Advanced in vitro exposure systems.

A novel TEM grid sampler for airborne particles to measure the cell culture surface dose

21. May. 2020

Sonja Mülhopt1, Christoph Schlager2, Markus Berger2, Sivakumar Murugadoss3, Peter H. Hoet3, Tobias Krebs2, Hanns-Rudolf paur1 & Dieter Stapf1
1Karlsruhe Institute of Technology (KIT), Institute for Technical Chemistry, Eggenstein-Leopoldshafen, 76344, Germany. 
2Vitrocell Systems GmbH, Waldkirch, 79183, Germany. 
3KU Leuven, Environment and Health, Leuven, 3000, Belgium.

 

The surface dose and the spatial distribution on the membrane delivers important data for  measuring dose-response relationships in toxicity studies.  Image evaluation of transmission electron  microscopy (TEM) samples is a highly sensitive method for determination of deposition. This paper reports  the development and characterization of a novel holder for film coated TEM copper grids, which allows for  sampling under identical geometric and ambient conditions as in a cell culture chamber. 

 

Abstract

The applied surface dose is a key parameter for the measurement of toxic effects of airborne particles by air liquid interface exposure of human lung cells. Besides online measurement of the deposited particle mass by quartz crystal microbalance frequently other dose metrics such as particle size distribution, surface and agglomeration state are required. these particle properties and their spatial distribution can be determined by digital processing of micrographs obtained by transmission electron microscopy (TEM). Here, we report the development and characterization of a novel holder for film coated teM copper grids, which allows for sampling under identical geometric and ambient conditions as in a cell culture chamber. the sample holder avoids artefacts by reliable grounding of the grids and improves handling of the grids to prevent damage of the sensitive film. This sample holder is applied during exposure experiments with titanium dioxide nanoparticles. The measured dose of 0.2 µg/cm² corresponds well to the mass loading signal of the quartz crystal microbalance. Additionally, the spatial distribution of particles on the sampling surface shows a good homogeneity of deposition. this novel sampling method allows verifying other dosimetry methods and gives additional information about particle properties and homogeneity of the dose.
 

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