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Polita AR, Bagdonaitė RT, Shivabalan AP, Valinčius G. Influence of Simvastatin and Pravastatin on the Biophysical Properties of Model Lipid Bilayers and Plasma Membranes of Live Cells. ACS Biomater Sci Eng 2024; 10:5714-5722. [PMID: 39180473 PMCID: PMC11388144 DOI: 10.1021/acsbiomaterials.4c00911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2024]
Abstract
Statins are among the most widely used drugs for the inhibition of cholesterol biosynthesis, prevention of cardiovascular diseases, and treatment of hypercholesterolemia. Additionally, statins also exhibit cholesterol-independent benefits in various diseases, including neuroprotective properties in Alzheimer's disease, anti-inflammatory effects in coronary artery disease, and antiproliferative activities in cancer, which likely result from the statins' interaction and alteration of lipid bilayers. However, the membrane-modulatory effects of statins and the mechanisms by which statins alter lipid bilayers remain poorly understood. In this work, we explore the membrane-modulating effects of statins on model lipid bilayers and live cells. Through the use of fluorescence lifetime imaging microscopy (FLIM) combined with viscosity-sensitive environmental probes, we demonstrate that hydrophobic, but not hydrophilic, statins are capable of changing the microviscosity and lipid order in model and live cell membranes. Furthermore, we show that hydrophobic simvastatin is capable of forming nanoscale cholesterol-rich domains and homogenizing the cholesterol concentrations in lipid bilayers. Our results provide a mechanistic framework for understanding the bimodal effects of simvastatin on the lipid order and the lateral organization of cholesterol in lipid bilayers. Finally, we demonstrate that simvastatin temporarily decreases the microviscosity of live cell plasma membranes, making them more permeable and increasing the level of intracellular chemotherapeutic drug accumulation.
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Affiliation(s)
- Artu Ras Polita
- Department of Biospectroscopy and bioelectrochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Ru Ta Bagdonaitė
- Department of Biospectroscopy and bioelectrochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Arun Prabha Shivabalan
- Department of Biospectroscopy and bioelectrochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Gintaras Valinčius
- Department of Biospectroscopy and bioelectrochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
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2
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Su Z, Chen A, Lipkowski J. Electrochemical and Infrared Studies of a Model Bilayer of the Outer Membrane of Gram-Negative Bacteria and its Interaction with polymyxin─the Last-Resort Antibiotic. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:8248-8259. [PMID: 38578277 DOI: 10.1021/acs.langmuir.4c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
A model bilayer of the outer membrane (OM) of Gram-negative bacteria, composed of lipid A and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), was assembled on the β-Tg modified gold (111) single crystal surface using a combination of Langmuir-Blodgett and Langmuir-Schaefer transfer. Electrochemical and spectroscopic methods were employed to study the properties of the model bilayer and its interaction with polymyxin. The model bilayer is stable on the gold surface in the transmembrane potential region between 0.0 and -0.7 V. The presence of Mg2+ coordinates with the phosphate and carboxylate groups in the leaflet of lipid A and stabilizes the structure of the model bilayer. Polymyxin causes the model bilayer leakage and damage in the transmembrane potential region between 0.2 and -0.4 V. At transmembrane potentials lower than -0.5 V, polymyxin does not affect the membrane integrity. Polymyxin binds to the phosphate and carboxylate groups in lipid A molecules and causes the increase of the tilt angle of acyl chains and the decrease of the tilt of the C═O bond. The results in this paper indicate that the antimicrobial activity of polymyxin depends on the transmembrane potential at the model bilayer and provides useful information for the development of new antibiotics.
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Affiliation(s)
- ZhangFei Su
- Electrochemical Technology Center, Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Aicheng Chen
- Electrochemical Technology Center, Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jacek Lipkowski
- Electrochemical Technology Center, Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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3
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Tan SW, Yoon BK, Jackman JA. Membrane-Disruptive Effects of Fatty Acid and Monoglyceride Mitigants on E. coli Bacteria-Derived Tethered Lipid Bilayers. Molecules 2024; 29:237. [PMID: 38202820 PMCID: PMC10780109 DOI: 10.3390/molecules29010237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 12/23/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
We report electrochemical impedance spectroscopy measurements to characterize the membrane-disruptive properties of medium-chain fatty acid and monoglyceride mitigants interacting with tethered bilayer lipid membrane (tBLM) platforms composed of E. coli bacterial lipid extracts. The tested mitigants included capric acid (CA) and monocaprin (MC) with 10-carbon long hydrocarbon chains, and lauric acid (LA) and glycerol monolaurate (GML) with 12-carbon long hydrocarbon chains. All four mitigants disrupted E. coli tBLM platforms above their respective critical micelle concentration (CMC) values; however, there were marked differences in the extent of membrane disruption. In general, CA and MC caused larger changes in ionic permeability and structural damage, whereas the membrane-disruptive effects of LA and GML were appreciably smaller. Importantly, the distinct magnitudes of permeability changes agreed well with the known antibacterial activity levels of the different mitigants against E. coli, whereby CA and MC are inhibitory and LA and GML are non-inhibitory. Mechanistic insights obtained from the EIS data help to rationalize why CA and MC are more effective than LA and GML at disrupting E. coli membranes, and these measurement capabilities support the potential of utilizing bacterial lipid-derived tethered lipid bilayers for predictive assessment of antibacterial drug candidates and mitigants.
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Affiliation(s)
- Sue Woon Tan
- School of Chemical Engineering and Translational Nanobioscience Research Center, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Bo Kyeong Yoon
- School of Healthcare and Biomedical Engineering, Chonnam National University, Yeosu 59626, Republic of Korea
| | - Joshua A. Jackman
- School of Chemical Engineering and Translational Nanobioscience Research Center, Sungkyunkwan University, Suwon 16419, Republic of Korea
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4
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Dziubak D, Sęk S. Sparsely tethered bilayer lipid membranes formed by self-assembly of bicelles: Spectroelectrochemical characterization and incorporation of transmembrane protein. Bioelectrochemistry 2023; 153:108482. [PMID: 37271008 DOI: 10.1016/j.bioelechem.2023.108482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/17/2023] [Accepted: 05/26/2023] [Indexed: 06/06/2023]
Abstract
Many biochemical processes related to proper homeostasis take place in cell membranes. The key molecules involved in these processes are proteins, including transmembrane proteins. These macromolecules still challenge the understanding of their function within the membrane. Biomimetic models that mimic the properties of the cell membrane can help understand their functionality. Unfortunately, preserving the native protein structure in such systems is problematic. A possible solution to this problem involves the use of bicelles. Their unique properties make integrating bicelles with transmembrane proteins manageable while preserving their native structure. Hitherto, bicelles have not been used as precursors for protein-hosting lipid membranes deposited on solid substrates like pre-modified gold. Here, we demonstrated that bicelles can be self-assembled to form sparsely tethered bilayer lipid membranes and the properties of the resulting membrane satisfy the conditions suitable for transmembrane protein insertion. We showed that the incorporation of α-hemolysin toxin in the lipid membrane leads to a decrease in membrane resistance due to pore formation. Simultaneously, the insertion of the protein causes a drop in the capacitance of the membrane-modified electrode, which can be explained by the dehydration of the polar region of the lipid bilayer and the loss of water from the submembrane region.
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Affiliation(s)
- Damian Dziubak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
| | - Sławomir Sęk
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland.
