Interfacing artificial life with natural life: liquid droplets as transporters for living cells
Silvia Holler & Martin Hanczyc
University of Trento, Trento, Italy
May 28, 2020, 7 a.m. UTC // May 28, 2020, 7 a.m. in UTC
Soft matter systems can be driven out of equilibrium and can respond to externally imposed stimuli. The transition from equilibrium to non-equilibrium can be driven through for example chemical potential, external fluid flow or static external fields. An example of soft matter systems that show response to these kinds of transitions are liquid droplets. Liquid droplets can be created mixing two immiscible fluids (oil and water) and can exhibit behaviors such as fission, fusion and movement. Movement is normally shown by living cells and organisms and can be defined as a ‘life-like’ behavior. We were able to create systems of oil-in-water droplets that self-organize and move in response to external stimuli. Decanol droplets move for example in response to pH or salt gradients. We exploited droplets to transport objects such as cells. Specifically, we developed chemotactic droplets able to move light cargos such as hydrogel alginate capsules embedded with living cells. Using this system, we demonstrate efficient and sterile transport of a few types of bacteria and yeast, and even human cell lines. We recently discovered that some eukaryotic cell lines, only when placed in capsules, secrete compounds that act as surfactants, thereby reinforcing the interface between the artificial and living systems. This is an example of not only how the interface between artificial life and biological life could be designed but how the one system can augment the other.