1
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Mallick S, Agmon N. Lateral diffusion of ions near membrane surface. Phys Chem Chem Phys 2024. [PMID: 38973628 DOI: 10.1039/d3cp04112c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Biological membranes isolate living cells from their environment, while allowing selective molecular transport between the inner and outer realms. For example, Na+ and K+ permeability through ionic channels contributes to neural conduction. Whether the ionic currents arise directly from cations in the bulk, or from the interface, is currently unclear. There are only scant results concerning lateral diffusion of ions on aquated membrane surfaces (and strong belief that this occurs through binding to a diffusing lipid). We performed classical molecular dynamics (MD) simulations of monovalent ions, Na+, K+, and Cl-, near the surface of the zwitterionic palmitoyl-oleoyl-phosphatidylcholine (POPC) membrane. Realistic force-fields for lipids (Amber's Lipid17 and Lipid21) and water (TIP4P-Ew) are tested for the mass and charge densities and the electrostatic potential across the membrane. These calculations reveal that the chloride can bind to the choline moiety through an intervening water molecule by forming a CH⋯OH hydrogen bond, while cations bind to both the phosphatic and carbonyl oxygens of phosphatidylcholine moieties. Upon transitioning from the bulk to the interface, a cation sheds some of its hydration water, which are replaced by headgroup atoms. Notably, an interfacial cation can bind 1-4 headgroup atoms, which is a key to understanding its surface hopping mechanism. We find that cation binding to three headgroup atoms immobilizes it, while binding to four energizes it. Consequently, the lateral cation diffusion rate is only 15-25 times slower than in the bulk, and 4-5 times faster than lipid self-diffusion. K+ diffusion is notably more anomalous than Na+, switching from sub- to super-diffusion after about 2 ns.
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Affiliation(s)
- Subhasish Mallick
- The Fritz Haber Research Center, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Noam Agmon
- The Fritz Haber Research Center, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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2
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Limmer DT, Götz AW, Bertram TH, Nathanson GM. Molecular Insights into Chemical Reactions at Aqueous Aerosol Interfaces. Annu Rev Phys Chem 2024; 75:111-135. [PMID: 38360527 DOI: 10.1146/annurev-physchem-083122-121620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Atmospheric aerosols facilitate reactions between ambient gases and dissolved species. Here, we review our efforts to interrogate the uptake of these gases and the mechanisms of their reactions both theoretically and experimentally. We highlight the fascinating behavior of N2O5 in solutions ranging from pure water to complex mixtures, chosen because its aerosol-mediated reactions significantly impact global ozone, hydroxyl, and methane concentrations. As a hydrophobic, weakly soluble, and highly reactive species, N2O5 is a sensitive probe of the chemical and physical properties of aerosol interfaces. We employ contemporary theory to disentangle the fate of N2O5 as it approaches pure and salty water, starting with adsorption and ending with hydrolysis to HNO3, chlorination to ClNO2, or evaporation. Flow reactor and gas-liquid scattering experiments probe even greater complexity as added ions, organic molecules, and surfactants alter the interfacial composition and reaction rates. Together, we reveal a new perspective on multiphase chemistry in the atmosphere.
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Affiliation(s)
- David T Limmer
- Department of Chemistry, University of California, Berkeley, California, USA;
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Kavli Energy NanoScience Institute, Berkeley, California, USA
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Andreas W Götz
- San Diego Supercomputer Center, University of California San Diego, La Jolla, California, USA;
| | - Timothy H Bertram
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; ,
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA; ,
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3
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Jordan J, Gibb CL, Tran T, Yao W, Rose A, Mague JT, Easson MW, Gibb BC. Anion Binding to Ammonium and Guanidinium Hosts: Implications for the Reverse Hofmeister Effects Induced by Lysine and Arginine Residues. J Org Chem 2024; 89:6877-6891. [PMID: 38662908 PMCID: PMC11110012 DOI: 10.1021/acs.joc.4c00242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/09/2024] [Accepted: 04/11/2024] [Indexed: 05/18/2024]
Abstract
Anions have a profound effect on the properties of soluble proteins. Such Hofmeister effects have implications in biologics stability, protein aggregation, amyloidogenesis, and crystallization. However, the interplay between the important noncovalent interactions (NCIs) responsible for Hofmeister effects is poorly understood. To contribute to improving this state of affairs, we report on the NCIs between anions and ammonium and guanidinium hosts 1 and 2, and the consequences of these. Specifically, we investigate the properties of cavitands designed to mimic two prime residues for anion-protein NCIs─lysines and arginines─and the solubility consequences of complex formation. Thus, we report NMR and ITC affinity studies, X-ray analysis, MD simulations, and anion-induced critical precipitation concentrations. Our findings emphasize the multitude of NCIs that guanidiniums can form and how this repertoire qualitatively surpasses that of ammoniums. Additionally, our studies demonstrate the ease by which anions can dispense with a fraction of their hydration-shell waters, rearrange those that remain, and form direct NCIs with the hosts. This raises many questions concerning how solvent shell plasticity varies as a function of anion, how the energetics of this impact the different NCIs between anions and ammoniums/guanidiniums, and how this affects the aggregation of solutes at high anion concentrations.
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Affiliation(s)
- Jacobs
H. Jordan
- The
Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 1100 Allen Toussaint Blvd., New Orleans, Louisiana 70124, United States
| | - Corinne L.D. Gibb
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Thien Tran
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Wei Yao
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Austin Rose
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Joel T. Mague
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Michael W. Easson
- The
Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 1100 Allen Toussaint Blvd., New Orleans, Louisiana 70124, United States
| | - Bruce C. Gibb
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
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4
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Xu J, Karra V, Large DE, Auguste DT, Hung FR. Understanding the Mechanical Properties of Ultradeformable Liposomes Using Molecular Dynamics Simulations. J Phys Chem B 2023; 127:9496-9512. [PMID: 37879075 PMCID: PMC10641833 DOI: 10.1021/acs.jpcb.3c04386] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/19/2023] [Accepted: 10/04/2023] [Indexed: 10/27/2023]
Abstract
Improving drug delivery efficiency to solid tumor sites is a central challenge in anticancer therapeutic research. Our previous experimental study (Guo et al., Nat. Commun. 2018, 9, 130) showed that soft, elastic liposomes had increased uptake and accumulation in cancer cells and tumors in vitro and in vivo respectively, relative to rigid particles. As a first step toward understanding how liposomes' molecular structure and composition modulates their elasticity, we performed all-atom and coarse-grained classical molecular dynamics (MD) simulations of lipid bilayers formed by mixing a long-tailed unsaturated phospholipid with a short-tailed saturated lipid with the same headgroup. The former types of phospholipids considered were 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine (termed here DPMPC). The shorter saturated lipids examined were 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), 1,2-didecanoyl-sn-glycero-3-phosphocholine (DDPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Several lipid concentrations and surface tensions were considered. Our results show that DOPC or DPMPC systems having 25-35 mol % of the shortest lipids DHPC or DDPC are the least rigid, having area compressibility moduli KA that are ∼10% smaller than the values observed in pure DOPC or DPMPC bilayers. These results agree with experimental measurements of the stretching modulus and lysis tension in liposomes with the same compositions. These mixed systems also have lower areas per lipid and form more uneven x-y interfaces with water, the tails of both primary and secondary lipids are more disordered, and the terminal methyl groups in the tails of the long lipid DOPC or DPMPC wriggle more in the vertical direction, compared to pure DOPC or DPMPC bilayers or their mixtures with the longer saturated lipid DLPC or DMPC. These observations confirm our hypothesis that adding increasing concentrations of the short unsaturated lipid DHPC or DDPC to DOPC or DPMPC bilayers alters lipid packing and thus makes the resulting liposomes more elastic and less rigid. No formation of lipid nanodomains was noted in our simulations, and no clear trends were observed in the lateral diffusivities of the lipids as the concentration, type of secondary lipid, and surface tension were varied.
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Affiliation(s)
- Jiaming Xu
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Vyshnavi Karra
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Danielle E. Large
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Debra T. Auguste
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Francisco R. Hung
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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5
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Chattopadhyay M, Krok E, Orlikowska-Rzeznik H, Piatkowski L. Cooperativity between sodium ions and water molecules facilitates lipid mobility in model cell membranes. Chem Sci 2023; 14:4002-4011. [PMID: 37063804 PMCID: PMC10094088 DOI: 10.1039/d2sc06836b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Cellular membranes are surrounded by an aqueous buffer solution containing various ions, which influence the hydration layer of the lipid head groups. At the same time, water molecules hydrating the lipids play a major role in facilitating the organisation and dynamics of membrane lipids. Employing fluorescence microscopy imaging and fluorescence recovery after photobleaching measurements, we demonstrate that the cooperativity between water and sodium (Na+) ions is crucial to maintain lipid mobility upon the removal of the outer hydration layer of the lipid membrane. Under similar hydration conditions, lipid diffusion ceases in the absence of Na+ ions. We find that Na+ ions (and similarly K+ ions) strengthen the water clathrate cage around the lipid phosphocholine headgroup and thus prevent its breaking upon removal of bulk water. Intriguingly, Ca2+ and Mg2+ do not show this effect. In this article, we provide a detailed molecular-level picture of ion specific dependence of lipid mobility and membrane hydration properties.