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5
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Péter L, Tsirlina G. Electrochemical traditions in Eastern Europe. J Solid State Electrochem 2023; 27:1-6. [PMID: 37363393 PMCID: PMC10264217 DOI: 10.1007/s10008-023-05528-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 06/28/2023]
Affiliation(s)
- László Péter
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Konkoly-Thege út 29-33, Budapest, 1121 Hungary
| | - Galina Tsirlina
- Department of Electrochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 1130 Rue de la Piscine, Domaine Universitaire, Gières, 38610 France
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6
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Stefanowska A, Koprowski P, Bednarczyk P, Szewczyk A, Krysinski P. Electrochemical studies of the mitochondrial ROMK2 potassium channel activity reconstituted into the free-standing and tethered bilayer lipid membranes. Bioelectrochemistry 2023; 151:108372. [PMID: 36680942 DOI: 10.1016/j.bioelechem.2023.108372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023]
Abstract
The renal-outer-medullary‑potassium (ROMK2) channel modulates potassium transport in the kidney. It has been postulated that the ROMK2 is the pore-forming subunit of the mitochondrial ATP-sensitive potassium channel as a mediator of cardioprotection. In this study, cell-free synthesis of the ROMK2 was performed in presence of membrane scaffold protein (MSP1D1) nanodiscs. Activity measurements were achieved after channel reconstitution into the planar lipid bilayer and tethered bilayer lipid membranes. Both methods allowed for monitoring of channel function, verified with channel blocking and activation/re-activation experiments. The primary function of the mitochondrial potassium channels is to regulate the potential of the mitochondrial membrane, which allows them to play an important role in cytoprotection. This work focuses on obtaining the ROMK2 using a cell-free expression system, followed by the incorporation of the channel protein into the lipid bilayer and studying the influence of voltage changes and molecular modulators on channel activity. Channel activity was measured after its reconstitution into two models of lipid bilayers - BLM (Bilayer Lipid Membrane) and tBLM (Tethered Bilayer Lipid Membrane) deposited on a solid gold electrode. These two model membranes and electrochemical measurements made it possible to measure the flux of K+ ions in the presence of channel modulators.
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Affiliation(s)
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteur str. 3, Warsaw 02-093, Poland
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Warsaw University of Life Sciences (SGGW), Warsaw 02-78, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteur str. 3, Warsaw 02-093, Poland
| | - Pawel Krysinski
- Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland.
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7
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Andersson J, Kleinheinz D, Ramach U, Kiesenhofer N, Ashenden A, Valtiner M, Holt S, Koeper I, Schmidpeter PAM, Knoll W. Native Function of the Bacterial Ion Channel SthK in a Sparsely Tethered Lipid Bilayer Membrane Architecture. J Phys Chem B 2023; 127:3641-3650. [PMID: 37072125 PMCID: PMC10150356 DOI: 10.1021/acs.jpcb.2c07252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
The plasma membrane protects the interiors of cells from their surroundings and also plays a critical role in communication, sensing, and nutrient import. As a result, the cell membrane and its constituents are among the most important drug targets. Studying the cell membrane and the processes it facilitates is therefore crucial, but it is a highly complex environment that is difficult to access experimentally. Various model membrane systems have been developed to provide an environment in which membrane proteins can be studied in isolation. Among them, tethered bilayer lipid membranes (tBLMs) are a promising model system providing a solvent-free membrane environment which can be prepared by self-assembly, is resistant to mechanical disturbances and has a high electrical resistance. tBLMs are therefore uniquely suitable to study ion channels and charge transport processes. However, ion channels are often large, complex, multimeric structures and their function requires a particular lipid environment. In this paper, we show that SthK, a bacterial cyclic nucleotide gated (CNG) ion channel that is strongly dependent on the surrounding lipid composition, functions normally when embedded into a sparsely tethered lipid bilayer. As SthK has been very well characterized in terms of structure and function, it is well-suited to demonstrate the utility of tethered membrane systems. A model membrane system suitable for studying CNG ion channels would be useful, as this type of ion channel performs a wide range of physiological functions in bacteria, plants, and mammals and is therefore of fundamental scientific interest as well as being highly relevant to medicine.
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Affiliation(s)
- Jakob Andersson
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
| | - David Kleinheinz
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
| | - Ulrich Ramach
- Technische Universität Wien, Wiedner Hauptstr. 8-10/134, 1040 Wien, Austria
- CEST Kompetenzzentrum für Oberflächentechnologie, Viktor Kaplan-Straße 2, 2700 Wiener Neustadt, Austria
| | | | - Alex Ashenden
- Flinders University of South Australia, Bedford Park SA, 5042 Adelaide, Australia
| | - Markus Valtiner
- Technische Universität Wien, Wiedner Hauptstr. 8-10/134, 1040 Wien, Austria
- CEST Kompetenzzentrum für Oberflächentechnologie, Viktor Kaplan-Straße 2, 2700 Wiener Neustadt, Austria
| | - Stephen Holt
- Australian Nuclear Science and Technology Organization, New Illawarra Rd, Lucas Heights, NSW 2234, Australia
| | - Ingo Koeper
- Flinders University of South Australia, Bedford Park SA, 5042 Adelaide, Australia
| | - Philipp A M Schmidpeter
- Weill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, New York 10065, United States
| | - Wolfgang Knoll
- Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
- Danube Private University, Steiner Landstraße 124, 3500 Krems an der Donau, Austria
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8
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Lee S, Chung M. DNA-Tethered Lipid Membrane Formation via Solvent-Assisted Self-Assembly. J Phys Chem B 2023; 127:1350-1356. [PMID: 36733188 DOI: 10.1021/acs.jpcb.2c07978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
DNA-tethered lipid bilayers have been used in many studies, based on the controllable and well-defined properties of DNA tethers. However, their application has been limited, because it is difficult to cover a wide range of surfaces and achieve electrical insulation. We implemented an existing method, where a DNA hybrid chip on a silica or glass surface supports a lipid membrane using solvent-assisted self-assembly. The formation of a continuous lipid bilayer was confirmed through the change in quartz crystal microbalance dissipation results, depending on the presence or absence of DNA hybrids. The fluidity of the DNA-tethered lipid membranes was analyzed using a fluorescence microscope. The electrochemical analysis demonstrated the versatility of this new technique, which can be used for sensor or electrode surface modification for biosensors or bioelectronics.
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Affiliation(s)
- Sangmin Lee
- Department of Chemical Engineering, Hongik University, Mapo-gu, Seoul 04066, Republic of Korea
| | - Minsub Chung
- Department of Chemical Engineering, Hongik University, Mapo-gu, Seoul 04066, Republic of Korea
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9
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Su Z, Leitch JJ, Lipkowski J. Effect of Lipid Composition on the Inhibition Mechanism of Amiloride on Alamethicin Ion Channels in Supported Phospholipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8398-8406. [PMID: 35749587 DOI: 10.1021/acs.langmuir.2c00953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The inhibition effect of amiloride on alamethicin ion channels was studied in a model zwitterionic floating bilayer lipid membrane (fBLM). The EIS studies indicated that amiloride prevents the transport of ions through the alamethicin channels leading to an overall increase in membrane resistance. The PM-IRRAS data demonstrated that amiloride has no influence on the secondary structure of alamethicin but restricts the insertion of the peptides into the bilayer and blocks ion transport through preformed alamethicin channels. The effect of amiloride on ion channel formation in the floating bilayer formed by a zwitterionic lipid was compared to those of previous studies involving negatively charged fBLMs and tethered zwitterionic lipid bilayers. The findings from these studies show that the effects of amiloride on ion channel formation strongly depend on the mobility and charge of the membrane lipids.
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Affiliation(s)
- ZhangFei Su
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - J Jay Leitch
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jacek Lipkowski
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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10
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Hussein EA, Rice B, White RJ. Recent advances in ion-channel probes for nanopore sensing: Insights into the probe architectures. Anal Chim Acta 2022; 1224:340162. [DOI: 10.1016/j.aca.2022.340162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/05/2022] [Accepted: 07/08/2022] [Indexed: 11/01/2022]
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11
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Yudovich S, Marzouqe A, Kantorovitsch J, Teblum E, Chen T, Enderlein J, Miller EW, Weiss S. Electrically Controlling and Optically Observing the Membrane Potential of Supported Lipid Bilayers. Biophys J 2022; 121:2624-2637. [PMID: 35619563 DOI: 10.1016/j.bpj.2022.05.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 11/02/2022] Open
Abstract
Supported lipid bilayers are a well-developed model system for the study of membranes and their associated proteins, such as membrane channels, enzymes, and receptors. These versatile model membranes can be made from various components, ranging from simple synthetic phospholipids to complex mixtures of constituents, mimicking the cell membrane with its relevant physiochemical and molecular phenomena. In addition, the high stability of supported lipid bilayers allows for their study via a wide array of experimental probes. In this work, we describe a platform for supported lipid bilayers that is accessible both electrically and optically, and demonstrate direct optical observation of the transmembrane potential of supported lipid bilayers. We show that the polarization of the supported membrane can be electrically controlled and optically probed using voltage-sensitive dyes. Membrane polarization dynamics is understood through electrochemical impedance spectroscopy and the analysis of an equivalent electrical circuit model. In addition, we describe the effect of the conducting electrode layer on the fluorescence of the optical probe through metal-induced energy transfer, and show that while this energy transfer has an adverse effect on the voltage sensitivity of the fluorescent probe, its strong distance dependency allows for axial localization of fluorescent emitters with ultrahigh accuracy. We conclude with a discussion on possible applications of this platform for the study of voltage-dependent membrane proteins and other processes in membrane biology and surface science.
