Endotoxin or lipopolysaccharides (LPS) are highly toxic components of the cell wall of Gram-negative bacteria and are often present in significant amounts in bacterial cell culture expression systems such as E. coli. A number of methods have been adopted for the removal of endotoxin based on adsorption, in particular ion-exchange chromatography. Although downstream processing can significantly reduce endotoxin levels in the product, efficient and cost-effective removal of residual endotoxin from biopharmaceutical preparations remains a challenge.

This technical poster addresses the issues of removal of endotoxin from biological preparations. Specific reference will be made to a new synthetic ligand affinity adsorbent, EtoxiClear™, which exhibits high affinity for endotoxin, low protein binding and can be depyrogenated using sodium hydroxide. The bi-dentate ligand, attached to PBL’s proprietary base matrix – PuraBead®, binds in a spatially selective and optimal manner to the LPS molecule with a dynamic binding capacity for endotoxin in excess of 1,000,000 EU/mL of adsorbent (5 minute residence time). A number of biomolecules with different isoelectric points were used to demonstrate efficient recovery and clearance of residual endotoxin across the pH range. Protein recoveries in excess of 95% are achievable with endotoxin clearance to below 0.1 EU/mg protein.