1
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Ma YH, Li B, Wang C, Yang J, Han X, Lu X. Unsaturation effects on lipid transmembrane asymmetry. J Chem Phys 2024; 160:215102. [PMID: 38842495 DOI: 10.1063/5.0209950] [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: 03/24/2024] [Accepted: 05/15/2024] [Indexed: 06/07/2024] Open
Abstract
Within cell plasma membranes, unsaturated lipids are asymmetrically distributed over the inner and outer leaflets, offering an attractive local structural feature. However, the mechanism to keep lipid transmembrane asymmetry and the closely related transmembrane movement (flip-flop) for unsaturated lipids remain poorly understood. Here, we applied sum frequency generation vibrational spectroscopy to investigate this lipid transmembrane asymmetry upon mimicking the cell membrane homeostatic processes. On the one hand, unsaturated lipids were found to hinder the flip-flop process and preserve lipid transmembrane asymmetry in model cell membranes, owing to the steric hindrance caused by their bent tails. On the other hand, local unsaturated lipids in the mixed unsaturated/saturated lipid bilayer were conducive to the formation of the local asymmetry. Therefore, lipid unsaturation can be recognized as an intrinsic key factor to form and maintain lipid transmembrane asymmetry in cell membranes.
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Affiliation(s)
- Yong-Hao Ma
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Bolin Li
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Chu Wang
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jingjing Yang
- Department of Biochemistry and Molecular Biology, School of Medicine and Holistic Integrative Medicine, Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xiaofeng Han
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xiaolin Lu
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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2
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Pullanchery S, Dupertuis N, Roesel T, Roke S. Liposomes and Lipid Droplets Display a Reversal of Charge-Induced Hydration Asymmetry. NANO LETTERS 2023; 23:9858-9864. [PMID: 37869786 PMCID: PMC10636888 DOI: 10.1021/acs.nanolett.3c02653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/03/2023] [Indexed: 10/24/2023]
Abstract
The unique properties of water are critical for life. Water molecules have been reported to hydrate cations and anions asymmetrically in bulk water, being a key element in the balance of biochemical interactions. We show here that this behavior extends to charged lipid nanoscale interfaces. Charge hydration asymmetry was investigated by using nonlinear light scattering methods on lipid nanodroplets and liposomes. Nanodroplets covered with negatively charged lipids induce strong water ordering, while droplets covered with positively charged lipids induce negligible water ordering. Surprisingly, this charge-induced hydration asymmetry is reversed around liposomes. This opposite behavior in charge hydration asymmetry is caused by a delicate balance of electrostatic and hydrogen-bonding interactions. These findings highlight the importance of not only the charge state but also the specific distribution of neutral and charged lipids in cellular membranes.
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Affiliation(s)
- Saranya Pullanchery
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
School of Engineering (STI), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nathan Dupertuis
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
School of Engineering (STI), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Tereza Roesel
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
School of Engineering (STI), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI),
School of Engineering (STI), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science (IMX), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne
Centre for Ultrafast Science (LACUS), École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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3
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Pullanchery S, Zhang L, Kulik S, Roke S. Interfacial Inversion, Interference, and IR Absorption in Vibrational Sum Frequency Scattering Experiments. J Phys Chem B 2023; 127:6795-6803. [PMID: 37470215 PMCID: PMC10405221 DOI: 10.1021/acs.jpcb.3c02727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/26/2023] [Indexed: 07/21/2023]
Abstract
Molecular interfacial structure greatly determines the properties of nano- and microscale systems. Vibrational sum frequency scattering (SFS) spectroscopy is a unique interface-selective tool to measure the interfacial vibrational spectrum of sub-micron to micron-scale objects dispersed in liquid and solid media. The interfacial structure is extracted from the interfacial susceptibility, a physical property derived from the intensity. Here, we describe the effect of infrared absorption that occurs in a bulk medium that is spectroscopically complex and use the results to investigate the effects of interfacial inversion, interfacial interference, and interfacial interference combined with absorption. We use the same three chemicals to do so, hexadecane oil, water, and a neutral Span80 surfactant. For all cases, the effective surface susceptibility can be retrieved from the intensity. We further find that inverting the phases results in different interfacial structures, even though they are composed of the same three chemicals, and explain this in terms of the different interactions that are necessary to stabilize the drops: steric stabilization for water drops in oil vs. charge stabilization for oil drops in water. Interfacial interference can be used to estimate the surface density of different compounds.
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Affiliation(s)
- S. Pullanchery
- Laboratory
for Fundamental BioPhotonics, Institute of Bioengineering (IBI), School
of Engineering (STI), École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - L. Zhang
- Laboratory
for Fundamental BioPhotonics, Institute of Bioengineering (IBI), School
of Engineering (STI), École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - S. Kulik
- Laboratory
for Fundamental BioPhotonics, Institute of Bioengineering (IBI), School
of Engineering (STI), École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - S. Roke
- Laboratory
for Fundamental BioPhotonics, Institute of Bioengineering (IBI), School
of Engineering (STI), École Polytechnique
Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute
of Materials Science and Engineering (IMX), School of Engineering
(STI), École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne
Centre for Ultrafast Science, École
Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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4
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Golbek TW, Okur HI, Kulik S, Dedic J, Roke S, Weidner T. Lysozyme Interaction with Phospholipid Nanodroplets Probed by Sum Frequency Scattering Vibrational Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6447-6454. [PMID: 37125843 DOI: 10.1021/acs.langmuir.3c00276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
When a nanoparticle (NP) is introduced into a biological environment, its identity and interactions are immediately attributed to the dense layer of proteins that quickly covers the particle. The formation of this layer, dubbed the protein corona, is in general a combination of proteins interacting with the surface of the NP and a contest between other proteins for binding sites either at the surface of the NP or upon the dense layer. Despite the importance for surface engineering and drug development, the molecular mechanisms and structure behind interfacial biomolecule action have largely remained elusive. We use ultrafast sum frequency scattering (SFS) spectroscopy to determine the structure and the mode of action by which these biomolecules interact with and manipulate interfaces. The majority of work in the field of sum frequency generation has been done on flat model interfaces. This limits some important membrane properties such as membrane fluidity and dimensionality─important factors in biomolecule-membrane interactions. To move toward three-dimensional (3D) nanoscopic interfaces, we utilize SFS spectroscopy to interrogate the surface of 3D lipid monolayers, which can be used as a model lipid-based nanocarrier system. In this study, we have utilized SFS spectroscopy to follow the action of lysozyme. SFS spectra in the amide I region suggest that there is lysozyme at the interface and that the lysozyme induces an increased lipid monolayer order. The binding of lysozyme with the NP is demonstrated by an increase in acyl chain order determined by the ratio of the CH3 symmetric and CH2 symmetric peak amplitudes. Furthermore, the lipid headgroup orientation s-PO2- change strongly supports lysozyme insertion into the lipid layer causing lipid disruption and reorientation. Altogether, with SFS, we have made a huge stride toward understanding the binding and structure change of proteins within the protein corona.