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Affiliation(s)
- Shimon Yudovich
- Department of Physics, Bar-Ilan University, Ramat-Gan, 52900, Israel; Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel.
| | - Adan Marzouqe
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel; Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Joseph Kantorovitsch
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Eti Teblum
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Tao Chen
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany
| | - Jörg Enderlein
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, Germany
| | - Evan W Miller
- Departments of Chemistry, Molecular & Cell Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Shimon Weiss
- Department of Physics, Bar-Ilan University, Ramat-Gan, 52900, Israel; Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel; Departments of Chemistry and Biochemistry, Physiology, and California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA 90095.
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12
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Ambrulevičius F, Valinčius G. Electrochemical impedance spectrum reveals structural details of distribution of pores and defects in supported phospholipid bilayers. Bioelectrochemistry 2022; 146:108092. [DOI: 10.1016/j.bioelechem.2022.108092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/23/2022] [Accepted: 02/26/2022] [Indexed: 11/15/2022]
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13
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Budvytyte R, Ambrulevičius F, Jankaityte E, Valincius G. Electrochemical Assessment of Dielectric Damage to Phospholipid Bilayers by Amyloid β-Oligomers. Bioelectrochemistry 2022; 145:108091. [DOI: 10.1016/j.bioelechem.2022.108091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/02/2022]
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14
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AI-based atomic force microscopy image analysis allows to predict electrochemical impedance spectra of defects in tethered bilayer membranes. Sci Rep 2022; 12:1127. [PMID: 35064137 PMCID: PMC8783026 DOI: 10.1038/s41598-022-04853-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/24/2021] [Indexed: 01/08/2023] Open
Abstract
Atomic force microscopy (AFM) image analysis of supported bilayers, such as tethered bilayer membranes (tBLMs) can reveal the nature of the membrane damage by pore-forming proteins and predict the electrochemical impedance spectroscopy (EIS) response of such objects. However, automated analysis involving pore detection in such images is often non-trivial and can require AI-based object detection techniques. The specific object-detection algorithm we used to determine the defect coordinates in real AFM images was a convolutional neural network (CNN). Defect coordinates allow to predict the EIS response of tBLMs populated by the pore-forming toxins using finite element analysis (FEA) modeling. We tested if the accuracy of the CNN algorithm affected the EIS spectral features sensitive to defect densities and other physical parameters of tBLMs. We found that the EIS spectra can be predicted sufficiently well, however, systematic errors of characteristic spectral points were observed and need to be taken into account. Importantly, the comparison of predicted EIS curves with experimental ones allowed to estimate important physical parameters of tBLMs such as the specific resistance of submembrane reservoir. This reservoir separates phospholipid bilayer from the solid support. We found that the specific resistance of the reservoir amounts to \documentclass[12pt]{minimal}
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\begin{document}$$\Omega \cdot cm$$\end{document}Ω·cm which is approximately two orders of a magnitude higher compared to the specific resistance of the buffer bathing tBLMs studied in this work. We hypothesize that such effect may be related in part due to decreased concentration of ionic carriers in the submembrane due to decreased relative dielectric permittivity in this region.
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15
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Bilewicz R, Wieckowska A, Jablonowska E, Dzwonek M, Jaskolowski M. Tailored lipid monolayers doped with gold nanoclusters: surface studies and electrochemistry of hybrid‐film‐covered electrodes. ChemElectroChem 2022. [DOI: 10.1002/celc.202101367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Renata Bilewicz
- Uniwersytet Warszawski Faculty of Chemistry Pasteura 1 02-093 Warsaw POLAND
| | | | | | - Maciej Dzwonek
- University of Warsaw: Uniwersytet Warszawski Chemistry POLAND
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16
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Penkauskas T, Ambrulevičius F, Valinčius G. Electrochemical Impedance Spectroscopy as a Convenient Tool to Characterize Tethered Bilayer Membranes. Methods Mol Biol 2022; 2402:31-59. [PMID: 34854034 DOI: 10.1007/978-1-0716-1843-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this paper, we describe the application of electrochemical impedance spectroscopy (EIS) to characterize process of formation and properties of solid-supported tethered bilayer membranes on solid conducting substrates. Along with the description of experimental procedures to prepare substrates and self-assembly of phospholipid bilayers onto gold-coated glass slides, we describe the detailed protocols of EIS measurements. We demonstrate the utility of EIS in the evaluation of the properties of both molecular anchor layers used to immobilize tBLMs as well as characterization of tBLMs. We show that the EIS methodology extends the applicability of this technique well beyond the mere evaluation of electric parameters. Specifically, we demonstrate how by using EIS one may evaluate both density and size of water-filled defects (ion-channels) in tBLMs, to determine the structural mode (homogeneous, heterogeneous, or clustered) of distribution of defects in tBLMs. Our methodology can be applied in both basic protein membrane interaction studies, as well as in the development of precision biosensoric systems with tBLMs as a sensing element.
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Affiliation(s)
- Tadas Penkauskas
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Filipas Ambrulevičius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Gintaras Valinčius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
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17
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Guidelli R, Becucci L. Functional activity of peptide ion channels in tethered bilayer lipid membranes: Review. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rolando Guidelli
- Department of Chemistry University of Florence Sesto Fiorentino Firenze Italy
| | - Lucia Becucci
- Ministero dell'Istruzione Scuola Media “Guglielmo Marconi” San Giovanni Valdarno Arezzo Italy
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David M, Budziak-Wieczorek I, Karcz D, Florescu M, Matwijczuk A. Insight into dual fluorescence effects induced by molecular aggregation occurring in membrane model systems containing 1,3,4-thiadiazole derivatives. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:1083-1101. [PMID: 34515830 PMCID: PMC8566415 DOI: 10.1007/s00249-021-01569-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 05/23/2021] [Accepted: 06/02/2021] [Indexed: 11/27/2022]
Abstract
This work reports on biophysical insights into the excited state intramolecular proton transfer (ESIPT) processes taking place in three 1,3,4-thiadiazole derivatives that served as model compounds, on which electronic absorption, fluorescence, Fourier-transform infrared spectroscopy (FTIR), surface plasmon resonance (SPR) and electrochemical impedance spectroscopy (EIS) studies were performed. The fluorescence spectra recorded in various solvents revealed an interesting dual fluorescence effect. In molecules in their monomeric form, the effect is associated with the ESIPT phenomenon, and may be further enhanced by aggregation-related effects, such as aggregation-induced emissions. Other spectroscopic studies on the selected molecules in a liposomal medium as a model revealed that, in a biomimetic environment, they can exist in both monomeric and aggregated forms. In both cases, however, the effects observed are closely related to the lipid's main phase transition temperature and the structure of the molecule. Introduction of specific substituents to the phenyl moiety either allows or prevents proton transfer from occurring in the excited state. The hydrophobicity changes in a lipid environment may result in an emergence of specific molecular forms and therefore either facilitate or hinder ESIPT processes. SPR and EIS confirmed the significant hydrophobicity changes in the model lipid systems, while FTIR measurements revealed a notable influence of 1,3,4-thiadiazoles on the fluidity of liposomal membranes. The results obtained clearly show that the thiadiazole derivatives are very good model molecules for studying hydrophobic-hydrophilic environments, and particularly with polymers or liposomes used as drug delivery systems.
