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Vasyankin AV, Panteleev SV, Steshin IS, Shirokova EA, Rozhkov AV, Livshits GD, Radchenko EV, Ignatov SK, Palyulin VA. Temperature-Induced Restructuring of Mycolic Acid Bilayers Modeling the Mycobacterium tuberculosis Outer Membrane: A Molecular Dynamics Study. Molecules 2024; 29:696. [PMID: 38338443 PMCID: PMC10856651 DOI: 10.3390/molecules29030696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/12/2024] Open
Abstract
The emergence of new drug-resistant strains of the tuberculosis pathogen Mycobacterium tuberculosis (Mtb) is a new challenge for modern medicine. Its resistance capacity is closely related to the properties of the outer membrane of the Mtb cell wall, which is a bilayer membrane formed by mycolic acids (MAs) and their derivatives. To date, the molecular mechanisms of the response of the Mtb outer membrane to external factors and, in particular, elevated temperatures have not been sufficiently studied. In this work, we consider the temperature-induced changes in the structure, ordering, and molecular mobility of bilayer MA membranes of various chemical and conformational compositions. Using all-atom long-term molecular dynamics simulations of various MA membranes, we report the kinetic parameters of temperature-dependent changes in the MA self-diffusion coefficients and conformational compositions, including the apparent activation energies of these processes, as well as the characteristic times of ordering changes and the features of phase transitions occurring over a wide range of elevated temperatures. Understanding these effects could be useful for the prevention of drug resistance and the development of membrane-targeting pharmaceuticals, as well as in the design of membrane-based materials.
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Affiliation(s)
- Alexander V. Vasyankin
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Sergey V. Panteleev
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Ilya S. Steshin
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Ekaterina A. Shirokova
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Alexey V. Rozhkov
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Grigory D. Livshits
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Eugene V. Radchenko
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Stanislav K. Ignatov
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
| | - Vladimir A. Palyulin
- Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603022, Russia; (A.V.V.); (S.V.P.); (I.S.S.); (E.A.S.); (A.V.R.); (G.D.L.); (E.V.R.)
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
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Tseng YC, Chang HY, Sheng YJ, Tsao HK. Atypical vesicles and membranes with monolayer and multilayer structures formed by graft copolymers with diblock side-chains: nonlamellar structures and curvature-enhanced permeability. SOFT MATTER 2022; 18:7559-7568. [PMID: 36164856 DOI: 10.1039/d2sm01055k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Graft copolymers with diblock side-chains Am(-graft-B3Ay)n in a selective solvent have been reported to self-assemble into vesicles, but the structure is expected to differ distinctly from those of lipid bilayers. Surprisingly, the number of alternating hydrophobic A-block and hydrophilic B-block layers in the vesicle can vary from a monolayer to multilayers such as the hepta-layer, subject to the same copolymer concentration. The area density of the copolymer layer is not uniform across the membrane. This structural difference among different layers is attributed to the neighboring environment and the curvature of the layer. Because of the unusual polymer conformations, nonlamellar structures of polymersomes are formed, and they are much more intricate than those of liposomes. In fact, a copolymer can contribute to a single or two hydrophilic layers, and it can provide up to three hydrophobic layers. The influence of the backbone length (m) and side-chain length (y) and the permeation dynamics are also studied. The thickness of hydrophobic layers is found to increase with increasing side-chain length but is not sensitive to the backbone length. Although the permeation time increases with the layer number for planar membranes, the opposite behavior is observed for spherical vesicles owing to the curvature-enhanced permeability associated with Laplace pressure.
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Affiliation(s)
- Yueh-Chi Tseng
- Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan.
| | - Hsin-Yu Chang
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan.
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan.
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan.
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3
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Liu L, Bai X, Martikainen MV, Kårlund A, Roponen M, Xu W, Hu G, Tasciotti E, Lehto VP. Cell membrane coating integrity affects the internalization mechanism of biomimetic nanoparticles. Nat Commun 2021; 12:5726. [PMID: 34593813 PMCID: PMC8484581 DOI: 10.1038/s41467-021-26052-x] [Citation(s) in RCA: 118] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 09/03/2021] [Indexed: 12/12/2022] Open
Abstract
Cell membrane coated nanoparticles (NPs) have recently been recognized as attractive nanomedical tools because of their unique properties such as immune escape, long blood circulation time, specific molecular recognition and cell targeting. However, the integrity of the cell membrane coating on NPs, a key metrics related to the quality of these biomimetic-systems and their resulting biomedical function, has remained largely unexplored. Here, we report a fluorescence quenching assay to probe the integrity of cell membrane coating. In contradiction to the common assumption of perfect coating, we uncover that up to 90% of the biomimetic NPs are only partially coated. Using in vitro homologous targeting studies, we demonstrate that partially coated NPs could still be internalized by the target cells. By combining molecular simulations with experimental analysis, we further identify an endocytic entry mechanism for these NPs. We unravel that NPs with a high coating degree (≥50%) enter the cells individually, whereas the NPs with a low coating degree (<50%) need to aggregate together before internalization. This quantitative method and the fundamental understanding of how cell membrane coated NPs enter the cells will enhance the rational designing of biomimetic nanosystems and pave the way for more effective cancer nanomedicine.