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Affiliation(s)
| | - Halil I Okur
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bio-engineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Sergey Kulik
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bio-engineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jan Dedic
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bio-engineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bio-engineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
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5
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Bogdanov M. Renovating a double fence with or without notifying the next door and across the street neighbors: why the biogenic cytoplasmic membrane of Gram-negative bacteria display asymmetry? Emerg Top Life Sci 2023; 7:137-150. [PMID: 36960750 PMCID: PMC10725183 DOI: 10.1042/etls20230042] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 03/03/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023]
Abstract
The complex two-membrane organization of the envelope of Gram-negative bacteria imposes an unique biosynthetic and topological constraints that can affect translocation of lipids and proteins synthesized on the cytoplasm facing leaflet of the cytoplasmic (inner) membrane (IM), across the IM and between the IM and outer membrane (OM). Balanced growth of two membranes and continuous loss of phospholipids in the periplasmic leaflet of the IM as metabolic precursors for envelope components and for translocation to the OM requires a constant supply of phospholipids in the IM cytosolic leaflet. At present we have no explanation as to why the biogenic E. coli IM displays asymmetry. Lipid asymmetry is largely related to highly entropically disfavored, unequal headgroup and acyl group asymmetries which are usually actively maintained by active mechanisms. However, these mechanisms are largely unknown for bacteria. Alternatively, lipid asymmetry in biogenic IM could be metabolically controlled in order to maintain uniform bilayer growth and asymmetric transmembrane arrangement by balancing temporally the net rates of synthesis and flip-flop, inter IM and OM bidirectional flows and bilayer chemical and physical properties as spontaneous response. Does such flippase-less or 'lipid only", 'passive' mechanism of generation and maintenance of lipid asymmetry exists in the IM? The driving force for IM asymmetry can arise from the packing requirements imposed upon the bilayer system during cell division through disproportional distribution of two negatively curved phospholipids, phosphatidylethanolamine and cardiolipin, with consistent reciprocal tendency to increase and decrease lipid order in each membrane leaflet respectively.
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Affiliation(s)
- Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, TX 77030, U.S.A
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6
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Page EF, Blake MJ, Foley GA, Calhoun TR. Monitoring membranes: The exploration of biological bilayers with second harmonic generation. CHEMICAL PHYSICS REVIEWS 2022; 3:041307. [PMID: 36536669 PMCID: PMC9756348 DOI: 10.1063/5.0120888] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
Nature's seemingly controlled chaos in heterogeneous two-dimensional cell membranes stands in stark contrast to the precise, often homogeneous, environment in an experimentalist's flask or carefully designed material system. Yet cell membranes can play a direct role, or serve as inspiration, in all fields of biology, chemistry, physics, and engineering. Our understanding of these ubiquitous structures continues to evolve despite over a century of study largely driven by the application of new technologies. Here, we review the insight afforded by second harmonic generation (SHG), a nonlinear optical technique. From potential measurements to adsorption and diffusion on both model and living systems, SHG complements existing techniques while presenting a large exploratory space for new discoveries.
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Affiliation(s)
- Eleanor F. Page
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Marea J. Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Grant A. Foley
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
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7
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Dupertuis N, Tarun OB, Lütgebaucks C, Roke S. Three-Dimensional Confinement of Water: H 2O Exhibits Long-Range (>50 nm) Structure while D 2O Does Not. NANO LETTERS 2022; 22:7394-7400. [PMID: 36067223 DOI: 10.1021/acs.nanolett.2c02206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Water is the liquid of life thanks to its three-dimensional adaptive hydrogen (H)-bond network. Confinement of this network may lead to dramatic structural changes influencing chemical and physical transformations. Although confinement effects occur on a <1 nm length scale, the upper length scale limit is unknown. Here, we investigate 3D-confinement over lengths scales ranging from 58-140 nm. By confining water in zwitterionic liposomes of different sizes and measuring the change in H-bond network conformation using second harmonic scattering (SHS), we determined long-range confinement effects in light and heavy water. D2O displays no detectable 3D-confinement effects <58 nm (<3 × 106 D2O molecules). H2O is distinctly different. The vesicle enclosed inner H-bond network has a different conformation compared to the outside network and the SHS response scales with the volume of the confining space. H2O displays confinement effects over distances >100 nm (>2 × 107 H2O molecules).
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Affiliation(s)
- Nathan Dupertuis
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Orly B Tarun
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Cornelis Lütgebaucks
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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8
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Xu B, Chen SL, Zhang Y, Li B, Yuan Q, Gan W. Evaluating the cross-membrane dynamics of a charged molecule on lipid films with different surface curvature. J Colloid Interface Sci 2021; 610:376-384. [PMID: 34923275 DOI: 10.1016/j.jcis.2021.12.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/27/2021] [Accepted: 12/04/2021] [Indexed: 11/25/2022]
Abstract
Does the curvature of a phospholipid membrane influence the permeability of the lipid bilayers? This is a question of great importance yet hard to answer. In this work the permeability of a positively charged rod like probing molecule (D289 dye) on the bilayers of DOPG lipid vesicles was investigated using angle resolved second harmonic generation method. It was revealed that the permeability of D289 on the surface of small vesicles with ∼ 100 nm diameter was notably lower than that on giant vesicles with ∼ 1000 nm diameter. With the increasing of temperature or the introducing of dimethyl sulfoxide (DMSO) in the solutions, the D289 permeability of the lipid bilayers was notably enhanced as expected, on both the small and the giant vesicles. Still, the D289 permeability of the lipid film with more curvature is lower than the relatively flat film in all these cases. This work demonstrated a general protocol for the investigating of surface permeability of lipid films with various curvature.
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Affiliation(s)
- Baomei Xu
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, and School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China
| | - Shun-Li Chen
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Province, Shantou University, Shantou 515063, Guangdong, China
| | - Yiru Zhang
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, and School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, China
| | - Bifei Li
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, and School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China
| | - Qunhui Yuan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, and School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, China
| | - Wei Gan
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, and School of Science, Harbin Institute of Technology (Shenzhen), University Town, Shenzhen 518055, Guangdong, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China.
