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Jurku̅nas M, Talaikis M, Klimkevičius V, Pudžaitis V, Niaura G, Makuška R. Diblock Copolymers of Methacryloyloxyethyl Phosphorylcholine and Dopamine Methacrylamide: Synthesis and Real-Time Adsorption Dynamics by SEIRAS and RAIRS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:5945-5958. [PMID: 38456424 PMCID: PMC10956495 DOI: 10.1021/acs.langmuir.3c03925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/18/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024]
Abstract
Amphiphilic diblock copolymers containing a block of 2-methacryloyloxyethyl phosphorylcholine (MPC) with unique properties to prevent nonspecific protein adsorption and enhance lubrication in aqueous media and a block of dopamine methacrylamide (DOPMA) distinguished by excellent adhesion performance were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization for the first time. The DOPMA monomer with an acetonide-protected catechol group (acetonide-protected dopamine methacrylamide (ADOPMA)) was used, allowing the prevention of undesirable side reactions during polymerization and oxidation during storage. The adsorption behavior of the diblock copolymers with protected and unprotected catechol groups on gold surfaces was probed using attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy, surface-enhanced infrared absorption spectroscopy (SEIRAS), and reflection-absorption infrared spectroscopy (RAIRS). The copolymers pMPC-b-pADOPMA demonstrated physisorption with rapid adsorption and ultrasound-assisted desorption, while the copolymers pMPC-b-DOPMA exhibited chemical adsorption with slower dynamics but a stronger interaction with the gold surface. SEIRAS and RAIRS allowed proving the reorientation of the diblock copolymers during adsorption, demonstrating the exposure of the pMPC block toward the aqueous phase.
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Affiliation(s)
- Marijus Jurku̅nas
- Institute
of Chemistry, Vilnius University, Naugarduko Str. 24, 03225 Vilnius, Lithuania
| | - Martynas Talaikis
- Department
of Organic Chemistry, Center for Physical
Sciences and Technology (FTMC), Sauletekio Ave. 3, 10257 Vilnius, Lithuania
| | - Vaidas Klimkevičius
- Institute
of Chemistry, Vilnius University, Naugarduko Str. 24, 03225 Vilnius, Lithuania
| | - Vaidas Pudžaitis
- Department
of Organic Chemistry, Center for Physical
Sciences and Technology (FTMC), Sauletekio Ave. 3, 10257 Vilnius, Lithuania
| | - Gediminas Niaura
- Department
of Organic Chemistry, Center for Physical
Sciences and Technology (FTMC), Sauletekio Ave. 3, 10257 Vilnius, Lithuania
| | - Ričardas Makuška
- Institute
of Chemistry, Vilnius University, Naugarduko Str. 24, 03225 Vilnius, Lithuania
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Gabriunaite I, Valiuniene A, Ramanavicius S, Ramanavicius A. Biosensors Based on Bio-Functionalized Semiconducting Metal Oxides. Crit Rev Anal Chem 2022; 54:549-564. [PMID: 35714203 DOI: 10.1080/10408347.2022.2088226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Immobilization of biomaterials is a very important task in the development of biofuel cells and biosensors. Some semiconducting metal-oxide-based supporting materials can be used in these bioelectronics-based devices. In this article, we are reviewing some functionalization methods that are applied for the immobilization of biomaterials. The most significant attention is paid to the immobilization of biomolecules on the surface of semiconducting metal oxides. The improvement of biomaterials immobilization on metal oxides and analytical performance of biosensors by coatings based on conducting polymers, self-assembled monolayers and lipid membranes is discussed.
