Engineered nanomaterials in in vivo and in vitro models

Abstract: Nanotechnology and engineered nanomaterials (ENM) empower existing technologies. One of the great examples are III-V semiconductor nanowires (NW), which have a broad application range. The occupational safety and hazard organizations draw attention to ENM, as their physical and chemical characteristics differ from the ones of bulk materials. Additionally, the NW high aspect ratio geometry is of great concern, since it resembles the morphology of asbestos. Moreover, due to their small size, ENM materials are hard to detect and identify using conventional methods. During ENM technology development and large-scale production, the highest risk of human exposure is via inhalation. Therefore, we need to study how NW affect lung tissue using experimental exposure models. The work in this thesis aimed at filling the knowledge gap in ENM detection and identification, as well as understanding III-V semiconductor NW effects in in vitro and in vitro models.We have used enhanced darkfield microscopy – hyperspectral imaging method to detect and identify ceria nanoparticles in three differently prepared samples, and compared different combinations of data analysis methods. The remaining part of the thesis was devoted to the study of the III-V semiconductor NW effects on cells and tissue in vitro and in vivo. We have exposed two types of cell cultures (primary human lung (SAE) and human lung adenocarcinoma cell line (A549)) to gallium phosphide (GaP) NW. We observed that both type of cells are capable to engulf NW after 2 days, and that NW do not have any effect on the SAE and A549 cell morphology after 7 and 5 days, respectively. The NW concentrations used in this work are not toxic to A549 cells, since we did not see a change in cell mobility, viability or changes in ROS levels. After inhibiting specific endocytosis pathways in A549 cells, we showed that NW are actively taken up via phagocytosis and/or macropinocytosis.Additionally, we have performed in vivo mice exposure to GaP NW via intratracheal instillation. We have observed that NW induce an inflammation and allergic reaction of similar levels as the ones observed after exposure to carcinogenic multiwall carbon nanotubes. Additionally, we show that NW are capable to cross tissue barriers and reach distant organs after 28 days, however without introducing changes to the organ tissues. Lastly, we have performed a pilot study, where we investigated the effect of NW photodiodes on A549 cells. We observed that the presence of light inhibits cell proliferation. Furthermore, we show that the chemical make-up of the photodiodes is important, since some photodiodes dissolve in water based cell culturing media and release toxic compounds.