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9
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Recent progress of vibrational spectroscopic study on the interfacial structure of biomimetic membranes. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2021. [DOI: 10.1016/j.cjac.2021.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Schönfeldová T, Piller P, Kovacik F, Pabst G, Okur HI, Roke S. Lipid Melting Transitions Involve Structural Redistribution of Interfacial Water. J Phys Chem B 2021; 125:12457-12465. [PMID: 34730965 PMCID: PMC8607985 DOI: 10.1021/acs.jpcb.1c06868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/15/2021] [Indexed: 11/29/2022]
Abstract
Morphological and gel-to-liquid phase transitions of lipid membranes are generally considered to primarily depend on the structural motifs in the hydrophobic core of the bilayer. Structural changes in the aqueous headgroup phase are typically not considered, primarily because they are difficult to quantify. Here, we investigate structural changes of the hydration shells around large unilamellar vesicles (LUVs) in aqueous solution, using differential scanning calorimetry (DSC), and temperature-dependent ζ-potential and high-throughput angle-resolved second harmonic scattering measurements (AR-SHS). Varying the lipid composition from 1,2-dimyristoyl-sn-glycero-3-phosphocholine(DMPC) to 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA), to 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS), we observe surprisingly distinct behavior for the different systems that depend on the chemical composition of the hydrated headgroups. These differences involve changes in hydration following temperature-induced counterion redistribution, or changes in hydration following headgroup reorientation and Stern layer compression.
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Affiliation(s)
- Tereza Schönfeldová
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), 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
| | - Paulina Piller
- Institute
of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstrasse 50/III, Graz 8010, Austria
| | - Filip Kovacik
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), 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
| | - Georg Pabst
- Institute
of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstrasse 50/III, Graz 8010, Austria
| | - Halil I. Okur
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), 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
- Department
of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Sylvie Roke
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), 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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11
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Observing the structural variations on binary complex vesicle surfaces and the influence on molecular transportation. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111250] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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12
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Windowless detection geometry for sum frequency scattering spectroscopy in the C-D and amide I regions. Biointerphases 2021; 16:011201. [PMID: 33706523 DOI: 10.1116/6.0000419] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Understanding the structure and chemistry of nanoscopic surfaces is an important challenge for biointerface sciences. Sum frequency scattering (SFS) spectroscopy can specifically probe the surfaces of nanoparticles, vesicles, liposomes, and other materials relevant to biomaterial research, and, as a vibrational spectroscopy method, it can provide molecular level information about the surface chemistry. SFS is particularly promising to probe the structure of proteins, and other biological molecules, at nanoparticle surfaces. Here, amide I spectra can provide information about protein folding and orientation, while spectra in the C-D and C-H stretching regions allow experiments to determine the mode of interaction between particle surfaces and proteins. Methods used currently employ a closed liquid cell or cuvette, which works extremely well for C-H and phosphate regions but is often impeded in the amide I and C-D regions by a strong background signal that originates from the window material of the sample cells. Here, we discuss a windowless geometry for collecting background-free and high-fidelity SFS spectra in the amide I and C-D regions. We demonstrate the improvement in spectra quality by comparing SFS spectra of unextruded, multilamellar vesicles in a sample cuvette with those recorded using the windowless geometry. The sample geometry we propose will enable new experiments using SFS as a probe for protein-particle interactions.
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13
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14
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Guo HY, Sun HY, Deng G, Xu J, Wu FG, Yu ZW. Fabrication of Asymmetric Phosphatidylserine-Containing Lipid Vesicles: A Study on the Effects of Size, Temperature, and Lipid Composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12684-12691. [PMID: 33047603 DOI: 10.1021/acs.langmuir.0c02273] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The asymmetric distribution of lipids in plasma membranes is closely related to the physiological functions of cells. To improve our previous approach in fabricating asymmetric vesicles, we defined a parameter, asymmetric degree, in this work and investigated the effects of vesicle size, incubation temperature, and lipid composition on the formation process of asymmetric phosphatidylserine (PS)-containing lipid vesicles. The results indicate that all of the three factors have marked but different effects on the time-dependent asymmetric degree of the vesicles as well as the flip and flop rate constants of the PS lipids. However, only vesicle size and PS content show significant influence on the maximal asymmetric degree of the vesicles, while the incubation temperature exhibits negligible effect. This work not only deepens our understanding on the packing property of PS molecules in self-assembled membranes and the formation mechanism of asymmetric vesicles but also practically provides a solution to regulate the asymmetric degree of the PS-containing vesicles using the established kinetic equation. In addition, the method would facilitate researches related to asymmetric vesicles or reconstruction of biological membranes.
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Affiliation(s)
- Hao-Yue Guo
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Hai-Yuan Sun
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Geng Deng
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Jing Xu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Fu-Gen Wu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, P. R. China
| | - Zhi-Wu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
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15
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Deplazes E, Hartmann LM, Cranfield CG, Garcia A. Structural Characterization of a Cation-Selective, Self-Assembled Peptide Pore in Planar Phospholipid Bilayers. J Phys Chem Lett 2020; 11:8152-8156. [PMID: 32902292 DOI: 10.1021/acs.jpclett.0c02335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
GALA is a 30-residue amphipathic peptide that self-assembles into multimeric transmembrane pores in a pH-dependent fashion. In this study, we characterize the size, multimeric structure, and cation selectivity of GALA pores in planar phospholipid bilayers using electrical impedance spectroscopy and molecular dynamics simulations. We demonstrate that in planar bilayers GALA pores are likely formed by six peptide monomers rather than eight to 12 monomers as previously reported for lipid vesicles. We further show that in planar bilayers, GALA pores exhibit previously unreported cation selectivity. We propose that the difference between the predicted pore structures in planar bilayers and lipid vesicles exemplifies the importance of phospholipid bilayer structural properties on the aggregation of transmembrane helical structures.
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Affiliation(s)
- Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Lissy M Hartmann
- 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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16
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Lipid asymmetry of a model mitochondrial outer membrane affects Bax-dependent permeabilization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183241. [DOI: 10.1016/j.bbamem.2020.183241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/16/2020] [Accepted: 02/12/2020] [Indexed: 11/24/2022]
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17
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Transient domains of ordered water induced by divalent ions lead to lipid membrane curvature fluctuations. Commun Chem 2020; 3:17. [PMID: 36703372 PMCID: PMC9814626 DOI: 10.1038/s42004-020-0263-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/19/2019] [Indexed: 01/29/2023] Open
Abstract
Cell membranes are composed of a hydrated lipid bilayer that is molecularly complex and diverse, and the link between molecular hydration structure and membrane macroscopic properties is not well understood, due to a lack of technology that can probe and relate molecular level hydration information to micro- and macroscopic properties. Here, we demonstrate a direct link between lipid hydration structure and macroscopic dynamic curvature fluctuations. Using high-throughput wide-field second harmonic (SH) microscopy, we observe the formation of transient domains of ordered water at the interface of freestanding lipid membranes. These domains are induced by the binding of divalent ions and their structure is ion specific. Using nonlinear optical theory, we convert the spatiotemporal SH intensity into maps of membrane potential, surface charge density, and binding free energy. Using an electromechanical theory of membrane bending, we show that transient electric field gradients across the membrane induce spatiotemporal membrane curvature fluctuations.
