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Slavkova Z, Yancheva D, Genova J. Phase behaviour and structural properties of SOPC model lipid system in a sucrose solution. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 304:123287. [PMID: 37633099 DOI: 10.1016/j.saa.2023.123287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 08/17/2023] [Accepted: 08/19/2023] [Indexed: 08/28/2023]
Abstract
Lipid membranes are an important component of the biological cell. The profound understanding of their structure and functionality, as well as, the influence of various biologically relevant admixtures on their main characteristics is of great importance for research and development in medicine and pharmacology. The effect of sugars on the behaviour of the membrane cell enjoys an ever-increasing interest as they are biologically significant substances. We have studied the influence of the disaccharide sucrose on the physicochemical properties of SOPC (1-stearoyl-2-oleoyl-sn- glycero-3-phosphocholine) lipid system aiming to gain better understanding of the mechanisms of the interaction between both substances. For that purpose, we have used differential scanning calorimetry and Fourier-transform infrared spectroscopy. Our results show that adding sugar up to 300 mM concentration substantially alters the thermodynamic and structural properties of SOPC. The DSC thermograms at heating reveal a general lowering of the SOPC transition temperature Tm from gel to liquid crystalline phase (main phase transition, ordered-disordered phase transition) in the presence of sugar. The corresponding peaks are smeared and harder to trace. In agreement with this, a gradual decrease of the enthalpy values up to 300 mM was measured. The IR spectroscopy study provided spectral evidence for two states of hydration of the phosphate groups in the sugar-SOPC model systems suggesting a mechanism of interaction where only part of the phospholipid headgroups are hydrogen bonded to the sugar molecules. The obtained results are in good agreement with various earlier data including results about the bending elasticity moduli, as well as, some theoretical simulations on the sugar-lipid interactions. The current results also reinforce the potential of sucrose to be used as a cell protector against drought at, both, high and low temperatures.
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Affiliation(s)
- Zdravka Slavkova
- G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussée blvd., 1784 Sofia, Bulgaria; Joint Institute for Nuclear Research, 6 Joliot-Curie St., Dubna, Moscow Region 141980, Russia
| | - Denitsa Yancheva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Build. 9, 1113 Sofia, Bulgaria.
| | - Julia Genova
- G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussée blvd., 1784 Sofia, Bulgaria
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2
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Mesarec L, Góźdź W, Kralj-Iglič V, Kralj S, Iglič A. Coupling of nematic in-plane orientational ordering and equilibrium shapes of closed flexible nematic shells. Sci Rep 2023; 13:10663. [PMID: 37393271 DOI: 10.1038/s41598-023-37664-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/25/2023] [Indexed: 07/03/2023] Open
Abstract
The impact of the intrinsic curvature of in-plane orientationally ordered curved flexible nematic molecules attached to closed 3D flexible shells was studied numerically. A Helfrich-Landau-de Gennes-type mesoscopic approach was adopted where the flexible shell's curvature field and in-plane nematic field are coupled and concomitantly determined in the process of free energy minimisation. We demonstrate that this coupling has the potential to generate a rich diversity of qualitatively new shapes of closed 3D nematic shells and the corresponding specific in-plane orientational ordering textures, which strongly depend on the shell's volume-to-surface area ratio, so far not predicted in mesoscopic-type numerical studies of 3D shapes of closed flexible nematic shells.
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Affiliation(s)
- Luka Mesarec
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška Cesta 25, 1000, Ljubljana, Slovenia.
| | - Wojciech Góźdź
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena 5, 1000, Ljubljana, Slovenia
| | - Samo Kralj
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška Cesta 160, 2000, Maribor, Slovenia
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška Cesta 25, 1000, Ljubljana, Slovenia
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3
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Carbohydrate-carbohydrate interaction drives the preferential insertion of dirhamnolipid into glycosphingolipid enriched membranes. J Colloid Interface Sci 2022; 616:739-748. [PMID: 35247812 DOI: 10.1016/j.jcis.2022.02.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/04/2022] [Accepted: 02/24/2022] [Indexed: 11/22/2022]
Abstract
Rhamnolipids (RLs) are among the most important biosurfactants produced by microorganisms, and have been widely investigated because of their multiple biological activities. Their action appears to depend on their structural interference with lipid membranes, therefore several studies have been performed to investigate this aspect. We studied by X-ray scattering, neutron reflectometry and molecular dynamic simulations the insertion of dirhamnolipid (diRL), the most abundant RL, in model cellular membranes made of phospholipids and glycosphingolipids. In our model systems the affinity of diRL to the membrane is highly promoted by the presence of the glycosphingolipids and molecular dynamics simulations unveil that this evidence is related to sugar-sugar attractive interactions at the membrane surface. Our results improve the understanding of the plethora of activities associated with RLs, also opening new perspectives in their selective use for pharmaceutical and cosmetics formulations. Additionally, they shed light on the still debated role of carbohydrate-carbohydrate interactions as driving force for molecular contacts at membrane surface.