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Affiliation(s)
| | - Emilia Krok
- Institute of Physics, Poznan University of Technology Piotrowo 3 60-965 Poznan Poland
| | | | - Lukasz Piatkowski
- Institute of Physics, Poznan University of Technology Piotrowo 3 60-965 Poznan Poland
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6
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Abdel-Gawad WM, Abdelmohsen M, Gaber MH, Khalil WMA, Abu-Elmagd MSM. Molecular dynamics simulation of phosphatidylcholine membrane in low ionic strengths of sodium chloride. J Biomol Struct Dyn 2023; 41:13891-13901. [PMID: 36812302 DOI: 10.1080/07391102.2023.2183040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 02/14/2023] [Indexed: 02/24/2023]
Abstract
The one-microsecond molecular dynamics simulations of a membrane-protein complex investigate the influence of the aqueous sodium chloride solutions on the structure and dynamics of a palmitoyl-oleoyl-phosphatidylcholine bilayer membrane. The simulations were performed on five different concentrations (40, 150, 200, 300, and 400 mM) in addition to a salt-free system by using the charmm36 force field for all atoms. Four biophysical parameters, (membrane thicknesses of annular and bulk lipids, and the area per lipid of both leaflets), were computed separately. Nevertheless, the area per lipid was expressed by using the Voronoi algorithm. All time-independent analyses were carried out for the last 400 ns trajectories. Different concentrations revealed dissimilar membrane dynamics before equilibration. The biophysical properties of the membrane (thickness, area-per-lipid, and order parameter) have non-significant changes with increasing ionic strength, however, the 150 mM system had exceptional behavior. Sodium cations were dynamically penetrating the membrane forming weak coordinate bonds with single or multiple lipids. Nevertheless, the binding constant was unaffected by the cation concentration. The electrostatic and Van der Waals energies of lipid-lipid interactions were influenced by the ionic strength. On the other hand, the Fast Fourier Transform was performed to figure out the dynamics at the membrane-protein interface. The nonbonding energies of membrane-protein interactions and order parameters explained the differences in the synchronization pattern. All results were consensus with experimental and theoretical works.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | - Mahmoud Abdelmohsen
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
- Mathematics and Engineering Physics Department, The Higher Institute of Engineering, Shorouk Academy, El-Shorouk City, Cairo, Egypt
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7
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Hossain SI, Seppelt M, Nguyen N, Stokes C, Deplazes E. The role of ion-lipid interactions and lipid packing in transient defects caused by phenolic compounds. Biophys J 2022; 121:3520-3532. [PMID: 35932150 PMCID: PMC9515000 DOI: 10.1016/j.bpj.2022.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/19/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
The transient disruption of membranes for the passive permeation of ions or small molecules is a complex process relevant to understanding physiological processes and biotechnology applications. Phenolic compounds are widely studied for their antioxidant and antimicrobial properties, and some of these activities are based on the interactions of the phenolic compound with membranes. Ions are ubiquitous in cells and are known to alter the structure of phospholipid bilayers. Yet, ion-lipid interactions are usually ignored when studying the membrane-altering properties of phenolic compounds. This study aims to assess the role of Ca2+ ions on the membrane-disrupting activity of two phenolic acids and to highlight the role of local changes in lipid packing in forming transient defects or pores. Results from tethered bilayer lipid membrane electrical impedance spectroscopy experiments showed that Ca2+ significantly reduces membrane disruption by caffeic acid methyl ester and caffeic acid. As phenolic acids are known metal chelators, we used UV-vis and fluorescence spectroscopy to exclude the possibility that Ca2+ interferes with membrane disruption by binding to the phenolic compound and subsequently preventing membrane binding. Molecular dynamics simulations showed that Ca2+ but not caffeic acid methyl ester or caffeic acid increases lipid packing in POPC bilayers. The combined data confirm that Ca2+ reduces the membrane-disrupting activity of the phenolic compounds, and that Ca2+-induced changes to lipid packing govern this effect. We discuss our data in the context of ion-induced pores and transient defects and how lipid packing affects membrane disruption by small molecules.
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Affiliation(s)
- Sheikh I Hossain
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Mathilda Seppelt
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Natalie Nguyen
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Chelsea Stokes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia.
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8
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Laudadio E, Minnelli C, Mobbili G, Sabbatini G, Stipa P, Rusciano D, Galeazzi R. Salt effects on mixed composition membranes containing an antioxidant lipophilic edaravone derivative: a computational-experimental study. Org Biomol Chem 2022; 20:5784-5795. [PMID: 35822625 DOI: 10.1039/d2ob01143c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The protection of lipid membranes against oxidation avoids diseases associated with oxidative stress. As a strategy to contrast it, functionalized lipids with antioxidant activity are used to become part of membranes thus protecting them. For this purpose, a lipophilic edaravone derivative has been synthesized, adding a C18 saturated chain to the original structure. The antioxidant activity of C18-Edv has been demonstrated in our previous work. In this study, molecular dynamics simulations have been performed to define the effects of NaCl, MgCl2, KCl, and CaCl2 salts on a palmitoyl-oleoyl-sn-glycero-phosphocholine (POPC) lipid bilayer encapsulating C18-Edv. The results showed how different salts influence POPC lateral diffusion, and the movements of C18-Edv heads, which are antioxidant moieties, were correlated to the ability of C18-Edv molecules to protect membranes. MgCl2 showed a negative impact leading to C18-Edv clusterization and membrane stretching, while KCl and NaCl showed a moderate influence on the mixed lipid membrane structure. CaCl2 increased the exposure of the C18-Edv heads to the lipid-water interface, resulting in the salt with a higher propensity to guarantee protection against radicals in the aqueous phase. Finally, C18-Edv-POPC liposomes have been prepared following the simulation conditions, and then an experimental Oxygen Radical Absorbance Capacity (ORAC) assay has been performed to confirm the in silico predicted results.
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Affiliation(s)
- Emiliano Laudadio
- Department SIMAU, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Cristina Minnelli
- Department DISVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
| | - Giovanna Mobbili
- Department DISVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
| | - Giulia Sabbatini
- Department DISVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
| | - Pierluigi Stipa
- Department SIMAU, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Dario Rusciano
- Research Center, Sooft Italia SpA, 95100, Catania, Italy
| | - Roberta Galeazzi
- Department DISVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
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9
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Andrews JT, Baker KE, Handloser JT, Bridges N, Krone AA, Kett PJN. Formation of Supported Lipid Bilayers (SLBs) from Buffers Containing Low Concentrations of Group I Chloride Salts. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12819-12833. [PMID: 34699227 DOI: 10.1021/acs.langmuir.1c01707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Supported lipid bilayers (SLBs) are a useful tool for studying the interactions between lipids and other biomolecules that make up a cell membrane. SLBs are typically formed by the adsorption and rupture of vesicles from solution. Although it is known that many experimental factors can affect whether SLB formation is successful, there is no comprehensive understanding of the mechanism. In this work, we have used a quartz crystal microbalance (QCM) to investigate the role of the salt in the buffer on the formation of phosphatidylcholine SLBs on a silicon dioxide (SiO2) surface. We varied the concentration of sodium chloride in the buffer, from 5 to 150 mM, to find the minimum concentration of NaCl that was required for the successful formation of an SLB. We then repeated the experiments with other group I chloride salts (LiCl, KCl, and CsCl) and found that at higher salt concentrations (150 mM) SLB formation was successful for all of the salts used, and the degree of deformation of the adsorbed vesicles at the critical vesicle coverage was cation-dependent. The results showed that at an intermediate salt concentration (50 mM) the critical vesicle coverage was cation-dependent and at low salt concentrations (12.5 mM) the cation used determined whether SLB formation was successful. We found that the successful formation of SLBs could occur at lower electrolyte concentrations for KCl and CsCl than it did for NaCl. To understand these results, we calculated the magnitude of the vesicle-surface interaction energy using the Derjaguin-Landau-Verwey-Overbeek (DLVO) and extended-DLVO theory. We managed to explain the results obtained at higher salt concentrations by including cation-dependent surface potentials in the calculations and at lower salt concentrations by the addition of a cation-dependent hydration force. These results showed that the way that different cations in solution affect the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-SiO2 surface interaction energy depends on the ionic strength of the solution.
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Affiliation(s)
- J Tucker Andrews
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Kirstyn E Baker
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Jacob T Handloser
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Natalie Bridges
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Alexis A Krone
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Peter J N Kett
- Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
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10
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Wieser V, Mears LLE, Barker RD, Cheng HW, Valtiner M. Hydration Forces Dominate Surface Charge Dependent Lipid Bilayer Interactions under Physiological Conditions. J Phys Chem Lett 2021; 12:9248-9252. [PMID: 34533315 PMCID: PMC8488952 DOI: 10.1021/acs.jpclett.1c02572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Indexed: 06/13/2023]
Abstract
Lipid bilayer interactions are essential to a vast range of biological functions, such as intracellular transport mechanisms. Surface charging mediated by concentration dependent ion adsorption and desorption on lipid headgroups alters electric double layers as well as van der Waals and steric hydration forces of interacting bilayers. Here, we directly measure bilayer interactions during charge modulation in a symmetrically polarized electrochemical three-mirror interferometer surface forces apparatus. We quantify polarization and concentration dependent hydration and electric double layer forces due to cation adsorption/desorption. Our results demonstrate that exponential hydration layer interactions effectively describe surface potential dependent surface forces due to cation adsorption at high salt concentrations. Hence, electric double layers of lipid bilayers are exclusively dominated by inner Helmholtz charge regulation under physiological conditions. These results are important for rationalizing bilayer behavior under physiological conditions, where charge and concentration modulation may act as biological triggers for function and signaling.
