Direct and indirect force measurements on living cells

Application of optical tweezers for investigation of viscoelastic deformations of living cells

Forces acting in- and outside of cells are a key factor of live. Mechanical disturbances from the outside or the inside of cells have strong influence on biological, chemical and biophysical processes of these cells. They do affect the extracellular matrix as well. Literature shows that the motion of cells is influenced by the viscoelasticity of the cell and the surrounding tissue. This has been researched with special focus within living zebrafish embryo. One can observe cells moving through the tissue, meeting at a place to form new organs together there. This motion is of high interest due to its similarity to the migration of cancer cells. What makes cells move towards a certain point within a large, complex environment like a developing embryo is the main research topic of this thesis.

For investigation holographic optical tweezers (HOT) are employed. Through strong, biocompatible lasers, transparent objects can be moved contactless in three dimensions. With HOT, tiny particles can be trapped and brought close to cells. These particles are used as handles to deform the cell membrane yielding data to obtain viscoelastic parameter of the cell. Due to the complexity of the living cell sophisticated measurement protocols are required. These are known in literature and have been partially realized in our labs.

The goal of this Master thesis is to obtain quantitative results in living cells in vitro and in vivo as well as further improving the applied protocols. It therefore encompasses preparation, conduction and evaluation of measurements, reading of literature, programming (Matlab, LabView) and adjustment of optical setups. Help and support by the supervisor will be granted on all related topics.

This Master thesis is organized thematically into the ongoing research of the "optical tweezers" team in the group of Nonlinear Photonics. In our team, Bachelor, Master and PhD students discuss frequently about results, problems, scientific related articles and new ideas. Students are encouraged to present their projects on national and/or international conferences. Publications are possible as well

We are looking for committed students who are interested in biophysical applications of Photonics and want to work on current research. German and English working environment is possible. Some knowledge in biology and programming (Matlab, LabView, C++) is good, but not necessary.

Contact person: if you are interested you can contact Robert Meißner who will be happy to show you our labs and present the offered thesis in the areas of optical micromanipulation.