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4
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2D fluorescence correlation to visualize influence of size curvature and phase structure of silica nanoparticle-supported small unilamellar vesicle membrane. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Xia J, MacLachlan S, Atherton TJ, Farrell PE. Structural Landscapes in Geometrically Frustrated Smectics. PHYSICAL REVIEW LETTERS 2021; 126:177801. [PMID: 33988388 DOI: 10.1103/physrevlett.126.177801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
A phenomenological free energy model is proposed to describe the behavior of smectic liquid crystals, an intermediate phase that exhibits orientational order and layering at the molecular scale. Advantageous properties render the functional amenable to numerical simulation. The model is applied to a number of scenarios involving geometric frustration, leading to emergent structures such as focal conic domains and oily streaks and enabling detailed elucidation of the very rich energy landscapes that arise in these problems.
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Affiliation(s)
- Jingmin Xia
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
| | - Scott MacLachlan
- Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada
| | - Timothy J Atherton
- Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155, USA
| | - Patrick E Farrell
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
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6
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Maximino MD, Silva CY, Cavalcante DGSM, Martin CS, Job AE, Oliveira ON, Aléssio P. Consequences of the exposure to bisphenol A in cell membrane models at the molecular level and hamster ovary cells viability. Colloids Surf B Biointerfaces 2021; 203:111762. [PMID: 33887667 DOI: 10.1016/j.colsurfb.2021.111762] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 12/26/2022]
Abstract
The inadequate disposal and the difficulty in its removal from water treatment systems have made the endocrine disruptor bisphenol A (BPA) a significant hazard for humans and animals. The molecular-level mechanisms of BPA action are not known in detail, which calls for systematic investigations using cell membrane models. This paper shows that BPA affects Langmuir monolayers and giant unilamellar vesicles (GUVs) of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) used as membrane models, in a concentration-dependent manner and with effects that depend on BPA aggregation. BPA increases DPPC monolayer fluidity in surface pressure isotherms upon interacting with the headgroups through hydrogen bonding, according to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). In DPPC GUVs, BPA induced wrinkling and distortion in the spherical shape of the vesicles, but this was only observed for fresh solutions where it is not aggregated. BPA also decreased the viability of hamster ovary cells (CHO) in in vitro experiments. In contrast, aged, aggregated BPA solutions did not affect the GUVs and even increased CHO viability. These results may be rationalized in terms of size-dependent effects of BPA, which may be relevant for its endocrine-disrupting effects.
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Affiliation(s)
- Mateus D Maximino
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil.
| | - Carla Y Silva
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil
| | - Dalita G S M Cavalcante
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil
| | - Cibely S Martin
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil
| | - Aldo E Job
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil
| | - Osvaldo N Oliveira
- São Carlos Institute of Physics, University of São Paulo, CP 369, 13560-970, São Carlos, SP, Brazil
| | - Priscila Aléssio
- São Paulo State University (UNESP), School of Technology and Applied Sciences, Presidente Prudente, SP, 19060-080, Brazil
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Radja A. Pollen wall patterns as a model for biological self-assembly. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 336:629-641. [PMID: 32991047 PMCID: PMC9292386 DOI: 10.1002/jez.b.23005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 12/21/2022]
Abstract
We are still far from being able to predict organisms' shapes purely from their genetic codes. While it is imperative to identify which encoded macromolecules contribute to a phenotype, determining how macromolecules self-assemble independently of the genetic code may be equally crucial for understanding shape development. Pollen grains are typically single-celled microgametophytes that have decorated walls of various shapes and patterns. The accumulation of morphological data and a comprehensive understanding of the wall development makes this system ripe for mathematical and physical modeling. Therefore, pollen walls are an excellent system for identifying both the genetic products and the physical processes that result in a huge diversity of extracellular morphologies. In this piece, I highlight the current understanding of pollen wall biology relevant for quantification studies and enumerate the modellable aspects of pollen wall patterning and specific approaches that one may take to elucidate how pollen grains build their beautifully patterned walls.
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Affiliation(s)
- Asja Radja
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
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Suryabrahmam B, Agrawal A, Raghunathan VA. Fluid-fluid coexistence in phospholipid membranes induced by decanol. SOFT MATTER 2020; 16:9002-9005. [PMID: 32975548 DOI: 10.1039/d0sm01417f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We have observed fluid-fluid coexistence in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membrane containing 1-decanol, using different experimental techniques and membrane morphologies. This phase behavior is reversible and occurs over a temperature range just above the chain melting transition temperature of the membrane. Although earlier experimental studies and computer simulations have shown the ability of decanol to enhance lipid chain ordering, its potential to induce fluid-fluid coexistence in membranes has not been hitherto recognized. Being the only binary membrane system known so far to exhibit fluid-fluid coexistence, the present system can serve as a simple model to gain a better understanding of mechanisms that drive this unusual phase behavior, which is believed to play an important role in the functioning of cell membranes.