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Affiliation(s)
- Valentina Wieser
- Institute
for Applied Physics, Vienna University of
Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - Laura L. E. Mears
- Institute
for Applied Physics, Vienna University of
Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - Robert D. Barker
- School
of Physical Sciences, University of Kent, Canterbury CT2 7NZ, United Kingdom
| | - Hsiu-Wei Cheng
- Institute
for Applied Physics, Vienna University of
Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - Markus Valtiner
- Institute
for Applied Physics, Vienna University of
Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
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11
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Silin VI, Hoogerheide DP. pH dependent electrical properties of the inner- and outer- leaflets of biomimetic cell membranes. J Colloid Interface Sci 2021; 594:279-289. [PMID: 33765647 DOI: 10.1016/j.jcis.2021.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/16/2021] [Accepted: 03/03/2021] [Indexed: 10/21/2022]
Abstract
Composition and asymmetry of lipid membranes provide a means for regulation of trans-membrane permeability of ions and small molecules. The pH dependence of these processes plays an important role in the functioning and survival of cells. In this work, we study the pH dependence of membrane electrical resistance and capacitance using electrochemical impedance spectroscopy (EIS), surface plasmon resonance (SPR) and neutron reflectometry (NR) measurements of biomimetic tethered bilayer lipid membranes (tBLMs). tBLMs were prepared with single-component phospholipid compositions, as well as mixtures of phospholipids (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, sphingomyelin and cholesterol) that mimic the inner- and outer- leaflets of plasma cell membranes. We found that all studied tBLMs have a resistance maximum at pHs near the pKas of the phospholipids. SPR and NR indicated that surface concentration of phospholipids and the thickness of the hydrophobic part of the membrane did not change versus pH. We postulate that these maxima are the result of protonation of the phosphate oxygen of the phospholipids and that hydronium ions play a major role in the conductance at pHs < pKas while sodium ions play the major role at pHs > pKas. An additional sharp resistance maximum of the PE tBLMs found at pH 5.9 and most likely represents the phosphatidylethanolamine's isoelectric point. The data show the key roles of the characteristic parts of phospholipid molecules: terminal group (choline, carboxyl, amine), phosphate, glycerol and ester oxygens on the permeability and selectivity of ions through the membrane. The interactions between these groups lead to significant differences in the electrical properties of biomimetic models of inner- and outer- leaflets of the plasma cell membranes.
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Affiliation(s)
- Vitalii I Silin
- University of Maryland, Institute for Bioscience and Biotechnology Research, Rockville MD 20850, USA.
| | - David P Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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12
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Vodopivec AA, Chen Y, Russo PS, Hung FR. Molecular Dynamics Simulations of Nanostructures Formed by Hydrophobins and Oil in Seawater. J Phys Chem B 2021; 125:7886-7899. [PMID: 34236182 DOI: 10.1021/acs.jpcb.1c02040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Classical molecular dynamics simulations using the Martini coarse-grained force field were performed to study oil nanodroplets surrounded by fungal hydrophobin (HP) proteins in seawater. The class I EAS and the class II HFBII HPs were studied along with two model oils, namely, benzene and n-decane. Both HPs exhibit free energy minima at the oil-seawater interface, which is deeper in benzene compared to the n-decane systems. Larger constraint forces are required to keep both HPs within the n-decane phase compared to inside benzene, with HFBII being more affine to benzene compared to EAS. Smaller surface tensions are observed at benzene-seawater interfaces coated with HPs compared to their n-decane counterparts. In the latter the surface tension remains unchanged upon increases in the concentration of HPs, whereas in benzene systems adding more HPs lead to decreases in surface tension. EAS has a larger tendency to cluster together in the interface compared to HFBII, with both HPs having larger coordination numbers when surrounding benzene droplets compared to when they are around n-decane nanoblobs. The HP-oil nanostructures in seawater examined have radii of gyration ranging between 2 and 12 nm, where the n-decane structures are larger and have more irregular shapes compared to the benzene systems. The n-decane molecules within the nanostructures form a compact spherical core, with the HPs partially covering its surface and clustering together, conferring irregular shapes to the nanostructures. The EAS with n-decane structures are larger and have more irregular shapes compared to their HFBII counterparts. In contrast, in the HP-benzene structures both HPs tend to penetrate the oil part of the droplet. The HFBII-benzene structures having the larger oil/HP ratios examined tend to be more compact and spherical compared to their EAS counterparts; however, some of the HFBII-benzene systems that have smaller oil/HP ratios have a more elongated structure compared to their EAS counterparts. This simulation study provides insights into HP-oil nanostructures that are smaller than the oil droplets and gas bubbles recently studied in experiments and, thus, might be challenging to examine with experimental techniques.
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Affiliation(s)
- Andrés A Vodopivec
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Yuwu Chen
- Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Paul S Russo
- School of Materials Science and Engineering and School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Francisco R Hung
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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13
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Jiang L, Wang Q, Lei J, Tao K, Huang J, Zhao S, Hu N, Yang J. Mechanism study of how lipid vesicle electroformation is suppressed by the presence of sodium chloride. Colloids Surf B Biointerfaces 2021; 206:111951. [PMID: 34243032 DOI: 10.1016/j.colsurfb.2021.111951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 06/09/2021] [Accepted: 06/26/2021] [Indexed: 10/21/2022]
Abstract
Giant lipid vesicles (GLVs) are usually adopted as models of cell membranes and electroformation is the most commonly used method for GLV formation. However, GLV electroformation are known to be suppressed by the presence of salt and the mechanism is not clear so far. In this paper, the lipid hydration and GLV electroformation were investigated as a function of the concentration of sodium chloride by depositing the lipids on the bottom substrates and top substrates. In addition, the electrohydrodynamic force generated by the electroosmotic flow (EOF) on the lipid phase was calculated with COMSOL Multiphysics. It was found that the mechanisms for the failure of GLV electroformation in salt solutions are: 1) the presence of sodium chloride decreases the membrane permeability to aqueous solution by accelerating the formation of well-packed membranes, suppressing the swelling and detachment of the lipid membranes; 2) the presence of sodium chloride decreased the electrohydrodynamic force by increasing the medium conductivity.
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Affiliation(s)
- Lihua Jiang
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China
| | - Qiong Wang
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400030, China.
| | - Jincan Lei
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China
| | - Ke Tao
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China
| | - Jing Huang
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China
| | - Shixian Zhao
- Chongqing Engineering and Technology Research Center of Intelligent Rehabilitation and Eldercare, Chongqing City Management College, Chongqing 400055, China
| | - Ning Hu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400030, China
| | - Jun Yang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400030, China.
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14
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Abstract
The ubiquity of aqueous solutions in contact with charged surfaces and the realization that the molecular-level details of water-surface interactions often determine interfacial functions and properties relevant in many natural processes have led to intensive research. Even so, many open questions remain regarding the molecular picture of the interfacial organization and preferential alignment of water molecules, as well as the structure of water molecules and ion distributions at different charged interfaces. While water, solutes and charge are present in each of these systems, the substrate can range from living tissues to metals. This diversity in substrates has led to different communities considering each of these types of aqueous interface. In this Review, by considering water in contact with metals, oxides and biomembranes, we show the essential similarity of these disparate systems. While in each case the classical mean-field theories can explain many macroscopic and mesoscopic observations, it soon becomes apparent that such theories fail to explain phenomena for which molecular properties are relevant, such as interfacial chemical conversion. We highlight the current knowledge and limitations in our understanding and end with a view towards future opportunities in the field.
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15
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Formation of Giant Lipid Vesicles in the Presence of Nonelectrolytes—Glucose, Sucrose, Sorbitol and Ethanol. Processes (Basel) 2021. [DOI: 10.3390/pr9060945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Lipid vesicles, especially giant lipid vesicles (GLVs), are usually adopted as cell membrane models and their preparation has been widely studied. However, the effects of some nonelectrolytes on GLV formation have not been specifically studied so far. In this paper, the effects of the nonelectrolytes, including sucrose, glucose, sorbitol and ethanol, and their coexistence with sodium chloride, on the lipid hydration and GLV formation were investigated. With the hydration method, it was found that the sucrose, glucose and sorbitol showed almost the same effect. Their presence in the medium enhanced the hydrodynamic force on the lipid membranes, promoting the GLV formation. GLV formation was also promoted by the presence of ethanol with ethanol volume fraction in the range of 0 to 20 percent, but higher ethanol content resulted in failure of GLV formation. However, the participation of sodium chloride in sugar solution and ethanol solution stabilized the lipid membranes, suppressing the GLV formation. In addition, the ethanol and the sodium chloride showed the completely opposite effects on lipid hydration. These results could provide some suggestions for the efficient preparation of GLVs.
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16
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Božič A, Kanduč M. Relative humidity in droplet and airborne transmission of disease. J Biol Phys 2021; 47:1-29. [PMID: 33564965 PMCID: PMC7872882 DOI: 10.1007/s10867-020-09562-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/22/2020] [Indexed: 02/06/2023] Open
Abstract
A large number of infectious diseases are transmitted by respiratory droplets. How long these droplets persist in the air, how far they can travel, and how long the pathogens they might carry survive are all decisive factors for the spread of droplet-borne diseases. The subject is extremely multifaceted and its aspects range across different disciplines, yet most of them have only seldom been considered in the physics community. In this review, we discuss the physical principles that govern the fate of respiratory droplets and any viruses trapped inside them, with a focus on the role of relative humidity. Importantly, low relative humidity-as encountered, for instance, indoors during winter and inside aircraft-facilitates evaporation and keeps even initially large droplets suspended in air as aerosol for extended periods of time. What is more, relative humidity affects the stability of viruses in aerosol through several physical mechanisms such as efflorescence and inactivation at the air-water interface, whose role in virus inactivation nonetheless remains poorly understood. Elucidating the role of relative humidity in the droplet spread of disease would permit us to design preventive measures that could aid in reducing the chance of transmission, particularly in indoor environment.
