Institut für Theoretische Physik

17.04.2023

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof.dr. Gijsje Koenderink

The paradoxical material properties of living matter

Cells and tissues are dynamic but also need to withstand large mechanical loads. This paradoxical mechanical behavior is governed by fibrous protein scaffolds known as the cytoskeleton and the extracellular matrix. It is still poorly understood how these biopolymer networks can combine mechanical strength with the ability to dynamically adapt their structure and mechanics. I will summarize our recent findings obtained via quantitative measurements on synthetic cells reconstituted from purified biological constituents. I will focus on the role of mechanical crosstalk between the four cytoskeletal networks in the cell: actin filaments, microtubules, intermediate filaments and septins. These four filamentous systems contribute different structural and dynamical properties, enabling specific cellular functions. I will highlight our recent efforts to biochemically reconstitute their interplay, which allows us to connect the collective mechanical properties of cytoskeletal networks to the underlying molecular interactions, which involve cytoskeletal crosslinkers, motors, and the plasma membrane. Our findings may eventually be interesting to guide the search for selective anticancer drugs, since cancer cells often overexpress specific septins, intermediate filaments, and cytoskeletal crosslinker proteins leading to abnormal mechanical behaviors.

Kontakt: Prof. Laura Covi / Dr. Richard Vink

15.05.2023

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Jerome Wenger

Label-free detection of single proteins with their UV autofluorescence enhanced by nanophotonics

The vast majority of proteins contains tryptophan and tyrosine amino-acids which can be excited by deep-ultraviolet light and emit auto-fluorescence. Ultraviolet autofluorescence opens the possibility to study protein dynamics without labelling, removing all the issues of dye-induced changes in proteins. However, the UV autofluorescence brightness per protein remains quite weak denting the applicability of this technique. Here, we discuss optical horn antennas to provide signal enhancement, background screening and high collection efficiency. Using this technique we can detect and study the dynamics of label-free proteins like beta-galactosidase and streptavidin at single molecule-sensitivity. This design and method involving deep-UV light help us to monitor protein unfolding and dissociation during denaturation of protein at single molecule resolution. The optical horn antenna paves the way to UV auto-fluorescence spectroscopy with single molecule resolution and further extends the applicability of aluminum plasmonics into the UV domain.

Kontakt: Prof. Laura Covi / Dr. Richard Vink

26.06.2023

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Dr. Rainer G. Ulbrich

Physik in Göttingen: Geschichte mit Zukunft

Die Göttinger Physik hat vor 20 Jahren den Sprung ins 21. Jahrhundert geschafft -- von der ehrwürdigen Bunsenstrasse ganz hoch in den Norden der Stadt. Wie es dazu kam und wie sich ihr Bild seither gewandelt hat, soll mit einem kurzen Blick auf Geschichte in der alten und neuen Architektur, auf Gewerke und Wirken ihrer Protagonisten aus vergangenen drei Dezennien erinnert werden.

Kontakt: Prof. Laura Covi / Dr. Richard Vink

03.07.2023

Fakultät für Physik

Göttinger Physikalisches Kolloquium

Prof. Dr. Josef A. Käs

Does Oncology need Physics of Cancer?

Soft matter physics is essential to understand the onset of cancer metastasis. We have recently proven that the pathological changes in tumors cause cancer cell unjamming as a collective fluidity (i.e. cell motility) transition. A fundamental questions remains. Is unjamming just a side-effect or is it essential for tumor progression? Like the annual rings in a tree slice we have developed a morphodynamic link that uses the static morphology in cancer cell clusters to predict the dynamics of cancer cells that leads to metastasis. The provided phase diagram of cancer cell unjamming establishes a link between cancer cell motility and morphological changes in tumors that even prognosticates long-term distant metastatic risk that can occur after a decade. Our results demonstrate that an emergent physical phenomenon contributes to tumor progression. 92% of all cancer patients will benefit from this diagnostic insight.

Kontakt: Prof. Laura Covi / Dr. Richard Vink