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Duncan KM, Casey A, Gobrogge CA, Trousdale RC, Piontek SM, Cook MJ, Steel WH, Walker RA. Coumarin Partitioning in Model Biological Membranes: Limitations of log P as a Predictor. J Phys Chem B 2020; 124:8299-8308. [DOI: 10.1021/acs.jpcb.0c06109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Katelyn M. Duncan
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Aoife Casey
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Christine A. Gobrogge
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Rhys C. Trousdale
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Stefan M. Piontek
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Matthew J. Cook
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - William H. Steel
- Department of Chemistry, York College of Pennsylvania, York, Pennsylvania 17403, United States
| | - Robert A. Walker
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
- Montana Materials Science Program, Montana State University, Bozeman, Montana 59717, United States
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10
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Ruiz GCM, Pazin WM, do Carmo Morato LF, Oliveira ON, Constantino CJL. Correlating mono- and bilayers of lipids to investigate the pronounced effects of steroid hormone 17α-ethynylestradiol on membrane models of DPPC/cholesterol. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Saroj S, Janni DS, Ummadi CR, Kannoth Manheri M. Functionalizable oxanorbornane-based head-group in the design of new Non-ionic amphiphiles and their drug delivery properties. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 112:110857. [PMID: 32409031 DOI: 10.1016/j.msec.2020.110857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/23/2019] [Accepted: 03/16/2020] [Indexed: 11/20/2022]
Abstract
A new group of non-ionic amphiphiles with short alkyl chains and functionalizable oxanorbornane-based head group for drug delivery application are presented. They can be prepared through a sequence that starts with cycloaddition of Boc-protected furfuryl amine with maleic anhydride and reduction of the resulting adduct with LiAlH4 to get a diol intermediate. Introduction of alkyl chains through these primary hydroxyl groups and subsequent head-group modification via cis-hydroxylation resulted in a number of new amphiphiles in good yields. They were characterized by various spectro-analytical techniques and then subjected to drug-delivery studies using ibuprofen as a model drug. Functionalization of the head group through the amine functionality was also done with an intention to improve lipid packing to get better drug-loading and release properties. Irrespective of the nature of groups attached through this amine unit, all amphiphiles with short alkyl chains were found to assemble into spherical aggregates when drop-casted from various organic solvents. The same assembly preference prevailed in their formulations containing lipid-cholesterol-drug in 1: 0.5:1 ratio as well, and these particles had diameters <300 nm. Apart from good drug-loading efficiencies, these amphiphiles exhibited controlled release properties and did not show any indication of toxicity when assayed against NIH3T3 cells. The formulation based on lipid having a phenylalanine unit on the head group (1.10c) turned out to be the best in this series which showed a loading efficiency of 57.6% with a controlled release of ~42% by end of 24 h. Because of efficient layering that is facilitated by hydrogen bonding involving well-directed hydroxyl groups on the head group, amphiphiles with alkyl chains as short as C5 are able to act as efficient drug delivery systems, which is one of the highlights of this work.
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Affiliation(s)
- Soumya Saroj
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Devi Sirisha Janni
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
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12
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Zhou YM, Liu XC, Li YQ, Wang P, Han RM, Zhang JP, Skibsted LH. Synergy between plant phenols and carotenoids in stabilizing lipid-bilayer membranes of giant unilamellar vesicles against oxidative destruction. SOFT MATTER 2020; 16:1792-1800. [PMID: 31970380 DOI: 10.1039/c9sm01415b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have investigated the synergism between plant phenols and carotenoids in protecting the phosphatidylcholine (PC) membranes of giant unilamellar vesicles (GUVs) from oxidative destruction, for which chlorophyll-a (Chl-a) was used as a lipophilic photosensitizer. The effect was examined for seven different combinations of β-carotene (β-CAR) and plant phenols. The light-induced change in GUV morphology was monitored via conventional optical microscopy, and quantified by a dimensionless image-entropy parameter, ΔE. The ΔE-t time evolution profiles exhibiting successive lag phase, budding phase and ending phase could be accounted for by a Boltzmann model function. The length of the lag phase (LP in s) for the combination of syringic acid and β-CAR was more than seven fold longer than for β-CAR alone, and those for other different combinations followed the order: salicylic acid < vanillic acid < syringic acid > rutin > caffeic acid > quercetin > catechin, indicating that moderately reducing phenols appeared to be the most efficient membrane co-stabilizers. The same order held for the residual contents of β-CAR in membranes after light-induced oxidative degradation as determined by resonance Raman spectroscopy. The dependence of LP on the reducing power of phenols coincided with the Marcus theory plot for the rate of electron transfer from phenols to the radical cation β-CAR˙+ as a primary oxidative product, suggesting that the plant phenol regeneration of β-CAR plays an important role in stabilizing the GUV membranes, as further supported by the involvement of CAR˙+ and the distinct shortening of its lifetime as shown by transient absorption spectroscopy.
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Affiliation(s)
- Yi-Ming Zhou
- Department of Chemistry, Renmin University of China, Beijing, 100872, China.