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Affiliation(s)
- Anže Božič
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia
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17
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Karanth S, Meesaragandla B, Delcea M. Changing surface properties of artificial lipid membranes at the interface with biopolymer coated gold nanoparticles under normal and redox conditions. Biophys Chem 2020; 267:106465. [DOI: 10.1016/j.bpc.2020.106465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 12/28/2022]
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18
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Deplazes E, Tafalla BD, Cranfield CG, Garcia A. Role of Ion-Phospholipid Interactions in Zwitterionic Phospholipid Bilayer Ion Permeation. J Phys Chem Lett 2020; 11:6353-6358. [PMID: 32687371 DOI: 10.1021/acs.jpclett.0c01479] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Despite the central role of Na+ and K+ in physiological processes, it is still unclear whether they interact or alter the physical properties of simple zwitterionic phospholipid bilayers at physiologically relevant concentrations. Here we report a difference in membrane permeability between Na+ and K+, as measured with electrical impedance spectroscopy and tethered bilayer lipid membranes. We reveal that the differences in membrane permeability originate from distinct ion coordination by carbonyl oxygens at the phospholipid-water interface, altering the propensity for bilayer pore formation. Molecular dynamics simulations showed differences in the coordination of Na+ and K+ at the phospholipid-water interface of zwitterionic phospholipid bilayers. The ability of Na+ to conscript more phospholipids with a greater number of coordinating interactions causes a higher localized energy barrier for pore formation. These results provide evidence that ion-specific interactions at the phospholipid-water interface can modulate the physical properties of zwitterionic phospholipid bilayers.
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Affiliation(s)
- Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | | | - Charles G Cranfield
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Alvaro Garcia
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
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19
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Sarmento MJ, Hof M, Šachl R. Interleaflet Coupling of Lipid Nanodomains - Insights From in vitro Systems. Front Cell Dev Biol 2020; 8:284. [PMID: 32411705 PMCID: PMC7198703 DOI: 10.3389/fcell.2020.00284] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/02/2020] [Indexed: 01/09/2023] Open
Abstract
The plasma membrane is a complex system, consisting of two layers of lipids and proteins compartmentalized into small structures called nanodomains. Despite the asymmetric composition of both leaflets, coupling between the layers is surprisingly strong. This can be evidenced, for example, by recent experimental studies performed on phospholipid giant unilamellar vesicles showing that nanodomains formed in the outer layer are perfectly registered with those in the inner leaflet. Similarly, microscopic phase separation in one leaflet can induce phase separation in the opposing leaflet that would otherwise be homogeneous. In this review, we summarize the current theoretical and experimental knowledge that led to the current view that domains are – irrespective of their size – commonly registered across the bilayer. Mechanisms inducing registration of nanodomains suggested by theory and calculations are discussed. Furthermore, domain coupling is evidenced by experimental studies based on the sparse number of methods that can resolve registered from independent nanodomains. Finally, implications that those findings using model membrane studies might have for cellular membranes are discussed.
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Affiliation(s)
- Maria J Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova, Prague, Czechia
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova, Prague, Czechia
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova, Prague, Czechia
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20
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Yagasaki T, Matsumoto M, Tanaka H. Lennard-Jones Parameters Determined to Reproduce the Solubility of NaCl and KCl in SPC/E, TIP3P, and TIP4P/2005 Water. J Chem Theory Comput 2020; 16:2460-2473. [PMID: 32207974 DOI: 10.1021/acs.jctc.9b00941] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most classical nonpolarizable ion potential models underestimate the solubility values of NaCl and KCl in water significantly. We determine Lennard-Jones parameters of Na+, K+, and Cl- that reproduce the solubility as well as the hydration free energy in dilute aqueous solutions for three water potential models, SPC/E, TIP3P, and TIP4P/2005. The ion-oxygen distance in the solution and the cation-anion distance in salt are also considered in the parametrization. In addition to the target properties, the hydration enthalpy, hydration entropy, self-diffusion coefficient, coordination number, lattice energy, enthalpy of solution, density, viscosity, and number of contact ion pairs are calculated for comparison with 17 frequently used or recently developed ion potential models. The overall performance of each ion model is represented by a global score using a scheme that was originally developed for comparison of water potential models. The global score is better for our models than for the other 17 models not only because of the quite good prediction for the solubility but also because of the relatively small deviation from the experimental value for many of the other properties.
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Affiliation(s)
- Takuma Yagasaki
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.,Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Masakazu Matsumoto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.,Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Hideki Tanaka
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan.,Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
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21
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Theoretical Considerations and the Microelectrophoresis Experiment on the Influence of Selected Chaotropic Anions on Phosphatidylcholine Membrane Surface Charge Density. Molecules 2019; 25:molecules25010132. [PMID: 31905730 PMCID: PMC6982888 DOI: 10.3390/molecules25010132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/21/2019] [Accepted: 12/27/2019] [Indexed: 11/17/2022] Open
Abstract
Influence of sodium salts of selected chaotropic anions from the Hofmeister series (NaCl, NaBr, NaNO3, NaI) on the surface charge density of phosphatidylcholine membranes was studied. Small unilamellar lipid vesicles were used as a model system in the investigations. The theoretical and experimental approach to the interactions between inorganic anions and phosphatidylcholine membranes is presented. Experimental membrane surface charge densities data were determined as a function of pH of the aqueous electrolytes using microelectrophoresis method. The quantitative description of the interactions between zwitterionic phosphatidylcholine membrane and monovalent anions is presented. The equilibria constants of the binding of solution ions onto phospholipid surface were calculated. Knowledge of these parameters was essential to determine the theoretical membrane surface charge density values. The theoretical data were compared to the experimental ones in order to verify the mathematical model. Both approaches indicate that the anion-phosphatidylcholine membrane interaction increases with the size of the anion. The adsorption of chaotropic anions to membranes was found to follow the Hofmeister series I- > NO3- > Br- > Cl-.
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22
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Melcr J, Piquemal JP. Accurate Biomolecular Simulations Account for Electronic Polarization. Front Mol Biosci 2019; 6:143. [PMID: 31867342 PMCID: PMC6904368 DOI: 10.3389/fmolb.2019.00143] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 11/20/2019] [Indexed: 11/29/2022] Open
Abstract
In this perspective, we discuss where and how accounting for electronic many-body polarization affects the accuracy of classical molecular dynamics simulations of biomolecules. While the effects of electronic polarization are highly pronounced for molecules with an opposite total charge, they are also non-negligible for interactions with overall neutral molecules. For instance, neglecting these effects in important biomolecules like amino acids and phospholipids affects the structure of proteins and membranes having a large impact on interpreting experimental data as well as building coarse grained models. With the combined advances in theory, algorithms and computational power it is currently realistic to perform simulations with explicit polarizable dipoles on systems with relevant sizes and complexity. Alternatively, the effects of electronic polarization can also be included at zero additional computational cost compared to standard fixed-charge force fields using the electronic continuum correction, as was recently demonstrated for several classes of biomolecules.
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Affiliation(s)
- Josef Melcr
- Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Jean-Philip Piquemal
- Laboratoire de Chimie Théorique, Sorbonne Université, UMR7616 CNRS, Paris, France
- Institut Universitaire de France, Paris, France
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, United States
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23
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Sut TN, Jackman JA, Yoon BK, Park S, Kolahdouzan K, Ma GJ, Zhdanov VP, Cho NJ. Influence of NaCl Concentration on Bicelle-Mediated SLB Formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10658-10666. [PMID: 31318563 DOI: 10.1021/acs.langmuir.9b01644] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The deposition of two-dimensional bicellar disks on hydrophilic surfaces is an emerging approach to fabricate supported lipid bilayers (SLBs) that requires minimal sample preparation, works at low lipid concentrations, and yields high-quality SLBs. While basic operating steps in the fabrication protocol mimic aspects of the conventional vesicle fusion method, lipid bicelles and vesicles have distinct architectural properties, and understanding how experimental parameters affect the efficiency of bicelle-mediated SLB formation remains to be investigated. Herein, using the quartz crystal microbalance-dissipation and localized surface plasmon resonance techniques, we investigated the effect of bulk NaCl concentration on bicelle-mediated SLB formation on silicon dioxide surfaces. For comparison, similar experiments were conducted with vesicles as well. In both cases, SLB formation was observed to occur rapidly provided that the NaCl concentration was sufficiently high (>50 mM). Under such conditions, the effect of NaCl concentration on SLB formation was minor in the case of bicelles and significant in the case of vesicles where it is expected to be related primarily to osmotic pressure. At lower NaCl concentrations, bicelles also formed SLBs but slowly, whereas adsorbed vesicles remained intact. These findings were complemented by time-lapsed fluorescence microscopy imaging and fluorescence recovery after photobleaching measurements that corroborated bicelle-mediated SLB formation across the range of tested NaCl concentrations. The results are discussed by comparing the architectural properties of bicelles and vesicles along with theoretical analysis of the corresponding adsorption kinetics.