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Affiliation(s)
- Inga Gabriunaite
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
| | - Ausra Valiuniene
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
| | - Simonas Ramanavicius
- Centre for Physical Sciences and Technology, Department of Electrochemical Material Science, Vilnius, Lithuania
| | - Arunas Ramanavicius
- Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Department of Physical Chemistry, Vilnius, Lithuania
- Centre for Physical Sciences and Technology, Department of Electrochemical Material Science, Vilnius, Lithuania
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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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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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Thorsen MK, Lai A, Lee MW, Hoogerheide DP, Wong GCL, Freed JH, Heldwein EE. Highly Basic Clusters in the Herpes Simplex Virus 1 Nuclear Egress Complex Drive Membrane Budding by Inducing Lipid Ordering. mBio 2021; 12:e0154821. [PMID: 34425706 PMCID: PMC8406295 DOI: 10.1128/mbio.01548-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/28/2021] [Indexed: 02/01/2023] Open
Abstract
During replication of herpesviruses, capsids escape from the nucleus into the cytoplasm by budding at the inner nuclear membrane. This unusual process is mediated by the viral nuclear egress complex (NEC) that deforms the membrane around the capsid by oligomerizing into a hexagonal, membrane-bound scaffold. Here, we found that highly basic membrane-proximal regions (MPRs) of the NEC alter lipid order by inserting into the lipid headgroups and promote negative Gaussian curvature. We also find that the electrostatic interactions between the MPRs and the membranes are essential for membrane deformation. One of the MPRs is phosphorylated by a viral kinase during infection, and the corresponding phosphomimicking mutations block capsid nuclear egress. We show that the same phosphomimicking mutations disrupt the NEC-membrane interactions and inhibit NEC-mediated budding in vitro, providing a biophysical explanation for the in vivo phenomenon. Our data suggest that the NEC generates negative membrane curvature by both lipid ordering and protein scaffolding and that phosphorylation acts as an off switch that inhibits the membrane-budding activity of the NEC to prevent capsid-less budding. IMPORTANCE Herpesviruses are large viruses that infect nearly all vertebrates and some invertebrates and cause lifelong infections in most of the world's population. During replication, herpesviruses export their capsids from the nucleus into the cytoplasm by an unusual mechanism in which the viral nuclear egress complex (NEC) deforms the nuclear membrane around the capsid. However, how membrane deformation is achieved is unclear. Here, we show that the NEC from herpes simplex virus 1, a prototypical herpesvirus, uses clusters of positive charges to bind membranes and order membrane lipids. Reducing the positive charge or introducing negative charges weakens the membrane deforming ability of the NEC. We propose that the virus employs electrostatics to deform nuclear membrane around the capsid and can control this process by changing the NEC charge through phosphorylation. Blocking NEC-membrane interactions could be exploited as a therapeutic strategy.
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Affiliation(s)
- Michael K. Thorsen
- Department of Molecular Biology and Microbiology, Graduate Program in Cellular, Molecular and Developmental Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Alex Lai
- Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University, Ithaca, New York, USA
| | - Michelle W. Lee
- Department of Bioengineering, Department of Chemistry and Biochemistry, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - David P. Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Gerard C. L. Wong
- Department of Bioengineering, Department of Chemistry and Biochemistry, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - Jack H. Freed
- Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University, Ithaca, New York, USA
| | - Ekaterina E. Heldwein
- Department of Molecular Biology and Microbiology, Graduate Program in Cellular, Molecular and Developmental Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
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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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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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Gabriunaite I, Valiūnienė A, Sabirovas T, Valincius G. Mixed Silane‐based Self‐assembled Monolayers Deposited on Fluorine Doped Tin Oxide as Model System for Development of Biosensors for Toxin Detection. ELECTROANAL 2021. [DOI: 10.1002/elan.202060578] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Inga Gabriunaite
- 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
| | - Tomas Sabirovas
- Institute of Biochemistry Life Sciences Centre Vilnius University Sauletekio ave. 7 Vilnius, LT 10257 Lithuania
| | - Gintaras Valincius
- Institute of Biochemistry Life Sciences Centre Vilnius University Sauletekio ave. 7 Vilnius, LT 10257 Lithuania
