Endotoxin Removal Using a Synthetic Adsorbent of Crystalline Calcium Silicate Hydrate

Abstract

A synthetic adsorbent of crystalline calcium silicate hydrate, the product LRA by Advanced Minerals Corp., has been studied for endotoxin removal from aqueous solutions. This adsorbent removes endotoxin effectively, and the removal is greatly enhanced by the presence of an electrolyte such as NaCl, Tris-HCl, or Na2HPO4. It has an endotoxin removal capacity as high as 6 million endotoxin units (EU) per gram. Its endotoxin removal kinetics is fast, and for instance, over 99.9% endotoxin in a 5000 EU/mL solution was removed by mixing for 2 min at an adsorbent usage of 10 g/L. Using the chromatographic column method to treat a 5000 EU/mL solution, an endotoxin log-reduction factor of 6.2 was achieved with a single pass. This adsorbent also demonstrated significantly better performance when compared to many commonly used endotoxin removal agents, such as ActiClean Etox Endotoxin Removal Resin, Affi-Prep Polymyxin Support, Detroxi-Gel Endotoxin Removing Gel, Q Sepharose Fast Flow Media, and Sigma Endotoxin Removal Solution. Furthermore, it demonstrated a high selective removal of endotoxin from a solution of lambda DNA. This adsorbent provides opportunities for developing disposable, scaleable, and cost-effective methods for endotoxin reduction in many biotechnological and pharmaceutical processes.

Phage Display of Tissue Inhibitor of Metalloproteinases-2 (TIMP-2)

“…Inclusion bodies containing N-TIMP-2 or a mutant were dissolved in 8 M urea containing 20 mM Tris-HCl, pH 8.0, and 10 mM DTT. Before separating insoluble cell debris from the lysate, the solution was treated with 20 g/liter LRA (calcium silicate hydrate) for 1 h at room temperature to remove endotoxin and DNA (25). The cleared lysate was centrifuged using a BeckmanCoulter ultracentrifuge at 30,000 rpm to remove insoluble material, and the soluble fraction was applied at a flow rate of 1 ml/min to a column of Q-Sepharose (GE Healthcare, 1.5 ϫ 10 cm) pre-equilibrated with 20 mM Tris HCl, pH 8.0, containing 8 M urea.…”

Preparation and Characterization of Calcium Silicate for CO2 Sorption

“…An earlier study reported the preparation of calcium silicate hydrate (CSH) solids using hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 °C (Brodnax and Rochelle 2000). A synthetic adsorbent crystalline CSH was used to remove endotoxin (Zhang et al 2005). The calcium silicate absorbent was prepared from recycled glass (Arthur and Rochelle 1998).…”

Chromatographic Removal of Endotoxins: A Bioprocess Engineer's Perspective

“…The selection of a suitable endotoxin removal system is based on the properties of the bioproducts being purified. The interaction between the anionic phosphate in LPS and the cationic ligands on the sorbents are mostly utilised as the mechanism of endotoxin removal [4]. Anion exchange and affinity chromatography are based on cationic functional ligands such as diethylaminoethanol, histidine, polymyxin B, poly (ε-lysine), and poly (ethyleneimine) [4].…”

“…The interaction between the anionic phosphate in LPS and the cationic ligands on the sorbents are mostly utilised as the mechanism of endotoxin removal [4]. Anion exchange and affinity chromatography are based on cationic functional ligands such as diethylaminoethanol, histidine, polymyxin B, poly (ε-lysine), and poly (ethyleneimine) [4]. Hydrophobic interactions between the lipid A portion and sorbent are also considered to be important attributes that removal techniques can take advantage of [4].…”

“…Anion exchange and affinity chromatography are based on cationic functional ligands such as diethylaminoethanol, histidine, polymyxin B, poly (ε-lysine), and poly (ethyleneimine) [4]. Hydrophobic interactions between the lipid A portion and sorbent are also considered to be important attributes that removal techniques can take advantage of [4]. Endotoxin molecules tend to form micelles or vesicles in aqueous solution [5].…”