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Collective Behaviour of Protocells

Collective Behaviour of Protocells

Recent progress in the chemical construction of colloidal objects comprising integrated biomimetic functions is paving the way towards rudimentary forms of artificial cell-like entities (protocells). Materials based on consortia of micro-compartmentalized colloidal objects could have potential use in synergistic sensing systems and biomimetic systems engineering. We recently addressed the challenge of how to design micro-compartmentalized colloidal objects as a model of a synthetic protocell community exhibiting a rudimentary form of materials based colloidal objects, and provided a novel microscale engineering approach to inducing higher-order behaviour in mixed populations of synthetic protocells.


Phagocytosis-inspired behaviour in synthetic protocell communities of compartmentalized colloidal objects:

The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). We developed a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures. Engulfment of the colloidosomes enables selective delivery and release of water-soluble payloads, and can be coupled to enzyme activity within the MPE droplets.

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Predatory behaviour in synthetic protocell Communities:

We demonstrate an artificial form of predatory behaviour in a community of protease-containing coacervate microdroplets and protein–polymer microcapsules (proteinosomes) that interact via electrostatic binding. The coacervate microdroplets act as killer protocells for the obliteration of the target proteinosome population by protease-induced lysis of the protein–polymer membrane. As a consequence, the proteinosome payload (dextran, singlestranded DNA, platinum nanoparticles) is trafficked into the attached coacervate microdroplets, which are then released as functionally modified killer protocells capable of rekilling. Our results highlight opportunities for the development of interacting artificial protocell communities, and provide a strategy for inducing collective behaviour in soft matter microcompartmentalized systems and synthetic protocell consortia.

7-NatChem - Yan Qiao

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6-NatComm-Liangfei Tian

 

Spontaneous assembly of chemically encoded two-dimensional coacervate droplet arrays by acoustic wave patterning:

The spontaneous assembly of chemically encoded, molecularly crowded, water-rich micro-droplets into periodic defect-free two-dimensional arrays is achieved in aqueous media by a combination of an acoustic standing wave pressure field and in situ complex coacervation. Acoustically mediated coalescence of primary droplets generates single-droplet per node micro-arrays that exhibit variable surface-attachment properties, spontaneously uptake dyes, enzymes and particles, and display spatial and time-dependent fluorescence outputs when exposed to a reactant diffusion gradient. The technology of acoustic radiation forces offer a novel route to the design and construction of ‘water-in-water’ micro-droplet arrays with controllable spatial organization, programmable signalling pathways and higher order collective behaviour.

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Chemical signalling and functional activation in colloidosome-based protocells:

The emergence of new functionalities in inorganic colloidosomes via chemical communication between different protocell populations provides a first step toward the realization of interacting communities of synthetic functional microcompartments. An aqueous-based microcompartmentalized model involving the integration of partially hydrophobic Fe(III)-rich montmorillonite (FeM) clay particles as structural and catalytic building blocks for colloidosome membrane assembly, selfdirected membrane remodeling, and signal-induced protocell communication is described. The clay colloidosomes exhibit size- and charge-selective permeability, and show catalytic function involving peroxidase-like membrane activity, that is used for the colloidosome-mediated synthesis and assembly of a temperature-responsive poly(N-isopropylacrylamide)(PNIPAM)/clay-integrated hybrid membrane. In situ PNIPAM elaboration of the membrane is coupled to a glucose oxidase (GOx)-mediated signalling pathway to establish a primitive model of chemical communication and functional activation within a synthetic “protocell community” comprising a mixed population of GOx-containing silica colloidosomes and FeM-clay colloidosomes. Triggering the enzyme reaction in the silica colloidosomes gives a hydrogen peroxide signal that induces polymer wall formation in a coexistent population of the FeM-clay colloidosomes, which in turn generates self-regulated membrane-gated activity within the clay microcompartments.

9-Small-Shiyong Sun

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