Predicting the Dynamic Binding Capacities for Adsorbents Using BSA As a Model Protein

Author’s name: Gaoshan Li

Presenter’s name: Gaoshan Li

Faculty mentor: Dr. Heather Chenette

Abstract

Membrane adsorbers are one alternative to traditional bead-based chromatography that receive attention in the bioseparation process because of their ability to process material with lower residence times, and thus, higher product throughput. Another important metric is the dynamic binding capacity (DBC), which is defined as the mass of protein bound to the column per volume of the column adsorbent when the outlet stream reaches a certain concentration [2]. The equilibrium binding capacity (EBC) is the binding capacity when mass transfer is at equilibrium status such that the rate of protein adsorbing is equal and opposite to the rate of protein desorbing. While the DBC includes the effects of mass transfer under dynamic conditions, there are instances when it is more convenient to measure EBC, as it can be performed easily by measuring the equilibrium concentration. Along with determining the processing time and product resolution, determining the dynamic binding capacities (DBC) of innovative protein adsorbers as a performance characterization is also of importance. This is relevant for selecting appropriate materials for the purification process of biological products, such as monoclonal antibodies. Researchers have shown how EBC measurements can predict DBC values for specific cases when assuming that the Langmuir isotherm is rectangular and the intra-particle mass transfer is controlled by pore diffusion [1,2]. However, some properties of membranes, for example, the substrate morphology, make the assumptions that apply to the traditional bead-based chromatography invalid. Therefore, the model that predicts the DBC from the EBC cannot be applied to the membrane adsorbers. The goal of this research is to extend our analysis to determine DBC values using the existing theory and experimental EBC measurements using bovine serum albumin (BSA) as a model protein for commercial anion exchange resin (Q-Sepharose Fast Flow) adsorbers. In addition, this work explores existing literature on predicting DBC values for non-traditional adsorbent types, like those used in membrane chromatography, identifies the challenges with this method, and presents preliminary experimental EBC results for commercial anion exchange membrane adsorbers (Sartobind Q).

Reference

[1]Carta, Giorgio, and A. Jungbauer. Protein Chromatography: Process Development and Scale-Up. 2010.

[2]Carta, Giorgio. "Predicting protein dynamic binding capacity from batch adsorption

tests." Biotechnology Journal 7.10(2012):1216–1220.