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18
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Elmer-Dixon MM, Hoody J, Steele HBB, Becht DC, Bowler BE. Cardiolipin Preferentially Partitions to the Inner Leaflet of Mixed Lipid Large Unilamellar Vesicles. J Phys Chem B 2019; 123:9111-9122. [DOI: 10.1021/acs.jpcb.9b07690] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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19
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Okur HI, Tarun OB, Roke S. Chemistry of Lipid Membranes from Models to Living Systems: A Perspective of Hydration, Surface Potential, Curvature, Confinement and Heterogeneity. J Am Chem Soc 2019; 141:12168-12181. [DOI: 10.1021/jacs.9b02820] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Halil I. Okur
- Laboratory for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI) and Institute of Materials
Science (IMX), School of Engineering (STI) and Lausanne Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Orly B. Tarun
- Laboratory for Fundamental BioPhotonics
(LBP), Institute of Bioengineering (IBI) and Institute of Materials
Science (IMX), School of Engineering (STI) and Lausanne Center 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 Center for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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20
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Johansson PK, Castner DG. Vibrational Sum-Frequency Scattering as a Sensitive Approach to Detect Structural Changes in Collagen Fibers Treated with Surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7848-7857. [PMID: 31117724 PMCID: PMC6648693 DOI: 10.1021/acs.langmuir.9b00412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Optimizing protocols so that the structure of the collagen fibers in the extracellular matrix remains intact during the decellularization process requires techniques with high structural sensitivity, especially for the surface region of the collagen fibers. Here, we demonstrate that vibrational sum-frequency scattering (SFS) spectroscopy in the protein-specific amide I region provides vibrational spectra and scattering patterns characteristic of protein fiber networks self-assembled in vitro from collagen type I, which are kept in aqueous environments during the analysis. At scattering angles away from the phase-matched direction, the relative strengths of various polarization combinations are highly reproducible, and changes in their ratios can be followed in real time during exposure to sodium dodecyl sulfate surfactant solutions. For the fibers in this work, a scattering angle of about 22° provided specificity for the surface region of the fibers, as it allowed monitoring of immediate structural changes during the surfactant exposure. With further development, we hypothesize that the information from the SFS characterization of collagen fibers may complement information from other techniques with sensitivity to the overall structure, such as second-harmonic generation imaging and infrared spectroscopy, and provide a more complete understanding of fiber molecular structures and interactions during exposure to various environments and conditions.
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Affiliation(s)
- Patrik K. Johansson
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Seattle, 98195, United States
- Department of Bioengineering, University of Washington, Seattle, 98195, United States
- Corresponding Author ,
| | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Seattle, 98195, United States
- Department of Bioengineering, University of Washington, Seattle, 98195, United States
- Department of Chemical Engineering, University of Washington, Seattle, 98195, United States
- Corresponding Author ,
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21
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Zdrali E, Etienne G, Smolentsev N, Amstad E, Roke S. The interfacial structure of nano- and micron-sized oil and water droplets stabilized with SDS and Span80. J Chem Phys 2019; 150:204704. [PMID: 31153210 DOI: 10.1063/1.5083844] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this work, we provide a comparison between the stability and the interfacial structure of micrometer-sized and nanometer-sized droplets by employing a multi-instrumental approach comprised of the surface-sensitive technique of sum frequency scattering as well as dynamic light scattering and microscopy. We monitor the stability of oil-in-water and water-in-oil emulsions and the structure of surfactants at the oil/water nano-interface, when stabilized with an oil-soluble neutral surfactant (Span80), a water-soluble anionic surfactant (sodium dodecyl sulfate, SDS), or with a combination of the two. Micron-sized droplets are found to be stabilized only when a surfactant soluble in the continuous phase is present in the system, in agreement with what is traditionally observed empirically. Surprisingly, the nanodroplets behave differently. Both oil and water nanodroplets can be stabilized by the same (neutral Span80) surfactant but with different surface structures. A combination of SDS and Span80 also suffices, but for the case of water droplets, the strongly amphiphilic SDS molecules are not detected at the interface. For the case of oil droplets, both surfactants are at the interface but do not structurally affect one another. Thus, it appears that, in this study, empirical rules such as the Bancroft rule, the hydrophile-lipophile-balance scale, and the surfactant affinity difference predict the stability of the micrometer-sized droplets better than the nanometer-sized ones, probably due to a different balance of interactions on different length scales.
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Affiliation(s)
- Evangelia Zdrali
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Gianluca Etienne
- Soft Materials Laboratory, Institute of Materials, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nikolay Smolentsev
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Esther Amstad
- Soft Materials Laboratory, Institute of Materials, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Wilhelm MJ, Sharifian Gh M, Dai HL. Influence of molecular structure on passive membrane transport: A case study by second harmonic light scattering. J Chem Phys 2019; 150:104705. [PMID: 30876365 DOI: 10.1063/1.5081720] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present an experimental study, using the surface sensitive technique, second harmonic light scattering (SHS), to examine the influence of structure on the propensity of a molecule to passively diffuse across a phospholipid membrane. Specifically, we monitor the relative tendency of the structurally similar amphiphilic cationic dyes, malachite green (MG) and crystal violet (CV), to transport across membranes in living cells (E. coli) and biomimetic liposomes. Despite having nearly identical molecular structures, molecular weights, cationic charges, and functional groups, MG is of lower overall symmetry and consequently has a symmetry allowed permanent dipole moment, which CV does not. The two molecules showed drastically different interactions with phospholipid membranes. MG is observed to readily cross the hydrophobic interior of the bacterial cytoplasmic membrane. Conversely, CV does not. Furthermore, experiments conducted with biomimetic liposomes, constructed from the total lipid extract of E. coli and containing no proteins, show that while MG is able to diffuse across the liposome membrane, CV does not. These observations indicate that the SHS results measured with bacteria do not result from the functions of efflux pumps, but suggests that MG possesses an innate molecular property (which is absent in CV) that allows it to passively diffuse across the hydrophobic interior of a phospholipid membrane.
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Affiliation(s)
- Michael J Wilhelm
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
| | - Mohammad Sharifian Gh
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
| | - Hai-Lung Dai
- Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, Pennsylvania 19122, USA
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23
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Dedic J, Rocha S, Okur HI, Wittung-Stafshede P, Roke S. Membrane-Protein-Hydration Interaction of α-Synuclein with Anionic Vesicles Probed via Angle-Resolved Second-Harmonic Scattering. J Phys Chem B 2019; 123:1044-1049. [PMID: 30625272 DOI: 10.1021/acs.jpcb.8b11096] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Amyloid formation of the protein α-synuclein promotes neurodegeneration in Parkinson's disease. The normal function of α-synuclein includes synaptic vesicle transport and fusion, and the protein binds strongly to negatively charged vesicles in vitro. Here, we demonstrate that nonresonant angle-resolved second-harmonic scattering detects α-synuclein binding to liposomes through changes in water orientational correlations and can thus be used as a high-accuracy and high-throughput label-free probe of protein-liposome interactions. The obtained results support a binding model in which the N-terminus of α-synuclein adopts an α-helical conformation that lies flat on the vesicle surface while the negatively charged C-terminus remains in solution.