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Affiliation(s)
- Melinda David
- Faculty of Medicine, Transilvania University of Brașov, 500019, Brașov, Romania
| | | | - Dariusz Karcz
- Department of Chemical Technology and Environmental Analytics (C1), Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24, 31-155, Kraków, Poland
| | - Monica Florescu
- Faculty of Medicine, Transilvania University of Brașov, 500019, Brașov, Romania.
| | - Arkadiusz Matwijczuk
- Department of Biophysics, University of Life Sciences in Lublin, Lublin, Poland.
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The Impact of an Anchoring Layer on the Formation of Tethered Bilayer Lipid Membranes on Silver Substrates. Molecules 2021; 26:molecules26226878. [PMID: 34833969 PMCID: PMC8624891 DOI: 10.3390/molecules26226878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 12/05/2022] Open
Abstract
Tethered bilayer lipid membranes (tBLMs) have been known as stable and versatile experimental platforms for protein–membrane interaction studies. In this work, the assembly of functional tBLMs on silver substrates and the effect of the molecular chain-length of backfiller molecules on their properties were investigated. The following backfillers 3-mercapto-1-propanol (3M1P), 4-mercapto-1-butanol (4M1B), 6-mercapto-1-hexanol (6M1H), and 9-mercapto-1-nonanol (9M1N) mixed with the molecular anchor WC14 (20-tetradecyloxy-3,6,9,12,15,18,22 heptaoxahexatricontane-1-thiol) were used to form self-assembled monolayers (SAMs) on silver, which influenced a fusion of multilamellar vesicles and the formation of tBLMs. Spectroscopic analysis by SERS and RAIRS has shown that by using different-length backfiller molecules, it is possible to control WC14 anchor molecules orientation on the surface. An introduction of increasingly longer surface backfillers in the mixed SAM may be related to the increasing SAMs molecular order and more vertical orientation of WC14 at both the hydrophilic ethylenoxide segment and the hydrophobic lipid bilayer anchoring alkane chains. Since no clustering of WC14 alkane chains, which is deleterious for tBLM integrity, was observed on dry samples, the suitability of mixed-component SAMs for subsequent tBLM formation was further interrogated by electrochemical impedance spectroscopy (EIS). EIS showed the arrangement of well-insulating tBLMs if 3M1P was used as a backfiller. An increase in the length of the backfiller led to increased defectiveness of tBLMs. Despite variable defectiveness, all tBLMs responded to the pore-forming cholesterol-dependent cytolysin, vaginolysin in a manner consistent with the functional reconstitution of the toxin into phospholipid bilayer. This experiment demonstrates the biological relevance of tBLMs assembled on silver surfaces and indicates their utility as biosensing elements for the detection of pore-forming toxins in liquid samples.
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20
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Zaborowska M, Dziubak D, Matyszewska D, Sek S, Bilewicz R. Designing a Useful Lipid Raft Model Membrane for Electrochemical and Surface Analytical Studies. Molecules 2021; 26:5483. [PMID: 34576954 PMCID: PMC8467995 DOI: 10.3390/molecules26185483] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 12/04/2022] Open
Abstract
A model biomimetic system for the study of protein reconstitution or drug interactions should include lipid rafts in the mixed lipid monolayer, since they are usually the domains embedding membrane proteins and peptides. Four model lipid films composed of three components: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), cholesterol (Chol) and sphingomyelin (SM) mixed in different molar ratios were proposed and investigated using surface pressure measurements and thermodynamic analysis of the monolayers at the air-water interface and imaged by Brewster angle microscopy. The ternary monolayers were transferred from the air-water onto the gold electrodes to form bilayer films and were studied for the first time by electrochemical methods: alternative current voltammetry and electrochemical impedance spectroscopy and imaged by atomic force microscopy. In excess of DOPC, the ternary systems remained too liquid for the raft region to be stable, while in the excess of cholesterol the layers were too solid. The layers with SM in excess lead to the formation of Chol:SM complexes but the amount of the fluid matrix was very low. The equimolar content of the three components lead to the formation of a stable and well-organized assembly with well-developed raft microdomains of larger thickness, surrounded by the more fluid part of the bilayer. The latter is proposed as a convenient raft model membrane for further physicochemical studies of interactions with drugs or pollutants or incorporation of membrane proteins.
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Affiliation(s)
| | - Damian Dziubak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland; (D.D.); (S.S.)
| | - Dorota Matyszewska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland; (D.D.); (S.S.)
| | - Slawomir Sek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland; (D.D.); (S.S.)
| | - Renata Bilewicz
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02093 Warsaw, Poland;
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21
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22
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Su Z, Leitch JJ, Sek S, Lipkowski J. Ion-Pairing Mechanism for the Valinomycin-Mediated Transport of Potassium Ions across Phospholipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9613-9621. [PMID: 34323494 DOI: 10.1021/acs.langmuir.1c01500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The role of the anion on the ionophore properties of valinomycin was studied in a model floating bilayer lipid membrane (fBLM) using supporting electrolytes containing K+ with four different counter anion species (ClO4-, H2PO4-, Cl-, and F-). The electrochemical impedance spectra indicate that the membrane resistance of the bilayer decreases with the decrease of Gibbs free energy of anion solvation. The IR spectra demonstrate that valinomycin does not readily bind to K+ in the KH2PO4, KCl, and KF electrolyte solutions, but in the presence of KClO4, valinomycin readily binds to K+, forming a valinomycin-K+ complex. The results in the present paper reveal the role of the counter anion on the transport of cations by valinomycin across the lipid bilayer. The valinomycin-cation complex creates an ion pair with the anion, and this ion pair can enter the hydrophobic region of the bilayer transporting the cation across the membrane. Anions with low solvation energies facilitate the formation of the ion pair improving the ion conductivity of valinomycin-incorporated bilayers. This paper sheds new light on the transport mechanism of valinomycin ionophores and provides new information about the bioactivity of this molecule.
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Affiliation(s)
- ZhangFei Su
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - J Jay Leitch
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Slawomir Sek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Jacek Lipkowski
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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23
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Zaborowska M, Dziubak D, Matyszewska D, Bilewicz R. Surface and electrochemical properties of lipid raft model membranes and how they are affected by incorporation of statin. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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24
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Silin VI, Hoogerheide DP. pH dependent electrical properties of the inner- and outer- leaflets of biomimetic cell membranes. J Colloid Interface Sci 2021; 594:279-289. [PMID: 33765647 DOI: 10.1016/j.jcis.2021.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/16/2021] [Accepted: 03/03/2021] [Indexed: 10/21/2022]
Abstract
Composition and asymmetry of lipid membranes provide a means for regulation of trans-membrane permeability of ions and small molecules. The pH dependence of these processes plays an important role in the functioning and survival of cells. In this work, we study the pH dependence of membrane electrical resistance and capacitance using electrochemical impedance spectroscopy (EIS), surface plasmon resonance (SPR) and neutron reflectometry (NR) measurements of biomimetic tethered bilayer lipid membranes (tBLMs). tBLMs were prepared with single-component phospholipid compositions, as well as mixtures of phospholipids (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, sphingomyelin and cholesterol) that mimic the inner- and outer- leaflets of plasma cell membranes. We found that all studied tBLMs have a resistance maximum at pHs near the pKas of the phospholipids. SPR and NR indicated that surface concentration of phospholipids and the thickness of the hydrophobic part of the membrane did not change versus pH. We postulate that these maxima are the result of protonation of the phosphate oxygen of the phospholipids and that hydronium ions play a major role in the conductance at pHs < pKas while sodium ions play the major role at pHs > pKas. An additional sharp resistance maximum of the PE tBLMs found at pH 5.9 and most likely represents the phosphatidylethanolamine's isoelectric point. The data show the key roles of the characteristic parts of phospholipid molecules: terminal group (choline, carboxyl, amine), phosphate, glycerol and ester oxygens on the permeability and selectivity of ions through the membrane. The interactions between these groups lead to significant differences in the electrical properties of biomimetic models of inner- and outer- leaflets of the plasma cell membranes.
