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Kanduč M, Stubenrauch C, Miller R, Schneck E. Interface Adsorption versus Bulk Micellization of Surfactants: Insights from Molecular Simulations. J Chem Theory Comput 2024; 20:1568-1578. [PMID: 37216476 PMCID: PMC10902850 DOI: 10.1021/acs.jctc.3c00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Surfactants play essential roles in many commonplace applications and industrial processes. Although significant progress has been made over the past decades with regard to model-based predictions of the behavior of surfactants, important challenges have remained. Notably, the characteristic time scales of surfactant exchange among micelles, interfaces, and the bulk solution typically exceed the time scales currently accessible with atomistic molecular dynamics (MD) simulations. Here, we circumvent this problem by introducing a framework that combines the general thermodynamic principles of self-assembly and interfacial adsorption with atomistic MD simulations. This approach provides a full thermodynamic description based on equal chemical potentials and connects the surfactant bulk concentration, the experimental control parameter, with the surfactant surface density, the suitable control parameter in MD simulations. Self-consistency is demonstrated for the nonionic surfactant C12EO6 (hexaethylene glycol monododecyl ether) at an alkane/water interface, for which the adsorption and pressure isotherms are computed. The agreement between the simulation results and experiments is semiquantitative. A detailed analysis reveals that the used atomistic model captures well the interactions between surfactants at the interface but less so their adsorption affinities to the interface and incorporation into micelles. Based on a comparison with other recent studies that pursued similar modeling challenges, we conclude that the current atomistic models systematically overestimate the surfactant affinities to aggregates, which calls for improved models in the future.
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Affiliation(s)
- Matej Kanduč
- Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Cosima Stubenrauch
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Reinhard Miller
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany
| | - Emanuel Schneck
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany
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2
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Yu Z, Ma W, Ji H, Fan Y, Zhao W. Interaction mechanism of egg derived peptides RVPSL and QIGLF with dipalmitoyl phosphatidylcholine membrane: microcalorimetric and molecular dynamics simulation studies. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2023; 103:6383-6393. [PMID: 37205773 DOI: 10.1002/jsfa.12714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 05/03/2023] [Accepted: 05/17/2023] [Indexed: 05/21/2023]
Abstract
BACKGROUND Egg-derived peptides are becoming increasingly popular due to their biological activity and non-toxic effects. The egg-derived peptides Arg-Val-Pro-Ser-Leu (RVPSL) and Gln-Ile-Gly-Leu-Phe (QIGLF) display strong angiotensin-converting enzyme inhibitory activity and they can be taken up by intestinal epithelial cells. The interaction of the egg-derived peptides RVPSL and QIGLF with the membrane remains unclear. RESULTS The position and structure of the peptides in the membrane were calculated. The maximum density values of RVPSL and QIGLF were 2.27 and 1.22 nm from the center of the 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) membrane, respectively, indicating that peptides penetrated the membrane-water interface and were embedded in the membrane. The interaction of RVPSL and QIGLF with the DPPC membrane did not affect the average area per lipid or the lipid sequence parameters. The thermodynamic parameters ΔH, ΔG, and ΔS of the interaction between the peptide RVPSL with the DPPC membrane were 17.91 kJ mol-1 , -17.63 kJ mol-1 , 187.5 J mol-1 ·k-1 , respectively. The thermodynamic parameters ΔH, ΔG, and ΔS of the interaction between peptide QIGLF with DPPC membrane were 17.10 kJ mol-1 , -17.12 kJ mol-1 , 114.8 J mol-1 ·k-1 , respectively. CONCLUSION The results indicated that the binding of peptides RVPSL and QIGLF to DPPC is an endothermic, spontaneous, and entropy-driven reaction. The results of the study are relevant to the problem of the low bioavailability of bioactive peptides (BP). © 2023 Society of Chemical Industry.
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Affiliation(s)
- Zhipeng Yu
- School of Food Science and Engineering, Hainan University, Haikou, P. R. China
| | - Wenhao Ma
- College of Food Science and Engineering, Bohai University, Jinzhou, P. R. China
| | - Huizhuo Ji
- College of Food Science and Engineering, Bohai University, Jinzhou, P. R. China
| | - Yue Fan
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xian, P. R. China
| | - Wenzhu Zhao
- School of Food Science and Engineering, Hainan University, Haikou, P. R. China
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3
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Sarkar S, Singh PC. Selective Action of Antimalarial Hydroxychloroquine on the Packing of Phospholipids and Interfacial Water Associated with Lysosomal Model Membranes: A Vibrational Sum Frequency Generation Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:2435-2443. [PMID: 36735290 DOI: 10.1021/acs.langmuir.2c03321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Understanding the structural change of lysosomal membranes induced by hydroxychloroquine (HCQ) drug is essential as it has been considered as one of the probable mechanisms of its antimalarial action. In this context, vibrational sum frequency generation (VSFG) spectra of the O-H region of water and C-H of the hydrocarbon chain of negatively charged and zwitterionic phospholipids associated with the lysosomal membrane in the absence and presence of different concentrations of HCQ have been measured at the air/water interface. The interfacial water at the negatively charged and zwitterionic lipids gets restructured in the presence of HCQ; however, the mechanism of restructuring is different due to the charge of the head groups of lipids. Interestingly, the presence of HCQ leads to a disorder in the negatively charged lipids, irrespective of their chemical nature, mainly by creating the gauche defect in the hydrocarbon chain of the lipid. In contrast, the ordering of the zwitterionic lipid does not show any appreciable change with the addition of HCQ. The finding on the selectivity of HCQ in affecting the ordering of the lipid depending on its head group charge and restructuring of interfacial water may be useful in understanding the molecular level mechanism of the antimalarial action of HCQ.
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Affiliation(s)
- Sunipa Sarkar
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata700032, India
| | - Prashant Chandra Singh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata700032, India
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Dronadula MT, Aluru NR. Phospholipid Monolayer/Graphene Interfaces: Curvature Effect on Lipid Morphology and Dynamics. J Phys Chem B 2022; 126:6261-6270. [PMID: 35951540 DOI: 10.1021/acs.jpcb.2c00896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phospholipids are an important class of lipids that are widely used as model platforms for the study of biological processes and interactions. These lipids can form stable interfaces with solid substrates, such as graphene, and these interfaces have potential applications in biosensing and targeted drug delivery. In this paper, we perform molecular dynamics simulations of graphene-supported lipid monolayers to characterize the lipid properties of such interfaces. We observed substantial differences between the supported monolayer and free-standing bilayer in terms of the lipid properties, such as the tail order parameters, density profiles, diffusion rates, and so on. Furthermore, we studied these interfaces on sinusoidally deformed graphene substrates to understand the effect of curvature on the supported lipids. Here, we observed that the nature of the substrate curvature, that is, concave or convex, can locally affect the lipid/substrate adhesion strength and induce structural and dynamic changes in the adsorbed lipid monolayer. Together, these results help characterize the properties of lipid/graphene interfaces and provide insights into the substrate curvature effect on these interfaces, which can enable the tuning of lipid properties for various sensor devices and drug delivery applications.
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Affiliation(s)
- Mohan Teja Dronadula
- Oden Institute for Computational Engineering and Sciences, Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - N R Aluru
- Oden Institute for Computational Engineering and Sciences, Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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5
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Ramos-Martín F, D'Amelio N. Biomembrane lipids: When physics and chemistry join to shape biological activity. Biochimie 2022; 203:118-138. [PMID: 35926681 DOI: 10.1016/j.biochi.2022.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/13/2022] [Accepted: 07/21/2022] [Indexed: 11/02/2022]
Abstract
Biomembranes constitute the first lines of defense of cells. While small molecules can often permeate cell walls in bacteria and plants, they are generally unable to penetrate the barrier constituted by the double layer of phospholipids, unless specific receptors or channels are present. Antimicrobial or cell-penetrating peptides are in fact highly specialized molecules able to bypass this barrier and even discriminate among different cell types. This capacity is made possible by the intrinsic properties of its phospholipids, their distribution between the internal and external leaflet, and their ability to mutually interact, modulating the membrane fluidity and the exposition of key headgroups. Although common phospholipids can be found in the membranes of most organisms, some are characteristic of specific cell types. Here, we review the properties of the most common lipids and describe how they interact with each other in biomembrane. We then discuss how their assembly in bilayers determines some key physical-chemical properties such as permeability, potential and phase status. Finally, we describe how the exposition of specific phospholipids determines the recognition of cell types by membrane-targeting molecules.
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Affiliation(s)
- Francisco Ramos-Martín
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, Amiens, 80039, France.
| | - Nicola D'Amelio
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, Amiens, 80039, France.
