To understand how surface modification can change the interaction of CBNP with biological systems we used PAHs to modify the surface of a toxicologically well-defined CBNP, Printex®90 (P90). This is characterized by a high surface area and has been widely used in toxicological studies, resulting in only minor toxic effects [1 (link), 33 (link), 34 (link)].
For modification of the P90 surface, we used benzo[a]pyrene (BaP) and 9-nitroanthracene (9NA). BaP was chosen because of the well characterized toxicity of its metabolites, which are known to induce ROS and DNA adducts [23 (link), 35 (link)–38 (link)]. BaP is known to induce Cyp1A1 and 1B1, which then metabolize BaP to toxic metabolites; this therefore allows monitoring of BaP activity and its biological effect [39 (link), 40 (link)]. In contrast, 9NA is a PAH that occurs during combustion, and is regarded as a low toxicity PAH, as predicted by the Ames test and human cell mutagenicity assay [41 (link)–43 (link)]. However, due to its nitro group other toxic mechanisms can occur induced by intermediates resulting from reduction of the nitro group [41 (link)]. As coating of a particle does not necessarily represent the situation found in nanoparticles that acquire PAH during synthesis, we also generated CBNP by acetylene combustion [44 ]. The resulting acetylene soot (AS) had a mixture of PAHs on the surface (AS-PAH). In the suspensions we used, AS-PAH had a slightly larger specific surface area, but similar aggregate size and ζ-potential compared to PAH-coated P90, The physicochemical parameters of the different particles were evaluated by a variety of analytic test methods (see Tables1 , 2 in the Results section and Additional files 1 , 2 ).
For modification of the P90 surface, we used benzo[a]pyrene (BaP) and 9-nitroanthracene (9NA). BaP was chosen because of the well characterized toxicity of its metabolites, which are known to induce ROS and DNA adducts [23 (link), 35 (link)–38 (link)]. BaP is known to induce Cyp1A1 and 1B1, which then metabolize BaP to toxic metabolites; this therefore allows monitoring of BaP activity and its biological effect [39 (link), 40 (link)]. In contrast, 9NA is a PAH that occurs during combustion, and is regarded as a low toxicity PAH, as predicted by the Ames test and human cell mutagenicity assay [41 (link)–43 (link)]. However, due to its nitro group other toxic mechanisms can occur induced by intermediates resulting from reduction of the nitro group [41 (link)]. As coating of a particle does not necessarily represent the situation found in nanoparticles that acquire PAH during synthesis, we also generated CBNP by acetylene combustion [44 ]. The resulting acetylene soot (AS) had a mixture of PAHs on the surface (AS-PAH). In the suspensions we used, AS-PAH had a slightly larger specific surface area, but similar aggregate size and ζ-potential compared to PAH-coated P90, The physicochemical parameters of the different particles were evaluated by a variety of analytic test methods (see Tables
Free full text: Click here
