SKM 2023 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 52: Statistical Physics of Biological Systems II (joint session BP/DY)

DY 52.3: Vortrag

Freitag, 31. März 2023, 10:00–10:15, BAR Schö

Dynamics of vesicle clusters studied by passive x-ray microrheology — •Titus Czajka1, Charlotte Neuhaus1, Jette Alfken1, Moritz Stammer1, Yuriy Chushkin2, Diego Pontoni2, Christian Hoffmann3, Dragomir Milovanovic3, and Tim Salditt11Institut for X-ray Physics, Georg-August-Universität Göttingen, Germany — 2ESRF, Grenoble, France — 3Laboratory of Molecular Neuroscience, DZNE, Berlin, Germany

Inferring the viscoelastic properties of a complex fluid from the dynamics of suspended tracer particles is a common method to perform rheological measurements where a direct measurement of the constituents of the system is not possible or impractical. The previously observed pool formation of vesicles induced by divalent salts or the protein synapsin I is a case in point. One would like to know how the mobility of a single (tracer) particle changes in a dense pool as compared to a homogeneous vesicle suspension. Here we used x-ray correlation spectroscopy (XPCS) to measure silica nanoparticles immersed in a complex biomolecular fluid composed of small unilamellar vesicles and CaCl2, or SUVs and Synapsin-Ia protein, both in buffer solution. While the former system leads to irregular clusters, the latter has been observed to form protein induced vesicle pools, suggesting a liquid-liquid phase separation. Analysis of the photon correlation functions reveals the presence of different timescales, which we attribute to the free diffusive motion of the tracer particles and the motion of the tracer particles that interact with the cluster.

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