Uncovering a hidden world of dynamic structure using high resolution optical microspectroscopy: biological and medical applications and implications

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Speaker: Kareem Elsayad, Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna.

Host: Dag Hanstorp, Assistant Head of Department, Department of Physics.

While anatomical and molecular information can paint a seemingly complete picture of many biological systems, it is ultimately collective dynamic properties that define function. Translational dynamics at so-called physiological time scales can readily be obtained using e.g. optical microscopy and other methods, however functional behavior is sensitive to properties across a much broader range of time scales that are not that easily accessible. These include collective phenomena that occur at orders of magnitude higher frequencies (shorter time scales) than can be visualized, and where hydrodynamic interactions are more pronounced and dictate e.g. the phase state of a material. Here I will talk about some of our recent work using high-resolution wavelength and time resolved optical microspectroscopy to investigate this regime in biological cells,  tissues and fluids. Among other things, I will show how angle-resolved Brillouin light scattering imaging can reveal an otherwise completely hidden dynamic structure in living systems that is distinct from any more apparent static structure.  I will discuss several cases, where this can give us fundamental insight into the mechanical properties of plant cell walls and plant cell morphology,  the dynamics of water in muscle fibers, and unexpected structural dynamics in living cell nuclei that we are able to associate with chromatin condensation and genetic transcription. I will also touch upon two projects involving the measurement of phase waves supported by membranes, and the unusual viscoelastic scaling properties of diseased blood plasma and serum that have come out of recent studies we performed on samples from severely ill COVID-19 patients at a local hospital.