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6
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Zhu Y, Bai X, Hu G. Interfacial behavior of phospholipid monolayers revealed by mesoscopic simulation. Biophys J 2021; 120:4751-4762. [PMID: 34562445 DOI: 10.1016/j.bpj.2021.09.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/28/2021] [Accepted: 09/20/2021] [Indexed: 12/01/2022] Open
Abstract
A mesoscopic model with molecular resolution is presented for dipalmitoyl phosphatidylcholine (DPPC) and palmitoyl oleoyl phosphatidylcholine (POPC) monolayer simulations at the air-water interface using many-body dissipative particle dynamics (MDPD). The parameterization scheme is rigorously based on reproducing the physical properties of water and alkane and the interfacial property of the phospholipid monolayer by comparison with experimental results. Using much less computing cost, these MDPD simulations yield a similar surface pressure-area isotherm as well as similar pressure-related morphologies as all-atom simulations and experiments. Moreover, the compressibility modulus, order parameter of lipid tails, and thickness of the phospholipid monolayer are quantitatively in line with the all-atom simulations and experiments. This model also captures the sensitive changes in the pressure-area isotherms of mixed DPPC/POPC monolayers with altered mixing ratios, indicating that the model is promising for applications with complex natural phospholipid monolayers. These results demonstrate a significant improvement of quantitative phospholipid monolayer simulations over previous coarse-grained models.
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Affiliation(s)
- Yongzheng Zhu
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou, China; The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Xuan Bai
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou, China
| | - Guoqing Hu
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou, China.
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7
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Ramos-Martín F, D’Amelio N. Molecular Basis of the Anticancer and Antibacterial Properties of CecropinXJ Peptide: An In Silico Study. Int J Mol Sci 2021; 22:E691. [PMID: 33445613 PMCID: PMC7826669 DOI: 10.3390/ijms22020691] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 02/04/2023] Open
Abstract
Esophageal cancer is an aggressive lethal malignancy causing thousands of deaths every year. While current treatments have poor outcomes, cecropinXJ (CXJ) is one of the very few peptides with demonstrated in vivo activity. The great interest in CXJ stems from its low toxicity and additional activity against most ESKAPE bacteria and fungi. Here, we present the first study of its mechanism of action based on molecular dynamics (MD) simulations and sequence-property alignment. Although unstructured in solution, predictions highlight the presence of two helices separated by a flexible hinge containing P24 and stabilized by the interaction of W2 with target biomembranes: an amphipathic helix-I and a poorly structured helix-II. Both MD and sequence-property alignment point to the important role of helix I in both the activity and the interaction with biomembranes. MD reveals that CXJ interacts mainly with phosphatidylserine (PS) but also with phosphatidylethanolamine (PE) headgroups, both found in the outer leaflet of cancer cells, while salt bridges with phosphate moieties are prevalent in bacterial biomimetic membranes composed of PE, phosphatidylglycerol (PG) and cardiolipin (CL). The antibacterial activity of CXJ might also explain its interaction with mitochondria, whose phospholipid composition recalls that of bacteria and its capability to induce apoptosis in cancer cells.
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Affiliation(s)
- Francisco Ramos-Martín
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
| | - Nicola D’Amelio
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
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8
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Wang X, Santo KP, Neimark AV. Modeling Gas-Liquid Interfaces by Dissipative Particle Dynamics: Adsorption and Surface Tension of Cetyl Trimethyl Ammonium Bromide at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14686-14698. [PMID: 33216560 DOI: 10.1021/acs.langmuir.0c02572] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Adsorption of surfactants at gas-liquid interfaces that causes reduction in the surface tension is a classical problem in colloid and interface science with multiple practical applications in oil and gas recovery, separations, cosmetics, personal care, and biomedicine. Here, we develop an original coarse-grained model of the liquid-gas interface within the conventional dissipative particle dynamics (DPD) framework with the goal of quantitatively predicting the surface tension in the presence of surfactants. As a practical case-study example, we explore the adsorption of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) on the air-water interface. The gas phase is modeled as a DPD fluid composed of fictitious hard-core "gas" beads with exponentially decaying repulsive potentials to prevent penetration of the liquid phase components. A rigorous parametrization scheme is proposed based on matching the bulk and interfacial properties of water and octane taken as the reference compounds. Quantitative agreement between the simulated and experimental surface tension of CTAB solutions is found for a wide range of bulk surfactant concentrations (∼10-3 to ∼1 mmol/L) with the reduction of the surface tension from ∼72 mN/m (pure water) to the limiting value of ∼37.5 mN/m at the critical micelle concentration. The gas phase DPD model with the proposed parametrization scheme can be extended and applied to modeling various gas-liquid interfaces with surfactant and lipid monolayers, such as bubble suspensions, foams, froths, etc.
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Affiliation(s)
- Xinyang Wang
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
- School of Resources and Civil Engineering, Northeastern University, Shenyang, Liaoning 110819, China
| | - Kolattukudy P Santo
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Alexander V Neimark
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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9
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Moreira LG, Almeida AM, Camacho SA, Estevão BM, Oliveira ON, Aoki PHB. Chain Cleavage of Bioinspired Bacterial Membranes Photoinduced by Eosin Decyl Ester. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9578-9585. [PMID: 32672975 DOI: 10.1021/acs.langmuir.0c01600] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Photodynamic therapy (PDT) is promising for bacterial inactivation since cellular internalization of photosensitizers (PS) is not crucial for the treatment effectiveness. Photoinduced damage in the lipid envelope may already induce microbial inactivation, which requires PS capable of easily penetrating into the membrane. Herein, we report on the insertion of the PS eosin decyl ester (EosDec) into Langmuir films of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG), and cardiolipin (CLP) used as mimetic systems of bacterial membranes. Surface pressure isotherms and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) indicated that the hydrophobic nature of EosDec favored deeper penetration in all the phospholipid monolayers. The incorporation of EosDec led to monolayer expansion, especially in the anionic DOPG and CLP owing to repulsive electrostatic interactions, and induced disorder in the lipid chains. Light irradiation of DOPE, DOPG, and CLP monolayers containing EosDec increased the rate of material loss to the subphase, which is attributed to cleavage of lipid chains triggered by contact-dependent reactions between excited states of EosDec and lipid unsaturations. The latter is key for membrane permeabilization and efficiency in microbial inactivation.
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Affiliation(s)
- Lucas G Moreira
- School of Sciences, Humanities and Languages, São Paulo State University (UNESP), Assis, SP 19806-900, Brazil
| | - Alexandre M Almeida
- School of Sciences, Humanities and Languages, São Paulo State University (UNESP), Assis, SP 19806-900, Brazil
| | - Sabrina A Camacho
- School of Sciences, Humanities and Languages, São Paulo State University (UNESP), Assis, SP 19806-900, Brazil
- IFSC, São Carlos Institute of Physics, University of São Paulo (USP), São Carlos, SP 13566-590, Brazil
| | - Bianca M Estevão
- IFSC, São Carlos Institute of Physics, University of São Paulo (USP), São Carlos, SP 13566-590, Brazil
- Department of Chemistry, State University of Maringá (UEM), Maringá, PR 87020-900, Brazil
| | - Osvaldo N Oliveira
- IFSC, São Carlos Institute of Physics, University of São Paulo (USP), São Carlos, SP 13566-590, Brazil
| | - Pedro H B Aoki
- School of Sciences, Humanities and Languages, São Paulo State University (UNESP), Assis, SP 19806-900, Brazil
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10
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Zhang Y, Zhang HX, Zheng QC. In Silico Study of Membrane Lipid Composition Regulating Conformation and Hydration of Influenza Virus B M2 Channel. J Chem Inf Model 2020; 60:3603-3615. [PMID: 32589410 DOI: 10.1021/acs.jcim.0c00329] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The proton conduction of transmembrane influenza virus B M2 (BM2) proton channel is possibly mediated by the membrane environment, but the detailed molecular mechanism is challenging to determine. In this work, how membrane lipid composition regulates the conformation and hydration of BM2 channel is elucidated in silico. The appearance of several important hydrogen-bond networks has been discovered, as the addition of negatively charged lipid palmitoyloleoyl phosphatidylglycerol (POPG) and cholesterol reduces membrane fluidity and augments membrane rigidity. A more rigid membrane environment is beneficial to expand the channel, allow more water to enter the channel, promote channel hydration, and then even affect the proton conduction facilitated by the hydrated channel. Thus, membrane environment could be identified as an important influence factor of conformation and hydration of BM2. These findings can provide a unique perspective for understanding the mechanism of membrane lipid composition regulating conformation and hydration of BM2 and have important significance to the further study of anti-influenza virus B drugs.