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Affiliation(s)
- Lizhi Liu
- Department of Applied Physics, University of Eastern Finland, 70210, Kuopio, Finland
| | - Xuan Bai
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027, Hangzhou, China
| | - Maria-Viola Martikainen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 70210, Kuopio, Finland
| | - Anna Kårlund
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland, 70211, Kuopio, Finland
| | - Marjut Roponen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 70210, Kuopio, Finland
| | - Wujun Xu
- Department of Applied Physics, University of Eastern Finland, 70210, Kuopio, Finland.
| | - Guoqing Hu
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, 310027, Hangzhou, China
| | - Ennio Tasciotti
- IRCCS San Raffaele Pisana Hospital and San Raffaele University, Rome, Italy
- Sclavo Pharma, Siena, Italy
| | - Vesa-Pekka Lehto
- Department of Applied Physics, University of Eastern Finland, 70210, Kuopio, Finland.
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4
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Chang HY, Tsai HC, Sheng YJ, Tsao HK. Floating and Diving Loops of ABA Triblock Copolymers in Lipid Bilayers and Stability Enhancement for Asymmetric Membranes. Biomacromolecules 2020; 22:494-503. [PMID: 33356177 DOI: 10.1021/acs.biomac.0c01328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hybrid membranes of lipids and AxByAz triblock copolymers can possess better biocompatibility and mechanical stability. In this work, triblock copolymer conformations and stability of asymmetric membranes are explored by dissipative particle dynamics. The triblock copolymers in the membranes exhibit either the bridge or loop conformation. As hydrophobic B-blocks interact attractively with lipid heads, bridge-shaped copolymers are significantly inhibited and loop-shaped copolymers prefer to stay at the interface between hydrophilic and hydrophobic layers. This floating loop has a flattened conformation, consistent with the experimental findings. In contrast, for repulsive interactions between B-blocks and lipid heads, bridge-shaped copolymers are abundant and loop-shaped copolymers tend to plunge into the hydrophobic layer. This diving loop displays a random coil conformation. The asymmetric membrane in which the fractions of loop-shaped copolymers in the upper and lower leaflets are different is thermodynamically unstable. Two approaches are proposed to acquire kinetically stable asymmetric membranes. First, membrane symmetrization is arrested by eliminating bridge-shaped copolymers, which is achieved by B-block/lipid head attraction and B-block/lipid tail repulsion. Second, asymmetric triblock copolymers (x ≠ z) are used to prevent the passage of the long A-block through the hydrophobic layer.
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Affiliation(s)
- Hsin-Yu Chang
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Hsiang-Chi Tsai
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan
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Tsai HC, Yang YL, Sheng YJ, Tsao HK. Formation of Asymmetric and Symmetric Hybrid Membranes of Lipids and Triblock Copolymers. Polymers (Basel) 2020; 12:polym12030639. [PMID: 32168935 PMCID: PMC7183320 DOI: 10.3390/polym12030639] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/08/2020] [Accepted: 03/10/2020] [Indexed: 12/28/2022] Open
Abstract
Hybrid membranes formed by co-assembly of AxByAx (hydrophilic-hydrophobic-hydrophilic) triblock copolymers into lipid bilayers are investigated by dissipative particle dynamics. Homogeneous hybrid membranes are developed as lipids and polymers are fully compatible. The polymer conformations can be simply classified into bridge- and loop-structures in the membranes. It is interesting to find that the long-time fraction of loop-conformation (fL) of copolymers in the membrane depends significantly on the hydrophilic block length (x). As x is small, an equilibrium fL* always results irrespective of the initial conformation distribution and its value depends on the hydrophobic block length (y). For large x, fL tends to be time-invariant because polymers are kinetically trapped in their initial structures. Our findings reveal that only symmetric hybrid membranes are formed for small x, while membranes with stable asymmetric leaflets can be constructed with large x. The effects of block lengths on the polymer conformations, such as transverse and lateral spans (d⊥ and d‖) of bridge- and loop-conformations, are discussed as well.