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Affiliation(s)
- Vitalii I Silin
- University of Maryland, Institute for Bioscience and Biotechnology Research, Rockville MD 20850, USA.
| | - David P Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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25
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Dziubak D, Sek S. Physicochemical Characterization of Sparsely Tethered Bilayer Lipid Membranes: Structure of Submembrane Water and Nanomechanical Properties. ChemElectroChem 2021. [DOI: 10.1002/celc.202100721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Damian Dziubak
- Faculty of Chemistry, Biological & Chemical Research Centre University of Warsaw Zwirki i Wigury 101 02-089 Warsaw Poland
| | - Slawomir Sek
- Faculty of Chemistry, Biological & Chemical Research Centre University of Warsaw Zwirki i Wigury 101 02-089 Warsaw Poland
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26
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Tethered Lipid Membranes as a Nanoscale Arrangement towards Non-Invasive Analysis of Acute Pancreatitis. Biomedicines 2021; 9:biomedicines9070755. [PMID: 34210023 PMCID: PMC8301313 DOI: 10.3390/biomedicines9070755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 12/17/2022] Open
Abstract
Extracellular heat shock proteins (HSPs) mediate immunological functions and are involved in pathologies such as infection, stress, and cancer. Here, we demonstrated the dependence of an amount of HSP70 and HSP90 in serum vs. severity of acute pancreatitis (AP) on a cohort of 49 patients. Tethered bilayer lipid membranes (tBLMs) have been developed to investigate HSPs’ interactions with tBLMs that can be probed by electrochemical impedance spectroscopy (EIS). The results revealed that HSP70 and HSP90 interact via different mechanisms. HSP70 shows the damage of the membrane, while HSP90 increases the insulation properties of tBLM. These findings provide evidence that EIS offers a novel approach for the study of the changes in membrane integrity induced by HSPs proteins. Herein, we present an alternative electrochemical technique, without any immunoprobes, that allows for the monitoring of HSPs on nanoscaled tBLM arrangement in biologics samples such us human urine. This study demonstrates the great potential of tBLM to be used as a membrane based biosensor for novel, simple, and non-invasive label-free analytical system for the prediction of AP severity.
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Majewska M, Zamlynny V, Pieta IS, Nowakowski R, Pieta P. Interaction of LL-37 human cathelicidin peptide with a model microbial-like lipid membrane. Bioelectrochemistry 2021; 141:107842. [PMID: 34049238 DOI: 10.1016/j.bioelechem.2021.107842] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/07/2021] [Accepted: 05/09/2021] [Indexed: 10/21/2022]
Abstract
The only representative of cathelicidin peptides in humans is LL-37, a multifunctional antimicrobial peptide (AMP) that is a part of the innate immune response. Details of the LL-37 direct activity against pathogens are not well understood at the molecular level. Here, we present research on the mechanism of interaction between LL-37 and a model multicomponent bilayer lipid membrane (BLM), mimicking microbial cell membrane. Electrochemical impedance spectroscopy (EIS), high-resolution atomic force microscopy (AFM) imaging, and polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) were applied to study the peptide influence on a model microbial-like membrane. We show that LL-37 causes changes in the phospholipid molecules conformation and orientation, leading to membrane disintegration, significantly affecting the membrane electrical parameters, such as capacitance and resistance. High-resolution AFM imaging shows topographical and mechanical effects of such disintegration, while PM-IRRAS data indicates that introduction of LL-37 causes changes in the phospholipid acyl chains from all-trans to gauche conformations. Moreover, the presence of LL-37 significantly alters the value of the phospholipid tilt angle. Altogether, our results suggest a "carpet" membrane dissolution followed by a detergent-like membrane disruption mechanism upon LL-37 activity. This research gives a novel insight into the understanding of LL-37 influence on multicomponent model membranes and a promising contribution to the development of LL-37-derived therapeutic agents against drug-resistant bacteria.
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Affiliation(s)
- Marta Majewska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Vlad Zamlynny
- Chemistry Department, Acadia University, 6 University Avenue, Wolfville, NS B4P 2R6, Canada
| | - Izabela S Pieta
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Robert Nowakowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Piotr Pieta
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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28
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Sabirovas T, Valiūnienė A, Valincius G. Hybrid bilayer membranes on metallurgical polished aluminum. Sci Rep 2021; 11:9648. [PMID: 33958658 PMCID: PMC8102548 DOI: 10.1038/s41598-021-89150-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/15/2021] [Indexed: 11/09/2022] Open
Abstract
In this work we describe the functionalization of metallurgically polished aluminum surfaces yielding biomimetic electrodes suitable for probing protein/phospholipid interactions. The functionalization involves two simple steps: silanization of the aluminum and subsequent fusion of multilamellar vesicles which leads to the formation of a hybrid bilayer lipid membrane (hBLM). The vesicle fusion was followed in real-time by fast Fourier transform electrochemical impedance spectroscopy (FFT EIS). The impedance-derived complex capacitance of the hBLMs was approximately 0.61 µF cm−2, a value typical for intact phospholipid bilayers. We found that the hBLMs can be readily disrupted if exposed to > 400 nM solutions of the pore-forming peptide melittin. However, the presence of cholesterol at 40% (mol) in hBLMs exhibited an inhibitory effect on the membrane-damaging capacity of the peptide. The melittin-membrane interaction was concentration dependent decreasing with concentration. The hBLMs on Al surface can be regenerated multiple times, retaining their dielectric and functional properties essentially intact.
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Affiliation(s)
- Tomas Sabirovas
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio ave. 7, 10257, Vilnius, Lithuania
| | - Aušra Valiūnienė
- Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, 03225, Vilnius, Lithuania.
| | - Gintaras Valincius
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio ave. 7, 10257, Vilnius, Lithuania
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29
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El-Beyrouthy J, Freeman E. Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology. MEMBRANES 2021; 11:319. [PMID: 33925756 PMCID: PMC8145864 DOI: 10.3390/membranes11050319] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/22/2021] [Accepted: 04/25/2021] [Indexed: 11/16/2022]
Abstract
The cell membrane is a protective barrier whose configuration determines the exchange both between intracellular and extracellular regions and within the cell itself. Consequently, characterizing membrane properties and interactions is essential for advancements in topics such as limiting nanoparticle cytotoxicity. Characterization is often accomplished by recreating model membranes that approximate the structure of cellular membranes in a controlled environment, formed using self-assembly principles. The selected method for membrane creation influences the properties of the membrane assembly, including their response to electric fields used for characterizing transmembrane exchanges. When these self-assembled model membranes are combined with electrophysiology, it is possible to exploit their non-physiological mechanics to enable additional measurements of membrane interactions and phenomena. This review describes several common model membranes including liposomes, pore-spanning membranes, solid supported membranes, and emulsion-based membranes, emphasizing their varying structure due to the selected mode of production. Next, electrophysiology techniques that exploit these structures are discussed, including conductance measurements, electrowetting and electrocompression analysis, and electroimpedance spectroscopy. The focus of this review is linking each membrane assembly technique to the properties of the resulting membrane, discussing how these properties enable alternative electrophysiological approaches to measuring membrane characteristics and interactions.
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Affiliation(s)
| | - Eric Freeman
- School of Environmental, Civil, Agricultural and Mechanical Engineering, College of Engineering, University of Georgia, Athens, GA 30602, USA;
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Su Z, Goodall B, Leitch JJ, Lipkowski J. Ion transport mechanism in gramicidin A channels formed in floating bilayer lipid membranes supported on gold electrodes. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.137892] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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31
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Bryant SJ, Garcia A, Clarke RJ, Warr GG. Selective ion transport across a lipid bilayer in a protic ionic liquid. SOFT MATTER 2021; 17:2688-2694. [PMID: 33533359 DOI: 10.1039/d0sm02225j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ionic liquids (ILs) have exhibited enormous potential as electrolytes, designer solvents and reaction media, as well as being surprisingly effective platforms for amphiphile self-assembly and for preserving structure of complex biomolecules. This has led to their exploration as media for long-term biopreservation and in biosensors, for which their viability depends on their ability to sustain both structure and function within complex, multicomponent nanoscale compartments and assemblies. Here we show that a tethered lipid bilayer can be assembled directly in a purely IL environment that retains its structure upon exchange between IL and aqueous buffer, and that the membrane transporter valinomycin can be incorporated so as to retain its functionality and cation selectivity. This paves the way for the development of long-lived, non-aqueous microreactors and sensor assemblies, and demonstrates the potential for complex proteins to retain functionality in non-aqueous, ionic liquid solvents.