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Affiliation(s)
- Yue Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, College of Chemistry, Jilin University, Changchun 130023, People's Republic of China
| | - Hong-Xing Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, College of Chemistry, Jilin University, Changchun 130023, People's Republic of China
| | - Qing-Chuan Zheng
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, College of Chemistry, Jilin University, Changchun 130023, People's Republic of China.,Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun 130023, People's Republic of China
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11
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Wrobel EC, de Lara LS, do Carmo TAS, Castellen P, Lazzarotto M, de Lázaro SR, Camilo A, Caseli L, Schmidt R, DeWolf CE, Wohnrath K. The antibacterial activity of p-tert-butylcalix[6]arene and its effect on a membrane model: molecular dynamics and Langmuir film studies. Phys Chem Chem Phys 2020; 22:6154-6166. [PMID: 32124897 DOI: 10.1039/d0cp00432d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The antibacterial activity of a calixarene derivative, p-tert-butylcalix[6]arene (Calix6), was assessed and was shown not to inhibit the growth of E. coli, S. aureus and B. subtilis bacteria. With the aim of gaining more insights into the absence of antibacterial activity of Calix6, the interaction of this derivative with DPPG, a bacterial cell membrane lipid, was studied. Langmuir monolayers were used as the model membrane. Pure DPPG and pure Calix6 monolayers, as well as binary DPPG:Calix6 mixtures were studied using surface pressure measurements, compressional modulus, Brewster angle and fluorescence microscopies, ellipsometry, polarization-modulation infrared reflection absorption spectroscopy and molecular dynamics simulations. Thermodynamic properties of the mixed monolayers were additionally calculated using thermodynamic parameters. The analysis of isotherms showed that Calix6 significantly affects the DPPG monolayers, modifying the isotherm profile and increasing the molecular area, in agreement with the molecular dynamics simulations. The presence of Calix6 in the mixed monolayers decreased the interfacial elasticity, indicating that calixarene disrupts the strong intermolecular interactions of DPPG hindering its organization into a compact arrangement. At low molar ratios of Calix6, the DPPG:Calix6 interactions are preferentially attractive, due to the interactions between the hydrophobic tails of DPPG and the tert-butyl groups of Calix6. Increasing the proportion of calixarene generates repulsive interactions. Calix6 significantly affects the hydrophobic tail organization, which was confirmed by PM-IRRAS measurements. Calix6 appears to be expelled from the mixed films at a biologically relevant surface pressure, π = 30 mN m-1, indicating a low interaction with the cell membrane model related to the absence of antibacterial activity.
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Affiliation(s)
- Ellen C Wrobel
- Department of Chemistry, Universidade Estadual de Ponta Grossa, Ponta Grossa, Par84030-900, Brazil.
| | - Lucas S de Lara
- Department of Physics, Universidade Estadual de Ponta Grossa, Ponta Grossa, Paraná 84030-900, Brazil
| | - Taiza A S do Carmo
- Academic Department of Mathematic, Universidade Federal Tecnológica do Paraná - Campus Ponta Grossa, Ponta Grossa, Paraná 84016-210, Brazil
| | - Patrícia Castellen
- Department of Chemistry, Universidade Estadual de Ponta Grossa, Ponta Grossa, Par84030-900, Brazil.
| | - Márcio Lazzarotto
- Department of Organic Chemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970, Brazil
| | - Sérgio R de Lázaro
- Department of Chemistry, Universidade Estadual de Ponta Grossa, Ponta Grossa, Par84030-900, Brazil.
| | - Alexandre Camilo
- Department of Physics, Universidade Estadual de Ponta Grossa, Ponta Grossa, Paraná 84030-900, Brazil
| | - Luciano Caseli
- Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, São Paulo (SP) 09972-970, Brazil
| | - Rolf Schmidt
- Department of Chemistry and Biochemistry and Concordia Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Québec H4B 1R6, Canada
| | - Christine E DeWolf
- Department of Chemistry and Biochemistry and Concordia Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Québec H4B 1R6, Canada
| | - Karen Wohnrath
- Department of Chemistry, Universidade Estadual de Ponta Grossa, Ponta Grossa, Par84030-900, Brazil.
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Mitra S, Das R, Singh A, Mukhopadhyay MK, Roy G, Ghosh SK. Surface Activities of a Lipid Analogue Room-Temperature Ionic Liquid and Its Effects on Phospholipid Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:328-339. [PMID: 31826620 DOI: 10.1021/acs.langmuir.9b02716] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
There are great efforts of synthesizing imidazolium-based ionic liquids (ILs) for developing new antibiotics as these molecules have shown strong antibacterial activities. Compared to a single-hydrocarbon-chained IL, the lipid analogues (LAs) with two chains are more effective. In the present study, the LA molecule MeIm(COOH)Me(Oleylamine)Iodide has been synthesized and its surface activities along with the effectiveness in restructuring of a model cellular membrane have been quantified. The molecule is found to be highly surface active as estimated from the area-pressure isotherm of a monolayer of the molecules formed at the air-water interface. The X-ray reflectivity (XRR) studies of a monolayer dip-coated on a hydrophilic substrate have shown the structural properties of the layer which resembles to those of unsaturated phospholipids. The LA molecules are observed to fluidize a phospholipid bilayer formed by the saturated lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). At a lower surface pressure, the lipid monolayer of DPPC has exhibited a thickening effect at a low concentration of added LA and a thinning effect at higher concentration. However, at a high surface pressure of the monolayer, the thickness is found to decrease monotonically. The in-plane pressure-dependent interaction of LA molecules with model cellular membrane and the corresponding perturbation in the structure and physical properties of the membrane may be linked to the strong lysing effect of these types of molecules.
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Affiliation(s)
| | | | - A Singh
- Surface Physics and Material Science Division , Saha Institute of Nuclear Physics , AF Block, Bidhannagar , Kolkata 700064 , India
| | - M K Mukhopadhyay
- Surface Physics and Material Science Division , Saha Institute of Nuclear Physics , AF Block, Bidhannagar , Kolkata 700064 , India
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13
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Bai X, Xu L, Tang JY, Zuo YY, Hu G. Adsorption of Phospholipids at the Air-Water Surface. Biophys J 2019; 117:1224-1233. [PMID: 31519299 DOI: 10.1016/j.bpj.2019.08.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 08/03/2019] [Accepted: 08/19/2019] [Indexed: 11/15/2022] Open
Abstract
Phospholipids are ubiquitous components of biomembranes and common biomaterials used in many bioengineering applications. Understanding adsorption of phospholipids at the air-water surface plays an important role in the study of pulmonary surfactants and cell membranes. To date, however, the biophysical mechanisms of phospholipid adsorption are still unknown. It is challenging to reveal the molecular structure of adsorbed phospholipid films. Using combined experiments with constrained drop surfactometry and molecular dynamics simulations, here, we studied the biophysical mechanisms of dipalmitoylphosphatidylcholine (DPPC) adsorption at the air-water surface. It was found that the DPPC film adsorbed from vesicles showed distinct equilibrium surface tensions from the DPPC monolayer spread via organic solvents. Our simulations revealed that only the outer leaflet of the DPPC vesicle is capable of unzipping and spreading at the air-water surface, whereas the inner leaflet remains intact and forms an inverted micelle to the interfacial monolayer. This inverted micelle increases the local curvature of the monolayer, thus leading to a loosely packed monolayer at the air-water surface and hence a higher equilibrium surface tension. These findings provide novel insights, to our knowledge, into the mechanism of the phospholipid and pulmonary surfactant adsorption and may help understand the structure-function correlation in biomembranes.
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Affiliation(s)
- Xuan Bai
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, China; The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Lu Xu
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Jenny Y Tang
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii; Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii.
| | - Guoqing Hu
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, China.
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14
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Ermakov YA, Asadchikov VE, Roschin BS, Volkov YO, Khomich DA, Nesterenko AM, Tikhonov AM. Comprehensive Study of the Liquid Expanded-Liquid Condensed Phase Transition in 1,2-Dimyristoyl- sn-glycero-3-phospho-l-serine Monolayers: Surface Pressure, Volta Potential, X-ray Reflectivity, and Molecular Dynamics Modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12326-12338. [PMID: 31480848 DOI: 10.1021/acs.langmuir.9b01450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
An integrated approach is applied to reveal fine changes in the surface-normal structure of 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS) monolayers at the air-lipid-water interface occurring in a liquid expanded (LE)-liquid condensed (LC) transition. The combination of the Langmuir monolayer technique, X-ray reflectometry, and molecular dynamics (MD) modeling provides new insight into the molecular nature of electrostatic phenomena in different stages of lipid compression. A homemade setup with a laboratory X-ray source (λ = 1.54 Å) offers a nondestructive way to reveal the structural difference between the LE and LC phases of the lipid. The electron density profile in the direction normal to the interface is recovered from the X-ray reflectivity data with the use of both model-independent and model-based approaches. MD simulations of the DMPS monolayer are performed for several areas per lipid using the all-atom force field. Using the conventional theory of capillary waves, a comparison is made between the electron density profiles reconstructed from the X-ray data and those calculated directly from MD modeling, which demonstrates remarkable agreement between the experiment and simulations for all selected lipid densities. This confirms the validity of the simulations and allows an analysis of the contributions of the hydrophobic tails and hydrated polar groups to the electron density profile and to the dipole component of the electric field at the interface. According to the MD data, the dependence of the Volta potential on the area per lipid in the monolayer has a different molecular nature below and above the phase transition. In the LE state of the monolayer, the potential is determined mostly by the oriented water molecules in the polar region of the lipid. In the LE-LC transition, these molecules are displaced to the bulk, and their effect on the Volta potential becomes insignificant compared with the contribution of the hydrophobic tails. The hydrophobic tails are highly ordered in the state of the liquid crystal so that their dipole moments entirely determine the growth of the potential upon compression up to the monolayer collapse.