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13
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Stelter D, Keyes T. Simulation of fluid/gel phase equilibrium in lipid vesicles. SOFT MATTER 2019; 15:8102-8112. [PMID: 31588466 DOI: 10.1039/c9sm00854c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Simulation of single component dipalmitoylphosphatidylcholine (DPPC) coarse-grained DRY-MARTINI lipid vesicles of diameter 10 nm (1350 lipids), 20 nm (5100 lipids) and 40 nm (17 600 lipids) is performed using statistical temperature molecular dynamics (STMD), to study finite size effects upon the order-disorder gel/fluid transition. STMD obtains enhanced sampling using a generalized ensemble, obtaining a flat energy distribution between upper and lower cutoffs, with little computational cost over canonical molecular dynamics. A single STMD trajectory of moderate length is sufficient to sample 20+ transition events, without trapping in the gel phase, and obtain well averaged properties. Phase transitions are analyzed via the energy-dependence of the statistical temperature, TS(U). The transition temperature decreases with decreasing diameter, in agreement with experiment, and the transition changes from first order to borderline first-second order. The size- and layer-dependence of the structure of both stable phases, and of the pathway of the phase transition, are determined. It is argued that the finite size effects are primarily caused by the disruption of the gel packing by curvature. Inhomogeneous states with faceted gel patches connected by unusual fluid seams are observed at high curvature, with visually different structure in the inner and outer layers due to the different curvatures. Thus a simple physical picture describes phase transitions in nanoscale finite systems far from the thermodynamic limit.
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Affiliation(s)
- David Stelter
- Boston University, Chemistry Department, 590 Commonwealth Avenue, Boston, MA 02215, USA.
| | - Tom Keyes
- Boston University, Chemistry Department, 590 Commonwealth Avenue, Boston, MA 02215, USA.
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14
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Shi D, Liu X, Counil C, Krafft MP. Fluorocarbon Exposure Mode Markedly Affects Phospholipid Monolayer Behavior at the Gas/Liquid Interface: Impact on Size and Stability of Microbubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10025-10033. [PMID: 30548072 DOI: 10.1021/acs.langmuir.8b03546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Although most phospholipid-shelled microbubbles (MBs) investigated for medical applications are stabilized by a fluorocarbon (FC) gas, information on the interactions between the phospholipid and FC molecules at the gas/water interface remains scarce. We report that the procedure of introduction of perfluorohexane (F-hexane), that is, either in the gas phase above dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) Langmuir monolayers, or in the aqueous subphase, radically affects the compression isotherms. When introduced in the gas phase, F-hexane is rapidly incorporated in the interfacial film, but is also readily desorbed upon compression and eventually totally expelled from the phospholipid monolayers. By contrast, when introduced in the aqueous phase, F-hexane remains trapped at the interface. These dissimilar outcomes demonstrate that the phospholipid monolayer acts as a barrier that effectively hinders the transfer of the FC across the interfacial film. F-hexane was also found to significantly accelerate the adsorption kinetics of the phospholipids at the gas/water interface and to lower the interfacial tension, as assessed by bubble profile analysis tensiometry. The extent of these effects is more pronounced when F-hexane is provided from the gas phase. The size and stability characteristics of DMPC- and DPPC-shelled microbubbles were also found to depend on how the FC is introduced. As compared to reference MBs prepared under nitrogen only, introduction of F-hexane always causes a decrease in MB mean radius. However, while for DMPC this decrease depends on the F-hexane introduction procedure, it is independent from the procedure and most pronounced (from ∼2.0 μm to ∼1.0 μm) for DPPC. Introducing the FC in the gas phase has the strongest effect on MB half-life (t1/2 = ∼1.8 and 6.8 h for DMPC and DPPC, respectively), as compared to when it is delivered through the aqueous phase (∼0.8 and ∼1.7 h). Fluorocarbonless reference DMPC and DPPC bubbles had a half-life of ∼0.5 and 0.8 h, respectively. The effects of F-hexane on MB characteristics are discussed with regard to the interactions between phospholipids and F-hexane and monolayer fluidization effect, as revealed by the Langmuir and tensiometric studies.
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Affiliation(s)
- Da Shi
- University of Strasbourg , Institut Charles Sadron (CNRS) , 23 rue du Loess , 67034 Strasbourg , Cedex , France
| | - Xianhe Liu
- University of Strasbourg , Institut Charles Sadron (CNRS) , 23 rue du Loess , 67034 Strasbourg , Cedex , France
| | - Claire Counil
- University of Strasbourg , Institut Charles Sadron (CNRS) , 23 rue du Loess , 67034 Strasbourg , Cedex , France
| | - Marie Pierre Krafft
- University of Strasbourg , Institut Charles Sadron (CNRS) , 23 rue du Loess , 67034 Strasbourg , Cedex , France
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15
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Morandi MI, Sommer M, Kluzek M, Thalmann F, Schroder AP, Marques CM. DPPC Bilayers in Solutions of High Sucrose Content. Biophys J 2019; 114:2165-2173. [PMID: 29742409 DOI: 10.1016/j.bpj.2018.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/21/2018] [Accepted: 04/02/2018] [Indexed: 10/17/2022] Open
Abstract
The properties of lipid bilayers in sucrose solutions have been intensely scrutinized over recent decades because of the importance of sugars in the field of biopreservation. However, a consensus has not yet been formed on the mechanisms of sugar-lipid interaction. Here, we present a study on the effect of sucrose on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayers that combines calorimetry, spectral fluorimetry, and optical microscopy. Intriguingly, our results show a significant decrease in the transition enthalpy but only a minor shift in the transition temperature. Our observations can be quantitatively accounted for by a thermodynamic model that assumes partial delayed melting induced by sucrose adsorption at the membrane interface.
