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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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2
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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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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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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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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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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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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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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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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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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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Sabirovas T, Valiūnienė A, Gabriunaite I, Valincius G. Mixed hybrid bilayer lipid membranes on mechanically polished titanium surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183232. [PMID: 32119863 DOI: 10.1016/j.bbamem.2020.183232] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 02/07/2020] [Accepted: 02/20/2020] [Indexed: 02/04/2023]
Abstract
Mixed self-assembled monolayers of octadecyltrichlorosilane (OTS) and methyltrichlorosilane (MTS) were deposited via simple silanization procedure on a mechanically polished titanium surface. The monolayers act as molecular anchors for mixed hybrid bilayer lipid membranes (mhBLM) which were accomplished via vesicle fusion. A variation of the MTS concentration in silanization solutions significantly affects properties of mhBLMs composed of a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol (Chol). The bilayers become less insulating following an increase of the MTS content. On the other hand, an increase of the MTS concentration provides flexibility of the mhBLM membranes necessary for the functional reconstitution of membrane proteins. The optimal molar ratio of MTS in silanization solution is 40% providing anchors for intact mhBLMs as confirmed by their specific capacitance of 0.86 μF cm-2. We found that the bilayers containing 40% (mol) of cholesterol bind cholesterol dependent pneumolysin (PLY). However, we did not observe functional reconstitution of PLY. While α-hemolysin almost fully disrupts mhBLMs assembled from 100% diphytanoyl. An important advantage of the titanium/OTS/MTS molecular anchor systems is their ability of repetitive regeneration of phospholipid bilayers without losing functional properties as demonstrated in the current study. This creates a possibility for the multiple-use phospholipid membrane biosensors which have a potential of decreasing the cost of such electrochemical/electroanalytical devices.
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Affiliation(s)
- Tomas Sabirovas
- Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - Aušra Valiūnienė
- Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - Inga Gabriunaite
- Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - Gintaras Valincius
- Vilnius University, Institute of Biochemistry, Life Sciences Center, Sauletekio ave. 7, Vilnius LT-10257, Lithuania.
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