Endotoxin is a common contaminant of many of the formulations submitted to the NCL. In fact, nearly one-third of formulations submitted to the NCL have levels exceeding recommended limits. However, most labs can successfully overcome this hurdle and reduce endotoxin contamination by taking a few precautionary steps during the synthesis and purification procedure.
NCL has collected the attached recommendations and references to aid you in reducing endotoxin contamination. Also, consider detailing your synthetic procedure, noting every step, reagent, reaction vessel and other materials coming into contact with the sample, and handling procedure; this is often helpful to highlight steps where endotoxin can be introduced.
Please note that the methods and kits summarized below are not universal and may not work equally well for all types of nanomaterials. Applying your best knowledge of the nanoparticle formulation, select a product which would be optimal for the given nanoparticle. An educated guess is a good start, but experimentation and empirical confirmation of the optimal performance will be needed. For example, this reference (Nanomedicine (Lond). 2010;5(4):555-62. doi: 10.2217/nnm.10.29) used a Triton X-114 procedure originally described for proteins and found that it works well for endotoxin removal from polymer-based nanoparticles. Please also note, that after purification or depyrogenation, several key physicochemical characterization assays should be conducted to confirm the particle’s integrity (e.g., size, zeta potential, PEG density, drug loading) and concentration. (It is expected that some amount of particles will be lost during the purification.)
The NCL does not endorse any of the commercial suppliers mentioned herein. They are provided for informational purposes only. Alternate supplies from other vendors may be substituted.
- Endotoxin and Depyrogenation Tips_June2021.pdf(PDF | 404 KB)
Cite this work
Researchers should cite this work as follows: