Correlative microscopy of lung epithelial in vitro model exposed to nanoparticles by using super-resolution optical and advanced ion/electron based techniques

Clear understanding of molecular events followed by lung epithelial cells/tissue response to inhaled nanoparticles is still lacking. As these interaction events in lungs eventually lead to diseases and potentially persistent inflammation [1,2], one urgently needs new and relevant investigation methods which could provide new insights into the key mechanisms of interaction. In our latest research we have thus focused on this toxicology problem first by developing an appropriate in vitro lung epithelial model and second by developing and implementing relevant advanced correlative imaging techniques capable of gathering more insight of interaction properties on scales well below optical resolution limit. In order to understand the mechanisms of molecular initiative events we have first performed live cell imaging using STED super-resolution microscopy by which few tens to hundred nm resolution was achieved locally. As the technique is incapable of providing resolution further down to nm and lacks the visualization of non-labeled surrounding structures and morphology, we thus introduced suitable complementary correlative microscopy techniques with high surface contrast, SEM and Helium Ion Microscopy (HIM). Main focus, besides sample and sample holder preparation for these high vacuum techniques, was dedicated to HIM measurements which in general are capable of providing better resolution and sensitivity compared to SEM [3]. From this ongoing study we briefly present the first interesting results of correlative microscopy combining optical, electron and ion based techniques on the epithelial cells exposed to TiO2 nanoparticles from micro to nano scale.
References:
1. Li, X., Jin, L. & Kan, H. Air pollution: a global problem needs local fixes. Nature 570, 437–439 (2019).
2. Underwood, E. The polluted brain. Science 355, 342–345 (2017).
3. Hlawacek, G. et Al. Helium Ion Microscopy. J. Vac. Sci. Technol. 32, (2014)