Tools and techniques

Most of our research relies on quantitative observations on the single cell level. This requires techniques to manipulate individual cells in a well-controlled environment. We use established methods like microfluidics and optical tweezers but also develop our own dedicated methods. Recent examples include local membrane shielding by micropipette aspiration, single-cell impedance sensing on microelectrodes, micro-mechanical cell deformation and flattening, and combinations of microflow with photo-activatable caged compounds (flow photolysis).

Microfluidics provides a versatile platform for well-controlled live cell studies. In most of our projects, we are routinely using PDMS-based microfluidics to control the environmental conditions during single cell experiments. Besides standard approaches, we also develop our own microfluidic setups to implement, for example, mechanical actuation, readout via microelectrodes, or liquid supply by switchable hydrogels. For this purpose, we maintain a well-equipped microfabrication and microfluidics lab, focused mostly on photolithography and PDMS-based soft lithography.

Live cell imaging is an integral part of our work. We are equipped with a wide selection of optical imaging setups, including standard wide field microscopes as well as laser-scanning confocal and total internal reflection fluorescence (TIRF) microscopes. We also design our own computer-automated cell-tracking and high-speed imaging setups that are combined with optical tweezers or dedicated laser light sources for photo-activation. Besides our own instruments, we also have full access to several other advanced imaging methods on our campus, in particular, spinning-disk and electron microscopy. To analyze our imaging data, we have developed our own library of Matlab-based software tools for image segmentation, cell tracking, and quantification of intracellular fluorescence recordings.

We maintain fully equipped cell culture labs for both eukaryotic and bacterial cultures. At the moment, we mostly work with the social amoeba Dictyostelium discoideum, and several bacterial strains of Escherichia coli, and Pseudomonas putida. Besides the standard repertoire of cell culture techniques, we are also equipped for basic molecular biology approaches and cell fusion experiments.