Flexibility-induced effects in the Brownian motion of colloidal trimers

All microscopic objects, from enzymes to paint particles, are jittering constantly, bombarded by solvent particles: this is called Brownian motion. How does this motion change when the object is flexible instead of rigid? Together with Pepijn Moerman and colleagues, we have published the first measurements in Physical Review Research as part of my PhD research.

Flexible colloidal trimer
Flexible colloidal trimers change shape as they diffuse through the fluid. These shape changes lead to correlations, which cause the trimers at short times to diffuse mostly towards the central particle when the “scallop” closes (and in the other direction when it opens), which we call the Brownian quasiscallop mode.

The paper studies the diffusive motion of a segmentally flexible colloidal model system through experiments and numerical calculations. We observed hydrodynamic couplings between conformational changes and displacements, which may have implications for the transport and function of synthetic and biological flexible objects at the microscale.

A short summary of the work can be found on the Leiden University website: “How microscopic scallops wander“. To see the colloidal scallops in action, see the video below:

For the full story, the paper is available from the publisher: Ruben W. Verweij, Pepijn G. Moerman, Nathalie E. G. Ligthart, Loes P. P. Huijnen, Jan Groenewold, Willem K. Kegel, Alfons van Blaaderen, and Daniela J. Kraft, ‘Flexibility-induced effects in the Brownian motion of colloidal trimers’,  Phys. Rev. Research 2, 033136, 24 July 2020 (open access).

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