Gas-borne particles with tunable and highly controlled characteristics for nanotoxicology studies

Abstract

For nanotoxicology investigations of air-borne particles to provide relevant results it is ever so important that the particle exposure of, for example cells, closely resembles the “real” exposure situation, that the dosimetry is well defined, and that the characteristics of the deposited nanoparticles are known in detail. By synthesizing the particles in the gas-phase and directly depositing them on lung cells the particle deposition conditions in the lung is closely mimicked. In this work we present a setup for generation of gas-borne nanoparticles of a variety of different materials with highly controlled and tunable particle characteristics, and demonstrate the method by generation of gold particles. Particle size, number concentration and mass of individual particles of the population are measured on-line by means of differential mobility analyzers (DMA) and an aerosol particle mass analyzer (APM), whereas primary particle size and internal structure are investigated by transmission electron microscopy. A method for estimating the surface area dose from the DMA-APM measurements is applied and we further demonstrate that for the setup used, a deposition time of around 1 h is needed for deposition onto cells in an air–liquid interface chamber, using electrostatic deposition, to reach a toxicological relevant surface area dose.

Size-Resolved Respiratory Tract Deposition of Sub-Micrometer Aerosol Particles in a Residential Area with Wintertime Wood Combustion

“…For non-soluble particles, the particle surface area is attracting increasing interest as several studies have shown a close correlation with the toxicological response -a result that may be explained by the interactions at the interface between the particles and the exposed tissue or proteins body fluids (e.g., Stoeger et al, 2006). This particle property is however not always easy to attain for irregular particles (like soot agglomerates) (Messing et al, 2012), or particles containing soluble material with an insoluble core. Number concentration is sometimes more readily measured and has been indicated to be directly associated with health outcomes (Wittmaack, 2007).…”

Nano-objects emitted during maintenance of common particle generators: direct chemical characterization with aerosol mass spectrometry and implications for risk assessments

“…The geometric mean diameter (GMD) is typically 20-40 nm (Messing et al 2012) while the aggregates produced with the HT are larger, 50-100 nm (mobility diameter) depending on the temperature used. The primary particle size of the aggregates, formed by both generators, is 5-15 nm.…”

“…The sampling was performed close to the emission zone during a session that included maintenance of both the HT and the SDG. (Messing et al 2012). …”

“…The relationship between the two diameters is determined by the effective density (ρ eff ). For example, the smaller "as-produced" particles can be synthesized either as highly aggregated or as sintered spheres, with up to a factor of 10 in difference in their effective density (Messing et al 2012). The measurement techniques used to determine size distributions in this work (differential mobility particle sizer, DMPS, below 100 nm and Aerodynamic particle sizer, APS, above 500 nm) measure the equivalent diameter, which accurately describes the deposition in the lung of each size range.…”

“…Emission measurements were carried out during maintenance of a setup (Messing et al 2012) that consists of two generators, a spark discharge generator (SDG) and a high temperature furnace (HT). Downstream both generators a sintering furnace and a differential mobility analyzer (DMA) are used for particle processing and particle size selection, respectively.…”