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Affiliation(s)
- Saffron J Bryant
- School of Chemistry, The University of Sydney, NSW 2006, Australia and School of Science, RMIT University, Melbourne, Victoria 3001, Australia.
| | - Alvaro Garcia
- School of Chemistry, The University of Sydney, NSW 2006, Australia and School of Life Sciences, University of Technology Sydney, NSW 2007, Australia
| | - Ronald J Clarke
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | - Gregory G Warr
- School of Chemistry, The University of Sydney, NSW 2006, Australia and University of Sydney Nano Institute, The University of Sydney, NSW 2006, Australia
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Majewska M, Khan F, Pieta IS, Wróblewska A, Szmigielski R, Pieta P. Toxicity of selected airborne nitrophenols on eukaryotic cell membrane models. CHEMOSPHERE 2021; 266:128996. [PMID: 33288286 DOI: 10.1016/j.chemosphere.2020.128996] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/26/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
Nitroaromatics belong to the group of toxic components of aerosol particles and atmospheric hydrometeors that enter the atmosphere through biomass burning and fuel combustion. In the present work, we report on the cytotoxic effects of a 2-, 3- and 4-nitrophenol mixture on a model eukaryotic-like cell membrane and compared it with in vitro cellular models BEAS-2B (immortalized bronchial epithelial cells) and A549 (cancerous alveolar epithelial cells). A selected model biomembrane comprised of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) was studied. The electrochemical-based method, combined with atomic force microscopy (AFM) and phase-contrast microscopy imaging, allowed to get insights into the mechanism of cellular function disruption caused by airborne nitrophenols. The efficacy of the method is supported by the data obtained from in vitro experiments performed on cell models. The nitrophenol mixture exhibited cytotoxic effects at concentrations above 100 μg mL-1, as demonstrated by phase-contrast microscopy in real lung cell lines. Electrochemical impedance spectroscopy (EIS) revealed the formation of membrane defects at a nitrophenol concentration of 200 μg mL-1. AFM imaging confirmed the model membrane disintegration and phospholipids rearrangement in the presence of nitrophenols. These observations indicate that particle-bound nitrophenols induce substantial changes in cell membranes and make them more permeable to aerosol, resulting in major cellular damage in the lungs when inhaled. The study provides initial evidence of cellular membrane damage induced by three important nitrated phenols present in the environment.
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Affiliation(s)
- Marta Majewska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Faria Khan
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Izabela S Pieta
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Aleksandra Wróblewska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Rafal Szmigielski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland.
| | - Piotr Pieta
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland.
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Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles. MEMBRANES 2020; 11:membranes11010011. [PMID: 33374818 PMCID: PMC7824464 DOI: 10.3390/membranes11010011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 12/16/2022]
Abstract
Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.
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Raila T, Ambrulevičius F, Penkauskas T, Jankunec M, Meškauskas T, Vanderah DJ, Valincius G. Clusters of protein pores in phospholipid bilayer membranes can be identified and characterized by electrochemical impedance spectroscopy. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.137179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Andersson J, Bilotto P, Mears LLE, Fossati S, Ramach U, Köper I, Valtiner M, Knoll W. Solid-supported lipid bilayers - A versatile tool for the structural and functional characterization of membrane proteins. Methods 2020; 180:56-68. [PMID: 32920130 DOI: 10.1016/j.ymeth.2020.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 02/07/2023] Open
Abstract
The cellular membrane is central to the development of single-and multicellular life, as it separates the delicate cellular interior from the hostile environment. It exerts tight control over entry and exit of substances, is responsible for signaling with other cells in multicellular organisms and prevents pathogens from entering the cell. In the case of bacteria and viruses, the cellular membrane also hosts the proteins enabling invasion of the host organism. In a very real sense therefore, the cellular membrane is central to all life. The study of the cell membrane and membrane proteins in particular has therefore attracted significant attention. Due to the enormous variety of tasks performed by the membrane, it is a highly complex and challenging structure to study. Ideally, membrane components would be studied in isolation from this environment, but unlike water soluble proteins, the amphiphilic environment provided by the cellular membrane is key to the structure and function of the cell membrane. Therefore, model membranes have been developed to provide an environment in which a membrane protein can be studied. This review presents a set of tools that enable the comprehensive characterization of membrane proteins: electrochemical tools, surface plasmon resonance, neutron scattering, the surface forces apparatus and atomic force microscopy are discussed, with a particular focus on experimental technique and data evaluation.
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Affiliation(s)
| | - Pierluigi Bilotto
- Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria
| | - Laura L E Mears
- Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria
| | - Stefan Fossati
- AIT Austrian Institute of Technology, 1210 Vienna, Austria; Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria
| | - Ulrich Ramach
- Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria; CEST Kompetenzzentrum für elektrochemische Oberflächentechnologie, Wiener Neustadt 2700, Austria
| | - Ingo Köper
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA, Australia
| | - Markus Valtiner
- Institute of Applied Physics, Vienna University of Technology, Vienna 1040, Austria; CEST Kompetenzzentrum für elektrochemische Oberflächentechnologie, Wiener Neustadt 2700, Austria
| | - Wolfgang Knoll
- AIT Austrian Institute of Technology, 1210 Vienna, Austria; CEST Kompetenzzentrum für elektrochemische Oberflächentechnologie, Wiener Neustadt 2700, Austria
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Penkauskas T, Zentelyte A, Ganpule S, Valincius G, Preta G. Pleiotropic effects of statins via interaction with the lipid bilayer: A combined approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183306. [DOI: 10.1016/j.bbamem.2020.183306] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/18/2020] [Accepted: 04/07/2020] [Indexed: 12/25/2022]
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Mrdenovic D, Su Z, Kutner W, Lipkowski J, Pieta P. Alzheimer's disease-related amyloid β peptide causes structural disordering of lipids and changes the electric properties of a floating bilayer lipid membrane. NANOSCALE ADVANCES 2020; 2:3467-3480. [PMID: 36134289 PMCID: PMC9417616 DOI: 10.1039/d0na00292e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/27/2020] [Indexed: 05/10/2023]
Abstract
Neurodegeneration in Alzheimer's disease is associated with disruption of the neuronal cell membrane by the amyloid β (Aβ) peptide. However, the disruption mechanism and the resulting changes in membrane properties remain to be elucidated. To address this issue, herein the interaction of amyloid β monomers (AβMs) and amyloid β oligomers (AβOs) with a floating bilayer lipid membrane (fBLM) was studied using electrochemical and IR spectroscopy techniques. IR measurements showed that both Aβ forms interacted similarly with the hydrophobic membrane core (lipid acyl chains), causing conformational and orientational changes of the lipid acyl chains, thus decreasing acyl chain mobility and altering the lipid packing unit cell. In the presence of AβOs, these changes were more significant than those in the presence of AβMs. However, respective interactions of AβMs and AβOs with the membrane hydrophilic exterior (lipid heads) were quite different. AβMs dehydrated lipid heads without affecting their orientation while AβOs changed the orientation of lipid heads keeping their hydration level intact. Electrochemical measurements showed that only AβOs porated the fBLM, thus significantly changing the fBLM electrical properties. The present results provide new molecular-level insight into the mechanism of membrane destruction by AβOs and changes in the membrane properties.
