Endotoxin contamination of engineered nanomaterials

Abstract

Endotoxin has established health impacts and may be a potential confounding factor in toxicity studies of engineered nanomaterials (ENM). We aimed to characterize endotoxin contamination for a representative set of carbon-based ENM. The established method for quantifying endotoxin relies on its activity in a complex biochemical assay system. Because of their physical and chemical properties, measurement of endotoxin associated with many ENM presents non-trivial technical challenges. We have made progress in identifying and implementing methods for ENM analysis with respect to endotoxin content, revealing varying levels of endotoxin contamination in the ENM examined here. The physical association of ENM and endotoxin and their shared physiological effects suggest the possibility that contaminating endotoxin may contribute to the toxicity that is ascribed to ENM. We found in this small number of samples that endotoxin levels were not related to type of ENM or surface area but may be introduced randomly during manufacture.

Interference of engineered nanoparticles with in vitro toxicity assays

“…Dispersions of nanoparticles were prepared in a standardized procedure as previously described (Schulze et al 2008). Moreover, each NP dispersion was tested to be free of lipopolysaccharides, that is, endotoxins that induce inflammatory responses or oxidative stress in cultured cells (Esch et al 2010;Schulze et al 2008).…”

Graphene and carbon nanotubes activate different cell surface receptors on macrophages before and after deactivation of endotoxins

“…Previously, it was shown that activated carbon, a carbon allotrope, can adsorb endotoxins (Du et al, 1987). Recent studies have also tried to understand the interaction of endotoxins with CBNs (Esch et al, 2010;Jackson et al, 2015). However, the methodology of endotoxin detection used in the latter studies did not consider the fact that endotoxins can bind CBNs and, therefore, interfere with the LAL assay itself.…”

“…One of the major concerns in NMs manufacturing is the sterility of the environment in which the material is being synthesized. Even though a large number of publications have addressed the issue of CBNs toxicity, very few have warned about the potential for contamination with endotoxins (Esch et al, 2010;Cha et al, 2013;Zhang et al, 2013;Amenta and Aschberger, 2015;Jackson et al, 2015). Endotoxins are also known as lipopolysaccharide (LPS), an endogenous pyrogen.…”

Low-dose gold nanoparticles exert subtle endocrine-modulating effects on the ovarian steroidogenic pathwayex vivoindependent of oxidative stress

“…The adoption of MRG-qPCR to nanotoxicologic research is critical due to the unpredictability of nanoparticle-gene interactions and the complex intracellular behavior of GNPs in situ . The concentration of endotoxin (Esch et al 2010) in our cultures was also evaluated to confirm that steroidogenic modulation was due to low-dose GNP exposure and not to this toxic confounder (Taylor and Terranova 1996). This evidence together with the lack of an oxidative-stress response in the present study suggests that the endotoxin present in our culture solutions did not contribute to the observed steroidogenic responses.…”