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

微粒物质（PM）污染环境空气是一个日益严重的问题，对数百万人的健康构成严重威胁。暴露于高浓度的可吸入颗粒物会显著增加患心血管疾病、肺病和癌症的风险。直径< 1µm的细至超细颗粒可进入肺细胞，引发炎症反应。尽管有大量的流行病学研究，但控制颗粒物质与单细胞之间直接相互作用的机制几乎不为人所知。特别是，涉及结合和摄取的细胞力学概念是未知的。因此，需要研究光学概念，它可以在纳米和毫秒的尺度上访问细胞反应。为此，我们将使用新的光学技术和生物物理概念。特别是，我们将使用光学镊子，三维热噪声跟踪和快速，无标记的超分辨率显微镜来获得有关进入细胞的相关机制的新见解。通过这些工具，我们将回答有关什么生物物理原理支配颗粒物质进入细胞的过程，颗粒特性如何影响颗粒与细胞接触的命运，以及不同肺细胞类型如何处理颗粒物质的问题。利用我们的光子力显微镜，我们将以一种可重复的方式将颗粒物质带到肺细胞附近，以测量颗粒与细胞接触时结合强度和摩擦的变化。这些相互作用参数可以从粒子的热位置波动中提取出来。实验还辅以使用旋转相干散射（ROCS）显微镜的活细胞超分辨率显微镜，这使我们能够观察到细胞骨架在100 Hz下对颗粒物暴露的反应。通过使用各种荧光细胞毒性测定，细胞反应模式将与促炎细胞因子的存在相关。这项研究是为两位博士生设计的，他们在不同方面密切合作。一名博士生将使用光子力显微镜研究颗粒物质进入肺细胞，并通过热噪声跟踪描述控制不同颗粒吞没的机械原理。另一名博士生将使用ROCS显微镜研究不同颗粒结合和进入肺上皮细胞时的细胞骨架反应。通过这项研究项目，我们期望提供重要的额外知识，以更好地评估颗粒物质特性对肺部疾病的影响，这与环境毒理学和肺病学领域最为相关。

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.