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Affiliation(s)
- Hsiang-Chi Tsai
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Yan-Ling Yang
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
- Correspondence: (Y.-J.S.); (H.-K.T.)
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan
- Correspondence: (Y.-J.S.); (H.-K.T.)
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6
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Zaki AM, Carbone P. Amphiphilic copolymers change the nature of the ordered-to-disordered phase transition of lipid membranes from discontinuous to continuous. Phys Chem Chem Phys 2019; 21:13746-13757. [PMID: 31209450 DOI: 10.1039/c9cp01293a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phase behaviour as a function of temperature is explored for pure phospholipid (DPPC) and hybrid lipid-polymer (DPPC/Pluronic L64) bilayers with the aid of atomistic MD simulations. The range of the fixed-temperature simulations includes temperatures below and above the known melting temperature (Tm) for DPPC membranes. For the pure lipid bilayer, the main phase transition is discontinuous, as verified by the abrupt changes observed in the membrane structure, elasticity and the lipid diffusivity near the critical temperature Tm, which lies in the region 298.15-303.15 K. A pre-transition step is detected at 298.15 K which has been identified as the ripple phase (Pβ'), where ordered and disordered lipids coexist, causing thickness fluctuations. In the ordered gel phase, the positional ordering as assessed by the lipid radial distribution functions is long-range and some degree of hexagonal packing is measured. The hybrid bilayers on the other hand, transform from a more ordered to a disordered phase in a continuous manner, without finite jumps in their properties. No signs of the ripple phase are identified and the ordered phase exhibits very limited hexagonal packing and some positional ordering that decays fast. The effect of the inserted polymers in the two phases is reversed; at low temperatures, they render the membrane thinner, less cohesive and less ordered compared to the pure one, with the lipids assuming faster diffusion rates, whereas at high temperatures, the polymer interaction with the lipids acts reducing their diffusivity, but also increasing the lipid tail ordering and the membrane stiffness. The ability of the amphiphilic L64 copolymers to change the nature of the main phase transition of lipid membranes and their properties both in the ordered and the disordered phase is of vital importance for the prediction of both the efficacy of hybrid lipid/polymer nanoparticles as drug delivery vehicles as well as their potential adverse implications during interactions with healthy cell membranes.
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Affiliation(s)
- Afroditi Maria Zaki
- School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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7
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Hu SW, Huang CY, Tsao HK, Sheng YJ. Hybrid membranes of lipids and diblock copolymers: From homogeneity to rafts to phase separation. Phys Rev E 2019; 99:012403. [PMID: 30780280 DOI: 10.1103/physreve.99.012403] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Indexed: 06/09/2023]
Abstract
Hybrid lipid-polymer vesicles can integrate benefits of liposomes and polymersomes. In this work, the phase behavior of hybrid membranes containing lipids and diblock copolymers is explored by dissipative particle dynamics simulations. The influences of lipid unsaturation and thickness mismatch between lipids and polymers are considered. The transition from the mixing state (homogeneous distribution) to the demixing state (formation of bilayered lipid-rich domains) is always observed as the lipid concentration (φ_{l}) exceeds a critical value, which increases with the degree of unsaturation. It is found that phase separation is driven by weak energy incompatibility between the hydrophobic segments of lipids and polymers. When the effect of thickness mismatch becomes significant, the occurrence of the demixing state is retarded, and monolayer lipid rafts emerge before phase separation. Lipid fluidity associated with the physical state of a hybrid membrane can be characterized by lateral lipid diffusivity (D_{l}). In the polymer-rich membrane, D_{l} is higher in the mixing state, but decreases generally with φ_{l} due to lipid-lipid interactions and interdigitation.
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Affiliation(s)
- Ssu-Wei Hu
- Department of Chemical and Materials Engineering, National Central University, Jhongli, Taiwan 320, Republic of China
| | - Chun-Yen Huang
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, National Central University, Jhongli, Taiwan 320, Republic of China
- Department of Physics, National Central University, Jhongli, Taiwan 320, Republic of China
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China
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8
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Weng YH, Tsao HK, Sheng YJ. Self-healing and dewetting dynamics of a polymer nanofilm on a smooth substrate: strategies for dewetting suppression. Phys Chem Chem Phys 2018; 20:20459-20467. [PMID: 30043813 DOI: 10.1039/c8cp03215g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-healing and dewetting dynamics of a polymer nanofilm on a smooth, partial wetting surface are explored by many-body dissipative particle dynamics. Three types of dewetting phenomena are identified, (i) spinodal decomposition, (ii) nucleation and growth, and (iii) metastable self-healing. The outcome depends on the surface wettability (θY), the polymer film thickness (h0), and the radius of the dry hole (R0). The phase diagram of the dewetting mechanism as a function of θY and h0 is obtained for a specified R0. As the surface wettability decreases (increasing θY), the critical film thickness associated with the nucleation/self-healing crossover (hc) grows so that the metastability of the film can be retained by the self-healing process. In addition to θY and R0, hc depends on the polymer length (N) as well. It is found that a longer polymer requires a thicker nanofilm to avoid dewetting by nucleation. Two strategies for dewetting suppression are proposed. The metastability of a film of polymers with a large molecular weight can be promoted either by the addition of short polymers or by employing compact polymers such as star polymers. In the latter approach, the increment of the arm number enhances the nanofilm stability.
