The natural world is largely built on hierarchical structures of individual cells knit together into tissues. Therefore, it is possible to build new bioinspired engineering materials from minimal cellular elements that follow a similar hierarchical structure. While nature is astonishingly diverse, all living systems follow the same fundamental set of criteria to survive and flourish.  According to the original chemoton model proposed by Ganti, the primary rules of life for cellular organisms include: compartmentalization, growth and division (metabolism), information processing, energy transduction (self-maintenance), and adaptability. Here we examine incorporating these foundational rules into our synthetic tissues to improve their capabilities.  Tissue-spreading and cell-sorting movements observed *in vitro* in early stages of amphibian embryonic development are highly similar to droplet coalescence and separation events in systems of two immiscible liquids. Hence, stabilized adhesive emulsions are promising for developing and approximating synthetic tissues.

In this manuscript, we investigate the mimicry of living tissues through stabilized adhesive emulsions and interfacial chemistry. Our approach expands upon the droplet interface bilayer (DIB) technique and enables us to produce a collection of protocells able to mimic many of the qualities of living organisms. The DIB technique assembles model lipid membranes at the interface of lipid-coated aqueous droplets positioned into contact within an oil medium.  Compared to other platforms, the DIB technique presents many benefits including the ability to repetitively assemble and separate multiple lipid bilayers, the ability to create asymmetric membranes, and most significantly satisfies multiple criteria in the chemoton model including compartmentalization and information processing. Here we focus on implementing a third chemoton principle into 2D DIB structures: adaptability. By incorporating stabilized water-based ferrofluids into the DIB platform, individual magnetite-infused microdroplets can collectively move in response to a targeted magnetic field and induce reorganizations in the neighboring non-magnetic aqueous compartments.  In this manuscript we print heterogeneous structures of magnetic and non-magnetic aqueous droplets in a dish centered between four electromagnets.  Activating the electromagnets allows for the selective generation of force on the dispersed magnetic droplets, pulling them away from their adhered non-magnetic neighbors and generating avalanche or transition events.  In these events some of the interfacial membranes are separated and new membranes are formed as droplets reach new equilibrium positions, modifying the underlying membranous architecture. After showing that these DIB structures can rearrange and reconfigure in response to magnetic fields, we analyze how such responses compare to tissue cohesion and natural cellular rearrangement as well as events observed in living tissues during morphogenesis and gastrulation.


Adaptive Bioinspired Synthetic Tissues

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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