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Affiliation(s)
- Mattia I Morandi
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Mathieu Sommer
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Monika Kluzek
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Fabrice Thalmann
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - André P Schroder
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France
| | - Carlos M Marques
- Université de Strasbourg, CNRS, Institut Charles Sadron, UPR022, Strasbourg Cedex, France.
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16
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Taira T, Ishizaki Y, Yamamoto S, Sakai K, Sakai H, Imura T. Spontaneous Vesicle Formation of Monododecenyl Phosphonic Acid in Water. J Oleo Sci 2019; 68:1223-1230. [DOI: 10.5650/jos.ess19164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Toshiaki Taira
- National Institute of Advanced Industrial Science and Technology (AIST)
| | - Yuki Ishizaki
- Faculty of Science and Technology, Tokyo University of Science
| | - Shusei Yamamoto
- Faculty of Science and Technology, Tokyo University of Science
| | - Kenichi Sakai
- Faculty of Science and Technology, Tokyo University of Science
| | - Hideki Sakai
- Faculty of Science and Technology, Tokyo University of Science
| | - Tomohiro Imura
- National Institute of Advanced Industrial Science and Technology (AIST)
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17
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Cordeiro RM. Molecular Structure and Permeability at the Interface between Phase-Separated Membrane Domains. J Phys Chem B 2018; 122:6954-6965. [DOI: 10.1021/acs.jpcb.8b03406] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rodrigo M. Cordeiro
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Avenida dos Estados 5001, CEP 09210-580 Santo André, SP, Brazil
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Mineart KP, Venkataraman S, Yang YY, Hedrick JL, Prabhu VM. Fabrication and Characterization of Hybrid Stealth Liposomes. Macromolecules 2018; 51:3184-3192. [PMID: 32322115 PMCID: PMC7175670 DOI: 10.1021/acs.macromol.8b00361] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Next-generation liposome systems for anticancer and therapeutic delivery require the precise insertion of stabilizing polymers and targeting ligands. Many of these functional macromolecules may be lost to micellization as a competing self-assembly landscape. Here, hybrid stealth liposomes, which utilize novel cholesteryl-functionalized block copolymers as the molecular stabilizer, are explored as a scalable platform to address this limitation. The employed block copolymers offer resistance to micellization through multiple liposome insertion moieties per molecule. A combination of thermodynamic and structural investigations for a series of hybrid stealth liposome systems suggests that a critical number of cholesteryl moieties per molecule defines whether the copolymer will or will not insert into the liposome bilayer. Colloidal stability of formed hybrid stealth liposomes further corroborates the critical copolymer architecture value.
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Affiliation(s)
- Kenneth P. Mineart
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Shrinivas Venkataraman
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore
| | - Yi Yan Yang
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore
| | - James L. Hedrick
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, United States
| | - Vivek M. Prabhu
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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19
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Saw TB, Doostmohammadi A, Nier V, Kocgozlu L, Thampi S, Toyama Y, Marcq P, Lim CT, Yeomans JM, Ladoux B. Topological defects in epithelia govern cell death and extrusion. Nature 2017; 544:212-216. [PMID: 28406198 PMCID: PMC5439518 DOI: 10.1038/nature21718] [Citation(s) in RCA: 351] [Impact Index Per Article: 50.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 02/21/2017] [Indexed: 12/23/2022]
Abstract
Epithelial tissues (epithelia) remove excess cells through extrusion, preventing the accumulation of unnecessary or pathological cells. The extrusion process can be triggered by apoptotic signalling, oncogenic transformation and overcrowding of cells. Despite the important linkage of cell extrusion to developmental, homeostatic and pathological processes such as cancer metastasis, its underlying mechanism and connections to the intrinsic mechanics of the epithelium are largely unexplored. We approach this problem by modelling the epithelium as an active nematic liquid crystal (that has a long range directional order), and comparing numerical simulations to strain rate and stress measurements within monolayers of MDCK (Madin Darby canine kidney) cells. Here we show that apoptotic cell extrusion is provoked by singularities in cell alignments in the form of comet-shaped topological defects. We find a universal correlation between extrusion sites and positions of nematic defects in the cell orientation field in different epithelium types. The results confirm the active nematic nature of epithelia, and demonstrate that defect-induced isotropic stresses are the primary precursors of mechanotransductive responses in cells, including YAP (Yes-associated protein) transcription factor activity, caspase-3-mediated cell death, and extrusions. Importantly, the defect-driven extrusion mechanism depends on intercellular junctions, because the weakening of cell-cell interactions in an α-catenin knockdown monolayer reduces the defect size and increases both the number of defects and extrusion rates, as is also predicted by our model. We further demonstrate the ability to control extrusion hotspots by geometrically inducing defects through microcontact printing of patterned monolayers. On the basis of these results, we propose a mechanism for apoptotic cell extrusion: spontaneously formed topological defects in epithelia govern cell fate. This will be important in predicting extrusion hotspots and dynamics in vivo, with potential applications to tissue regeneration and the suppression of metastasis. Moreover, we anticipate that the analogy between the epithelium and active nematic liquid crystals will trigger further investigations of the link between cellular processes and the material properties of epithelia.