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Affiliation(s)
- Jan Dedic
- Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials Science (IMX), School of Engineering (STI), Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Sandra Rocha
- Department of Biology and Biological Engineering , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Halil I Okur
- Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials Science (IMX), School of Engineering (STI), Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Pernilla Wittung-Stafshede
- Department of Biology and Biological Engineering , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Sylvie Roke
- Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials Science (IMX), School of Engineering (STI), Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
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24
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Kovacik F, Okur HI, Smolentsev N, Scheu R, Roke S. Hydration mediated interfacial transitions on mixed hydrophobic/hydrophilic nanodroplet interfaces. J Chem Phys 2018; 149:234704. [PMID: 30579299 DOI: 10.1063/1.5035161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Interfacial phase transitions are of fundamental importance for climate, industry, and biological processes. In this work, we observe a hydration mediated surface transition in supercooled oil nanodroplets in aqueous solutions using second harmonic and sum frequency scattering techniques. Hexadecane nanodroplets dispersed in water freeze at a temperature of ∼15 °C below the melting point of the bulk alkane liquid. Addition of a trimethylammonium bromide (CXTA+) type surfactant with chain length equal to or longer than that of the alkane causes the bulk oil droplet freezing transition to be preceded by a structural interfacial transition that involves water, oil, and the surfactant. Upon cooling, the water loses some of its orientational order with respect to the surface normal, presumably by reorienting more parallel to the oil interface. This is followed by the surface oil and surfactant alkyl chains losing some of their flexibility, and this chain stretching induces alkyl chain ordering in the bulk of the alkane phase, which is then followed by the bulk transition occurring at a 3 °C lower temperature. This behavior is reminiscent of surface freezing observed in planar tertiary alkane/surfactant/water systems but differs distinctively in that it appears to be induced by the interfacial water and requires only a very small amount of surfactant.
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Affiliation(s)
- Filip Kovacik
- 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
| | - Nikolay Smolentsev
- Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Rüdiger Scheu
- 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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25
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Pullanchery S, Yang T, Cremer PS. Introduction of Positive Charges into Zwitterionic Phospholipid Monolayers Disrupts Water Structure Whereas Negative Charges Enhances It. J Phys Chem B 2018; 122:12260-12270. [DOI: 10.1021/acs.jpcb.8b08476] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Tarun OB, Eremchev MY, Roke S. Interaction of Oil and Lipids in Freestanding Lipid Bilayer Membranes Studied with Label-Free High-Throughput Wide-Field Second-Harmonic Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11305-11310. [PMID: 30157642 DOI: 10.1021/acs.langmuir.8b01790] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interaction of oils and lipids is relevant for membrane biochemistry since the cell uses bilayer membranes, lipid droplets, and oily substances in its metabolic cycle. In addition, a variety of model lipid membrane systems, such as freestanding horizontal membranes and droplet interface bilayers, are made using oil to facilitate membrane monolayer apposition. We characterize the behavior of excess oil inside horizontal freestanding lipid bilayers using different oils, focusing on hexadecane and squalene. Using a combination of second-harmonic (SH) and white-light imaging, we measure how oil redistributes within the membrane bilayer after formation. SH imaging shows that squalene forms a wider annulus compared with hexadecane, suggesting that there is a higher quantity of squalene remaining in the bilayer compared with hexadecane. Excess oil droplets that appear right after membrane formation are tracked with white-light microscopy. Hexadecane droplets move directionally to the edge of the membrane with diffusion constants similar to those of single lipids, whereas squalene oil droplets move randomly with lower diffusion speeds similar to lipid condensed domains and remain trapped in the center of the bilayer for ∼1-3 h. We discuss the observed differences in terms of different coupling mechanisms between the oil and lipid molecules induced by the different chemical structures of the oils.
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Affiliation(s)
- Orly B Tarun
- 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
| | - Maksim Yu Eremchev
- 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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27
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Morphology and structure of ZIF-8 during crystallisation measured by dynamic angle-resolved second harmonic scattering. Nat Commun 2018; 9:3418. [PMID: 30143611 PMCID: PMC6109061 DOI: 10.1038/s41467-018-05713-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 07/03/2018] [Indexed: 11/19/2022] Open
Abstract
Recent developments in nonlinear optical light scattering techniques have opened a window into morphological and structural characteristics for a variety of supramolecular systems. However, for the study of dynamic processes, the current way of measuring is often too slow. Here we present an alternative measurement scheme suitable for following dynamic processes. Fast acquisition times are achieved through Fourier imaging, allowing simultaneous detection at multiple scattering angles for different polarization combinations. This allows us to follow the crystal growth of the metal organic framework ZIF-8 in solution. The angle dependence of the signal provides insight into the growth mechanism by probing the evolution of size, shape and concentration, while polarization analysis yields structural information in terms of point group symmetry. Our findings highlight the potential of dynamic angle-resolved harmonic light scattering to probe crystal growth processes, assembly–disassembly of biological systems, adsorption, transport through membranes and myriad other applications. Angle-resolved monitoring of structure parameters during crystal growth is often slow owing to mechanical movements. Here, the authors use second harmonic scattering and Fourier-plane imaging to dynamically monitor size, shape and concentration of ZIF-8 in situ during the growth process.
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Vezočnik V, Hodnik V, Sitar S, Okur HI, Tušek-Žnidarič M, Lütgebaucks C, Sepčić K, Kogej K, Roke S, Žagar E, Maček P. Kinetically Stable Triglyceride-Based Nanodroplets and Their Interactions with Lipid-Specific Proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8983-8993. [PMID: 29983071 DOI: 10.1021/acs.langmuir.8b02180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding of the interactions between proteins and natural and artificially prepared lipid membrane surfaces and embedded nonpolar cores is important in studies of physiological processes and their pathologies and is applicable to nanotechnologies. In particular, rapidly growing interest in cellular droplets defines the need for simplified biomimetic lipid model systems to overcome in vivo complexity and variability. We present a protocol for the preparation of kinetically stable nanoemulsions with nanodroplets composed of sphingomyelin (SM) and cholesterol (Chol), as amphiphilic surfactants, and trioleoylglycerol (TOG), at various molar ratios. To prepare stable SM/Chol-coated monodisperse lipid nanodroplets, we modified a reverse phase evaporation method and combined it with ultrasonication. Lipid composition, ζ-potential, gyration and hydrodynamic radius, shape, and temporal stability of the lipid nanodroplets were characterized and compared to extruded SM/Chol large unilamellar vesicles. Lipid nanodroplets and large unilamellar vesicles with theoretical SM/Chol/TOG molar ratios of 1/1/4.7 and 4/1/11.7 were further investigated for the orientational order of their interfacial water molecules using a second harmonic scattering technique, and for interactions with the SM-binding and Chol-binding pore-forming toxins equinatoxin II and perfringolysin O, respectively. The surface characteristics (ζ-potential, orientational order of interfacial water molecules) and binding of these proteins to the nanodroplet SM/Chol monolayers were similar to those for the SM/Chol bilayers of the large unilamellar vesicles and SM/Chol Langmuir monolayers, in terms of their surface structures. We propose that such SM/Chol/TOG nanoparticles with the required lipid compositions can serve as experimental models for monolayer membrane to provide a system that imitates the natural lipid droplets.
