Autonomous Directional Motion of Actin‐Containing Cell‐Sized Droplets

Abstract

Cell motility is potentially the most apparent distinction of living matter, serving an essential purpose in single cells and multicellular organisms alike. Thus, the bottom‐up reconstitution of autonomous motion of cell‐sized compartments remains an exciting but challenging goal. Herein, actin‐driven Marangoni flows are engineered to generate rotational and translational motility of surfactant‐stabilized emulsion droplets. The interaction between actin filaments and the negatively charged block‐copolymer Krytox is identified as the driving force for Marangoni flows at the droplet interface. Tuning the actin–Krytox interplay, sustained autonomous unidirectional droplet rotation with 1.7 rot h−1 is achieved. Ultimately, this rotational motion is transformed into a translational rolling motion by introducing interactions between the droplets and the surface of the observation chamber. Accordingly, translational motility of actin‐containing droplets at velocities of 0.061 ± 0.014 μm s−1 is reported herein and an overall displacement of several hundreds of micrometers within 30 min is observed. These self‐propelled systems with biologically active molecules demonstrate how motility could be implemented for synthetic cells.

pH-Triggered Assembly of Endomembrane Multicompartments in Synthetic Cells

“…Up to now, protein-encapsulated dsGUVs in the presence of Mg 2+ ions showed poor production efficiency and depended on the isoelectric point P i of the protein. Negatively charged cytosolic proteins, such as actin, 49 may hinder the charge-mediated assembly of the lipid bilayer in the presence of high Mg 2+ ion concentration (i.e., 10 mM). To palliate this issue, microfluidic platforms incorporating pico-injectors 50 can be used to sequentially reconstruct an actin cytoskeleton, 3 but release of actin-containing dsGUVs remained challenging.…”

Integrin αIIbβ3 Activation and Clustering in Minimal Synthetic Cells

“…[29] For the charge-mediated formation of dsGUVs the oil phase consisted of FC-40 fluorinated oil (3M, USA) with 1 mM of the block-copolymer surfactant perfluorpolyether (PFPE)(7000 g mol À1 )-polyethylenglycol (PEG) (1400 g mol À1 )-PFPE(7000 g mol À1 ) (TRI7000) synthesized according to protocols published earlier [29,30] and %10 mM PFPE-carboxylic acid (Krytox, MW 7000-7500 g mol À1 ; DuPont, Germany). [31] The droplets were created at 1 kHz with a diameter of 30 μm by using syringe pumps (PUMP 11 ELITE; Harvard apparatus, USA). Each sample was prepared from 70 μl aqueous phase.…”

pH-Triggered Assembly of Endomembrane Multicompartments in Synthetic Cells

“…Up to now, protein-encapsulated dsGUVs in presence of Mg 2+ ions showed poor production efficiency, and depended on the isoelectric point Pi of the protein. Negatively charged proteins, such as actin 44 , may hinder the charge mediated assembly of the lipid bilayer in presence of high Mg 2+ ions concentration (i.e. 10 mM).…”