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Affiliation(s)
- Thuan Beng Saw
- Mechanobiology Institute, National University of Singapore, Singapore.,National University of Singapore Graduate School of Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore
| | | | - Vincent Nier
- Sorbonne Universités, UPMC Université Paris 6, Institut Curie, CNRS, UMR 168, Laboratoire Physico-Chimie Curie, Paris, France
| | - Leyla Kocgozlu
- Mechanobiology Institute, National University of Singapore, Singapore
| | - Sumesh Thampi
- The Rudolf Peierls Centre for Theoretical Physics, Oxford University, UK.,Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, India
| | - Yusuke Toyama
- Mechanobiology Institute, National University of Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, and Temasek Life Sciences Laboratory, Singapore
| | - Philippe Marcq
- Sorbonne Universités, UPMC Université Paris 6, Institut Curie, CNRS, UMR 168, Laboratoire Physico-Chimie Curie, Paris, France
| | - Chwee Teck Lim
- Mechanobiology Institute, National University of Singapore, Singapore.,National University of Singapore Graduate School of Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore
| | - Julia M Yeomans
- The Rudolf Peierls Centre for Theoretical Physics, Oxford University, UK
| | - Benoit Ladoux
- Mechanobiology Institute, National University of Singapore, Singapore.,Institut Jacques Monod (IJM), CNRS UMR 7592 & Université Paris Diderot, Paris, France
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20
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Kumar A, Dahl V, Kleinen J, Gambaryan-Roisman T, Venzmer J. Influence of lipid bilayer phase behavior and substrate roughness on the pathways of intact vesicle deposition: A streaming potential study. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2016.07.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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21
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Chao MH, Lin YT, Dhenadhayalan N, Lee HL, Lee HY, Lin KC. 3D Probed Lipid Dynamics in Small Unilamellar Vesicles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1603408. [PMID: 28092434 DOI: 10.1002/smll.201603408] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/02/2016] [Indexed: 06/06/2023]
Abstract
Single-molecule fluorescence correlation spectroscopy overcomes the resolution barrier of optical microscopy (10≈-20 nm) and is utilized to look into lipid dynamics in small unilamellar vesicles (SUVs; diameter < 100 nm). The fluorescence trajectories of lipid-like tracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine (DiD) in the membrane bilayers are acquired at a single-molecule level. The autocorrelation analysis yields the kinetic information on lipid organization, oxygen transport, and lateral diffusion in SUVs' membrane. First, the isomerization feasibility may be restricted by the addition of cholesterols, which form structure conjugation with DiD chromophore. Second, the oxygen transport is prevented from the ultrasmall cluster and cholesterol-rich regions, whereas it can pass through the membrane region with liquid-disordered phase (Ld ) and defects. Third, by analyzing 2D spectra correlating the lipid diffusion coefficient and triplet-state lifetime, the heterogeneity in lipid bilayer can be precisely visualized such as lipid domain with different phases, the defects of lipid packing, and DiD-induced "bouquet" ultrasmall clusters.
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Affiliation(s)
- Meng-Hsuan Chao
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - Yen-Ting Lin
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - Namasivayam Dhenadhayalan
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - Hsin-Lung Lee
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - Hsin-Yen Lee
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
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22
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Kresse KM, Xu M, Pazzi J, García-Ojeda M, Subramaniam AB. Novel Application of Cellulose Paper As a Platform for the Macromolecular Self-Assembly of Biomimetic Giant Liposomes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:32102-32107. [PMID: 27933839 DOI: 10.1021/acsami.6b11960] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a facile and scalable method to fabricate biomimetic giant liposomes by using a cellulose paper-based materials platform. Termed PAPYRUS for Paper-Abetted liPid hYdRation in aqUeous Solutions, the method is general and can produce liposomes in various aqueous media and at elevated temperatures. Encapsulation of macromolecules and production of liposomes with membranes of complex compositions is straightforward. The ease of manipulation of paper makes practical massive parallelization and scale-up of the fabrication of giant liposomes, demonstrating for the first time the surprising usefulness of paper as a platform for macromolecular self-assembly.