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Affiliation(s)
- Valerija Vezočnik
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Vesna Hodnik
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Simona Sitar
- Department of Polymer Chemistry and Technology , National Institute of Chemistry , Hajdrihova 19 , Ljubljana 1000 , Slovenia
| | - Halil I Okur
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | | | - Cornelis Lütgebaucks
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | - Kristina Sepčić
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
| | - Ksenija Kogej
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology , University of Ljubljana , Večna pot 113 , Ljubljana 1000 , Slovenia
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institute of Bio-Engineering, and Institute of Material Science, School of Engineering, and Lausanne Centre for Ultrafast Science , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland
| | - Ema Žagar
- Department of Polymer Chemistry and Technology , National Institute of Chemistry , Hajdrihova 19 , Ljubljana 1000 , Slovenia
| | - Peter Maček
- Department of Biology, Biotechnical Faculty , University of Ljubljana , Jamnikarjeva 101 , Ljubljana 1000 , Slovenia
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Abstract
The principles, strengths and limitations of several nonlinear optical (NLO) methods for characterizing biological systems are reviewed. NLO methods encompass a wide range of approaches that can be used for real-time, in-situ characterization of biological systems, typically in a label-free mode. Multiphoton excitation fluorescence (MPEF) is widely used for high-quality imaging based on electronic transitions, but lacks interface specificity. Second harmonic generation (SHG) is a parametric process that has all the virtues of the two-photon version of MPEF, yielding a signal at twice the frequency of the excitation light, which provides interface specificity. Both SHG and MPEF can provide images with high structural contrast, but they typically lack molecular or chemical specificity. Other NLO methods such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) can provide high-sensitivity imaging with chemical information since Raman active vibrations are probed. However, CARS and SRS lack interface and surface specificity. A NLO method that provides both interface/surface specificity as well as molecular specificity is vibrational sum frequency generation (SFG) spectroscopy. Vibration modes that are both Raman and IR active are probed in the SFG process, providing the molecular specificity. SFG, like SHG, is a parametric process, which provides the interface and surface specificity. SFG is typically done in the reflection mode from planar samples. This has yielded rich and detailed information about the molecular structure of biomaterial interfaces and biomolecules interacting with their surfaces. However, 2-D systems have limitations for understanding the interactions of biomolecules and interfaces in the 3-D biological environment. The recent advances made in instrumentation and analysis methods for sum frequency scattering (SFS) now present the opportunity for SFS to be used to directly study biological solutions. By detecting the scattering at angles away from the phase-matched direction even centrosymmetric structures that are isotropic (e.g., spherical nanoparticles functionalized with self-assembled monolayers or biomolecules) can be probed. Often a combination of multiple NLO methods or a combination of a NLO method with other spectroscopic methods is required to obtain a full understanding of the molecular structure and surface chemistry of biomaterials and the biomolecules that interact with them. Using the right combination methods provides a powerful approach for characterizing biological materials.
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30
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Lütgebaucks C, Macias-Romero C, Roke S. Characterization of the interface of binary mixed DOPC:DOPS liposomes in water: The impact of charge condensation. J Chem Phys 2018; 146:044701. [PMID: 28147550 DOI: 10.1063/1.4974084] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Solutions of liposomes composed of binary mixtures of anionic dioleoylphosphatidylserine (DOPS) and zwitterionic dioleoylphosphatidylcholine (DOPC) are investigated with label-free angle-resolved (AR) second harmonic scattering (SHS) and electrophoretic mobility measurements. The membrane surface potential is extracted from the AR-SHS response. The surface potential changes from -10 to -145 mV with varying DOPS content ( from 0% to 100%) and levels off already at ∼ 10 % DOPS content. The ζ-potential shows the same trend but with a drastically lower saturation value (-44 mV). This difference is explained by the formation of a condensed layer of Na+ counterions around the outer leaflet of the liposome as predicted by charge condensation theories for polyelectrolyte systems.
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Affiliation(s)
- 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
| | - Carlos Macias-Romero
- 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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31
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Olenick LL, Troiano JM, Smolentsev N, Ohno PE, Roke S, Geiger FM. Polycation Interactions with Zwitterionic Phospholipid Monolayers on Oil Nanodroplet Suspensions in Water (D2O) Probed by Sum Frequency Scattering. J Phys Chem B 2018; 122:5049-5056. [DOI: 10.1021/acs.jpcb.8b00309] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Laura L. Olenick
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Julianne M. Troiano
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Nikolay Smolentsev
- Laboratory for fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Paul E. Ohno
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Sylvie Roke
- Laboratory for fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Franz M. Geiger
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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32
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Tarun OB, Hannesschläger C, Pohl P, Roke S. Label-free and charge-sensitive dynamic imaging of lipid membrane hydration on millisecond time scales. Proc Natl Acad Sci U S A 2018; 115:4081-4086. [PMID: 29610320 PMCID: PMC5910843 DOI: 10.1073/pnas.1719347115] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Biological membranes are highly dynamic and complex lipid bilayers, responsible for the fate of living cells. To achieve this function, the hydrating environment is crucial. However, membrane imaging typically neglects water, focusing on the insertion of probes, resonant responses of lipids, or the hydrophobic core. Owing to a recent improvement of second-harmonic (SH) imaging throughput by three orders of magnitude, we show here that we can use SH microscopy to follow membrane hydration of freestanding lipid bilayers on millisecond time scales. Instead of using the UV/VIS resonant response of specific membrane-inserted fluorophores to record static SH images over time scales of >1,000 s, we SH imaged symmetric and asymmetric lipid membranes, while varying the ionic strength and pH of the adjacent solutions. We show that the nonresonant SH response of water molecules aligned by charge-dipole interactions with charged lipids can be used as a label-free probe of membrane structure and dynamics. Lipid domain diffusion is imaged label-free by means of the hydration of charged domains. The orientational ordering of water is used to construct electrostatic membrane potential maps. The average membrane potential depends quadratically on an applied external bias, which is modeled by nonlinear optical theory. Spatiotemporal fluctuations on the order of 100-mV changes in the membrane potential are seen. These changes imply that membranes are very dynamic, not only in their structure but also in their membrane potential landscape. This may have important consequences for membrane function, mechanical stability, and protein/pore distributions.
