Measurement of diameter of different nanoparticle agglomerates after contact with A549 cells revealed different size behavior

Nanomaterials and nanoparticles are gaining more and more importance in science, technology, and medicine. However, increasing usage and distribution of these materials may cause a potentially higher health risk. Additionally, the toxicity of nanoparticles is depending not only on the size of the primary particles but also on the size of their agglomerates. Consequently, studies are needed to examine the behavior and fate of nanoparticles in terms of their dimensions after they have gotten in contact with target cells. Therefore this study focused on the investigation of changes in the size of various commercially available nanoparticles such as TiO2 P25, TiO2 T805, Printex® 90, and a ZnO with particles smaller than 50 nm after applying them in-vitro to the human lung cell line A549. Cells were treated with a particle concentration of 1000 ng/cm2 using an air-liquid interface culture. Following an one hour or 24 hours treatment, cells were processed for electron microscopical investigation and diameters of agglomerates were measured. After one hour particles were predominantly found attached to the cellular surface whereas 24 hours later most particles were seen intracellularly. Comparing the diameter of the agglomerates after one and 24 hours, TiO2 P25 showed a tendency to increase, whereas ZnO