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Affiliation(s)
- Tun Naw Sut
- School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore
| | - Joshua A Jackman
- School of Chemical Engineering , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Bo Kyeong Yoon
- School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore
| | - Soohyun Park
- School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore
| | - Kavoos Kolahdouzan
- Department of Chemistry , Pomona College , 645 North College Avenue , Claremont , California 91711 , United States
| | - Gamaliel Junren Ma
- School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore
| | - Vladimir P Zhdanov
- Boreskov Institute of Catalysis, Russian Academy of Sciences , Novosibirsk 630090 , Russia
| | - Nam-Joon Cho
- School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore
- School of Chemical and Biomedical Engineering , Nanyang Technological University , 62 Nanyang Drive 637459 , Singapore
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24
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Temperature Dependence of the Structure and Dynamics of a Dye-Labeled Lipid in a Planar Phospholipid Bilayer: A Computational Study. J Membr Biol 2019; 252:227-240. [PMID: 31332471 DOI: 10.1007/s00232-019-00081-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022]
Abstract
Fluorescent probes are widely employed to label lipids for the investigation of structural and dynamic properties of model and cell membranes through optical microscopy techniques. Although the effect of tagging a lipid with an organic dye is generally assumed to be negligible, optically modified lipids can nonetheless affect the local lipid structure and, in turn, the lipid lateral mobility. To better assess this potential issue, all-atom (MD) molecular dynamics simulations have been performed to study structural and dynamic effects in a model DOPC membrane in the presence of a standard Rhodamine B-labeled DOPE lipid (RHB) as a function of temperature, i.e., 293 K, 303 K, and 320 K. As the temperature is increased, we observe similar changes in the structural properties of both pure DOPC and RHB-DOPC lipid bilayers: an increase of the area per lipid, a reduction of the membrane thickness and a decrease of lipid order parameters. The partial density profile of the RHB headgroups and their orientation within the lipid bilayer confirm the amphiphilic nature of the RHB fluorescent moiety, which mainly partitions in the DOPC glycerol backbone region at each temperature. Moreover, at all temperatures, our results on lipid lateral diffusion support a non-neutral role of the dye with respect to the unlabeled lipid mobility, thus suggesting important implications for optical microscopy studies of lipid membranes.
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25
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Deplazes E, White J, Murphy C, Cranfield CG, Garcia A. Competing for the same space: protons and alkali ions at the interface of phospholipid bilayers. Biophys Rev 2019; 11:483-490. [PMID: 31115866 DOI: 10.1007/s12551-019-00541-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 04/29/2019] [Indexed: 10/26/2022] Open
Abstract
Maintaining gradients of solvated protons and alkali metal ions such as Na+ and K+ across membranes is critical for cellular function. Over the last few decades, both the interactions of protons and alkali metal ions with phospholipid membranes have been studied extensively and the reported interactions of these ions with phospholipid headgroups are very similar, yet few studies have investigated the potential interdependence between proton and alkali metal ion binding at the water-lipid interface. In this short review, we discuss the similarities between the proton-membrane and alkali ion-membrane interactions. Such interactions include cation attraction to the phosphate and carbonyl oxygens of the phospholipid headgroups that form strong lipid-ion and lipid-ion-water complexes. We also propose potential mechanisms that may modulate the affinities of these cationic species to the water-phospholipid interfacial oxygen moieties. This review aims to highlight the potential interdependence between protons and alkali metal ions at the membrane surface and encourage a more nuanced understanding of the complex nature of these biologically relevant processes.
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Affiliation(s)
- Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia. .,School of Pharmacy and Biomedical Sciences, Curtin University, Perth, WA, 6845, Australia.
| | - Jacqueline White
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Christopher Murphy
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Charles G Cranfield
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Alvaro Garcia
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
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26
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Yang Y, Alford A, Kozlovskaya V, Zhao S, Joshi H, Kim E, Qian S, Urban V, Cropek D, Aksimentiev A, Kharlampieva E. Effect of temperature and hydrophilic ratio on the structure of poly(N-vinylcaprolactam)-block-poly(dimethylsiloxane)-block-poly(N-vinylcaprolactam) polymersomes. ACS APPLIED POLYMER MATERIALS 2019; 1:722-736. [PMID: 31828238 PMCID: PMC6905513 DOI: 10.1021/acsapm.8b00259] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanosized polymeric vesicles (polymersomes) assembled from ABA triblock copolymers of poly(N-vinylcaprolactam)-poly(dimethylsiloxane)-poly(N-vinylcaprolactam) (PVCL-PDMS-PVCL) are a promising platform for biomedical applications, as the temperature-responsiveness of the PVCL blocks enables reversible vesicle shrinkage and permeability of the polymersome shell at elevated temperatures. Herein, we explore the effects of molecular weight, polymer block weight ratios, and temperature on the structure of these polymersomes via electron microscopy, dynamic light scattering, small angle neutron scattering (SANS), and all-atom molecular dynamic methods. We show that the shell structure and overall size of the polymersome can be tuned by varying the hydrophilic (PVCL) weight fraction of the polymer: at room temperature, polymers of smaller hydrophilic ratios form larger vesicles that have thinner shells, whereas polymers with higher PVCL content exhibit interchain aggregation of PVCL blocks within the polymersome shell above 50 °C. Model fitting and model-free analysis of the SANS data reveals that increasing the mass ratio of PVCL to the total copolymer weight from 0.3 to 0.56 reduces the temperature-induced change in vesicle diameter by a factor of 3 while simultaneously increasing the change in shell thickness by a factor of 1.5. Finally, by analysis of the shell structures and overall size of polymersomes with various PVCL weight ratios and those without temperature-dependent polymer components, we bring into focus the mechanism of temperature-triggered drug release reported in a previous study. This work provides new fundamental perspectives on temperature-responsive polymersomes and elucidates important structure-property relationships of their constituent polymers.
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Affiliation(s)
- Yiming Yang
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35205, United States
| | - Aaron Alford
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35205, United States
| | - Veronika Kozlovskaya
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35205, United States
| | - Shidi Zhao
- Department of Physics, Beckman Institute, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, United States
| | - Himanshu Joshi
- Department of Physics, Beckman Institute, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, United States
| | - Eunjung Kim
- U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory, Champaign, Illinois 61822, United States
| | - Shuo Qian
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Volker Urban
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Donald Cropek
- U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory, Champaign, Illinois 61822, United States
| | - Aleksei Aksimentiev
- Department of Physics, Beckman Institute, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, United States
| | - Eugenia Kharlampieva
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35205, United States
- Center for Nanoscale Materials and Biointegration, University of Alabama at Birmingham, Birmingham, Alabama 35205, United States
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27
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Jan Akhunzada M, D'Autilia F, Chandramouli B, Bhattacharjee N, Catte A, Di Rienzo R, Cardarelli F, Brancato G. Interplay between lipid lateral diffusion, dye concentration and membrane permeability unveiled by a combined spectroscopic and computational study of a model lipid bilayer. Sci Rep 2019; 9:1508. [PMID: 30728410 PMCID: PMC6365552 DOI: 10.1038/s41598-018-37814-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 12/10/2018] [Indexed: 01/08/2023] Open
Abstract
Lipid lateral diffusion in membrane bilayers is a fundamental process exploited by cells to enable complex protein structural and dynamic reorganizations. For its importance, lipid mobility in both cellular and model bilayers has been extensively investigated in recent years, especially through the application of time-resolved, fluorescence-based, optical microscopy techniques. However, one caveat of fluorescence techniques is the need to use dye-labeled variants of the lipid of interest, thus potentially perturbing the structural and dynamic properties of the native species. Generally, the effect of the dye/tracer molecule is implicitly assumed to be negligible. Nevertheless, in view of the widespread use of optically modified lipids for studying lipid bilayer dynamics, it is highly desirable to well assess this point. Here, fluorescence correlation spectroscopy (FCS) and molecular dynamics (MD) simulations have been combined together to uncover subtle structural and dynamic effects in DOPC planar membranes enriched with a standard Rhodamine-labeled lipid. Our findings support a non-neutral role of the dye-labeled lipids in diffusion experiments, quantitatively estimating a decrease in lipid mobility of up to 20% with respect to the unlabeled species. Moreover, results highlight the existing interplay between dye concentration, lipid lateral diffusion and membrane permeability, thus suggesting possible implications for future optical microscopy studies of biophysical processes occurring at the membrane level.
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Affiliation(s)
- Muhammad Jan Akhunzada
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126, Pisa, Italy.,Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, I-56100, Pisa, Italy
| | | | - Balasubramanian Chandramouli
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126, Pisa, Italy.,Compunet, Istituto Italiano di Tecnologia (IIT), Via Morego 30, I-16163, Genova, Italy
| | - Nicholus Bhattacharjee
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126, Pisa, Italy.,Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, I-56100, Pisa, Italy
| | - Andrea Catte
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126, Pisa, Italy.,Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, I-56100, Pisa, Italy
| | - Roberto Di Rienzo
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, Via Girolamo Caruso 16, I-56122 Pisa, Italy
| | - Francesco Cardarelli
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Giuseppe Brancato
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126, Pisa, Italy. .,Istituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, I-56100, Pisa, Italy.
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28
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Wolde-Kidan A, Pham QD, Schlaich A, Loche P, Sparr E, Netz RR, Schneck E. Influence of polar co-solutes and salt on the hydration of lipid membranes. Phys Chem Chem Phys 2019; 21:16989-17000. [DOI: 10.1039/c9cp01953g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of the co-solutes TMAO, urea, and NaCl on the hydration repulsion between lipid membranes is investigated in a combined experimental/simulation approach.
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Affiliation(s)
| | - Quoc Dat Pham
- Division of Physical Chemistry
- Chemistry Department
- Lund University
- 22100 Lund
- Sweden
| | | | - Philip Loche
- Fachbereich Physik
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Emma Sparr
- Division of Physical Chemistry
- Chemistry Department
- Lund University
- 22100 Lund
- Sweden
| | - Roland R. Netz
- Fachbereich Physik
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Emanuel Schneck
- Biomaterials Department
- Max Planck Institute of Colloids and Interfaces
- 14476 Potsdam
- Germany
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29
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Meynaq MYK, Lindholm-Sethson B, Tesfalidet S. Interaction of anions with lipid cubic phase membranes, an electrochemical impedance study. J Colloid Interface Sci 2018; 528:263-270. [PMID: 29859451 DOI: 10.1016/j.jcis.2018.05.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Electrochemical impedance spectroscopy is useful to monitor anionic interactions with a Lipid Cubic Phase, as previously demonstrated for cationic interaction (Khani Meynaq et al., 2016). It was expected that the smaller hydrophilic anions, acetate and chloride, would interact differently than the large tryptophan anion with its hydrophobic tail. EXPERIMENT The impedance measurements enabled estimation of resistances and capacitances of a freestanding lipid cubic phase membrane at exposure to 4 and 40 mM solutions of NaCl, NaOAc and NaTrp. Small-angle X-ray scattering was used for cubic phase identification and to track structural changes within the cubic phase when exposed to the different electrolytes. FINDINGS The membrane resistance increases at exposure to the electrolytes in the order Cl- < OAc- < Trp-. The membrane resistance decreases with time at exposure to the hydrophilic anions and increases with time at Trp- exposure. The membrane capacitances were lower for NaTrp compared to NaCl and NaOAc at the corresponding concentrations which is consistent with the results from SAXRD. It is concluded that Trp- ions do not enter the aqueous channels of the cubic phase but are strongly adsorbed to the membrane/electrolyte interface leading to large alteration of the lipid phase structure and a high membrane resistance.
