Contamination of nanoparticles by endotoxin: evaluation of different test methods

Abstract

BackgroundNanomaterials can be contaminated with endotoxin (lipopolysaccharides, LPS) during production or handling. In this study, we searched for a convenient in vitro method to evaluate endotoxin contamination in nanoparticle samples. We assessed the reliability of the commonly used limulus amebocyte lysate (LAL) assay and an alternative method based on toll-like receptor (TLR) 4 reporter cells when applied with particles (TiO2, Ag, CaCO3 and SiO2), or after extraction of the endotoxin as described in the ISO norm 29701.ResultsOur results indicate that the gel clot LAL assay is easily disturbed in the presence of nanoparticles; and that the endotoxin extraction protocol is not suitable at high particle concentrations. The chromogenic-based LAL endotoxin detection systems (chromogenic LAL assay and Endosafe-PTS), and the TLR4 reporter cells were not significantly perturbed.ConclusionWe demonstrated that nanoparticles can interfere with endotoxin detection systems indicating that a convenient test method must be chosen before assessing endotoxin contamination in nanoparticle samples.

Formulation effects on the release of silica dioxide nanoparticles from paint debris to water

“…The SiO 2 ENPs detected in leachates of C1 sample resemble very well in size and form to pristine SiO 2 ENPs and to SiO 2 ENPs in paint C1 (Fig. 7) (Smulders et al, 2012). As shown in Fig.…”

“…The epoxy silane group has a low point of zero charge, which occurs at pH 2-3, giving the surface a negative charge at pH levels utilized in most paints (pH around 8-9) (Greenwood, 2010). The SiO 2 ENPs were characterized by a set of analytical techniques, such as dynamic light scattering (DLS), zeta potential analysis, transmission electron microscope (TEM) coupled with energy dispersive X-ray (EDX) system, according to Smulders et al (2012) and Zuin et al (2014). To gain information about distribution of SiO 2 ENPs in paints, TEM was used.…”

Evidence for the detection of non-endotoxin pyrogens by the whole blood monocyte activation test

“…However, the assay can only be performed with liquid samples, creating difficulties for the testing of solid materials, such as medical devices (Ross and Bruch, 1982;, of which only rinsing solutions can be tested. Similarly, the assay has problems with dialysis fluids (Bohrer et al, 2001), liposomes (Harmon et al, 1997), nanoparticles (Smulders et al, 2012), and cell therapies (Montag-lessing et al, 2010). Drugs that interfere with the clotting system, i.e., through inhibition (binding of divalent cations such as ethylenediaminetetraacetic acid, citrate, protease inhibitors) or enhancement (high protein content, proteases), cannot be tested with the lAl test (Cooper et al, 1997;Duner, 1995).…”

A rapid screening method to evaluate the impact of nanoparticles on macrophages

“…On the other hand, the observed immunoactivation may originate from immuno-contaminants introduced during synthesis. This may be verified using a further test, the limulus amebocyte lysate (LAL) assay, 51,52 which is used as a gold standard to test for endotoxin contaminants. If contaminations are detected, the conventional depyrogenation processes are often not suitable for NP, 53 so that the NP synthesis process may need to be revisited.…”