Review: Endotoxin removal by affinity sorbents

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Affinity sorbents and detoxification strategies are described to remove different amounts of endotoxin. Advantages and disadvantages of the employed ligands are discussed and it is shown that both electrostatic and hydrophobic interactions contribute to the association of ligands and endotoxins. Furthermore, the flexibility of the ligand is more important than an exact structural match between ligand and ligate. Owing to the formation of endotoxin micelles and vesicles, microfiltration membrane adsorbers are particularly effective since mass transfer restrictions are almost absent in the flow-through pores.q2001 Elsevier Science B.V. All rights reserved

Endotoxins show strong biological effects at very low concentrations in humanŽ.beings threshold level: 1 ng per kg body weight and hour and in many animals whenentering the blood stream. Because of this toxicity, the removal of even minute amountsis essential for safe parenteral administration. A generally applicable method for theremoval of endotoxins is not available; methods used for water purification, such as ultrafiltration, have little effect on low, but critical endotoxin levels in protein solutions.Ion exchangers, two-phase extraction, and affinity techniques have been applied withvarying success. Also, tailor-made endotoxin-selective adsorber matrices for the preven-tion of endotoxin contamination and endotoxin removal are used for this purpose. Aftergiving a short overview of the properties of endotoxins, this review intends to provide apicture of the various affinity techniques employed for their removal. Avenues arepointed out for optimizing methods with regard to the specific properties of endotoxinsin aqueous solution.

Reference: Anspach, Friedrich Birger  Review: Endotoxin removal by affinity sorbents J. Biochem. Biophys. Methods 49 (2001) 665–681

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