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30
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Cationic interaction with phosphatidylcholine in a lipid cubic phase studied with electrochemical impedance spectroscopy and small angle X-ray scattering. J Colloid Interface Sci 2018; 528:321-329. [PMID: 29860201 DOI: 10.1016/j.jcis.2018.05.065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS Electrochemical Impedance Spectroscopy (EIS) can be used to investigate cationic interaction with the choline headgroup in the ternary system of monoolein/dioleoylphosphatidylcholine/water (MO/DOPC/H2O). EXPERIMENTS EIS was used to estimate the resistance and capacitance of a freestanding membrane of a lipid cubic phase (LCP). The membrane was formed in a small cylindrical aperture separating two compartments, containing one Pt electrode each. The impedance experiments were carried out in a two electrode setup with electrolyte solutions made of KCl, CsCl, MgCl2 and CaCl2 filling the compartments at two different ionic strength. Small angle X-ray diffraction (SAXRD) was used to establish the structure and cell unit parameters of the LCP. FINDINGS The interpretation of ionic interaction with phosphatidylcholine was based on estimated membrane resistances and capacitances from EIS measurements. The magnitude of cationic interaction with the lipid headgroup in the water channels is correlated to the membrane resistance that increases in the order Cs+ < K+ < Mg2+ < Ca2+ following the Hofmeister direct series and also reflecting the order of intrinsic binding constants. The membrane capacitance and SAXRD results are discussed as an effect of cationic interaction and it was possible to observe both swelling and condensing effects. The stability of the cubic phase throughout the experiments was confirmed by SAXRD.
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31
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Kodama A, Morandi M, Ebihara R, Jimbo T, Toyoda M, Sakuma Y, Imai M, Puff N, Angelova MI. Migration of Deformable Vesicles Induced by Ionic Stimuli. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11484-11494. [PMID: 30156845 DOI: 10.1021/acs.langmuir.8b02105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have investigated the dynamics of phospholipid vesicles composed of 1,2-dioleoyl- sn-glycero-3-phosphocholine triggered by ionic stimuli using electrolytes such as CaCl2, NaCl, and NaOH. The ionic stimuli induce two characteristic vesicle dynamics, deformation due to the ion binding to the lipids in the outer leaflet of the vesicle and migration due to the concentration gradient of ions, that is, diffusiophoresis or the interfacial energy gradient mechanism. We examined the deformation pathway for each electrolyte as a function of time and analyzed it based on the surface dissociation model and the area difference elasticity model, which reveals the change of the cross-sectional area of the phospholipid by the ion binding. The metal ions such as Ca2+ and Na+ encourage inward budding deformation by decreasing the cross-sectional area of a lipid, whereas the hydroxide ion (OH-) encourages outward budding deformation by increasing the cross-sectional area of a lipid. When we microinjected these electrolytes toward the vesicles, a strong coupling between the deformation and the migration of the vesicle was observed for CaCl2 and NaOH, whereas for NaCl, the coupling was very weak. This difference probably originates from the binding constants of the ions.
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Affiliation(s)
- Atsuji Kodama
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Mattia Morandi
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Ryuta Ebihara
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Takehiro Jimbo
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Masayuki Toyoda
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Yuka Sakuma
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Masayuki Imai
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Nicolas Puff
- Laboratory Matière et Systèmes Complexes (MSC) UMR 7057 CNRS , Sorbonne Paris Cité - Paris 7 , F-75013 Paris , France
- Faculty of Science and Engineering - Paris 6 / Sorbonne University , F-75005 Paris , France
| | - Miglena I Angelova
- Laboratory Matière et Systèmes Complexes (MSC) UMR 7057 CNRS , Sorbonne Paris Cité - Paris 7 , F-75013 Paris , France
- Faculty of Science and Engineering - Paris 6 / Sorbonne University , F-75005 Paris , France
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32
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Anomalous behavior of membrane fluidity caused by copper-copper bond coupled phospholipids. Sci Rep 2018; 8:14093. [PMID: 30237448 PMCID: PMC6148289 DOI: 10.1038/s41598-018-32322-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 08/17/2018] [Indexed: 11/09/2022] Open
Abstract
Membrane fluidity, essential for cell functions, is obviously affected by copper, but the molecular mechanism is poorly understood. Here, we unexpectedly observed that a decrease in phospholipid (PL) bilayer fluidity caused by Cu2+ was more significant than those by Zn2+ and Ca2+, while a comparable reduction occurred in the last two ions. This finding disagrees with the placement in the periodic table of Cu just next to Zn and far from Ca. The physical nature was revealed to be an anomalous attraction between Cu+ cations, as well as the induced motif of two phospholipids coupled by Cu-Cu bond (PL-diCu-PL). Namely, upon Cu2+ ion binding to a negatively charged phosphate group of lipid, Cu2+ was reduced to Cu+. The attraction of the cations then caused one Cu+ ion simultaneously binding to two lipids and another Cu+, resulting in the formation of PL-diCu-PL structure. In contrast, this attraction cannot occur in the cases of Zn and Ca ions. Remarkably, besides lipids, the phosphate group also widely exists in other biological molecules, including DNA, RNA, ADP and ATP. Our findings thus provide a new view for understanding the biological functions of copper and the mechanism underlying copper-related diseases, as well as lipid assembly.
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33
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Maity P, Saha B, Suresh Kumar G, Karmakar S. Effect of Zwitterionic Phospholipid on the Interaction of Cationic Membranes with Monovalent Sodium Salts. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9810-9817. [PMID: 30056708 DOI: 10.1021/acs.langmuir.8b01792] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cationic lipids have attracted much attention because of their potential for biomedical applications, such as gene delivery. The gene transfection efficiency of cationic lipids is greatly influenced by the counterions as well as salt ions. We have systematically investigated the interaction of different monovalent sodium salts with positively charged membrane, composed of 1,2-dioleoyl- sn-glycero-3-phosphocholine (DOPC)/1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and DOTAP, using dynamic light scattering, zeta potential, isothermal titration calorimetry (ITC), and fluorescence spectroscopy techniques. Our results reveal that the affinity of anions with cationic membranes follows the sequence I- ≫ Br- > Cl- according to descending order of their sizes and is consistent with the Hofmeister series. Interestingly, the electrostatic behavior of the DOTAP membrane in the presence of monovalent anions differs significantly from the DOPC/DOTAP membrane. This difference is due to the strong interplay between phosphocholine and trimethylammonium-propane (TAP) headgroups leading to the reorientation of the TAP group in the membrane. The binding constant of anions, derived from zeta potential and ITC is in agreement with the affinity of anions mentioned above. Among all anions, I- shows strongest affinity, as evidenced from the rapid increase in hydrodynamic radius which eventually leads to the formation of large aggregates. The fluorescence spectroscopy of a lypophilic probe Nile red in the presence of cationic vesicles containing ions complements the I- adsorption onto the membrane. Nonlinear Stern-Volmer plot, consisting of accessible and inaccessible Nile red to I- is consistent with the zeta potential as well as ITC results.