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Affiliation(s)
- Yu A Ermakov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , Leninsky pr., 31/4 , Moscow 119071 , Russia
| | - V E Asadchikov
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
| | - B S Roschin
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
| | - Yu O Volkov
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
- Institute of Solid State Physics, Russian Academy of Sciences , Academician Ossipyan str. 2 , Moscow District, Chernogolovka 142432 , Russia
| | - D A Khomich
- Lomonosov Moscow State University , Biology Faculty, Leninskie gory 1/12 , Moscow 119234 , Russia
- Engelhardt Institute of Molecular Biology , Russian Academy of Sciences , Vavilova, 32 , Moscow 119991 , Russia
| | - A M Nesterenko
- Belozersky Institute of Physico-Chemical Biology , Lomonosov Moscow State University ; Leninskie gory 1/40 , Moscow , 119991 , Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences , Miklukho-Maklaya 16/10 , Moscow 117997 , Russia
| | - A M Tikhonov
- Institute of Solid State Physics, Russian Academy of Sciences , Academician Ossipyan str. 2 , Moscow District, Chernogolovka 142432 , Russia
- Kapitza Institute for Physical Problems, Russian Academy of Sciences , ul. Kosygina 2 , Moscow 119334 , Russia
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15
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Okur HI, Chen Y, Smolentsev N, Zdrali E, Roke S. Interfacial Structure and Hydration of 3D Lipid Monolayers in Aqueous Solution. J Phys Chem B 2017; 121:2808-2813. [DOI: 10.1021/acs.jpcb.7b00609] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Halil I. Okur
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Yixing Chen
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nikolay Smolentsev
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Evangelia Zdrali
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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16
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Gnanasambandam R, Ghatak C, Yasmann A, Nishizawa K, Sachs F, Ladokhin AS, Sukharev SI, Suchyna TM. GsMTx4: Mechanism of Inhibiting Mechanosensitive Ion Channels. Biophys J 2017; 112:31-45. [PMID: 28076814 PMCID: PMC5231890 DOI: 10.1016/j.bpj.2016.11.013] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/12/2016] [Accepted: 11/03/2016] [Indexed: 12/21/2022] Open
Abstract
GsMTx4 is a spider venom peptide that inhibits cationic mechanosensitive channels (MSCs). It has six lysine residues that have been proposed to affect membrane binding. We synthesized six analogs with single lysine-to-glutamate substitutions and tested them against Piezo1 channels in outside-out patches and independently measured lipid binding. Four analogs had ∼20% lower efficacy than the wild-type (WT) peptide. The equilibrium constants calculated from the rates of inhibition and washout did not correlate with the changes in inhibition. The lipid association strength of the WT GsMTx4 and the analogs was determined by tryptophan autofluorescence quenching and isothermal calorimetry with membrane vesicles and showed no significant differences in binding energy. Tryptophan fluorescence-quenching assays showed that both WT and analog peptides bound superficially near the lipid-water interface, although analogs penetrated deeper. Peptide-lipid association, as a function of lipid surface pressure, was investigated in Langmuir monolayers. The peptides occupied a large fraction of the expanded monolayer area, but that fraction was reduced by peptide expulsion as the pressure approached the monolayer-bilayer equivalence pressure. Analogs with compromised efficacy had pressure-area isotherms with steeper slopes in this region, suggesting tighter peptide association. The pressure-dependent redistribution of peptide between "deep" and "shallow" binding modes was supported by molecular dynamics (MD) simulations of the peptide-monolayer system under different area constraints. These data suggest a model placing GsMTx4 at the membrane surface, where it is stabilized by the lysines, and occupying a small fraction of the surface area in unstressed membranes. When applied tension reduces lateral pressure in the lipids, the peptides penetrate deeper acting as "area reservoirs" leading to partial relaxation of the outer monolayer, thereby reducing the effective magnitude of stimulus acting on the MSC gate.
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Affiliation(s)
| | - Chiranjib Ghatak
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Anthony Yasmann
- Department of Biology, University of Maryland, College Park, Maryland
| | - Kazuhisa Nishizawa
- Clinical Laboratory Science, Teikyo University School of Medical Technology, Tokyo, Japan
| | - Frederick Sachs
- Department of Physiology and Biophysics, State University of New York, Buffalo, New York
| | - Alexey S Ladokhin
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Sergei I Sukharev
- Department of Biology, University of Maryland, College Park, Maryland
| | - Thomas M Suchyna
- Department of Physiology and Biophysics, State University of New York, Buffalo, New York.
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17
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Klug J, Masone D, Del Pópolo MG. Molecular-level insight into the binding of arginine to a zwitterionic Langmuir monolayer. RSC Adv 2017. [DOI: 10.1039/c7ra05359b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Arginine molecules bind to a DPPC monolayer, altering the interfacial electrostatic potential and the lateral mobility of the lipids, while having little effect on the compression isotherm of the monolayer.
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Affiliation(s)
- Joaquín Klug
- CONICET & Facultad de Ciencias Exactas y Naturales
- Universidad Nacional de Cuyo
- Mendoza
- Argentina
- Atomistic Simulation Centre
| | - Diego Masone
- CONICET & Facultad de Ciencias Exactas y Naturales
- Universidad Nacional de Cuyo
- Mendoza
- Argentina
| | - Mario G. Del Pópolo
- CONICET & Facultad de Ciencias Exactas y Naturales
- Universidad Nacional de Cuyo
- Mendoza
- Argentina
- Atomistic Simulation Centre
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18
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Kellermann MY, Yoshinaga MY, Valentine RC, Wörmer L, Valentine DL. Important roles for membrane lipids in haloarchaeal bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2940-2956. [PMID: 27565574 DOI: 10.1016/j.bbamem.2016.08.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 08/11/2016] [Accepted: 08/19/2016] [Indexed: 10/21/2022]
Abstract
Recent advances in lipidomic analysis in combination with various physiological experiments set the stage for deciphering the structure-function of haloarchaeal membrane lipids. Here we focused primarily on changes in lipid composition of Haloferax volcanii, but also performed a comparative analysis with four other haloarchaeal species (Halobacterium salinarum, Halorubrum lacusprofundi, Halorubrum sodomense and Haloplanus natans) all representing distinctive cell morphologies and behaviors (i.e., rod shape vs. pleomorphic behavior). Common to all five haloarchaea, our data reveal an extraordinary high level of menaquinone, reaching up to 72% of the total lipids. This ubiquity suggests that menaquinones may function beyond their ordinary role as electron and proton transporter, acting simultaneously as ion permeability barriers and as powerful shield against oxidative stress. In addition, we aimed at understanding the role of cations interacting with the characteristic negatively charged surface of haloarchaeal membranes. We propose for instance that by bridging the negative charges of adjacent anionic phospholipids, Mg2+ acts as surrogate for cardiolipin, a molecule that is known to control curvature stress of membranes. This study further provides a bioenergetic perspective as to how haloarchaea evolved following oxygenation of Earth's atmosphere. The success of the aerobic lifestyle of haloarchaea includes multiple membrane-based strategies that successfully balance the need for a robust bilayer structure with the need for high rates of electron transport - collectively representing the molecular basis to inhabit hypersaline water bodies around the planet.
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Affiliation(s)
- Matthias Y Kellermann
- Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
| | - Marcos Y Yoshinaga
- MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany
| | | | - Lars Wörmer
- MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany
| | - David L Valentine
- Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
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19
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Eftaiha AF, Wanasundara SN, Paige MF, Bowles RK. Exploring the Impact of Tail Polarity on the Phase Behavior of Single Component and Mixed Lipid Monolayers Using a MARTINI Coarse-Grained Force Field. J Phys Chem B 2016; 120:7641-51. [DOI: 10.1021/acs.jpcb.6b03970] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ala’a F. Eftaiha
- Department
of Chemistry, The Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Surajith N. Wanasundara
- Department
of Medical Imaging, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK S7N 0W8, Canada
| | - Matthew F. Paige
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Richard K. Bowles
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
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20
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Baoukina S, Tieleman DP. Computer simulations of lung surfactant. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2431-2440. [PMID: 26922885 DOI: 10.1016/j.bbamem.2016.02.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/21/2016] [Accepted: 02/23/2016] [Indexed: 01/26/2023]
Abstract
Lung surfactant lines the gas-exchange interface in the lungs and reduces the surface tension, which is necessary for breathing. Lung surfactant consists mainly of lipids with a small amount of proteins and forms a monolayer at the air-water interface connected to bilayer reservoirs. Lung surfactant function involves transfer of material between the monolayer and bilayers during the breathing cycle. Lipids and proteins are organized laterally in the monolayer; selected species are possibly preferentially transferred to bilayers. The complex 3D structure of lung surfactant and the exact roles of lipid organization and proteins remain important goals for research. We review recent simulation studies on the properties of lipid monolayers, monolayers with phase coexistence, monolayer-bilayer transformations, lipid-protein interactions, and effects of nanoparticles on lung surfactant. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
| | - D Peter Tieleman
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
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21
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Hood RR, DeVoe DL. High-Throughput Continuous Flow Production of Nanoscale Liposomes by Microfluidic Vertical Flow Focusing. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5790-5799. [PMID: 26395346 DOI: 10.1002/smll.201501345] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/04/2015] [Indexed: 06/05/2023]
Abstract
Liposomes represent a leading class of nanoparticles for drug delivery. While a variety of techniques for liposome synthesis have been reported that take advantage of microfluidic flow elements to achieve precise control over the size and polydispersity of nanoscale liposomes, with important implications for nanomedicine applications, these methods suffer from extremely limited throughput, making them impractical for large-scale nanoparticle synthesis. High aspect ratio microfluidic vertical flow focusing is investigated here as a new approach to overcoming the throughput limits of established microfluidic nanoparticle synthesis techniques. Here the vertical flow focusing technique is utilized to generate populations of small, unilamellar, and nearly monodisperse liposomal nanoparticles with exceptionally high production rates and remarkable sample homogeneity. By leveraging this platform, liposomes with modal diameters ranging from 80 to 200 nm are prepared at production rates as high as 1.6 mg min(-1) in a simple flow-through process.
