Validity range of centrifuges for the regulation of nanomaterials: from classification to as-tested coronas

Abstract

Granulometry is the regulatory category where the differences between traditional materials and nanomaterials culminate. Reported herein is a careful validation of methods for the quantification of dispersability and size distribution in relevant media, and for the classification according to the EC nanodefinition recommendation. Suspension-based techniques can assess the nanodefinition only if the material in question is reasonably well dispersed. Using dispersed material of several chemical compositions (organic, metal, metal-oxide) as test cases we benchmark analytical ultracentrifugation (AUC), dynamic light scattering (DLS), hydrodynamic chromatography, nanoparticle tracking analysis (NTA) against the known content of bimodal suspensions in the commercially relevant range between 20 nm and a few microns. The results validate fractionating techniques, especially AUC, which successfully identifies any dispersed nanoparticle content from 14 to 99.9 nb% with less than 5 nb% deviation. In contrast, our screening casts severe doubt over the reliability of ensemble (scattering) techniques and highlights the potential of NTA to develop into a counting upgrade of DLS. The unique asset of centrifuges with interference, X-ray or absorption detectors—to quantify the dispersed solid content for each size interval from proteins over individualized nanoparticles up to agglomerates, while accounting for their loose packing—addresses also the adsorption/depletion of proteins and (de-)agglomeration of nanomaterials under cell culture conditions as tested for toxicological endpoints.

Releases from transparent blue automobile coatings containing nanoscale copper phthalocyanine and their effects on J774 A1 macrophages

“…6 (Wohlleben, 2012;Wohlleben et al, 2011Wohlleben et al, , 2013Walter et al, 2014). The size distribution analyses of pristine n-CuPc and Frag n-CuPc in RPMI showed that the dispersion of pristine n-CuPc contained smaller particles than the Frag n-CuPc.…”

Applicability of rat precision-cut lung slices in evaluating nanomaterial cytotoxicity, apoptosis, oxidative stress, and inflammation

“…Characterization of the NMs as prepared test items was performed using analytical ultracentrifugation (AUC) as described by Wohlleben (2012). Test substance stock dispersions were prepared 24 h before application onto the PCLuS and were analyzed on the day of exposure using the Beckman Ultracentrifuge XLI™ with integrated interference optics (Beckman Coulter, Palo Alto, CA, USA).…”

Centrifuges for Microgravity Simulation. The Reduced Gravity Paradigm

“…Centrifuges are applied in various disciplines mainly in material and particle technology like for separation (Sahuquillo et al, 1999;Kuang et al, 2015), for nanomaterials classification (Wohlleben, 2012), casting (Huisman et al, 1994;Liu and Barnett, 2002;Dikel et al, 2005;Velhinho and Rocha, 2011), combustion (Merzhanov, 1995), but also in areas like geology (Gopal Madabhushi, 2004;Costa et al, 2016), life sciences in plants (Musgrave et al, 2009;Herranz et al, 2013;Hoson and Wakabayashi, 2015), single cells (Loesberg et al, 2006;Tavakolinejad et al, 2015), animals (van Loon, 2001;van Loon et al, 2005;Tateishi et al, 2015) and humans (Akima et al, 2005;van Loon et al, 2012;Goswami et al, 2015).…”