(174d) Polymeric Adsorbent for Lipopolysaccharides (LPS) Removal from Biopharmaceutical Products

The presence of endotoxin, also known as lipopolysaccharides (LPS), as a side product appears to be a major drawback for the production of therapeutic products that are essential for biomedical applications. Gram-negative bacteria (e.g., Escherichia coli) finds widespread application to produce recombinant products such as proteins, plasmid DNAs and vaccines. These therapeutic products are often contaminated with LPS, which are released during cell lysis step to obtain the useful therapeutic products and are present in the outer cell membrane of the gram-negative bacteria. LPS contaminated drug if administrated to humans or animals may cause serious side effects. Purification of therapeutic product often suffers from high product loss. For this reason, special attention must be paid when purifying proteins aiming a product as free as possible of LPS with high product recovery. Although there are a number of methods for removing LPS, the question about how LPS removal can be carried out in an efficient and economical way is still one of the most intriguing issues and has no satisfactory solution yet. In this work, polymeric polycaprolactone (PCL) nanoparticles (NPs) ~ 800 nm were synthesized using solvent evaporation technique at a relatively low cost and demonstrated to possess sufficient binding sites for LPS adsorption and removal with ~100% protein recovery. The PCL NPs removed greater than 90% LPS from protein solutions suspended in water using only one milligram (mg) of NPs. The LPS removal efficacy increased to a higher level (~96%) when phosphate buffered saline (PBS containing 137 mM NaCl) was used as a protein suspending medium in place of water, highlighting the positive effects of increasing ionic strength on LPS binding interactions and adsorption. The results further showed that the PCL NPs not only achieved 96 % LPS removal but also ~100% protein recovery for a wide concentration range from 10 – 1000 mg/ml of protein solutions. The NPs were highly effective in different buffers and pHs. Additional features of these polymeric NPs are its biocompatibility (environmental friendly), reusability after repeated elution and adsorption with negligible changes in LPS removal efficiencies. The results indicate that PCL NPs are an effective LPS adsorbent in powder form, which have a great potential to be employed in large-scale downstream applications.