Daniela J Kraft

#Activematter research by Marine Le Blay, Joshua Saldi & Alexandre Morin from @unileiden.bsky.social published in @natphys.nature.com ! Read more: edu.nl/btmta. @leidenscience.bsky.social #physics

Cell membranes bend when proteins, viruses or nanoparticles stick to them. Two nearby bends “feel” each other through the lipid sheet, a bit like masses interact through curved spacetime. But do they always attract? We set out to measure that directly.

Repulsions and attractions between membrane-deforming spheres, Janus-particles, and opposite tube-like deformations in giant unilamellar vesicles Lipid membrane deformations have been predicted to lead to indirect forces between the objects that induce these deformations. Recent experimental measurements have found an attractive interaction bet...

🔗 Paper link below if you’d like the details.
doi.org/10.1039/d4sm...

🙌 Thanks to @danielajkraft.bsky.social for brilliant work and guidance, and to @leidenphysics.bsky.social for funding the project. Interested in membrane mechanics or how we perform experiments? Feel free to contact me.

It was a pleasure to give the talk, and such a lovely present to receive this amazing drawing! Thank you @gulliver-lab.bsky.social

It was a huge pleasure to listen to @danielajkraft.bsky.social yesterday.
Her talk was about ´Brownian mechanisms mechanical metamaterials and machines’.

She is an invited professor on the Paris Science chair.
@cnrs.fr @espciparispsl.bsky.social @justinlrt.bsky.social #liveSketching

Fabrication and Characterization of Bimetallic Silica-Based and 3D-Printed Active Colloidal Cubes Simulations on self-propelling active cubes reveal interesting behaviors at both the individual and the collective level, emphasizing the importance of developing experimental analogues that allow testing these theoretical predictions. The majority of experimental realizations of active colloidal cubes rely on light actuation and/or magnetic fields to have a persistent active mechanism and lack material versatility. Here, we propose a system of active bimetallic cubes whose propulsion mechanism is based on a catalytic reaction and study their behavior. We realize such a system from synthetic silica cuboids and 3D-printed microcubes, followed by the deposition of gold and platinum layers on their surface. We characterize the colloids’ dynamics for different thicknesses of the gold layer at low and high hydrogen peroxide concentrations. We show that the thickness of the base gold layer has only a minor effect on the self-propulsion speed and, in addition, induces a gravitational torque during sedimentation. For low activity, this gravitational torque orients the particles such that their velocity director is pointing out of the plane, thus effectively suppressing propulsion. We find that a higher active force can remedy the effects of torque, resulting in all possible particle orientations, including one with the metal cap on the side, which is favorable for in-plane propulsion. Finally, we use 3D printing to compare our results to cubes made from a different material, size, and roundness and demonstrate that the speed scaling with increasing particle size originates from the size-dependent drag. Our experiments extend the fabrication of active cubes to different materials and propulsion mechanisms and highlight that the design of active particles with anisotropic shapes requires consideration of the interplay between shape and activity to achieve favorable sedimentation and efficient in-plane propulsion.

Anisotropic active particles cannot always simply turn to change their orientation after having reached a surface: as we show for active colloidal cubes, this can lead to several populations with different particles speeds. Now out in Langmuir! pubs.acs.org/doi/10.1021/...

I know it's crazy timing, nuts but Michigan Biophysics is hiring on the tenure track! App deadline is May 15. Join our interdisciplinary community. careers.umich.edu/job_detail/2...

😅 Dankjewel!