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Affiliation(s)
- Kayleigh M Kresse
- School of Engineering and §School of Natural Sciences, University of California , Merced, California 95343, United States
| | - Melissa Xu
- School of Engineering and §School of Natural Sciences, University of California , Merced, California 95343, United States
| | - Joseph Pazzi
- School of Engineering and §School of Natural Sciences, University of California , Merced, California 95343, United States
| | - Marcos García-Ojeda
- School of Engineering and §School of Natural Sciences, University of California , Merced, California 95343, United States
| | - Anand Bala Subramaniam
- School of Engineering and §School of Natural Sciences, University of California , Merced, California 95343, United States
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23
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Affiliation(s)
- Gregory M. Grason
- Department of Polymer Science, University of Massachusetts, Amherst, Massachusetts 01003, USA
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24
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Intact deposition of cationic vesicles on anionic cellulose fibers: Role of vesicle size, polydispersity, and substrate roughness studied via streaming potential measurements. J Colloid Interface Sci 2016; 473:152-61. [DOI: 10.1016/j.jcis.2016.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 04/01/2016] [Accepted: 04/02/2016] [Indexed: 11/17/2022]
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25
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Liu K, Hamilton C, Allard J, Lowengrub J, Li S. Wrinkling dynamics of fluctuating vesicles in time-dependent viscous flow. SOFT MATTER 2016; 12:5663-5675. [PMID: 27136977 PMCID: PMC4927358 DOI: 10.1039/c6sm00499g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the fully nonlinear, nonlocal dynamics of two-dimensional vesicles in a time-dependent, incompressible viscous flow at finite temperature. We focus on a transient instability that can be observed when the direction of applied flow is suddenly reversed, which induces compressive forces on the vesicle interface, and small-scale interface perturbations known as wrinkles develop. These wrinkles are driven by regions of negative elastic tension on the membrane. Using a stochastic immersed boundary method with a biophysically motivated choice of thermal fluctuations, we investigate the wrinkling dynamics numerically. Different from deterministic wrinkling dynamics, thermal fluctuations lead to symmetry-breaking wrinkling patterns by exciting higher order modes. This leads to more rapid and more realistic wrinkling dynamics. Our results are in excellent agreement with the experimental data by Kantsler et al. [Kantsler et al., Phys. Rev. Lett., 2007, 99, 17802]. We compare the nonlinear simulation results with perturbation theory, modified to account for thermal fluctuations. The strength of the applied flow strongly influences the most unstable wavelength characterizing the wrinkles, and there are significant differences between the results from perturbation theory and the fully nonlinear simulations, which suggests that the perturbation theory misses important nonlinear interactions. Strikingly, we find that thermal fluctuations actually have the ability to attenuate variability of the characteristic wavelength of wrinkling by exciting a wider range of modes than the deterministic case, which makes the evolution less constrained and enables the most unstable wavelength to emerge more readily. We further find that thermal noise helps prevent the vesicle from rotating if it is misaligned with the direction of the applied extensional flow.
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Affiliation(s)
- Kai Liu
- Department of Applied Mathematics, Illinois Institute of Technology, Chicago, USA. and Department of Mathematics, University of California in Irvine, Irvine, USA
| | - Caleb Hamilton
- Department of Mathematics, University of California in Irvine, Irvine, USA
| | - Jun Allard
- Department of Mathematics, University of California in Irvine, Irvine, USA and Department of Physics, University of California in Irvine, USA
| | - John Lowengrub
- Department of Mathematics, University of California in Irvine, Irvine, USA
| | - Shuwang Li
- Department of Applied Mathematics, Illinois Institute of Technology, Chicago, USA.
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26
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Benedini LA, Sequeira MA, Fanani ML, Maggio B, Dodero VI. Development of a Nonionic Azobenzene Amphiphile for Remote Photocontrol of a Model Biomembrane. J Phys Chem B 2016; 120:4053-63. [DOI: 10.1021/acs.jpcb.6b00303] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Luciano A. Benedini
- Instituto
de Química del Sur (INQUISUR−CONICET), Departamento
de Química, Universidad Nacional del Sur, 8000FTN Bahía Blanca, Argentina
| | - M. Alejandra Sequeira
- Instituto
de Química del Sur (INQUISUR−CONICET), Departamento
de Química, Universidad Nacional del Sur, 8000FTN Bahía Blanca, Argentina
| | - Maria Laura Fanani
- Centro
de Investigaciones en Química Biológica de Córdoba
(CIQUIBIC−CONICET), Departamento de Química Biológica,
Facultad de Ciencias Químicas, Universidad Nacional del Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Bruno Maggio
- Centro
de Investigaciones en Química Biológica de Córdoba
(CIQUIBIC−CONICET), Departamento de Química Biológica,
Facultad de Ciencias Químicas, Universidad Nacional del Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Verónica I. Dodero
- Instituto
de Química del Sur (INQUISUR−CONICET), Departamento
de Química, Universidad Nacional del Sur, 8000FTN Bahía Blanca, Argentina
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27
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Su J, Yao Z, de la Cruz MO. Vesicle Geometries Enabled by Dynamically Trapped States. ACS NANO 2016; 10:2287-2294. [PMID: 26795199 DOI: 10.1021/acsnano.5b06991] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding and controlling vesicle shapes is a fundamental challenge in biophysics and materials design. In this paper, we design dynamic protocols for enlarging the shape space of both fluid and crystalline vesicles beyond the equilibrium zone. By removing water from within the vesicle at different rates, we numerically produced a series of dynamically trapped stable vesicle shapes for both fluid and crystalline vesicles in a highly controllable fashion. In crystalline vesicles that are continuously dehydrated, simulations show the initial appearance of small flat areas over the surface of the vesicles that ultimately merge to form fewer flat faces. In this way, the vesicles transform from a fullerene-like shape into various faceted polyhedrons. We perform analytical elasticity analysis to show that these salient features are attributable to the crystalline nature of the vesicle. The potential to use dynamic protocols, such as those used in this study, to engineer vesicle shape transformations is helpful for exploiting the richness of vesicle geometries for desired applications.
