Nano Cell Interactions

The Program Division “Nano Cell Interactions” focuses on the interactions of human cells with engineered materials and, in particular, nanoparticles. We investigate the interactions of biological and synthetic structures on small scales, even down to the nanoscale.

Background

Engineered nanoparticles are very small particles, with dimensions in the range of 1-100 nm. Due to their particular chemical and physical properties, they offer a great potential for applications in a wide variety of fields from the chemical industry or energy management to medical sciences. Nanoparticles are already increasingly used in convenience goods.

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Sizes of macro- and microscopical objects (top, from the left: pebbles and coarse sand, dispersions of various sizes of silicon oxide particles, water) and electron micrographs of corresponding particles (bottom).

Motivation

What happens if living organisms or the human body are exposed to nanoparticles or if the latter enter the human body via inhalation or through the mouth? We are especially interested in the processes that take place, when nanoparticles encounter single cells. It is already known that due to their small size and other characteristics, nanoparticles are able to enter cells. But, what mechanisms are involved in that uptake process and in which subcellular regions do the nanoparticles end up? Which cellular structures come in direct contact with the nanoparticles and what state do the particles exhibit within the cells, do they form agglomerates or do they dissolve? Does their interaction with cellular components induce a cellular response or are the cells unaffected by the presence of the particles? These are some of the questions we are dealing with.

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Human lung epithelial cells with nanoparticles (red), structures of the actin cytoskeleton (green).

Topics

One main aspect of our activities is associated with the synthesis of specific nanoparticles. In part, we label the particles, to be able to detect them by use of optical techniques like microscopy. We also characterize the particles, in order to gain accurate knowledge of their properties. For biological experiments we cultivate cells of human origin –outside of the human body- and expose them to nanoparticles. By use of biochemical assays we determine the subsequent cellular response. Last but not least, we apply methods of microscopy that permit the detection of nanoparticles within the cellular environment. Thus we combine chemical, biological, as well as physical skills and methods.

STED Microscopy

To investigate the interactions of nanoparticles with cellular components, we apply the recently developed STED (Stimulated Emission Depletion) microscopy as one of our main methods. This technique is a high-resolution version of fluorescence or confocal microscopy. Compared to the conventional technique, the former features a lateral resolution below 100 nm, thus enabling the detailed imaging of nanoparticles as well as biological structures at the nanoscale.

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STED-microscope used for the imaging of nanoparticles in interaction with biological structures (funded by the Federal Ministry of Education and Research, 2008-2011).