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Affiliation(s)
- Renee R Hood
- Department of Mechanical Engineering, 3126 Glenn L Martin Hall, University of Maryland, College Park, College Park, MD, 20742, USA
| | - Don L DeVoe
- Department of Mechanical Engineering, 3126 Glenn L Martin Hall, University of Maryland, College Park, College Park, MD, 20742, USA
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22
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Chen Y, Jena KC, Lütgebaucks C, Okur HI, Roke S. Three Dimensional Nano "Langmuir Trough" for Lipid Studies. NANO LETTERS 2015; 15:5558-5563. [PMID: 26151602 DOI: 10.1021/acs.nanolett.5b02143] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A three-dimensional-phospholipid monolayer with tunable molecular structure was created on the surface of oil nanodroplets from a mixture of phospholipids, oil, and water. This simple nanoemulsion preparation technique generates an in situ prepared membrane model system with controllable molecular surface properties that resembles a lipid droplet. The molecular interfacial structure of such a nanoscopic system composed of hexadecane, 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC), and water was determined using vibrational sum frequency scattering and second harmonic scattering techniques. The droplet surface structure of DPPC can be tuned from a tightly packed liquid condensed phase like monolayer to a more dilute one that resembles the liquid condensed/liquid expanded coexistence phase by varying the DPPC/oil/water ratio. The tunability of the chemical structure, the high surface-to-volume ratio, and the small sample volume make this system an ideal model membrane for biochemical research.
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Affiliation(s)
- Yixing Chen
- †Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Kailash C Jena
- †Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- ‡Department of Physics, Indian Institute of Technology Ropar, Rupnagar, 140001, India
| | - Cornelis Lütgebaucks
- †Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Halil I Okur
- †Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Sylvie Roke
- †Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
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23
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Huston KJ, Larson RG. Reversible and Irreversible Adsorption Energetics of Poly(ethylene glycol) and Sorbitan Poly(ethoxylate) at a Water/Alkane Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7503-7511. [PMID: 26079039 DOI: 10.1021/acs.langmuir.5b00398] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We simulate poly(ethylene glycol) (PEG) oligomers and model Tween 80 (polyoxyethylene sorbitan monooleate) molecules at water/alkane interfaces. Using the weighted histogram analysis method (WHAM), including an extension of WHAM to two reaction coordinates to remove hysteresis, we calculate interfacial potentials of mean force (PMFs) for PEG and Tween 80 using three force fields: the atomistic GROMOS 53a6OXY+D and two coarse-grained (CG) MARTINI force fields. Because the force fields have not yet been validated for PEO adsorption to hydrophobic interfaces, we calculate PMFs for alcohol ethoxylates C12E2 and C12E8 and find that they agree with semiempirical results of Mulqueen and Blankschtein [Langmuir 2002, 18 (2), 365-376] for the GROMOS 53a6OXY+D force field, whereas for both MARTINI force fields, PEO adsorbs too weakly to a clean hydrophobic interface. One MARTINI force field incorrectly shows depletion rather than adsorption to a clean hydrophobic interface. We find that the adsorption free energy for PEG oligomers at a clean, planar water/alkane interface is around 1.3 kBT per monomer for the atomistic force field but is less than half of this for the two CG force fields. With the newly validated GROMOS 53a6OXY+D force field, we bracket the dilute adsorption free energy for a model Tween 80 molecule at the clean water/squalane interface. We also calculate the pressure-area isotherm. We exploit these data with the Nikas-Mulqueen-Blankschtein (NMB) theory and a simple transport model to demonstrate a transition from irreversible to reversible adsorption with increasing surface coverage, consistent with experimental results of Reichert and Walker [Langmuir 2013, 29 (6), 1857-1867].
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Affiliation(s)
- Kyle J Huston
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
| | - Ronald G Larson
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
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24
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González-Castro CA, Ramírez-Santiago G. Phase behavior of Langmuir monolayers with ionic molecular heads: Molecular simulations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:032409. [PMID: 25871125 DOI: 10.1103/physreve.91.032409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Indexed: 06/04/2023]
Abstract
We carried out Monte Carlo simulations in the N,Π,T ensemble of a Langmuir monolayer coarse-grained molecular model. Considering that the hydrophilic groups can be ionized by modulating acid-base interactions, here we study the phase behavior of a model that incorporates the short-range steric and long-range ionic interactions. The simulations were carried out in the reduced temperature range 0.1≤T*<4.0, where there is a competition of these interactions. Different order parameters were calculated and analyzed for several values of the reduced surface pressure in the interval, 1≤Π*≤40. For most of the surface pressures two directions of molecular tilt were found: (i) towards the nearest neighbor (NN) at low temperatures, T*<0.7, and most of the values of Π* and (ii) towards next-nearest neighbors (NNN) in the temperature interval 0.7≤T*<1.1 for Π*<25. We also found the coexistence of the NN and NNN at intermediate temperatures and Π*>25. A low-temperature reentrant disorder-order-disorder transition in the positions of the molecular heads and in the collective tilt of the tails was found for all the surface pressure values. It was also found that the molecular tails arranged forming "rotating patterns" in the temperature interval, 0.5<T*<1.5, at intermediate surface pressures. We estimated the monolayer's surface pressure versus temperature and the temperature versus area per molecule phase diagrams. It was found that the LE↔LC phase transition shifts to smaller temperatures when the molecular heads carry an ion in qualitative agreement with experimental observations of fatty acid monolayers with ionic head groups. Two surface pressure versus area per molecule isotherms were also calculated. At low temperatures near the LC-NN ↔ LC-NNN transitions and at higher temperatures close to the LE ↔ LC transitions. From these isotherms the monolayer's area compression modulus was obtained and its variation ranges in the LE and LC phases were found to be consistent with the experimental values.
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Affiliation(s)
- Carlos A González-Castro
- Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, México 01000, D.F., Mexico
| | - Guillermo Ramírez-Santiago
- Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, México 01000, D.F., Mexico
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25
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Liu B, Hoopes MI, Karttunen M. Molecular Dynamics Simulations of DPPC/CTAB Monolayers at the Air/Water Interface. J Phys Chem B 2014; 118:11723-37. [PMID: 25222268 DOI: 10.1021/jp5050892] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Bin Liu
- Department of Chemistry and
Waterloo Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Matthew I. Hoopes
- Department of Chemistry and
Waterloo Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Mikko Karttunen
- Department of Chemistry and
Waterloo Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario, Canada N2L 3G1
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26
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Poojari C, Xiao D, Batista VS, Strodel B. Membrane permeation induced by aggregates of human islet amyloid polypeptides. Biophys J 2014; 105:2323-32. [PMID: 24268144 DOI: 10.1016/j.bpj.2013.09.045] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 09/12/2013] [Accepted: 09/30/2013] [Indexed: 01/23/2023] Open
Abstract
Several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases as well as nonneuropathic diseases such as type II diabetes and atrial amyloidosis are associated with aggregation of amyloid polypeptides into fibrillar structures, or plaques. In this study, we use molecular dynamics simulations to test the stability and orientation of membrane-embedded aggregates of the human islet amyloid polypeptide (hIAPP) implicated in type II diabetes. We find that in both monolayers and bilayers of dipalmitoylphosphatidylglycerol (DPPG) hIAPP trimers and tetramers remain inside the membranes and preserve their β-sheet secondary structure. Lipid bilayer-inserted hIAPP trimers and tetramers orient inside DPPG at 60° relative to the membrane/water interface and lead to water permeation and Na(+) intrusion, consistent with ion-toxicity in islet β-cells. In particular, hIAPP trimers form a water-filled β-sandwich that induce water permeability comparable with channel-forming proteins, such as aquaporins and gramicidin-A. The predicted disruptive orientation is consistent with the amphiphilic properties of the hIAPP aggregates and could be probed by chiral sum frequency generation (SFG) spectroscopy, as predicted by the simulated SFG spectra.
