Impact of ultrasonication on the delivered dose of metal oxide particle dispersions in vitro

Abstract

Particle dispersions with a stable size distribution are required to assess the risk of metal oxide nanopowders in cell culture experiments. The preparation process includes the disruption of larger particle aggregates and agglomerates by ultrasonication with a subsequent stabilization of the obtained particles. The applied particle dose during in vitro investigations may vary depending on particle diffusion and sedimentation processes, which are influenced by particle size and agglomeration behavior. The preparation process itself, as well as particle stability and dissolution, exert an influence on the physicochemical properties of the dispersed particles; they can decrease or increase delivered doses to the cellular system. The simulation of transport processes using the distorted grid (DG) and the three-dimensional sedimentation, diffusion, and dosimetry (3DSDD) models shows the influence of sonication treatment and the presence of stabilizing proteins in biological media for chosen metal oxide particles. This paper presents the effects of two different sonication methods (indirect and direct) on the delivered dose for different metal oxide nanopowders (CuO, MgO, and ZnO). Our results demonstrate that the use of less effective sonication power (indirect sonication) results in larger mean particle diameters and higher effective densities, leading to an increased delivered particle dose in vitro. For a higher effective acoustic power (direct sonication), the particle delivery decreased down to 20 % (for MgO) of the administered material; these data indicate that a large amount of particle material was not able to reach the cells. Thus, knowledge about preparation parameters of particle dispersions is required to generate comparable toxicological data with respect to the delivered dose.