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Affiliation(s)
- Orly B Tarun
- Laboratory for Fundamental BioPhotonics, Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Institute of Materials Science, School of Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland;
- Institute of Materials Science, School of Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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33
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Sanders SE, Vanselous H, Petersen PB. Water at surfaces with tunable surface chemistries. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:113001. [PMID: 29393860 DOI: 10.1088/1361-648x/aaacb5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Aqueous interfaces are ubiquitous in natural environments, spanning atmospheric, geological, oceanographic, and biological systems, as well as in technical applications, such as fuel cells and membrane filtration. Where liquid water terminates at a surface, an interfacial region is formed, which exhibits distinct properties from the bulk aqueous phase. The unique properties of water are governed by the hydrogen-bonded network. The chemical and physical properties of the surface dictate the boundary conditions of the bulk hydrogen-bonded network and thus the interfacial properties of the water and any molecules in that region. Understanding the properties of interfacial water requires systematically characterizing the structure and dynamics of interfacial water as a function of the surface chemistry. In this review, we focus on the use of experimental surface-specific spectroscopic methods to understand the properties of interfacial water as a function of surface chemistry. Investigations of the air-water interface, as well as efforts in tuning the properties of the air-water interface by adding solutes or surfactants, are briefly discussed. Buried aqueous interfaces can be accessed with careful selection of spectroscopic technique and sample configuration, further expanding the range of chemical environments that can be probed, including solid inorganic materials, polymers, and water immiscible liquids. Solid substrates can be finely tuned by functionalization with self-assembled monolayers, polymers, or biomolecules. These variables provide a platform for systematically tuning the chemical nature of the interface and examining the resulting water structure. Finally, time-resolved methods to probe the dynamics of interfacial water are briefly summarized before discussing the current status and future directions in studying the structure and dynamics of interfacial water.
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Affiliation(s)
- Stephanie E Sanders
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States of America
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34
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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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35
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Olenick LL, Chase HM, Fu L, Zhang Y, McGeachy AC, Dogangun M, Walter SR, Wang HF, Geiger FM. Single-component supported lipid bilayers probed using broadband nonlinear optics. Phys Chem Chem Phys 2018; 20:3063-3072. [DOI: 10.1039/c7cp02549a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Broadband SFG spectroscopy is shown to offer considerable advantages over scanning systems in terms of signal-to-noise ratios when probing well-formed single-component supported lipid bilayers formed from zwitterionic lipids with PC headgroups.
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Affiliation(s)
| | | | - Li Fu
- William R. Wiley Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
- Sanofi-Genzyme
| | - Yun Zhang
- William R. Wiley Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
- Institute of Optics and Electronics
| | | | - Merve Dogangun
- Department of Chemistry
- Northwestern University
- Evanston
- USA
| | | | - Hong-fei Wang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
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36
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Zdrali E, Chen Y, Okur HI, Wilkins DM, Roke S. The Molecular Mechanism of Nanodroplet Stability. ACS NANO 2017; 11:12111-12120. [PMID: 29224343 DOI: 10.1021/acsnano.7b05100] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Mixtures of nano- and microscopic oil droplets in water have recently been rediscovered as miniature reaction vessels in microfluidic environments and are important constituents of many environmental systems, food, personal care, and medical products. The oil nanodroplet/water interface stabilized by surfactants determines the physicochemical properties of the droplets. Surfactants are thought to stabilize nanodroplets by forming densely packed monolayers that shield the oil phase from the water. This idea has been inferred from droplet stability measurements in combination with molecular structural data obtained from extended planar interfaces. Here, we present a molecular level investigation of the surface structure and stability of nanodroplets and show that the surface structure of nanodroplets is significantly different from that of extended planar interfaces. Charged surfactants form monolayers that are more than 1 order of magnitude more dilute than geometrically packed ones, and there is no experimental correlation between stability and surfactant surface density. Moreover, dilute negatively charged surfactant monolayers produce more stable nanodroplets than dilute positively charged and dense geometrically packed neutral surfactant monolayers. Droplet stability is found to depend on the relative cooperativity between charge-charge, charge-dipole, and hydrogen-bonding interactions. The difference between extended planar interfaces and nanoscale interfaces stems from a difference in the thermally averaged total charge-charge interactions in the two systems. Low dielectric oil droplets with a size smaller than the Debye length in oil permit repulsive interactions between like charges from opposing interfaces in small droplets. This behavior is generic and extends up to the micrometer length scale.
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Affiliation(s)
- Evangelia Zdrali
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Yixing Chen
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Halil I Okur
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - David M Wilkins
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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37
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Niether D, Kawaguchi T, Hovancová J, Eguchi K, Dhont JKG, Kita R, Wiegand S. Role of Hydrogen Bonding of Cyclodextrin-Drug Complexes Probed by Thermodiffusion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8483-8492. [PMID: 28780866 DOI: 10.1021/acs.langmuir.7b02313] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Temperature gradient-induced migration of biomolecules, known as thermophoresis or thermodiffusion, changes upon ligand binding. In recent years, this effect has been used to determine protein-ligand binding constants. The mechanism through which thermodiffusive properties change when complexes are formed, however, is not understood. An important contribution to thermodiffusive properties originates from the thermal response of hydrogen bonds. Because there is a considerable difference between the degree of solvation of the protein-ligand complex and its isolated components, ligand-binding is accompanied by a significant change in hydration. The aim of the present work is therefore to investigate the role played by hydrogen bonding on the change in thermodiffusive behavior upon ligand-binding. As a model system, we use cyclodextrins (CDs) and acetylsalicylic acid (ASA), where quite a significant change in hydration is expected and where no conformational changes occur when a CD/ASA complex is formed in aqueous solution. Thermophoresis was investigated in the temperature range of 10-50 °C by infrared thermal diffusion forced Rayleigh scattering. Nuclear magnetic resonance measurements were performed at 25 °C to obtain information about the structure of the complexes. All CD/ASA complexes show a stronger affinity toward regions of lower temperature compared to the free CDs. We found that the temperature sensitivity of thermophoresis correlates with the 1-octanol/water partition coefficient. This observation not only establishes the relation between thermodiffusion and degree of hydrogen bonding but also opens the possibility to relate thermodiffusive properties of complexes to their partition coefficient, which cannot be determined otherwise. This concept is especially interesting for protein-ligand complexes where the protein undergoes a conformational change, different from the CD/ASA complexes, giving rise to additional changes in their hydrophilicity.
