Microphase separation as the cause of structural complexity in 2D liquids

Patashinski, Alexander Z.; Orlik, Rafal; Mituś, Antoni C.; Ratner, Mark A.; Grzybowski, Bartosz A.

doi:10.1039/c3sm51394g

Cited by 6 publications

(6 citation statements)

References 30 publications

(98 reference statements)

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“…Therefore, using recently developed theoretical frameworks, including exactly solvable models, one can potentially use these treatments to solve domain-domain PDFs of experimentally studied spherical vesicles [38][39][40][41][42][43][44]. Since, the complete physical description of both intra-and inter-domain correlations, and lipid phase separation is still a work in progress, the applicability of alternative computational approaches to interpret experimental data should be of interest [45][46][47][48][49][50].…”

Section: Discussionmentioning

confidence: 99%

Models for randomly distributed nanoscopic domains on spherical vesicles

2018

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The existence of lipid domains in the plasma membrane of biological systems has proven controversial, primarily due to their nanoscopic size-a length scale difficult to interrogate with most commonly used experimental techniques. Scattering techniques have recently proven capable of studying nanoscopic lipid domains populating spherical vesicles. However, the development of analytical methods able of predicting and analyzing domain pair correlations from such experiments has not kept pace. Here, we developed models for the random distribution of monodisperse, circular nanoscopic domains averaged on the surface of a spherical vesicle. Specifically, the models take into account (i) intradomain correlations corresponding to form factors and interdomain correlations corresponding to pair distribution functions, and (ii) the analytical computation of interdomain correlations for cases of two and three domains on a spherical vesicle. In the case of more than three domains, these correlations are treated either by Monte Carlo simulations or by spherical analogs of the Ornstein-Zernike and Percus-Yevick (PY) equations. Importantly, the spherical analog of the PY equation works best in the case of nanoscopic size domains, a length scale that is mostly inaccessible by experimental approaches such as, for example, fluorescent techniques and optical microscopies. The analytical form factors and structure factors of nanoscopic domains populating a spherical vesicle provide a new and important framework for the quantitative analysis of experimental data from commonly studied phase-separated vesicles used in a wide range of biophysical studies.

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Section: Discussionmentioning

confidence: 99%

Models for randomly distributed nanoscopic domains on spherical vesicles

2018

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“…The probabilistic formalism for the classification of fluctuating clusters was formulated in our papers. 29,38,39,41 In particular, a seven-atom cluster in a 2D liquid is classified as crystalline (hexagonal) when Q 6 > 0.555. 47 This criterion is additionally validated by an observation that in computer simulations of a 2D LJ crystal only a small fraction of seven-atom clusters had Q 6 < 0.555.…”

Section: Local Structure Of 2d Liquidbasic Conceptsmentioning

confidence: 99%

“…As a possible candidate for this task, we study here the 2D Lennard-Jones (LJ) liquid. The local (triangular) order in this liquid is unique and well quantified. − Another advantage of a 2D system is that a 2D configuration can be easily visualized and analyzed. In contrast, analysis of the local structures in even simple 3D liquids encounters serious methodological problems (see, e.g., refs and ) due to the competition between close packed local structures: fcc, hcp, and icosahedron.…”

Section: Nanofluidics and Local Order In Liquids: A Physical Picturementioning

confidence: 99%

Nanofluidic Manifestations of Structure in Liquids: A Toy Model

Patashinski¹,

Ratner

Orlik

et al. 2019

J. Phys. Chem. C

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Interaction with a solid boundary can alter the local order in the liquid near the boundaryan effect that is of special importance in geometries where these layers of altered structure occupy a significant part of the liquid. Currently, the local order is unambiguously confirmed and visualized only in two-dimensional (2D) liquids. A 2D liquid may play the role of a toy model for more complex liquids. We use molecular dynamic simulations to study instantaneous and time-averaged particle positions and velocities, quantitative characteristics of the local order, and drag forces in a 2D Lennard-Jones liquid occupying a narrow channel with moving walls. In layers of the liquid adjacent to the walls, long-time-averaged velocity significantly deviates from the predictions of conventional hydrodynamics. In the same layers, the time-averaged local order characteristics and the particle density show significant changes, with the amplitudes of these changes depending on the thermodynamic state of the liquid, the wall roughness, and commensurability with the wall.

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“…For example, it has recently been established that, under particular thermodynamic conditions, a two-dimensional fluid can become a stable mosaic of small differently ordered clusters which can be described as a state of micro-phase separation between amorphous and crystalline domains (Patashinski et al, 2013). …”

Section: The Solid Docks Hypothesismentioning

confidence: 99%

“…Within the framework of an out-of-equilibrium description of the cell membrane, the density fluctuations characteristic of amorphous states could explain membrane properties that are usually ascribed to the Ld/Lo coexistence paradigm. For example, it has recently been established that, under particular thermodynamic conditions, a two-dimensional fluid can become a stable mosaic of small differently ordered clusters which can be described as a state of micro-phase separation between amorphous and crystalline domains ( Patashinski et al, 2013 ).…”

Section: The Solid Docks Hypothesismentioning

confidence: 99%

Crystallization around solid-like nanosized docks can explain the specificity, diversity, and stability of membrane microdomains

Almeida

Joly

2014

Front. Plant Sci.

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To date, it is widely accepted that microdomains do form in the biological membranes of all eukaryotic cells, and quite possibly also in prokaryotes. Those sub-micrometric domains play crucial roles in signaling, in intracellular transport, and even in inter-cellular communications. Despite their ubiquitous distribution, and the broad and lasting interest invested in those microdomains, their actual nature and composition, and even the physical rules that regiment their assembly still remain elusive and hotly debated. One of the most often considered models is the raft hypothesis, i.e., the partition of lipids between liquid disordered and ordered phases (Ld and Lo, respectively), the latter being enriched in sphingolipids and cholesterol. Although it is experimentally possible to obtain the formation of microdomains in synthetic membranes through Ld/Lo phase separation, there is an ever increasing amount of evidence, obtained with a wide array of experimental approaches, that a partition between domains in Ld and Lo phases cannot account for many of the observations collected in real cells. In particular, it is now commonly perceived that the plasma membrane of cells is mostly in Lo phase and recent data support the existence of gel or solid ordered domains in a whole variety of live cells under physiological conditions. Here, we present a model whereby seeds comprised of oligomerised proteins and/or lipids would serve as crystal nucleation centers for the formation of diverse gel/crystalline nanodomains. This could confer the selectivity necessary for the formation of multiple types of membrane domains, as well as the stability required to match the time frames of cellular events, such as intra- or inter-cellular transport or assembly of signaling platforms. Testing of this model will, however, require the development of new methods allowing the clear-cut discrimination between Lo and solid nanoscopic phases in live cells.

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Microphase separation as the cause of structural complexity in 2D liquids

Cited by 6 publications

References 30 publications

Models for randomly distributed nanoscopic domains on spherical vesicles

Models for randomly distributed nanoscopic domains on spherical vesicles

Nanofluidic Manifestations of Structure in Liquids: A Toy Model

Crystallization around solid-like nanosized docks can explain the specificity, diversity, and stability of membrane microdomains

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