Regensburg 2025 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 28: Microswimmers and Microfluidics (joint session DY/BP/CPP)

BP 28.4: Vortrag

Donnerstag, 20. März 2025, 16:00–16:15, H37

Trypanosoma brucei in microchannels: the role of constrictions — •Zihan Tan, Julian I. U. Peters, and Holger Stark — Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

Trypanosoma brucei (T. brucei), a single-celled parasite and natural microswimmer, is responsible for the fatal sleeping sickness in infected mammals, including humans. Understanding how T. brucei interacts with fluid environments and navigates through confinements is crucial for elucidating its movement through blood vessels and tissues, and across the blood-brain barrier.

Using a hybrid multiparticle collision dynamics (MPCD)–molecular dynamics (MD) approach, we investigate the locomotion of an in-silico T. brucei in three types of fluid environments: bulk fluid, straight cylindrical microchannels, and microchannels with constrictions. We observe that the helical swimming trajectory of the in-silico T. brucei becomes rectified in straight cylindrical channels compared to bulk fluid. The swimming speed for different channel widths is governed by the diameter of the helical trajectory. The speed first slightly increases as the channel narrows and then decreases when the helix diameter is compressed. An optimal swimming speed is achieved when the channel width is approximately twice the bulk helix diameter. Furthermore, T. brucei notably slows down when entering the narrow constriction in a microchannel and strongly speeds up upon exiting due to a release of deformation energy of the straightened cell body.

Keywords: Microswimmers; Mesoscopic Hydrodynamics; Multiparticle Collision Dynamics; Active Matter; Parasitism