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Affiliation(s)
- Doreen Niether
- ICS-3 Soft Condensed Matter, Forschungszentrum Jülich GmbH , D-52428 Jülich, Germany
| | | | - Jana Hovancová
- Chemistry Department, Pavol Jozef Šafárik Univerzity , 041 80 Košice, Slovakia
| | | | - Jan K G Dhont
- ICS-3 Soft Condensed Matter, Forschungszentrum Jülich GmbH , D-52428 Jülich, Germany
- Department of Physics, Heinrich-Heine-Universität Düsseldorf , D-40225 Düsseldorf, Germany
| | | | - Simone Wiegand
- ICS-3 Soft Condensed Matter, Forschungszentrum Jülich GmbH , D-52428 Jülich, Germany
- Department für Chemie-Physikalische Chemie, Universität zu Köln , D-50939 Cologne, Germany
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38
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Wah B, Breidigan JM, Adams J, Horbal P, Garg S, Porcar L, Perez-Salas U. Reconciling Differences between Lipid Transfer in Free-Standing and Solid Supported Membranes: A Time-Resolved Small-Angle Neutron Scattering Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3384-3394. [PMID: 28300412 DOI: 10.1021/acs.langmuir.6b04013] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Maintaining compositional lipid gradients across membranes in animal cells is essential to biological function, but what is the energetic cost to maintain these differences? It has long been recognized that studying the passive movement of lipids in membranes can provide insight into this toll. Confusingly the reported values of inter- and, particularly, intra-lipid transport rates of lipids in membranes show significant differences. To overcome this difficulty, biases introduced by experimental approaches have to be identified. The present study addresses the difference in the reported intramembrane transport rates of dimyristoylphosphatidylcholine (DMPC) on flat solid supports (fast flipping) and in curved free-standing membranes (slow flipping). Two possible scenarios are potentially at play: one is the difference in curvature of the membranes studied and the other the presence (or not) of the support. Using DMPC vesicles and DMPC supported membranes on silica nanoparticles of different radii, we found that an increase in curvature (from a diameter of 30 nm to a diameter of 100 nm) does not change the rates significantly, differing only by factors of order ∼1. Additionally, we found that the exchange rates of DMPC in supported membranes are similar to the ones in vesicles. And as previously reported, we found that the activation energies for exchange on free-standing and supported membranes are similar (84 and 78 kJ/mol, respectively). However, DMPC's flip-flop rates increase significantly when in a supported membrane, surpassing the exchange rates and no longer limiting the exchange process. Although the presence of holes or cracks in supported membranes explains the occurrence of fast lipid flip-flop in many studies, in defect-free supported membranes we find that fast flip-flop is driven by the surface's induced disorder of the bilayer's acyl chain packing as evidenced from their broad melting temperature behavior.
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Affiliation(s)
- Benny Wah
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | - Jeffrey M Breidigan
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | - Joseph Adams
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | - Piotr Horbal
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | - Sumit Garg
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
| | - Lionel Porcar
- Large Scale Structure Group, Institut Laue-Langevin , Grenoble F-38042, France
- Department of Chemical Engineering, Colburn Laboratory, University of Delaware , Newark, Delaware 19716, United States
| | - Ursula Perez-Salas
- Physics Department, University of Illinois at Chicago , Chicago, Illinois 60607, United States
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
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39
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Okur HI, Chen Y, Smolentsev N, Zdrali E, Roke S. Interfacial Structure and Hydration of 3D Lipid Monolayers in Aqueous Solution. J Phys Chem B 2017; 121:2808-2813. [DOI: 10.1021/acs.jpcb.7b00609] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Halil I. Okur
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Yixing Chen
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nikolay Smolentsev
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Evangelia Zdrali
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental
BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute
of Materials Science (IMX), School of Engineering (STI), and Lausanne
Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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40
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Eicher B, Heberle FA, Marquardt D, Rechberger GN, Katsaras J, Pabst G. Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles. J Appl Crystallogr 2017; 50:419-429. [PMID: 28381971 PMCID: PMC5377341 DOI: 10.1107/s1600576717000656] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/12/2017] [Indexed: 11/10/2022] Open
Abstract
Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effort but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ∼120 nm diameter palmitoyl-oleoyl phosphatidyl-choline (POPC) vesicles, compared to the inner leaflet. Analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K, i.e. above the melting transition temperature of the two lipids.
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Affiliation(s)
- Barbara Eicher
- Instiute of Molecular Biosciences, Biophysics Division, University of Graz, Austria; BioTechMed-Graz, Graz, 8010, Austria
| | - Frederick A Heberle
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, USA; Joint Institute for Biological Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Drew Marquardt
- Instiute of Molecular Biosciences, Biophysics Division, University of Graz, Austria; BioTechMed-Graz, Graz, 8010, Austria
| | - Gerald N Rechberger
- Instiute of Molecular Biosciences, University of Graz, Austria; Omics-Center Graz, BioTechMed-Graz, Austria
| | - John Katsaras
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Georg Pabst
- Instiute of Molecular Biosciences, Biophysics Division, University of Graz, Austria; BioTechMed-Graz, Graz, 8010, Austria
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41
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Sun HY, Deng G, Jiang YW, Zhou Y, Xu J, Wu FG, Yu ZW. Controllable engineering of asymmetric phosphatidylserine-containing lipid vesicles using calcium cations. Chem Commun (Camb) 2017; 53:12762-12765. [DOI: 10.1039/c7cc05114j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The presence of Ca2+ significantly increases the flip rate of DOPS lipid molecules due to the local membrane curvature.
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Affiliation(s)
- Hai-Yuan Sun
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Geng Deng
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Yao-Wen Jiang
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- P. R. China
| | - Yu Zhou
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Jing Xu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Fu-Gen Wu
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- P. R. China
| | - Zhi-Wu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
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42
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Tocci G, Liang C, Wilkins DM, Roke S, Ceriotti M. Second-Harmonic Scattering as a Probe of Structural Correlations in Liquids. J Phys Chem Lett 2016; 7:4311-4316. [PMID: 27726403 DOI: 10.1021/acs.jpclett.6b01851] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Second-harmonic scattering experiments of water and other bulk molecular liquids have long been assumed to be insensitive to interactions between the molecules. The measured intensity is generally thought to arise from incoherent scattering due to individual molecules. We introduce a method to compute the second-harmonic scattering pattern of molecular liquids directly from atomistic computer simulations, which takes into account the coherent terms. We apply this approach to large-scale molecular dynamics simulations of liquid water, where we show that nanosecond second-harmonic scattering experiments contain a coherent contribution arising from radial and angular correlations on a length scale of ≲1 nm, much shorter than had been recently hypothesized ( Shelton , D. P. J. Chem. Phys. 2014 , 141 ). By combining structural correlations from simulations with experimental data ( Shelton , D. P. J. Chem. Phys. 2014 , 141 ), we can also extract an effective molecular hyperpolarizability in the liquid phase. This work demonstrates that second-harmonic scattering experiments and atomistic simulations can be used in synergy to investigate the structure of complex liquids, solutions, and biomembranes, including the intrinsic intermolecular correlations.
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Affiliation(s)
- Gabriele Tocci
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Chungwen Liang
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - David M Wilkins
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics, Institutes of Bioengineering and Materials Science and Engineering, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Michele Ceriotti
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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de Beer AGF, Roke S. What interactions can distort the orientational distribution of interfacial water molecules as probed by second harmonic and sum frequency generation? J Chem Phys 2016; 145:044705. [DOI: 10.1063/1.4959033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alex G. F. de Beer
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), 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), 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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