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Affiliation(s)
- Yu-Hsuan Weng
- Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
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9
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Lu T, Guo H. Phase Behavior of Lipid Bilayers: A Dissipative Particle Dynamics Simulation Study. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Teng Lu
- Beijing National Laboratory for Molecular Sciences; Joint Laboratory of Polymer Sciences and Materials; State Key Laboratory of Polymer Physics and Chemistry; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Hongxia Guo
- Beijing National Laboratory for Molecular Sciences; Joint Laboratory of Polymer Sciences and Materials; State Key Laboratory of Polymer Physics and Chemistry; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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10
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Yang YL, Chen MY, Tsao HK, Sheng YJ. Dynamics of bridge-loop transformation in a membrane with mixed monolayer/bilayer structures. Phys Chem Chem Phys 2018; 20:6582-6590. [PMID: 29450428 DOI: 10.1039/c7cp08107c] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Instead of forming a typical bilayer or monolayer membrane, both the bridge (I-shape) and loop (U-shape) conformations coexist in the planar membranes formed by ABA triblock copolymers in a selective solvent. The non-equilibrium and equilibrium relaxation dynamics of polymer conformations are monitored. The non-equilibrium relaxation time depends on the initial composition and increases with an increase in the immiscibility between A and B blocks. The equilibrium composition of the loop-shape polymer is independent of the initial composition and A-B immiscibility. However, the extent of equilibrium composition fluctuations subsides as the A and B blocks become highly incompatible. The influences of the A-B immiscibility on the geometrical, mechanical, and transport properties of the membrane have also been investigated. As the immiscibility increases, the overall membrane thickness and the B block layer thickness (h) increase because of the increment in the molecular packing density. As a result, both the stretching (KA) and bending (KB) moduli grow significantly with the increasing A-B immiscibility. Consistent with the case of typical membranes, the ratio KB/KAh2 = 2 × 10-3 is a constant. Although the lateral diffusivity of polymers is insensitive to immiscibility, the membrane permeability decreases substantially as the A-B immiscibility is increased.
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Affiliation(s)
- Yan-Ling Yang
- Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China.
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11
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Yang YL, Sheng YJ, Tsao HK. Branching pattern effect and co-assembly with lipids of amphiphilic Janus dendrimersomes. Phys Chem Chem Phys 2018; 20:27305-27313. [DOI: 10.1039/c8cp05268a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The influence of the branching patterns on the membrane properties of Janus dendrimers in water has been investigated by dissipative particle dynamics simulations.
