Water-in-Water Emulsions Based on Incompatible Polymers and Stabilized by Triblock Copolymers–Templated Polymersomes

Buzza, D. Martin A.; Fletcher, Paul D. I.; Georgiou, Theoni K.; Ghasdian, Negar

doi:10.1021/la403356j

Cited by 77 publications

(62 citation statements)

References 40 publications

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“…However, no detailed description of the mechanism could be given. Buzza, Fletcher, Georgiou and Ghasdian, (2013) showed that tri-and diblock copolymers can be used to stabilize D/P and P/D emulsions at neutral pH. Phase inversion was observed at approximately the same volume fraction as in presence of protein microgels.…”

Section: Ph-induced Stabilization and Destabilizationmentioning

confidence: 99%

Particle stabilized water in water emulsions

2017

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Food products often contain mixtures of incompatible water soluble macromolecules such as proteins and polysaccharides. When two aqueous solutions of incompatible macromolecules are mixed they separate into two phases each enriched in one of the two macromolecules. Contrary to oilwater (O/W) emulsions, water/water (W/W) emulsions cannot be stabilized by addition of surfactants and in food applications macroscopic phase separation is avoided by gelling one or both phases. However, recently it was shown that W/W emulsions can be stabilized to varying extents by addition of particles. Such particle stabilized emulsions are also known as Pickering emulsions and have been studied extensively for O/W emulsions. Here the literature on particle stabilization of W/W emulsions is reviewed. The behavior of particle stabilized W/W emulsions is found to be quite different from that of O/W emulsions due to the much smaller interfacial tension and the much larger length scale at which the interface expresses itself. Besides the particle size, interaction of the particles with the macromolecules in the mixture and with each other at the interface appears to play a decisive role for stabilization.

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Section: Ph-induced Stabilization and Destabilizationmentioning

confidence: 99%

Particle stabilized water in water emulsions

2017

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“…The much smaller interfacial tensions and less obvious wettability preferences at aqueous/aqueous as compared to oil/water interfaces makes stabilizing water-in-water emulsions more challenging. Nonetheless water-in-water Pickering emulsions stabilized by latex beads 42, 43 , protein particles 44 , triblock copolymers 45 , and synthetic clay particles 40 have been produced.…”

Section: Introductionmentioning

confidence: 99%

Combining Catalytic Microparticles with Droplets Formed by Phase Coexistence: Adsorption and Activity of Natural Clays at the Aqueous/Aqueous Interface

Cakmak

Keating

2017

Sci Rep

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Natural clay particles have been hypothesized as catalysts on the early Earth, potentially facilitating the formation of early organic (bio) molecules. Association of clay particles with droplets formed by liquidliquid phase separation could provide a physical mechanism for compartmentalization of inorganic catalysts in primitive protocells. Here we explore the distribution of natural clay mineral particles in poly(ethylene glycol) (PEG)/dextran (Dx) aqueous two-phase systems (ATPS). We compared the three main types of natural clay: kaolinite, montmorillonite and illite, all of which are aluminosilicates of similar composition and surface charge. The three clay types differ in particle size, crystal structure, and their accumulation at the ATPS interface and ability to stabilize droplets against coalescence. Illite and kaolinite accumulated at the aqueous/aqueous interface, stabilizing droplets against coalescence but not preventing their eventual sedimentation due to the mass of adsorbed particles. The ability of each clay-containing ATPS to catalyze reaction of o-phenylenediamine with peroxide to form 2,3-diaminophenazone was evaluated. We observed modest rate increases for this reaction in the presence of clay-containing ATPS over clay in buffer alone, with illite outperforming the other clays. These findings are encouraging because they support the potential of combining catalytic mineral particles with aqueous microcompartments to form primitive microreactors.Clay minerals, which are composed of aluminosilicates with layered structures, are major components of soils and sedimentary rocks and among the most abundant minerals at the surface of the Earth 1 . Clays have found a wide variety of applications since ancient times including ceramics 2 , electrochemistry 3 , organoclay/polymer nanocomposites 4 and as catalysts in chemical reactions [5][6][7] . The availability of clay minerals and their potential for catalytic activity led to the proposal of these materials as inorganic catalysts for chemical evolution of biomolecules on the early Earth 8 . Since then clay particles have been demonstrated as catalysts for polymerization of activated nucleotides and amino acids 9 , lipid self-organization 10-12 and many other possible prebiotic reactions 11,13,14 .An important step in the transition from nonliving towards living matter is thought to be compartmentalization of molecules and of reactions 15,16 . Candidates for early-Earth compartments include crevices or pores in rocks 17 , self-assemblies of lipids or simpler amphiphiles to form vesicles [18][19][20][21][22][23] , and aqueous droplets formed by liquid-liquid phase separation 15,21,24 . Combining catalytic mineral surfaces with compartments such as amphiphile vesicles or droplets formed by aqueous/aqueous phase coexistence is therefore appealing as primitive protocell models. Szostak and coworkers reported that clay minerals accelerate the spontaneous conversion of fatty acid micelles into vesicles and some clay might get encapsulated within the vesicle...

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“…For water-in-oil systems, emulsification is routinely accomplished using amphiphilic surfactants that adsorb at the water/oil interface. This approach, while not impossible for ATPS 20,21 , is much more challenging due to the chemical similarity of the two aqueous media. An alternative means of stabilizing a liquid/liquid interface is adsorption of particles to form a Pickering emulsion 22 .…”

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confidence: 99%

Bioreactor droplets from liposome-stabilized all-aqueous emulsions

et al. 2014

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Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed B130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.

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Water-in-Water Emulsions Based on Incompatible Polymers and Stabilized by Triblock Copolymers–Templated Polymersomes

Cited by 77 publications

References 40 publications

Particle stabilized water in water emulsions

Particle stabilized water in water emulsions

Combining Catalytic Microparticles with Droplets Formed by Phase Coexistence: Adsorption and Activity of Natural Clays at the Aqueous/Aqueous Interface

Bioreactor droplets from liposome-stabilized all-aqueous emulsions

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