Acceleration of Lipid Reproduction by Emergence of Microscopic Motion

Abstract

<p>Self-reproducing chemical systems are essential for organic matter to reproduce, move and grow. In artificial settings, chemical reactions can show rich dynamics and auto-catalytic characteristics, however achieving higher order functionality from self-reproducing chemical systems remains a current challenge. Here, we show that <a></a><a>self-reproducing lipids can initiate, sustain and accelerate the movement of microscopic oil droplets in water and, in return, the chemotactic movement of these droplets significantly accelerates the autocatalytic production of the lipids</a>. As droplet motion accelerates the chemical reaction through active chemotactic movement, a reciprocal, two-way interplay is established across length scales, between bond-forming chemistry at the molecular scale, and droplet motility at the near macroscopic level. This chemo-motile coupling between the self-reproducing chemistry of lipids and the microscopic movement of droplets offers new means of performing work and catalysis in micro-heterogeneous environments. </p> <p> <br></p>

Run-and-halt motility of droplets in response to light

“…These gradients initiate internal and external Marangoni flows that propel the droplet forward. [26][27][28] The system parameters defining the speed, 29 direction, 30 and trajectory 31 of the droplets are the concentration and chemical structure of the amphiphiles, as well as the size of the motile droplets and the viscosity of the aqueous solution in which they move.…”

“…In a solution of trans-azobenzene, the droplets move in all directions (Figure 2A), provided that the concentration of the switch is above a given concentration that we define as the critical propulsion concentration 29 (CPC trans = 0.8 mM). The CPC is typically larger than the CMC trans = 0.5 mM.…”

Run-and-Halt Behavior of Motile Droplets in Response to Light

“…In a solution of trans-Azo, the droplets move in all directions autonomously (Figure 2A), provided that the concentration of the Azo amphiphile is above a concentration that we call critical propulsion concentration 37 (CPCtrans = 0.8 mM), which is typically higher than the critical micellar concentration (CMCtrans = 0.5 mM). We found that increasing the concentration of trans-Azo amphiphile leads to an increase in the average speed of the oil droplets because the concentration of micelles that fuel motility increases with the concentration of switch (Figure 2B).…”

Engineering transient dynamics of artificial cells by stochastic distribution of enzymes

“…This has, for example, been achieved by the construction of Janus particles, which are hemi-spherically covered with active catalysts [11][12][13][14][15] . Marangoni flow has also been employed as a propulsion force, e.g., to drive autonomous motion of surfactant-stabilized droplets [16][17][18][19][20] , to induce collective motion 21 , or to navigate in complex environment 22 . Recently, a random surface distribution of enzymes has been shown to propel micromotors in the presence of fuel 4,5 .…”