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Affiliation(s)
- Chetan Poojari
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: Structural Biochemistry (ICS-6), 52425 Jülich, Germany
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27
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Rudolphi-Skórska E, Zembala M, Filek M. Mechanical and electrokinetic effects of polyamines/phospholipid interactions in model membranes. J Membr Biol 2014; 247:81-92. [PMID: 24337467 PMCID: PMC3889835 DOI: 10.1007/s00232-013-9614-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 11/08/2013] [Indexed: 10/25/2022]
Abstract
The mechanical and electrical properties of phospholipids layers influenced by interaction with polyamines were determined by measuring surface pressure and compression modulus of monolayers and zeta potential of liposomes. The saturated derivative of phosphatidic acid (DPPA) formed layers of the organization varying with compression degree. Contact of DPPA layers with polyamines present in the subphase resulted in changing their mechanical properties and the conditions in which the layer reorganization appears. The parameters corresponding to the layer reorganization depended on the size and charge of polyamines' molecules. The values of: area per DPPA molecule, surface pressure at the point of layer structure reorganization, and surface pressure at the point of collapse characterizing of DPPA layers in the studied systems were determined. It was found that polyamines influenced to a much lesser extent the mechanical properties of monolayers formed from unsaturated derivative of phosphatidic acid slightly increasing its mechanical resistance in the range of higher molecular packing. The results of electrokinetic measurements revealed that surface charge of phosphatidic acid liposomes was effectively neutralized in the presence of polyamines. A similar effect was observed for phosphatidyl glycerol and for negatively charged polystyrene latex particles used as a reference. The influence of polyamines on the mechanical properties of DPPA layers was interpreted assuming a possibility of penetration of the lipid layer by polyamines' molecules. Comparison of action of putrescine and calcium ions and effects of polyamines on phosphatidyl glycerol provided additional justification for the proposed interpretation of the observed effects.
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28
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Schulze N, Tiersch B, Zenke I, Koetz J. Polyampholyte-tuned lyotrop lamellar liquid crystalline systems. Colloid Polym Sci 2013. [DOI: 10.1007/s00396-013-2999-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Peng X, Zhao L, Du G, Wei X, Guo J, Wang X, Guo G, Pu Q. Charge tunable zwitterionic polyampholyte layers formed in cyclic olefin copolymer microchannels through photochemical graft polymerization. ACS APPLIED MATERIALS & INTERFACES 2013; 5:1017-23. [PMID: 23331535 DOI: 10.1021/am3027019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Zwitterionic layers immobilized on various surfaces exhibit ideal biocompatibility and antifouling capability, but direct immobilization of zwitterionic molecules provides limited choice of surface charges. In this paper, the formation of charge tunable zwitterionic polyampholyte layers onto the surface of microfluidic channels of cyclic olefin copolymer by photochemical graft polymerization of mixed acrylic monomers, [2-(acryloyloxy) ethyl] trimethyl ammonium chloride and 2-acrylamido-2-methyl-1-propanesulfonic, under UV illumination was reported. With this method, surface charge of the resulting modification layers could be tailored through the initial monomer ratio and reaction conditions. The incorporation of both monomers into the grafted layers was confirmed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared (ATR-FTIR). The results indicate that the modified layers are hydrophilic with contact angles of 33.0-44.3°, and the isoelectric points of the modified layers can be tuned from <3 to >9 simply by adjusting the monomer ratios. Elimination of the nonspecific adsorption of proteins on the zwitterionic layers thus formed was proved by fluorescent microscopy and streaming potential measurement. The uniformity of the modified layers was verified through a comparison of electrophoresis inside the modified and native microchannels. A whole blood coagulation time measurement was performed to show its applicability.
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Affiliation(s)
- Xianglu Peng
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, Department of Chemistry, Lanzhou University, Lanzhou, Gansu, 730000, China
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30
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Abstract
A lipid monolayer lining a boundary between two immiscible phases forms a complex interface with inhomogeneous distribution of forces. Unlike lipid bilayers, monolayers are formed in asymmetric environment and their properties depend strongly on lipid surface density. The monolayer properties are also affected significantly by the representation of the pure interface. Here we give a brief theoretical introduction and describe methods to simulate lipid monolayers starting from force-fields and system setup to reproducing state points on the surface tension (pressure)-area isotherms and transformations between them.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada.
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31
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Garaiová Z, Mohsin MA, Vargová V, Banica FG, Hianik T. Complexation of cytochrome c with calixarenes incorporated into the lipid vesicles and supported membranes. Bioelectrochemistry 2012; 87:220-5. [DOI: 10.1016/j.bioelechem.2011.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 11/21/2011] [Accepted: 12/08/2011] [Indexed: 01/01/2023]
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32
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Interaction of miltefosine with intercellular membranes of stratum corneum and biomimetic lipid vesicles. Int J Pharm 2012; 434:391-8. [DOI: 10.1016/j.ijpharm.2012.06.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 05/17/2012] [Accepted: 06/03/2012] [Indexed: 11/22/2022]
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33
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Pan J, Heberle FA, Tristram-Nagle S, Szymanski M, Koepfinger M, Katsaras J, Kučerka N. Molecular structures of fluid phase phosphatidylglycerol bilayers as determined by small angle neutron and X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2135-48. [PMID: 22583835 DOI: 10.1016/j.bbamem.2012.05.007] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 03/22/2012] [Accepted: 05/07/2012] [Indexed: 10/28/2022]
Abstract
We have determined the molecular structures of commonly used phosphatidylglycerols (PGs) in the commonly accepted biologically relevant fluid phase. This was done by simultaneously analyzing small angle neutron and X-ray scattering data, with the constraint of measured lipid volumes. We report the temperature dependence of bilayer parameters obtained using the one-dimensional scattering density profile model - which was derived from molecular dynamics simulations - including the area per lipid, the overall bilayer thickness, as well as other intrabilayer parameters (e.g., hydrocarbon thickness). Lipid areas are found to be larger than their phosphatidylcholine (PC) counterparts, a result likely due to repulsive electrostatic interactions taking place between the charged PG headgroups even in the presence of sodium counterions. In general, PG and PC bilayers show a similar response to changes in temperature and chain length, but differ in their response to chain unsaturation. For example, compared to PC bilayers, the inclusion of a first double bond in PG lipids results in a smaller incremental change to the area per lipid and bilayer thickness. However, the extrapolated lipid area of saturated PG lipids to infinite chain length is found to be similar to that of PCs, an indication of the glycerol-carbonyl backbone's pivotal role in influencing the lipid-water interface.
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Affiliation(s)
- Jianjun Pan
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6100, USA.
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34
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Ko JY, Choi SM, Rhee YM, Beauchamp JL, Kim HI. Studying interfacial reactions of cholesterol sulfate in an unsaturated phosphatidylglycerol layer with ozone using field induced droplet ionization mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:141-152. [PMID: 22069038 DOI: 10.1007/s13361-011-0275-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 10/03/2011] [Accepted: 10/08/2011] [Indexed: 05/31/2023]
Abstract
Field-induced droplet ionization (FIDI) is a recently developed ionization technique that can transfer ions from the surface of microliter droplets to the gas phase intact. The air-liquid interfacial reactions of cholesterol sulfate (CholSO(4)) in a 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol (POPG) surfactant layer with ozone (O(3)) are investigated using field-induced droplet ionization mass spectrometry (FIDI-MS). Time-resolved studies of interfacial ozonolysis of CholSO(4) reveal that water plays an important role in forming oxygenated products. An epoxide derivative is observed as a major product of CholSO(4) oxidation in the FIDI-MS spectrum after exposure of the droplet to O(3) for 5 s. The abundance of the epoxide product then decreases with continued O(3) exposure as the finite number of water molecules at the air-liquid interface becomes exhausted. Competitive oxidation of CholSO(4) and POPG is observed when they are present together in a lipid surfactant layer at the air-liquid interface. Competitive reactions of CholSO(4) and POPG with O(3) suggest that CholSO(4) is present with POPG as a well-mixed interfacial layer. Compared with CholSO(4) and POPG alone, the overall ozonolysis rates of both CholSO(4) and POPG are reduced in a mixed layer, suggesting the double bonds of both molecules are shielded by additional hydrocarbons from one another. Molecular dynamics simulations of a monolayer comprising POPG and CholSO(4) correlate well with experimental observations and provide a detailed picture of the interactions between CholSO(4), lipids, and water molecules in the interfacial region.