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Affiliation(s)
- Jiaye Su
- Department of Applied Physics, Nanjing University of Science and Technology , Nanjing, Jiangsu 210094, China
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28
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Patel LA, Kindt JT. Coarse-grained molecular simulations of the melting kinetics of small unilamellar vesicles. SOFT MATTER 2016; 12:1765-1777. [PMID: 26701014 DOI: 10.1039/c5sm02560e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Simulations of small unilamellar lipid bilayer vesicles have been performed to model their response to an instantaneous rise in temperature, starting from an initial low-temperature structure, to temperatures near or above the main chain transition temperature. The MARTINI coarse-grained force-field was used to construct slabs of gel-phase DPPC bilayers, which were assembled into truncated icosahedral structures containing 13,165 or 31,021 lipids. Equilibration at 280 K produced structures with several (5-8) domains, characterized by facets of lipids packed in the gel phase connected by disordered ridges. Instantaneous heating to final temperatures ranging from 290 K to 310 K led to partial or total melting over 500 ns trajectories, accompanied by changes in vesicle shape and the sizes and arrangements of remaining gel-phase domains. At temperatures that produced partial melting, the gel-phase lipid content of the vesicles followed an exponential decay, similar in form and timescale to the sub-microsecond phase of melting kinetics observed in recent ultrafast IR temperature-jump experiments. The changing rate of melting appears to be the outcome of a number of competing contributions, but changes in curvature stress arising from the expansion of the bilayer area upon melting are a major factor. The simulations give a more detailed picture of the changes that occur in frozen vesicles following a temperature jump, which will be of use for the interpretation of temperature-jump experiments on vesicles.
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Affiliation(s)
- Lara A Patel
- Emory University, Chemistry Department, 1515 Dickey Drive, Atlanta, GA 30322, USA.
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29
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Abstract
Liquid droplets, widely encountered in everyday life, have no flat facets. Here we show that water-dispersed oil droplets can be reversibly temperature-tuned to icosahedral and other faceted shapes, hitherto unreported for liquid droplets. These shape changes are shown to originate in the interplay between interfacial tension and the elasticity of the droplet's 2-nm-thick interfacial monolayer, which crystallizes at some T = Ts above the oil's melting point, with the droplet's bulk remaining liquid. Strikingly, at still-lower temperatures, this interfacial freezing (IF) effect also causes droplets to deform, split, and grow tails. Our findings provide deep insights into molecular-scale elasticity and allow formation of emulsions of tunable stability for directed self-assembly of complex-shaped particles and other future technologies.
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30
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Dreier J, Brewer J, Simonsen AC. Systematic variation of gel-phase texture in phospholipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:10678-10685. [PMID: 25122542 DOI: 10.1021/la5023054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The tilted gel phase of lipid bilayers can display in-plane orientational texture due to long-range alignment of the molecular director. We explore systematic variations of texture defects in a series of binary phospholipid membranes. Using polarized two-photon fluorescence microscopy, the texture pattern of single domains is revealed. The appearance of a central vortex-type defect in each domain correlates with a particular range of hydrophobic mismatch values h > 1 nm at the domain border while domains with h < 1 nm correlate with uniformly aligned texture. The central vortex defect is characterized by a defect angle, indicating its bend or splay nature. Using image analysis, we measure the defect angle and find that it has primarily bend character for small mismatch values (h ≈ 1 nm) and primarily splay nature for larger values of h. For domains containing a vortex, the domain shape is decoupled from the texture while for uniformly textured domains there is a preferred texture orientation of ≃45° along the domain border. The results establish a foundation for understanding texture phenomena in compositionally complex membranes.
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Affiliation(s)
- Jes Dreier
- MEMPHYS - Center for Biomembrane Physics, †Department of Physics Chemistry and Pharmacy and ‡Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
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31
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Castles F. Liquid crystal research highlights. LIQUID CRYSTALS TODAY 2013. [DOI: 10.1080/1358314x.2013.813726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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