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Affiliation(s)
- Pabitra Maity
- Soft Matter and Biophysics Laboratory, Department of Physics , Jadavpur University , 188, Raja S. C. Mallick Road , Kolkata 700032 , India
| | - Baishakhi Saha
- Biophysical Chemistry Laboratory, Organic and Medicinal Chemistry Division , CSIR-Indian Institute of Chemical Biology , 4, Raja S. C. Mallick Road , Kolkata 700 032 , India
| | - Gopinatha Suresh Kumar
- Biophysical Chemistry Laboratory, Organic and Medicinal Chemistry Division , CSIR-Indian Institute of Chemical Biology , 4, Raja S. C. Mallick Road , Kolkata 700 032 , India
| | - Sanat Karmakar
- Soft Matter and Biophysics Laboratory, Department of Physics , Jadavpur University , 188, Raja S. C. Mallick Road , Kolkata 700032 , India
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34
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Rezaei Sani SM, Akhavan M, Jalili S. Salt-induced effects on natural and inverse DPPC lipid membranes: Molecular dynamics simulation. Biophys Chem 2018; 239:7-15. [DOI: 10.1016/j.bpc.2018.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/22/2018] [Accepted: 04/22/2018] [Indexed: 11/29/2022]
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35
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Gord JR, Zhao X, Liu E, Bertram TH, Nathanson GM. Control of Interfacial Cl2 and N2O5 Reactivity by a Zwitterionic Phospholipid in Comparison with Ionic and Uncharged Surfactants. J Phys Chem A 2018; 122:6593-6604. [DOI: 10.1021/acs.jpca.8b04590] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Joseph R. Gord
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Xianyuan Zhao
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Erica Liu
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Timothy H. Bertram
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Gilbert M. Nathanson
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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36
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Melcr J, Martinez-Seara H, Nencini R, Kolafa J, Jungwirth P, Ollila OHS. Accurate Binding of Sodium and Calcium to a POPC Bilayer by Effective Inclusion of Electronic Polarization. J Phys Chem B 2018; 122:4546-4557. [DOI: 10.1021/acs.jpcb.7b12510] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Josef Melcr
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 117 20 Prague 6, Czech Republic
| | - Hector Martinez-Seara
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 117 20 Prague 6, Czech Republic
| | - Ricky Nencini
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 117 20 Prague 6, Czech Republic
| | - Jiří Kolafa
- Department of Physical Chemistry, Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 117 20 Prague 6, Czech Republic
- Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
| | - O. H. Samuli Ollila
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 117 20 Prague 6, Czech Republic
- Institute of Biotechnology, University of Helsinki, 00100 Helsinki, Finland
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37
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Schwörer F, Trapp M, Xu X, Soltwedel O, Dzubiella J, Steitz R, Dahint R. Drastic Swelling of Lipid Oligobilayers by Polyelectrolytes: A Potential Molecular Model for the Internal Structure of Lubricating Films in Mammalian Joints. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1287-1299. [PMID: 29251938 DOI: 10.1021/acs.langmuir.7b03229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Osteoarthritis is the most common arthropathy in western civilization. It is primarily caused by the degeneration of lipid-coated cartilage, leading to increased friction in joints. Hyaluronic acid (HA), a negatively charged polysaccharide and the main component of the synovial fluid, is held responsible for joint lubrication. It is believed that HA, adsorbed to the lipid-coated cartilage, forms a protective layer against wear. Studies have shown that the concentration and molecular weight (MW) of HA are reduced in joints suffering from osteoarthritis. On the basis of these observations, local joint injections of HA or mixtures of HA and surface-active phospholipids (SAPLs) have been applied as medical cures to restore the functionality of the joints in a procedure called viscosupplementation. However, this cure is still disputed, and no consensus has been reached with respect to optimum HA concentration and MW. To provide detailed insight in the structural rearrangement of lipid films upon contact with HA or polymeric analogues, we studied the interaction of the polyelectrolyte poly(allylamine hydrochloride) (PAH) with surface-bound oligobilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by neutron reflectivity (NR) and ellipsometry. Using this model system, we found a drastic swelling of the lipid films as a function of PAH concentration, whose strength compares to that in previous studies on HA incubation. In contrast, no significant dependence of film thickness on PAH MW was observed. A detailed picture of the film architecture was developed which inter alia shows that charged PAH is adsorbed to the lipid headgroups, leading to electrostatic repulsion. The swelling behavior is well explained by the equilibrium of Coulomb and van der Waals interactions in a DLVO-based model. Our detailed structural analysis of the PAH/lipid interfacial layer may help to elucidate the mechanisms of viscosupplementation and derive a structure-function relationship for the lubricating interface in mammalian joints.
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Affiliation(s)
- Felicitas Schwörer
- Applied Physical Chemistry, Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Marcus Trapp
- Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Xiao Xu
- Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Institut für Physik, Humboldt-Universität zu Berlin , Newtonstr. 15, 12159 Berlin, Germany
| | - Olaf Soltwedel
- Max Planck Society Outstation at the Heinz-Maier-Leibnitz-Zentrum (MLZ) , Lichtenbergstr. 1, 85747 Garching, Germany
- Physics Department, Technische Universität München , James-Franck-Str. 1, 85747, München, Germany
| | - Joachim Dzubiella
- Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Institut für Physik, Humboldt-Universität zu Berlin , Newtonstr. 15, 12159 Berlin, Germany
| | - Roland Steitz
- Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Reiner Dahint
- Applied Physical Chemistry, Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
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38
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Chen Y, Okur HI, Lütgebaucks C, Roke S. Zwitterionic and Charged Lipids Form Remarkably Different Structures on Nanoscale Oil Droplets in Aqueous Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1042-1050. [PMID: 29019694 DOI: 10.1021/acs.langmuir.7b02896] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The molecular structure of zwitterionic and charged monolayers on small oil droplets in aqueous solutions is determined using a combined second harmonic and sum frequency study. From the interfacial vibrational signature of the acyl chains and phosphate headgroups as well as the response of the hydrating water, we find that zwitterionic and charged lipids with identical acyl chains form remarkably different monolayers. Zwitterionic phospholipids form a closely packed monolayer with highly ordered acyl tails. In contrast, the charged phospholipids form a monolayer with a low number density and disordered acyl tails. The charged headgroups are oriented perpendicular to the monolayer rather than parallel, as is the case for zwitterionic lipids. These significant differences between the two types of phospholipids indicate important roles of phospholipid headgroups in the determination of properties of cellular membranes and lipid droplets. The observed behavior of charged phospholipids is different from expectations based on studies performed on extended planar interfaces, at which condensed monolayers are readily formed. The difference can be explained by nanoscale related changes in charge condensation behavior that has its origin in a different balance of interfacial intermolecular interactions.
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Affiliation(s)
- 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
| | - 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
| | - Cornelis Lütgebaucks
- 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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Abstract
Biomembranes assemble and operate at the interface with electrolyte solutions. Interactions between ions in solutions and the lipid affect the membrane structure, dynamics and electrostatic potential. In this article, I review some of the experimental and computational methods that are used to study membrane–ions interactions. Experimental methods that account for membrane–ion interactions directly and indirectly are presented first. Then, studies in which molecular dynamics simulations were used to gain an understanding of membrane–ion interactions are surveyed. Finally, the current view on membrane–ion interactions and their significance is briefly discussed.
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Affiliation(s)
- Ran Friedman
- Department of Chemistry and Biomedical Sciences and Centre of Excellence "Biomaterials Chemistry", Linnæus University, Kalmar, Sweden.
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40
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Martí J. Free-energy surfaces of ionic adsorption in cholesterol-free and cholesterol-rich phospholipid membranes. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2017.1391383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Jordi Martí
- Department of Physics, Technical University of Catalonia-Barcelona Tech, Barcelona, Spain
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41
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Kodama A, Sakuma Y, Imai M, Kawakatsu T, Puff N, Angelova MI. Migration of Phospholipid Vesicles Can Be Selectively Driven by Concentration Gradients of Metal Chloride Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10698-10706. [PMID: 28895737 DOI: 10.1021/acs.langmuir.7b02617] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have investigated the migrations of phospholipid vesicles under the concentration gradients of metal ions. We microinjected metal chloride solutions, monovalent (NaCl and KCl), divalent (CaCl2 and MgCl2), and trivalent (LaCl3) salts, toward phospholipid giant vesicles (GVs) composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). For NaCl, CaCl2, and MgCl2 solutions, the GVs migrated straight toward the tip of the micropipette in response to the concentration gradients, whereas for KCl and LaCl3, GVs moved to the opposite direction. Our motion tracking of lipid domains in a vesicle membrane showed no unidirectional flow in the membrane during the vesicle migration, indicating that the Marangoni mechanism is not responsible for the observed vesicle migration. We calculated the diffusiophoretic velocities for symmetric and asymmetrical electrolytes by solving the Stokes' equation numerically. The theoretical diffusiophoretic velocities described the observed migration velocities well. Thus, we can control the migration of vesicle in response to the concentration gradient by adapting the electrolytes and the lipids.
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Affiliation(s)
- Atsuji Kodama
- Department of Physics, Graduate School of Science, Tohoku University , 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Yuka Sakuma
- Department of Physics, Graduate School of Science, Tohoku University , 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Masayuki Imai
- Department of Physics, Graduate School of Science, Tohoku University , 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Toshihiro Kawakatsu
- Department of Physics, Graduate School of Science, Tohoku University , 6-3, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Nicolas Puff
- Laboratoire Matière et Systèmes Complexes, Universitè Paris Diderot (Paris 7) , F-75205 Paris Cedex 13, France
- Physics Department, Universitè Pierre et Marie Curie (Paris 6) , F-75005 Paris, France
| | - Miglena I Angelova
- Laboratoire Matière et Systèmes Complexes, Universitè Paris Diderot (Paris 7) , F-75205 Paris Cedex 13, France
- Physics Department, Universitè Pierre et Marie Curie (Paris 6) , F-75005 Paris, France
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Ionic interactions determine the morphology of dried alkali/liposome suspension droplets. Colloids Surf B Biointerfaces 2017; 160:473-482. [PMID: 28988125 DOI: 10.1016/j.colsurfb.2017.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/11/2017] [Accepted: 09/05/2017] [Indexed: 01/17/2023]
Abstract
We sought to understand why saline drops produce intriguing patterns when drying in the presence of zwitterionic liposomes. Specifically, we would like to comprehend why the nature of such patterns is hierarchically driven by the Hofmeister series. The liposome suspension is made of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with alkali metal chlorides. A complexity analysis of the patterns gives a fractal dimension around 1.71, which means that the drying process resembles a DLA mechanism. A physicochemical study, including the determination of zeta potential, molecular dynamics simulations, microrheology, and calorimetry, supports the fact that electrostatic interactions among head groups of phospholipids with alkali cations are the driven forces behind the assembling of the observed structures. Moreover, we found that the morphology of the dried droplets is sensitive to the substrate. Our findings could be used in a biological context, for example, to characterize cells in ionic media.
