High-Throughput Screening of Cell Repellent Substrate Chemistry for Application in Expanded Bed Adsorption Chromatography

Abstract

Expanded bed adsorption (EBA) chromatography is a cost effective downstream process to capture biomolecules from the unclarified feedstock. One of the main limitations, preventing its wide application, is severe adsorbent fouling. This happens due to the attachment of whole cells and cellular particles on to the adsorbent, which results in aggregation of the adsorbents, consequent formation of dead zones further leading to the collapse of the expanded bed. It is well known that hydrophilic and ionic chemical additives increase the performance of chromatographic adsorbents by modifying surface properties such as hydrophilicity, charge and roughness of the adsorbents. In this work, we have applied this principle of shielding or modifying chromatographic adsorbent surfaces with a layer of cell repellant polymer layers to reduce the non-specific interactions and it will be a helpful strategy to overcome the limitations of EBA chromatography. We have developed a microwell plate based assay primarily to screen polymers. Numerous interacting combinations were selected for this purpose. They are (i) common adsorbent mimicking surface harbouring diethylaminoethyl (DEAE) ligand and (ii) Yeast cells. Cell adhesion was quantified by crystal violet assay. Results showed that modification of ion exchanger with the synthetic polymer poly(acrylic acid) Mw ~345,000 (PAA) alleviated biomass adhesion. This behaviour correlated well with experiments on commercial anion-exchanger in absence and in the presence of PAA.