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Affiliation(s)
- Dusan Mrdenovic
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
- Department of Chemistry, University of Guelph 50 Stone Road East Guelph Ontario N1G 2W1 Canada
| | - Zhangfei Su
- Department of Chemistry, University of Guelph 50 Stone Road East Guelph Ontario N1G 2W1 Canada
| | - Wlodzimierz Kutner
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
- Faculty of Mathematics and Natural Sciences, School of Sciences, Cardinal Stefan Wyszynski University in Warsaw Wóycickiego 1/3 01-815 Warsaw Poland
| | - Jacek Lipkowski
- Department of Chemistry, University of Guelph 50 Stone Road East Guelph Ontario N1G 2W1 Canada
| | - Piotr Pieta
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
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38
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Ionophore properties of valinomycin in the model bilayer lipid membrane 1. Selectivity towards a cation. J Solid State Electrochem 2020. [DOI: 10.1007/s10008-020-04777-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Sieling T, Brand I. In Situ Spectroelectrochemical Investigation of Potential‐Dependent Changes in an Amphiphilic Imidazolium‐Based Ionic Liquid Film on the Au(111) Electrode Surface. ChemElectroChem 2020. [DOI: 10.1002/celc.202000385] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Thorben Sieling
- University of Oldenburg, Department of Chemistry 26111 Oldenburg Germany
| | - Izabella Brand
- University of Oldenburg, Department of Chemistry 26111 Oldenburg Germany
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40
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Electrochemical Biosensors Based on Membrane-Bound Enzymes in Biomimetic Configurations. SENSORS 2020; 20:s20123393. [PMID: 32560121 PMCID: PMC7349357 DOI: 10.3390/s20123393] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/12/2020] [Accepted: 06/14/2020] [Indexed: 02/07/2023]
Abstract
In nature, many enzymes are attached or inserted into the cell membrane, having hydrophobic subunits or lipid chains for this purpose. Their reconstitution on electrodes maintaining their natural structural characteristics allows for optimizing their electrocatalytic properties and stability. Different biomimetic strategies have been developed for modifying electrodes surfaces to accommodate membrane-bound enzymes, including the formation of self-assembled monolayers of hydrophobic compounds, lipid bilayers, or liposomes deposition. An overview of the different strategies used for the formation of biomimetic membranes, the reconstitution of membrane enzymes on electrodes, and their applications as biosensors is presented.
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Josey BP, Heinrich F, Silin V, Lösche M. Association of Model Neurotransmitters with Lipid Bilayer Membranes. Biophys J 2020; 118:1044-1057. [PMID: 32032504 DOI: 10.1016/j.bpj.2020.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 11/15/2022] Open
Abstract
Aimed at reproducing the results of electrophysiological studies of synaptic signal transduction, conventional models of neurotransmission are based on the specific binding of neurotransmitters to ligand-gated receptor ion channels. However, the complex kinetic behavior observed in synaptic transmission cannot be reproduced in a standard kinetic model without the ad hoc postulation of additional conformational channel states. On the other hand, if one invokes unspecific neurotransmitter adsorption to the bilayer-a process not considered in the established models-the electrophysiological data can be rationalized with only the standard set of three conformational receptor states that also depend on this indirect coupling of neurotransmitters via their membrane interaction. Experimental verification has been difficult because binding affinities of neurotransmitters to the lipid bilayer are low. We quantify this interaction with surface plasmon resonance to measure equilibrium dissociation constants in neurotransmitter membrane association. Neutron reflection measurements on artificial membranes, so-called sparsely tethered bilayer lipid membranes, reveal the structural aspects of neurotransmitters' association with zwitterionic and anionic bilayers. We thus establish that serotonin interacts nonspecifically with the membrane at physiologically relevant concentrations, whereas γ-aminobutyric acid does not. Surface plasmon resonance shows that serotonin adsorbs with millimolar affinity, and neutron reflectometry shows that it penetrates the membrane deeply, whereas γ-aminobutyric is excluded from the bilayer.
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Affiliation(s)
- Brian P Josey
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland
| | - Vitalii Silin
- Institute for Bioscience and Biotechnology Research, Rockville, Maryland
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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Su Z, Ran X, Leitch JJ, Schwan AL, Faragher R, Lipkowski J. How Valinomycin Ionophores Enter and Transport K + across Model Lipid Bilayer Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16935-16943. [PMID: 31742409 DOI: 10.1021/acs.langmuir.9b03064] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Valinomycin, a cyclic peptide, was incorporated into a biomimetic lipid membrane tethered to the surface of a gold (111) electrode. Electrochemical impedance spectroscopy was used to study the ionophore properties of the peptide, and polarization modulation infrared reflection absorption spectroscopy was employed to determine the conformation and orientation of valinomycin in the membrane. The combination of these two techniques provided unique information about the ionophore mechanism where valinomycin transports ions across the membrane by creating a complex with potassium ions and forming an ion pair with a counter anion. The ion pair resides within the hydrophobic fragment of the membrane and adopts a small angle of ∼22° with respect to the surface normal. This novel study provides new insights explaining the valinomycin ion transport mechanism in model biological membranes.
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Affiliation(s)
- ZhangFei Su
- Department of Chemistry , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
| | - XueQin Ran
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) , Nanjing Tech University (NanjingTech) , 30 South Puzhu Road , Nanjing 211816 , China
| | - J Jay Leitch
- Department of Chemistry , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
| | - Adrian L Schwan
- Department of Chemistry , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
| | - Robert Faragher
- Department of Chemistry , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
| | - Jacek Lipkowski
- Department of Chemistry , University of Guelph , Guelph , Ontario N1G 2W1 , Canada
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43
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Mechanisms of alamethicin ion channel inhibition by amiloride in zwitterionic tethered lipid bilayers. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2019.113281] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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44
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Inerolysin and vaginolysin, the cytolysins implicated in vaginal dysbiosis, differently impair molecular integrity of phospholipid membranes. Sci Rep 2019; 9:10606. [PMID: 31337831 PMCID: PMC6650466 DOI: 10.1038/s41598-019-47043-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/09/2019] [Indexed: 02/07/2023] Open
Abstract
The pore-forming toxins, inerolysin (INY) and vaginolysin (VLY), produced by vaginal bacteria Lactobacillus iners and Gardnerella vaginalis were studied using the artificial cholesterol-rich tethered bilayer membranes (tBLMs) by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) of tBLMs attested for the toxin-induced impairment of the integrity of phospholipid membranes. This observation was in line with the atomic force microscopy data demonstrating formation of oligomeric protein assemblies in tBLMs. These assemblies exhibited different morphologies: VLY mostly formed complete rings, whereas INY produced arciform structures. We found that both EIS (membrane damage) and the surface plasmon resonance (protein binding) data obtained on tBLMs are in-line with the data obtained in human cell lysis experiments. EIS, however, is capable of capturing effects inaccessible for biological activity assays. Specifically, we found that the INY-induced damage of tBLMs is nearly a linear function of membrane cholesterol content, whereas VLY triggered significant damage only at high (50 mol%) cholesterol concentrations. The observed differences of INY and VLY activities on phospholipid membranes might have clinical importance: both toxin-producing bacteria have been found in healthy vagina and dysbiosis, suggesting the need for adaptation at different vaginal conditions. Our results broaden the possibilities of application of tBLMs in medical diagnostics.
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Su Z, Ho D, Merrill AR, Lipkowski J. In Situ Electrochemical and PM-IRRAS Studies of Colicin E1 Ion Channels in the Floating Bilayer Lipid Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8452-8459. [PMID: 31194562 DOI: 10.1021/acs.langmuir.9b01251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Colicin E1 is a channel-forming bacteriocin produced by certain Escherichia coli cells in an effort to reduce competition from other bacterial strains. The colicin E1 channel domain was incorporated into a 1,2-diphytanoyl- sn-glycero-3-phosphocholine floating bilayer situated on a 1-thio-?-d-glucose-modified gold (111) surface. The electrochemical properties of the colicin E1 channel in the floating bilayer were measured by electrochemical impedance spectroscopy; the configuration and orientation of colicin E1 in the bilayer were determined by polarization-modulation-infrared-reflection absorption spectroscopy. The EIS and IR results indicate that colicin E1 adopts a closed-channel state at the positive transmembrane potential, leading to high membrane resistance and a large tilt angle of ?-helices. When the transmembrane potential becomes negative, colicin E1 begins to insert into the lipid bilayer, corresponding to low membrane resistance and a low tilt angle of ?-helices. The insertion of colicin E1 into the lipid bilayer is driven by the negative transmembrane potential, and the ion-channel open and closed states are potential reversible. The data in this report provide new insights into the voltage-gated mechanism of colicin E1 ion channels in phospholipid bilayers and illustrate that the floating bilayer lipid membrane at the metal electrode surface is a robust platform to study membrane-active proteins and peptides in a quasi-natural environment.