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Affiliation(s)
- Yan-Ling Yang
- Department of Chemical Engineering
- National Taiwan University
- Taipei 106
- Taiwan
| | - Yu-Jane Sheng
- Department of Chemical Engineering
- National Taiwan University
- Taipei 106
- Taiwan
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering
- National Central University
- Jhongli 320
- Taiwan
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12
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Skalová Š, Vyskočil V, Barek J, Navrátil T. Model Biological Membranes and Possibilities of Application of Electrochemical Impedance Spectroscopy for their Characterization. ELECTROANAL 2017. [DOI: 10.1002/elan.201700649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Štěpánka Skalová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences; Dolejškova 3 182 23 Prague 8 Czech Republic
- Charles University; Faculty of Science, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry; Hlavova 2030/8 128 43 Prague 2 Czech Republic
| | - Vlastimil Vyskočil
- Charles University; Faculty of Science, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry; Hlavova 2030/8 128 43 Prague 2 Czech Republic
| | - Jiří Barek
- Charles University; Faculty of Science, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry; Hlavova 2030/8 128 43 Prague 2 Czech Republic
| | - Tomáš Navrátil
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences; Dolejškova 3 182 23 Prague 8 Czech Republic
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Piantanida L, Bolt HL, Rozatian N, Cobb SL, Voïtchovsky K. Ions Modulate Stress-Induced Nanotexture in Supported Fluid Lipid Bilayers. Biophys J 2017; 113:426-439. [PMID: 28746853 PMCID: PMC5529180 DOI: 10.1016/j.bpj.2017.05.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 05/22/2017] [Accepted: 05/30/2017] [Indexed: 12/13/2022] Open
Abstract
Most plasma membranes comprise a large number of different molecules including lipids and proteins. In the standard fluid mosaic model, the membrane function is effected by proteins whereas lipids are largely passive and serve solely in the membrane cohesion. Here we show, using supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers in different saline solutions, that ions can locally induce ordering of the lipid molecules within the otherwise fluid bilayer when the latter is supported. This nanoordering exhibits a characteristic length scale of ∼20 nm, and manifests itself clearly when mechanical stress is applied to the membrane. Atomic force microscopy (AFM) measurements in aqueous solutions containing NaCl, KCl, CaCl2, and Tris buffer show that the magnitude of the effect is strongly ion-specific, with Ca2+ and Tris, respectively, promoting and reducing stress-induced nanotexturing of the membrane. The AFM results are complemented by fluorescence recovery after photobleaching experiments, which reveal an inverse correlation between the tendency for molecular nanoordering and the diffusion coefficient within the bilayer. Control AFM experiments on other lipids and at different temperatures support the hypothesis that the nanotexturing is induced by reversible, localized gel-like solidification of the membrane. These results suggest that supported fluid phospholipid bilayers are not homogenous at the nanoscale, but specific ions are able to locally alter molecular organization and mobility, and spatially modulate the membrane’s properties on a length scale of ∼20 nm. To illustrate this point, AFM was used to follow the adsorption of the membrane-penetrating antimicrobial peptide Temporin L in different solutions. The results confirm that the peptides do not absorb randomly, but follow the ion-induced spatial modulation of the membrane. Our results suggest that ionic effects have a significant impact for passively modulating the local properties of biological membranes, when in contact with a support such as the cytoskeleton.
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Affiliation(s)
- Luca Piantanida
- Department of Physics, Durham University, Durham, United Kingdom
| | - Hannah L Bolt
- Department of Chemistry, Durham University, Durham, United Kingdom
| | - Neshat Rozatian
- Department of Chemistry, Durham University, Durham, United Kingdom
| | - Steven L Cobb
- Department of Chemistry, Durham University, Durham, United Kingdom
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Cheng G, Liao M, Zhao D, Zhou J. Molecular Understanding on the Underwater Oleophobicity of Self-Assembled Monolayers: Zwitterionic versus Nonionic. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:1732-1741. [PMID: 28122450 DOI: 10.1021/acs.langmuir.6b03988] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Molecular dynamics simulations are conducted to investigate the underwater oleophobicity of self-assembled monolayers (SAMs) with different head groups. Simulation results show that the order of underwater oleophobicity of SAMs is methyl < amide < oligo(ethylene glycol) (OEG) < ethanolamine (ETA) < hydroxyl < mixed-charged zwitterionic. The underwater-oil contact angles (OCAs) are <133° for all nonionic hydrophilic SAMs, while the mixed-charged zwitterionic SAMs are underwater superoleophobic (OCA can reach 180°). It appears that surfaces with stronger underwater oleophobicity have better antifouling performance. Further study on the effect of different alkyl ammonium ions on mixed-charged SAMs reveals that the underwater OCAs are >143.6° for all SAMs; mixed-charged SAMs containing primary alkyl ammonium ion are likely to possess the best underwater oleophobicity for its strong hydration capacity. It seems that alkyl sulfonate anion (SO3-) is more hydrophilic than alkyl trimethylammonium ion (NC3+) for the hydrophobic methyl groups on nitrogen atoms and that the hydration of SO3- in mixed-charged SAMs can be seriously blocked by NC3+. The monomer of SO3- should be slightly longer than that of NC3+ to obtain better underwater oleophobicity in NC3+-/SO3--SAMs. In addition, the underwater oleophobicity of SAMs might become worse at low grafting densities. This work systematically proves that a zwitterionic surface is more underwater oleophobic than a nonionic surface. These results will help for the design and development of superoleophobic surfaces.
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Affiliation(s)
- Gang Cheng
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology , Guangzhou 510640, China
| | - Mingrui Liao
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology , Guangzhou 510640, China
| | - Daohui Zhao
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology , Guangzhou 510640, China
| | - Jian Zhou
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Laboratory for Green Chemical Product Technology, South China University of Technology , Guangzhou 510640, China
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