Detection and Quantitative Evaluation of Endotoxin Contamination in Nanoparticle Formulations by LAL-Based Assays
Bacterial endotoxin or lipopolysaccharide (LPS) is a membrane component of all Gram-negative bacteria. The administration of products contaminated with bacterial endotoxin can cause fever, shock, and even death. Accordingly, the FDA sets limits on the number of endotoxin units (EU) that may be present in a drug or device product. Limulus amoebocyte lysate (LAL) is the extract from amoebocytes of the horseshoe crab Limulus polyphemus, which reacts with bacterial endotoxin. Detection of the products of this reaction is an effective means of quantifying the EU present in a drug formulation. However, nanoparticles frequently interfere with the reactivity of endotoxin, the LAL reaction, or the detection of the reaction products. This interference can be manifested as either an enhancement or an inhibition, causing a respective overestimation or underestimation of the EU in the sample. Here, we present two methods for the detection and quantification of endotoxin in nanoparticle preparations: one is based on an end-point chromogenic LAL assay, and the second approach is based on measuring the turbidity of the LAL extract.
Key wordsendotoxin lipopolysaccharide Limulus amoebocyte lysate (LAL)
This project has been funded in whole or in part by federal funds from the National Cancer Institute, National Institutes of Health, under contract N01-CO-12400. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does the mention of trade names, commercial products, or organizations imply endorsement by the US Government.
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