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Affiliation(s)
- Jae Yoon Ko
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), 790-784, Pohang, Republic of Korea
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35
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Henriques VB, Germano R, Lamy MT, Tamashiro MN. Phase transitions and spatially ordered counterion association in ionic-lipid membranes: theory versus experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:13130-13143. [PMID: 21848301 DOI: 10.1021/la202302x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Aqueous dispersions of phosphatidylglycerol (PG) lipids may present an anomalous chain-melting transition at low ionic strengths, as seen by different experimental techniques such as calorimetry or light scattering. The anomaly disappears at high ionic strengths or for longer acyl-chain lengths. In this article, we use a statistical model for the bilayer that distinguishes both lipid chain and headgroup states in order to compare model and experimental thermotropic and electrical properties. The effective van der Waals interactions among hydrophobic chains compete with the electrostatic repulsions between polar headgroups, which may be ionized (counterion dissociated) or electrically neutral (associated with counterions). Electric degrees of freedom introduce new thermotropic charge-ordered phases in which headgroup charges may be spatially ordered, depending on the electrolyte ionic strength, introducing a new rationale for experimental data on PGs. The thermal phases presented by the model for different chain lengths, at fixed ionic strength, compare well with an experimental phase diagram constructed on the basis of differential scanning calorimetry profiles. In the case of dispersions of DMPG (dimyristoyl phosphatidylglycerol) with added monovalent salt, the model properties reproduce the main features displayed by data from differential scanning calorimetry as well as the characteristic profile for the degree of ionization of the bilayer surface across the anomalous transition region, obtained from the theoretical interpretation of electrokinetic (conductivity and electrophoretic mobility) measurements.
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Affiliation(s)
- V B Henriques
- Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, 05314-970 São Paulo, SP, Brazil.
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36
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Gang HZ, Liu JF, Mu BZ. Molecular Dynamics Study of Surfactin Monolayer at the Air/Water Interface. J Phys Chem B 2011; 115:12770-7. [DOI: 10.1021/jp206350j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Hong-Ze Gang
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai, People's Republic of China 200237
| | - Jin-Feng Liu
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai, People's Republic of China 200237
| | - Bo-Zhong Mu
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai, People's Republic of China 200237
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37
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Tamashiro MN, Barbetta C, Germano R, Henriques VB. Phase transitions and spatially ordered counterion association in ionic-lipid membranes: a statistical model. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031909. [PMID: 22060405 DOI: 10.1103/physreve.84.031909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Indexed: 05/31/2023]
Abstract
We propose a statistical model to account for the gel-fluid anomalous phase transitions in charged bilayer- or lamellae-forming ionic lipids. The model Hamiltonian comprises effective attractive interactions to describe neutral-lipid membranes as well as the effect of electrostatic repulsions of the discrete ionic charges on the lipid headgroups. The latter can be counterion dissociated (charged) or counterion associated (neutral), while the lipid acyl chains may be in gel (low-temperature or high-lateral-pressure) or fluid (high-temperature or low-lateral-pressure) states. The system is modeled as a lattice gas with two distinct particle types--each one associated, respectively, with the polar-headgroup and the acyl-chain states--which can be mapped onto an Ashkin-Teller model with the inclusion of cubic terms. The model displays a rich thermodynamic behavior in terms of the chemical potential of counterions (related to added salt concentration) and lateral pressure. In particular, we show the existence of semidissociated thermodynamic phases related to the onset of charge order in the system. This type of order stems from spatially ordered counterion association to the lipid headgroups, in which charged and neutral lipids alternate in a checkerboard-like order. Within the mean-field approximation, we predict that the acyl-chain order-disorder transition is discontinuous, with the first-order line ending at a critical point, as in the neutral case. Moreover, the charge order gives rise to continuous transitions, with the associated second-order lines joining the aforementioned first-order line at critical end points. We explore the thermodynamic behavior of some physical quantities, like the specific heat at constant lateral pressure and the degree of ionization, associated with the fraction of charged lipid headgroups.
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Affiliation(s)
- M N Tamashiro
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-970, Campinas, SP, Brazil.
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38
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Kim HI, Kim H, Shin YS, Beegle LW, Goddard WA, Heath JR, Kanik I, Beauchamp JL. Time resolved studies of interfacial reactions of ozone with pulmonary phospholipid surfactants using field induced droplet ionization mass spectrometry. J Phys Chem B 2010; 114:9496-503. [PMID: 20608690 DOI: 10.1021/jp102332g] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Field induced droplet ionization mass spectrometry (FIDI-MS) comprises a soft ionization method to sample ions from the surface of microliter droplets. A pulsed electric field stretches neutral droplets until they develop dual Taylor cones, emitting streams of positively and negatively charged submicrometer droplets in opposite directions, with the desired polarity being directed into a mass spectrometer for analysis. This methodology is employed to study the heterogeneous ozonolysis of 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol (POPG) at the air-liquid interface in negative ion mode using FIDI mass spectrometry. Our results demonstrate unique characteristics of the heterogeneous reactions at the air-liquid interface. We observe the hydroxyhydroperoxide and the secondary ozonide as major products of POPG ozonolysis in the FIDI-MS spectra. These products are metastable and difficult to observe in the bulk phase, using standard electrospray ionization (ESI) for mass spectrometric analysis. We also present studies of the heterogeneous ozonolysis of a mixture of saturated and unsaturated phospholipids at the air-liquid interface. A mixture of the saturated phospholipid 1,2-dipalmitoyl-sn-phosphatidylglycerol (DPPG) and unsaturated POPG is investigated in negative ion mode using FIDI-MS while a mixture of 1,2-dipalmitoyl-sn-phosphatidylcholine (DPPC) and 1-stearoyl-2-oleoyl-sn-phosphatidylcholine (SOPC) surfactant is studied in positive ion mode. In both cases FIDI-MS shows the saturated and unsaturated pulmonary surfactants form a mixed interfacial layer. Only the unsaturated phospholipid reacts with ozone, forming products that are more hydrophilic than the saturated phospholipid. With extensive ozonolysis only the saturated phospholipid remains at the droplet surface. Combining these experimental observations with the results of computational analysis provides an improved understanding of the interfacial structure and chemistry of a surfactant layer system when subject to oxidative stress.
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Affiliation(s)
- Hugh I Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea
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39
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Broemstrup T, Reuter N. Molecular dynamics simulations of mixed acidic/zwitterionic phospholipid bilayers. Biophys J 2010; 99:825-33. [PMID: 20682260 DOI: 10.1016/j.bpj.2010.04.064] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 04/21/2010] [Accepted: 04/23/2010] [Indexed: 10/19/2022] Open
Abstract
Anionic lipids are key components in the cell membranes. Many cell-regulatory and signaling mechanisms depend upon a complicated interplay between them and membrane-bound proteins. Phospholipid bilayers are commonly used as model systems in experimental or theoretical studies to gain insight into the structure and dynamics of biological membranes. We report here 200-ns-long MD simulations of pure (DMPC and DMPG) and mixed equimolar (DMPC/DMPG, DMPC/DMPS, and DMPC/DMPA) bilayers that each contain 256 lipids. The intra- and intermolecular interaction patterns in pure and mixed bilayers are analyzed and compared. The effect of monovalent ions (Na+) on the formation of salt-bridges is investigated. In particular, the number of Na(+)-mediated clusters in the presence of DMPS is higher than with DMPG and DMPA. We observe a preferential clustering of DMPS (and to some extent DMPA) lipids together rather than with DMPC molecules, which can explain the phase separation observed experimentally for DMPC/DMPS and DMPC/DMPA bilayers.
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Affiliation(s)
- Torben Broemstrup
- Computational Biology Unit, Bergen Center for Computational Science, University of Bergen, Bergen, Norway
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40
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Giner Casares JJ, Camacho L, Martín-Romero MT, López Cascales JJ. Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer. Chemphyschem 2010; 11:2241-7. [DOI: 10.1002/cphc.201000048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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41
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Tzvetanov S, Shushkov P, Velinova M, Ivanova A, Tadjer A. Molecular dynamics study of the electric and dielectric properties of model DPPC and dicaprin insoluble monolayers: size effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8093-8105. [PMID: 20337416 DOI: 10.1021/la9047352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Atomistic modeling of insoluble monolayers is currently used to inspect their organization and electric characteristics, providing a link between theory and experiment. Extensive molecular dynamics simulations at 300 K were carried out for model films of the lipids dipalmitoylphosphatidylcholine (DPPC) and dicaprin (DC) at the air/water interface. Surface concentrations corresponding to a set of points along the surface pressure/area isotherms of the surfactants were considered. The models contained 25 or 81 lipid molecules in hexagonal arrangement and explicit aqueous media (TIP3P) treated in periodic boundary conditions. Molecular dynamics simulations based on a classical force field (CHARMM27) were carried out and key characteristics of the studied films were estimated. The dielectric properties of the films in normal and tangential direction were quantified by means of dipole moment magnitude and orientation analysis and by monolayer dielectric permittivity. The contributions of lipids and interfacial water to each component of the considered characteristics were assessed and their variations upon film compression were discussed and compared for the two monolayers and to earlier results. The dielectric permittivity tensors were analyzed. Electrostatic potential profiles across the layers and surface pressure values were used for more detailed clarification of experimental measurements. The results show dissimilar behavior of the two lipids at the air-water interface. While the average electric and dielectric properties of DPPC monolayers result from opposite surfactant and water contributions, the two subsystems are synergetic in the DC films. The anisotropy of the monolayer dipole moment and dielectric permittivity is explained by domination of a different subsystem in the various components. Tangential characteristics turn out to be more sensitive to the size of the model and to the degree of film compression.