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46
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Squillace O, Esnault C, Pilard JF, Brotons G. Electrodes for Membrane Surface Science. Bilayer Lipid Membranes Tethered by Commercial Surfactants on Electrochemical Sensors. ACS Sens 2019; 4:1337-1345. [PMID: 30977639 DOI: 10.1021/acssensors.9b00267] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Commercial surfactants, which are inexpensive and abundant, were covalently grafted to flat and transparent electrodes, and it appears to be a simple functionalization route to design biomembrane sensors at large-scale production. Sparsely tethered bilayer lipid membranes (stBLM) were stabilized using such molecular coatings composed of diluted anchor-harpoon surfactants that grab the membrane with an alkyl chain out of a PEGylated-hydrogel layer, which acts as a soft hydration cushion. The goal of avoiding the synthesis of complex organic molecules to scale up sensors was achieved here by grafting nonionic diblock oligomers (Brij58 = C xH2 x+1(OCH2CH2) nOH with x = 16 and n = 23) and PEO short chains ((OCH2CH2) nOH with n = 9 and n = 23) from their hydroxyl (-OH) end-moiety to a monolayer of -Ar-SO2Cl groups, which are easy to form on electrodes (metals, semiconducting materials, ...) from aryl-diazonium salt reduction. A hybrid molecular coating on gold, with scarce Ar-SO2-Brij58 and PEO oligomers, was used to monitor immobilization and fusion kinetics of DOPC small unilamellar vesicles (SUV) by both quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. Using flat and transparent thin chromium film electrodes, we designed biosensors to couple surface sensitive techniques for membranes, including X-ray reflectivity (XRR), atomic force microscopy (AFM) with subnanometer resolution, and optical microscopy, such as fluorescence recovery after photobleaching measurements (FRAP), in addition to electrochemistry techniques (cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)). The advantages of this biomembrane-sensing platform are discussed for research and applications.
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Affiliation(s)
- Ophélie Squillace
- IMMM, Institut des Molécules et Matériaux du Mans, Le Mans Université—UFR Sciences et Techniques, Avenue Olivier Messiaen, 72085 Le Mans, France
| | - Charles Esnault
- IMMM, Institut des Molécules et Matériaux du Mans, Le Mans Université—UFR Sciences et Techniques, Avenue Olivier Messiaen, 72085 Le Mans, France
| | - Jean-François Pilard
- IMMM, Institut des Molécules et Matériaux du Mans, Le Mans Université—UFR Sciences et Techniques, Avenue Olivier Messiaen, 72085 Le Mans, France
| | - Guillaume Brotons
- IMMM, Institut des Molécules et Matériaux du Mans, Le Mans Université—UFR Sciences et Techniques, Avenue Olivier Messiaen, 72085 Le Mans, France
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Abbasi F, Su Z, Alvarez-Malmagro J, Leitch JJ, Lipkowski J. Effects of Amiloride, an Ion Channel Blocker, on Alamethicin Pore Formation in Negatively Charged, Gold-Supported, Phospholipid Bilayers: A Molecular View. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5060-5068. [PMID: 30888178 DOI: 10.1021/acs.langmuir.9b00187] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The effects of amiloride on the structure and conductivity of alamethicin ion pore formation within negatively charged, gold-supported, 1,2-dimyristoyl- sn-glycero-3-phosphocholine/Egg-PG membranes were investigated with the help of electrochemical impedance spectroscopy (EIS), photon polarization modulation-infrared reflection spectroscopy (PM-IRRAS), and atomic force microscopy (AFM). The EIS results indicate that ion conductivity across negatively charged phospholipid bilayers containing alamethicin decreases by an order of magnitude when amiloride is introduced to the system. Despite the reduction in ion conductivity, the PM-IRRAS data shows that amiloride does not inhibit ion channel formation by alamethicin peptides. High-resolution AFM images revealed that amiloride enlarges and distorts the shape of alamethicin ion pores when introduced to the system, indicating that it is inserting itself into the mouth of the alamethicin pores. This effect is driven by electrostatic interactions between positively charged amiloride molecules and the negative charge on the membrane.
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Affiliation(s)
- Fatemeh Abbasi
- Department of Chemistry , University of Guelph , Guelph , Ontario , Canada N1G 2W1
| | - ZhangFei Su
- Department of Chemistry , University of Guelph , Guelph , Ontario , Canada N1G 2W1
| | | | - J Jay Leitch
- Department of Chemistry , University of Guelph , Guelph , Ontario , Canada N1G 2W1
| | - Jacek Lipkowski
- Department of Chemistry , University of Guelph , Guelph , Ontario , Canada N1G 2W1
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48
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Electrochemical impedance of randomly distributed defects in tethered phospholipid bilayers: Finite element analysis. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2018.12.148] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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49
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Challita EJ, Freeman EC. Hydrogel Microelectrodes for the Rapid, Reliable, and Repeatable Characterization of Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15166-15173. [PMID: 30468580 DOI: 10.1021/acs.langmuir.8b02867] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Model lipid bilayer membranes provide approximations of natural cellular membranes that may be formed in the laboratory to study their mechanics and interactions with the surrounding environment. A new approach for their formation is proposed here based on the self-assembly of lipid monolayers at oil-water interfaces, creating a lipid-coated hydrogel-tipped electrode that produces a stable lipid membrane on the surface when introduced to a lipid-coated aqueous droplet. Membrane formation using the hydrogel microelectrode is tested for a variety of lipids and oils. The channel-forming peptide alamethicin is added to the membrane, and its functionality is verified. Finally, asymmetric membranes are created using varying lipid compositions, and the capacity for repeated quantification of membrane structure is demonstrated. The proposed hydrogel microelectrodes are compatible with multiple oils and lipids, simple to use, and suitable for detecting the presence of both biomolecular transporters and dissolved lipid compositions within aqueous droplets.
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Affiliation(s)
- Elio J Challita
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering , University of Georgia , 110 Riverbend Road , Athens , Georgia 30605 , United States
| | - Eric C Freeman
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering , University of Georgia , 110 Riverbend Road , Athens , Georgia 30605 , United States
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50
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Hoogerheide DP, Noskov SY, Kuszak AJ, Buchanan SK, Rostovtseva TK, Nanda H. Structure of voltage-dependent anion channel-tethered bilayer lipid membranes determined using neutron reflectivity. Acta Crystallogr D Struct Biol 2018; 74:1219-1232. [PMID: 30605136 PMCID: PMC6317592 DOI: 10.1107/s2059798318011749] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/20/2018] [Indexed: 01/05/2023] Open
Abstract
Neutron reflectivity (NR) has emerged as a powerful technique to study the structure and behavior of membrane proteins at planar lipid interfaces. Integral membrane proteins (IMPs) remain a significant challenge for NR owing to the difficulty of forming complete bilayers with sufficient protein density for scattering techniques. One strategy to achieve high protein density on a solid substrate is the capture of detergent-stabilized, affinity-tagged IMPs on a nitrilotriacetic acid (NTA)-functionalized self-assembled monolayer (SAM), followed by reconstitution into the lipids of interest. Such protein-tethered bilayer lipid membranes (ptBLMs) have the notable advantage of a uniform IMP orientation on the substrate. Here, NR is used to provide a structural characterization of the ptBLM process from formation of the SAM to capture of the detergent-stabilized IMP and lipid reconstitution. The mitochondrial outer-membrane voltage-dependent anion channel (VDAC), which controls the exchange of bioenergetic metabolites between mitochondria and the cytosol, was used as a model β-barrel IMP. Molecular dynamics simulations were used for comparison with the experimental results and to inform the parameters of the physical models describing the NR data. The detailed structure of the SAM is shown to depend on the density of the NTA chelating groups. The relative content of detergent and protein in surface-immobilized, detergent-stabilized VDAC is measured, while the reconstituted lipid bilayer is shown to be complete to within a few percent, using the known atomic structure of VDAC. Finally, excess lipid above the reconstituted bilayer, which is of consequence for more indirect structural and functional studies, is shown to be present.
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Affiliation(s)
- David P. Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20878, USA
| | - Sergei Yu. Noskov
- Centre for Molecular Simulations and Department of Biological Sciences, University of Calgary, Calgary T2N 1N4, Canada
| | - Adam J. Kuszak
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Susan K. Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tatiana K. Rostovtseva
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hirsh Nanda
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20878, USA
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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