity compared with packed bed resins. Reproducible performance of BSA purification was demonstrated using a 2-component protein solution of BSA and cytochrome c. The SMB system exploits the advantageous convective mass transfer properties of nanofiber adsorbents to provide productivities much greater than those achievable with conventional chromatography media.
authors.affiliation: Department of Biochemical Engineering, University College London, Torrington Place, WC1E 7JE London, United Kingdom; Micro and Nanotechnology Centre, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: Hardick
authors.affiliation: Department of Biochemical Engineering, University College London, Torrington Place, WC1E 7JE London, United Kingdom; Micro and Nanotechnology Centre, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom.
authors.forename: Stewart
authors.initials: S
authors.lastname: Dods
authors.affiliation: Micro and Nanotechnology Centre, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom; School of Science and Technology, Nottingham Trent University, NG1 4BU, Nottingham, United Kingdom.
authors.forename: Bob
authors.initials: B
authors.lastname: Stevens
authors.affiliation: Department of Biochemical Engineering, University College London, Torrington Place, WC1E 7JE London, United Kingdom. Electronic address: d.bracewell@ucl.ac.uk.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Bracewell
mesh_terms: D000327:Adsorption; D001709:Biotechnology / Q000379:methods; D002852:Chromatography, Ion Exchange; D045304:Cytochromes c / Q000737:chemistry; D003636:DEAE-Cellulose / Q000737:chemistry*; D057139:Nanofibers / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry
chemical_list: D012710:Serum Albumin, Bovine; D045304:Cytochromes c; D003636:DEAE-Cellulose
keywords: Anion exchange chromatography; Diethylaminoethyl; Nanofibers; Simulated moving bed