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Affiliation(s)
- Stanislav Tzvetanov
- Laboratory of Quantum and Computational Chemistry, Department of Physical Chemistry, Faculty of Chemistry, University of Sofia, 1 James Bourchier Avenue, 1164 Sofia, Bulgaria
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42
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Shushkov P, Tzvetanov S, Velinova M, Ivanova A, Tadjer A. Structural aspects of lipid monolayers: computer simulation analyses. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8081-8092. [PMID: 20337413 DOI: 10.1021/la904734b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Extensive molecular dynamics simulations at room temperature were carried out for model films of two dissimilar lipids (DPPC and dicaprin) at the air/water interface. To study the peculiarities of the organization patterns at different average areas per molecule, surface concentrations corresponding to five almost equally spaced points along the isotherms of the two surfactants were considered. A variable of prime interest was the density distribution in a direction normal to the interface of the monolayer components: interfacial water and surfactant on one hand and the separate moieties of the lipids on the other hand. The packing pattern and cluster size dispersion were studied by means of Voronoi tessellation and radial distribution functions. Speculations regarding structural changes upon phase-state changes during film compression were made. Individual characteristics for surfactant heads and tails as well as for interfacial water were outlined and related to the available experimental data. An analysis of the diffusion coefficients revealed the limiting factors for lipid lateral and normal diffusion. Structural arguments in support of changes in monolayer dielectric properties with the area per molecule were provided.
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Affiliation(s)
- Philip Shushkov
- Laboratory of Quantum and Computational Chemistry, Department of Physical Chemistry, Faculty of Chemistry, University of Sofia, 1 James Bourchier Avenue, 1164 Sofia, Bulgaria
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43
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Kim HI, Kim H, Shin YS, Beegle LW, Jang SS, Neidholdt EL, Goddard WA, Heath JR, Kanik I, Beauchamp JL. Interfacial reactions of ozone with surfactant protein B in a model lung surfactant system. J Am Chem Soc 2010; 132:2254-63. [PMID: 20121208 PMCID: PMC2830728 DOI: 10.1021/ja908477w] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Oxidative stresses from irritants such as hydrogen peroxide and ozone (O(3)) can cause dysfunction of the pulmonary surfactant (PS) layer in the human lung, resulting in chronic diseases of the respiratory tract. For identification of structural changes of pulmonary surfactant protein B (SP-B) due to the heterogeneous reaction with O(3), field-induced droplet ionization (FIDI) mass spectrometry has been utilized. FIDI is a soft ionization method in which ions are extracted from the surface of microliter-volume droplets. We report structurally specific oxidative changes of SP-B(1-25) (a shortened version of human SP-B) at the air-liquid interface. We also present studies of the interfacial oxidation of SP-B(1-25) in a nonionizable 1-palmitoyl-2-oleoyl-sn-glycerol (POG) surfactant layer as a model PS system, where competitive oxidation of the two components is observed. Our results indicate that the heterogeneous reaction of SP-B(1-25) at the interface is quite different from that in the solution phase. In comparison with the nearly complete homogeneous oxidation of SP-B(1-25), only a subset of the amino acids known to react with ozone are oxidized by direct ozonolysis in the hydrophobic interfacial environment, both with and without the lipid surfactant layer. Combining these experimental observations with the results of molecular dynamics simulations provides an improved understanding of the interfacial structure and chemistry of a model lung surfactant system subjected to oxidative stress.
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Affiliation(s)
- Hugh I. Kim
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
| | - Hyungjun Kim
- Materials and Process Simulation Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125
| | - Young Shik Shin
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - Luther W. Beegle
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
| | - Seung Soon Jang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245
| | - Evan L. Neidholdt
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - William A. Goddard
- Materials and Process Simulation Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125
| | - James R. Heath
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - Isik Kanik
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
| | - J. L. Beauchamp
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
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44
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Baoukina S, Marrink SJ, Tieleman DP. Lateral pressure profiles in lipid monolayers. Faraday Discuss 2010; 144:393-409; discussion 445-81. [DOI: 10.1039/b905647e] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Greiner AJ, Pillman HA, Worden RM, Blanchard GJ, Ofoli RY. Effect of hydrogen bonding on the rotational and translational dynamics of a headgroup-bound chromophore in bilayer lipid membranes. J Phys Chem B 2009; 113:13263-8. [PMID: 19761197 DOI: 10.1021/jp9057862] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have studied the interactions of the chromophore 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-7-nitro-2-1,3-benzoxadiazol-4-yl (18:1 NBD-PE) imbedded in the headgroup region of bilayer lipid membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DOPG). We have examined the molecular and mesoscale dynamics of the chromophore using time-correlated single photon counting (TCSPC) to measure rotational diffusion dynamics in lipid vesicles and fluorescence recovery after pattern photobleaching (FRAPP) to determine translational diffusion coefficients and mobile fractions in supported lipid bilayers. TCSPC data reveal that chromophore rotational diffusion rates in DOPG vesicles are statistically the same as in DOPC and mixed DOPC/DOPG vesicles, suggesting that the NBD-PE chromophore does not interact strongly with the headgroup region of these bilayers; however, FRAPP experiments show that lateral diffusion is statistically lower in mixed DOPC/DOPG-supported bilayers than in DOPC-supported bilayers. These results suggest that bilayers containing DOPG likely undergo interlipid headgroup hydrogen bonding interactions that suppress translational diffusion.
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Affiliation(s)
- Aaron J Greiner
- Department of Chemical Engineering and Materials Science and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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Shang BZ, Wang Z, Larson RG. Effect of Headgroup Size, Charge, and Solvent Structure on Polymer−Micelle Interactions, Studied by Molecular Dynamics Simulations. J Phys Chem B 2009; 113:15170-80. [DOI: 10.1021/jp9057737] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Barry Z. Shang
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136
| | - Zuowei Wang
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136
| | - Ronald G. Larson
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136
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Blanco E, Piñeiro A, Miller R, Ruso JM, Prieto G, Sarmiento F. Langmuir monolayers of a hydrogenated/fluorinated catanionic surfactant: from the macroscopic to the nanoscopic size scale. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8075-8082. [PMID: 19449890 DOI: 10.1021/la900593c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Langmuir monolayers of the hydrogenated/fluorinated catanionic surfactant cetyltrimethylammonium perfluorooctanoate at the air/water interface are studied at room temperature. Excess Gibbs energies of mixing, DeltaG(E), as well as transition areas and pressures, were obtained from the surface pressure-area isotherm. The DeltaG(E) curve indicates that tail-tail interactions are more important than head-head interactions at low pressures and vice versa. Atomic force microscopy and molecular dynamics simulations allowed a fine characterization of the monolayer structure as a function of the area per molecule at mesoscopic and nanoscopic size scales, respectively. A combined analysis of the techniques allow us to conclude that electrostatic interactions between the ionic head groups are dominant in the monolayer while hydrophobic parts are of secondary importance. Overall, results obtained from the different techniques complement to each other, giving a comprehensive characterization of the monolayer.
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Affiliation(s)
- Elena Blanco
- Department of Applied Physics, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Hénin J, Shinoda W, Klein ML. Models for phosphatidylglycerol lipids put to a structural test. J Phys Chem B 2009; 113:6958-63. [PMID: 19371035 DOI: 10.1021/jp900645z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three atomistic empirical models for phosphatidylglycerol (PG) lipids are tested against structural data in the crystal and liquid crystal states. Simulations of the anhydrous crystal of dimyristoyl-phosphatidylglycerol (DMPG) show that only the CHARMM force field describes the conformation and interactions of PG head groups accurately. The other two models do not reproduce the native network of hydrogen bonds, suggesting the presence of biases in their conformational and nonbonded interaction properties. The CHARMM model is further validated in the biologically relevant liquid crystal phase by comparing experimental small-angle X-ray scattering spectra from DMPG unilamellar vesicles with data calculated from fluid bilayer simulations. The good agreement found in this model-free comparison implies that liquid crystal PG bilayers as described by CHARMM exhibit realistic bilayer thickness and lateral packing. Last, this model is used to simulate a fluid bilayer of palmitoyl-oleoyl-phosphatidylglycerol (POPG). The resulting view of the POPG bilayer structure is at variance with that proposed previously based on simulations, in particular, with respect to lateral packing of head groups and the role of counterions.
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Affiliation(s)
- Jérôme Hénin
- Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
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Affiliation(s)
- Stefan Balaz
- Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo, North Dakota 58105, USA.
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Pimthon J, Willumeit R, Lendlein A, Hofmann D. All-atom molecular dynamics simulation studies of fully hydrated gel phase DPPG and DPPE bilayers. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2008.12.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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