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Mlayeh L, Krammer EM, Léonetti M, Prévost M, Homblé F. The mitochondrial VDAC of bean seeds recruits phosphatidylethanolamine lipids for its proper functioning. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:786-794. [PMID: 28666835 DOI: 10.1016/j.bbabio.2017.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/28/2017] [Accepted: 06/24/2017] [Indexed: 12/31/2022]
Abstract
The voltage-dependent anion-selective channel (VDAC) is the main pathway for inorganic ions and metabolites through the mitochondrial outer membrane. Studies recently demonstrated that membrane lipids regulate its function. It remains, however, unclear how this regulation takes place. In this study, we show that phospholipids are key regulators of Phaseolus VDAC function and, furthermore, that the salt concentration modulates this regulation. Both selectivity and voltage dependence of Phaseolus VDAC are very sensitive to a change in the lipid polar head from PC to PE. Interestingly enough, this dependence is observed only at low salt concentration. Furthermore, significant changes in VDAC functional properties also occur with the gradual methylation of the PE group pointing to the role of subtle chemical variations in the lipid head group. The dependence of PcVDAC gating upon the introduction of a small mole fraction of PE in a PC bilayer has prompted us to propose the existence of a specific interaction site for PE on the outer surface of PcVDAC. Eventually, comparative modeling and molecular dynamics simulations suggest a potential mechanism to get insight into the anion selectivity enhancement of PcVDAC observed in PE relative to PC.
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Affiliation(s)
- Lamia Mlayeh
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 206/2, B-1050 Brussels, Belgium
| | - Eva-Maria Krammer
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 206/2, B-1050 Brussels, Belgium.
| | - Marc Léonetti
- I.R.P.H.E., Aix-Marseille Université, CNRS, Technopôle de Château-Gombert, F-13384, Marseille Cedex 13, France.
| | - Martine Prévost
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 206/2, B-1050 Brussels, Belgium.
| | - Fabrice Homblé
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 206/2, B-1050 Brussels, Belgium.
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44
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Vosahlikova M, Ujcikova H, Chernyavskiy O, Brejchova J, Roubalova L, Alda M, Svoboda P. Effect of therapeutic concentration of lithium on live HEK293 cells; increase of Na + /K + -ATPase, change of overall protein composition and alteration of surface layer of plasma membrane. Biochim Biophys Acta Gen Subj 2017; 1861:1099-1112. [DOI: 10.1016/j.bbagen.2017.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 01/20/2017] [Accepted: 02/10/2017] [Indexed: 12/19/2022]
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Effect of Sodium and Chloride Binding on a Lecithin Bilayer. A Molecular Dynamics Study. MEMBRANES 2017; 7:membranes7010005. [PMID: 28125062 PMCID: PMC5371966 DOI: 10.3390/membranes7010005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/12/2017] [Accepted: 01/14/2017] [Indexed: 01/17/2023]
Abstract
The effect of ion binding on the structural, mechanical, dynamic and electrostatic properties of a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer in a 0.5 M aqueous NaCl solution is investigated using classical atomistic molecular dynamics simulation with different force-field descriptions for ion-ion and ion-lipid interactions. Most importantly, the repulsive Lennard-Jones parameters for the latter were modified, such that approximately similar binding of cations and anions to the lipid membrane is achieved. This was done to qualitatively improve the apparent ion-lipid binding constants obtained from simulations with the original force field (Berger lipids and GROMOS87 ions in combination with the SPC water model) in comparison to experimental data. Furthermore, various parameters characterizing membrane structure, elasticity, order and dynamics are analyzed. It is found that ion binding as observed in simulations involving the modified in comparison to the original force-field description leads to: (i) a smaller salt-induced change in the area per lipid, which is in closer agreement with the experiment; (ii) a decrease in the area compressibility and bilayer thickness to values comparable to a bilayer in pure water; (iii) lipid deuterium order parameters and lipid diffusion coefficients on nanosecond timescales that are very similar to the values for a membrane in pure water. In general, salt effects on the structural properties of a POPC bilayer in an aqueous sodium-chloride solution appear to be reproduced reasonably well by the new force-field description. An analysis of membrane-membrane disjoining pressure suggests that the smaller salt-induced change in area per lipid induced by the new force-field description is not due to the alteration of membrane-associated net charge, but must rather be understood as a consequence of ion-specific effects on the arrangement of lipid molecules.
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47
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Ganesan SJ, Xu H, Matysiak S. Influence of Monovalent Cation Size on Nanodomain Formation in Anionic–Zwitterionic Mixed Bilayers. J Phys Chem B 2017; 121:787-799. [DOI: 10.1021/acs.jpcb.6b10099] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sai J. Ganesan
- Fischell
Department of Bioengineering and ‡Biophysics Program, Institute of
Physical Science and Technology, University of Maryland, College
Park, Maryland 20742, United States
| | - Hongcheng Xu
- Fischell
Department of Bioengineering and ‡Biophysics Program, Institute of
Physical Science and Technology, University of Maryland, College
Park, Maryland 20742, United States
| | - Silvina Matysiak
- Fischell
Department of Bioengineering and ‡Biophysics Program, Institute of
Physical Science and Technology, University of Maryland, College
Park, Maryland 20742, United States
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48
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The complex nature of calcium cation interactions with phospholipid bilayers. Sci Rep 2016; 6:38035. [PMID: 27905555 PMCID: PMC5131315 DOI: 10.1038/srep38035] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 11/03/2016] [Indexed: 01/21/2023] Open
Abstract
Understanding interactions of calcium with lipid membranes at the molecular level is of great importance in light of their involvement in calcium signaling, association of proteins with cellular membranes, and membrane fusion. We quantify these interactions in detail by employing a combination of spectroscopic methods with atomistic molecular dynamics simulations. Namely, time-resolved fluorescent spectroscopy of lipid vesicles and vibrational sum frequency spectroscopy of lipid monolayers are used to characterize local binding sites of calcium in zwitterionic and anionic model lipid assemblies, while dynamic light scattering and zeta potential measurements are employed for macroscopic characterization of lipid vesicles in calcium-containing environments. To gain additional atomic-level information, the experiments are complemented by molecular simulations that utilize an accurate force field for calcium ions with scaled charges effectively accounting for electronic polarization effects. We demonstrate that lipid membranes have substantial calcium-binding capacity, with several types of binding sites present. Significantly, the binding mode depends on calcium concentration with important implications for calcium buffering, synaptic plasticity, and protein-membrane association.
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49
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Serpas L, Milorey B, Pandiscia LA, Addison AW, Schweitzer-Stenner R. Autoxidation of Reduced Horse Heart Cytochrome c Catalyzed by Cardiolipin-Containing Membranes. J Phys Chem B 2016; 120:12219-12231. [PMID: 27934230 DOI: 10.1021/acs.jpcb.6b05620] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Visible circular dichroism, absorption, and fluorescence spectroscopy were used to probe the binding of horse heart ferrocytochrome c to anionic cardiolipin (CL) head groups on the surface of 1,1',2,2'-tetraoleoyl cardiolipin (TOCL)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) (20%:80%) liposomes in an aerobic environment. We found that ferrocytochrome c undergoes a conformational transition upon binding that leads to complete oxidation of the protein at intermediate and high CL concentrations. At low lipid concentrations, the protein maintains a structure that is only slightly different from its native one, whereas an ensemble of misligated predominantly hexacoordinated low-spin states become increasingly populated at high lipid concentrations. A minor fraction of conformations with either high- or quantum-mixed-spin states were detected at a CL to protein ratio of 200 (the largest one investigated). The population of the non-native state is less pronounced than that found for cytochrome c-CL interactions initiated with oxidized cytochrome c. Under anaerobic conditions, the protein maintains its reduced state but still undergoes some conformational change upon binding to CL head groups on the liposome surface. Our data suggest that CL-containing liposomes function as catalysts by reducing the activation barrier for a Fe2+ → O2 electron transfer. Adding NaCl to the existing cytochrome-liposome mixtures under aerobic conditions inhibits protein autoxidation of ferrocytochrome c and stabilizes the reduced state of the membrane-bound protein.
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Affiliation(s)
- Lee Serpas
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Bridget Milorey
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Leah A Pandiscia
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Anthony W Addison
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Reinhard Schweitzer-Stenner
- Department of Chemistry, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States
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50
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Lin ST, Lin CS, Chang YY, Whitten AE, Sokolova A, Wu CM, Ivanov VA, Khokhlov AR, Tung SH. Effects of Alkali Cations and Halide Anions on the Self-Assembly of Phosphatidylcholine in Oils. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:12166-12174. [PMID: 27802053 DOI: 10.1021/acs.langmuir.6b03449] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The interactions between ions and phospholipids are closely associated with the structures and functions of cell membrane. Instead of conventional aqueous systems, we systematically investigated the effects of inorganic ions on the self-assembly of lecithin, a zwitterionic phosphatidylcholine, in cyclohexane. Previous studies have shown that addition of inorganic salts with specific divalent and trivalent cations can transform lecithin organosols into organogels. In this study, we focused on the effect of monovalent alkali halides. Fourier transform infrared spectroscopy was used to demonstrate that the binding strength of the alkali cations with the phosphate of lecithin is in the order Li+ > Na+ > K+. More importantly, the cation-phosphate interaction is affected by the paired halide anions, and the effect follows the series I- > Br- > Cl-. The salts of stronger interactions with lecithin, including LiCl, LiBr, LiI, and NaI, were found to induce cylindrical micelles sufficiently long to form organogels, while others remain organosols. A mechanism based on the charge density of ions and the enthalpy change of the ion exchange between alkali halides and lecithin headgroup is provided to explain the contrasting interactions and the effectiveness of the salts to induce organogelation.
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Affiliation(s)
- Shih-Ting Lin
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Chen-Shin Lin
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Ya-Ying Chang
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
| | - Andrew E Whitten
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Anna Sokolova
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Chun-Ming Wu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Viktor A Ivanov
- Faculty of Physics, Moscow State University , Moscow 119991, Russia
| | | | - Shih-Huang Tung
- Institute of Polymer Science and Engineering, National Taiwan University , Taipei 10617, Taiwan
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