The influence of particulate matter properties on the biophysical entry mechanisms into lung cells

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The pollution of the ambient air with particulate matter (PM), microscopic suspended particles, is an aggravating problem that poses a serious health risk to millions of people. The exposure to elevated levels of PM significantly increases the risk for cardiovascular diseases, lung diseases and cancer. Fine to ultrafine particles with diameters < 1µm can enter lung cells and trigger inflammatory responses. Despite a large number of epidemiological studies, the mechanisms governing the direct interaction between particulate matter and single cells is hardly understood. In particular, the cell mechanical concepts involving binding and uptake are unknown. Hence, investigative optical concepts are needed, which can access cellular responses on scales of nanometers and milliseconds.For this, we will use novel optical technologies and biophysical concepts. In particular, we will use optical tweezers, three-dimensional thermal noise tracking and fast, label-free super resolution microscopy to achieve new insights into the relevant entry mechanisms into cells. Through these tools, we will answer questions about what biophysical principles govern the entry process of particulate matter into cells and how particle properties influence the fate of the particle in contact with the cell, but also how different lung cell types handle particulate matter. With our Photonic Force Microscopy, we will bring particulate matter in the vicinity of lung cells in a reproducible way to measure the change in binding strength and friction of the particle in contact with the cell. These interaction parameters can be extracted from thermal position fluctuations of the particles. The experiments are complemented by live-cell super-resolution microscopy using rotating coherent scattering (ROCS) microscopy, which enables us to observe cytoskeleton reorganization in 100 Hz in response to particulate matter exposure. By using various fluorescence cytotoxicity assays, the cellular response pattern will be correlated with the presence of pro-inflammatory cytokines.The research is devised for two PhD students working closely together on different aspects. The one PhD-student shall investigate the entry of particulate matter into lung cells using photonic force microscopy and characterize the mechanical principles governing the engulfment of different particles by thermal noise tracking. The other PhD student will focus on the investigation of the cytoskeleton response during binding and entry of different particles into lung epithelial cells using ROCS microscopy. With this research project, we expect to provide important additional knowledge to better assess the influence of particulate matter properties on lung diseases, most relevant for the fields of environmental toxicology and pulmonology.