Actin Polymerizing Motors to Assist Cytoskeleton-like Networks Formation in Artificial Cells.

Artificial cells are man-made systems that imitate specific functions of biological cells to study or harness cellular behavior. Biological cells can respond to external forces and signals by altering their shape, undergoing deformation, and generating the mechanical forces required for their movement. The cytoskeleton orchestrates this process through the coordinated action of actin filaments, intermediate filaments, and microtubules. Examples of artificial cells that sense and adapt to changes in their environment owing to cytoskeleton rearrangement have extensively been explored. These efforts focus on the use of biomolecules that stochastically self-assemble in the lumen of an artificial cell. Here, we employ actin polymerizing nanomotors to assist cytoskeleton formation inside artificial cells. Nano- and micromotors are a class of active colloids that can self-propel outperforming Brownian motion. Inspired by natures' way of leveraging biopolymerization reactions to sustain locomotion in microorganisms or in organelles within cells, we imitate the mechanism of motion of the food-born bacteria Listeria monocytogenes. Specifically, we coat polystyrene particles with an actin recruiting protein that allows for actin filament polymerization in a mammalian cell lysate environment. This polymerization results in up to a 3-fold increase in the propulsion of the motors compared to their Brownian motion. Lastly, we show that these motors can be encapsulated inside hybrid vesicle-based artificial cells made of amphiphilic block copolymers and phospholipids, forming actin filaments that assemble into a cytoskeleton-like network. Taken together, this effort highlights the synergistic integration of bottom-up synthetic biology and active matter, demonstrating how their convergence can advance the design of life-like systems.