Polymer/nucleotide droplets as bio-inspired functional micro-compartments

Williams, David; Koga, Shogo; Hak, Cik Rohaida Che; Majrekar, Animesh; Patil, Avinash J.; Perriman, Adam W.; Mann, Stephen

doi:10.1039/c2sm25184a

Cited by 88 publications

(136 citation statements)

References 33 publications

(26 reference statements)

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“…[41,42] It is commonly considered that the general mechanism of phase separation occurs via two steps: an enthalpic contribution to the free energy from the electrostatic interaction between the molecules (in the case of charged polymers), which draws the molecules toward each other, and an entropic driving force from the rearrangement of ions and water leading to a lowering of the Gibbs free energy and the formation of membraneless, chemically enriched microdroplets. [47] The rate of coalescence and, therefore, growth can be tuned by the overall charge ratios of the coacervate components. [43,44] The surface tension of coacervates is low, between 1 µN/m and 1 mN/m, [45] and even lower for aqueous two-phase systems of neutral polymers.…”

Section: Polymer-rich Dropletsmentioning

confidence: 99%

Directed Growth of Biomimetic Microcompartments

et al. 2019

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twilight zone), it is widely recognized that the formation of micro-and nanocompartments is an essential ingredient of all forms of life. This spatial constraint serves numerous purposes, including the segregation and protection from the environment (to allow for individuality and maintenance), the establishment of gradients (to enable and make use of outof-equilibrium conditions), and the role of 2D and 3D confinement for self-organization phenomena, all of which serve to overcome the overall "dilution problem." In order to fulfill another cornerstone of life-proliferation-compartments also need to change with time by fusion, growth, and division. In particular, the dynamic growth of compartments is an essential prerequisite for enabling selfreproduction as a fundamental life process, both in simplistic systems such as droplets or fatty acid-based vesicles, as well as for lipid vesicle compartments with membranes that resemble the biomembranes of today's cells. In this context, we argue that growth deserves more attention, not only because growth precedes division but also because of the difficulty to realize growth compared to division, especially in the case of lipid vesicles, where budding and division has been observed in response to various factors. This growth aspect has also been recognized in basic theoretical models of living systems such as Ganti's chemoton, [1,2] for which the increase of membrane area (referred to as membrane formation) was postulated to be one of three subsystems, characterizing living entities from a chemical viewpoint. The autopoietic theory was also centered on the membrane but focused on self-maintenance rather than on (self-)reproduction. [3,4] However, such a self-maintaining system could also enter a self-reproduction mode, manifested by growth, if homeostatic misbalance leads to excess membrane formation as shown in a thought experiment by Luisi. [3] In this progress report, we review the existing approaches for growth of compartments in the context of bottom-up synthetic biology and protobiology. We consider mainly micrometer-sized compartments due to their characteristic cellular dimensions; this feature also ensures that the area and curvature of the interface or the bounding membrane has less influence on the enclosed solution. Microcompartments of various origins and chemistries have been used as protocell models, and many studies have addressed growth and division simultaneously in an ambitious effort to mimic self-reproduction. Contemporary biological cells are sophisticated and highly compartmentalized. Compartmentalization is an essential principle of prebiotic life as well as a key feature in bottom-up synthetic biology research.In this review, the dynamic growth of compartments as an essential prerequisite for enabling self-reproduction as a fundamental life process is discussed. The micrometer-sized compartments are focused on due to their cellular dimensions. Two types of compartments are considered, membraneless droplets and membrane-bound microcompartments. Gr...

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Section: Polymer-rich Dropletsmentioning

confidence: 99%

Directed Growth of Biomimetic Microcompartments

et al. 2019

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“…12,13 Cell-free gene expression systems have also been encapsulated within water-in-oil emulsion droplets, 14 as well as in non-lipid membrane-bound protocells produced by the spontaneous assembly of protein-polymer nanoconjugates (proteinosomes) 15 or amphiphilic silica nanoparticles (colloidosomes), 16 and in molecularly crowded environments such as aqueous dextran/polyethylene glycol (PEG) two-phase water-inoil emulsion droplets 17 and condensed droplets of a cell lysate. [20][21][22][23][24][25] As cell-free gene expression has not been demonstrated in coacervate-based protocells, we embarked on developing appropriate methodologies to establish this platform technology in chemically enriched, molecularly crowded micro-droplets. 19 We recently showed that coacervate micro-droplets prepared by complexation of cationic polyelectrolytes and anionic mono-or polynucleotides can be used as membrane-free, molecularly crowded protocells with a range of biomimetic characteristics.…”

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confidence: 99%

In vitro gene expression within membrane-free coacervate protocells

et al. 2015

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“…Although coacervate micro-droplets can be stabilized by excess surface charge [72], under many conditions they exhibit a propensity to coalesce into larger droplets or undergo macroscopic phase separation. As a consequence, their use as a protocell model can be compromised by their liquid-like behaviour and low surface tension.…”

Section: Hybrid Protocell Modelsmentioning

confidence: 99%