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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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11
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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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12
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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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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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Divya K, Anancia Grace A, Dharuman V. Rapid and sensitive electrochemical label free ion channel, membrane protein and DNA sensing on surface supported liposome-gold nanoparticle platform. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2018.12.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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15
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Gabriunaite I, Valiūnienė A, Valincius G. Formation and properties of phospholipid bilayers on fluorine doped tin oxide electrodes. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.04.160] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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16
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Zhou W, Burke PJ. Versatile Bottom-Up Synthesis of Tethered Bilayer Lipid Membranes on Nanoelectronic Biosensor Devices. ACS APPLIED MATERIALS & INTERFACES 2017; 9:14618-14632. [PMID: 28387499 PMCID: PMC6373873 DOI: 10.1021/acsami.7b00268] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Interfacing nanoelectronic devices with cell membranes can enable multiplexed detection of fundamental biological processes (such as signal transduction, electrophysiology, and import/export control) even down to the single ion channel level, which can lead to a variety of applications in pharmacology and clinical diagnosis. Therefore, it is necessary to understand and control the chemical and electrical interface between the device and the lipid bilayer membrane. Here, we develop a simple bottom-up approach to assemble tethered bilayer lipid membranes (tBLMs) on silicon wafers and glass slides, using a covalent tether attachment chemistry based on silane functionalization, followed by step-by-step stacking of two other functional molecular building blocks (oligo-poly(ethylene glycol) (PEG) and lipid). A standard vesicle fusion process was used to complete the bilayer formation. The monolayer synthetic scheme includes three well-established chemical reactions: self-assembly, epoxy-amine reaction, and EDC/NHS cross-linking reaction. All three reactions are facile and simple and can be easily implemented in many research labs, on the basis of common, commercially available precursors using mild reaction conditions. The oligo-PEG acts as the hydrophilic spacer, a key role in the formation of a homogeneous bilayer membrane. To explore the broad applicability of this approach, we have further demonstrated the formation of tBLMs on three common classes of (nano)electronic biosensor devices: indium-tin oxide-coated glass, silicon nanoribbon devices, and high-density single-walled carbon nanotubes (SWNT) networks on glass. More importantly, we incorporated alemethicin into tBLMs and realized the real-time recording of single ion channel activity with high sensitivity and high temporal resolution using the tBLMs/SWNT network transistor hybrid platform. This approach can provide a covalently bonded lipid coating on the oxide layer of nanoelectronic devices, which will enable a variety of applications in the emerging field of nanoelectronic interfaces to electrophysiology.
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Affiliation(s)
- Weiwei Zhou
- Integrated Nanosystems Research Facility, Department of Electrical Engineering and Computer Science, University of California at Irvine, Irvine, California 92697, United States
| | - Peter J. Burke
- Integrated Nanosystems Research Facility, Department of Electrical Engineering and Computer Science, University of California at Irvine, Irvine, California 92697, United States
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17
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Hoogerheide DP, Noskov SY, Jacobs D, Bergdoll L, Silin V, Worcester DL, Abramson J, Nanda H, Rostovtseva TK, Bezrukov SM. Structural features and lipid binding domain of tubulin on biomimetic mitochondrial membranes. Proc Natl Acad Sci U S A 2017; 114:E3622-E3631. [PMID: 28420794 PMCID: PMC5422764 DOI: 10.1073/pnas.1619806114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Dimeric tubulin, an abundant water-soluble cytosolic protein known primarily for its role in the cytoskeleton, is routinely found to be associated with mitochondrial outer membranes, although the structure and physiological role of mitochondria-bound tubulin are still unknown. There is also no consensus on whether tubulin is a peripheral membrane protein or is integrated into the outer mitochondrial membrane. Here the results of five independent techniques-surface plasmon resonance, electrochemical impedance spectroscopy, bilayer overtone analysis, neutron reflectometry, and molecular dynamics simulations-suggest that α-tubulin's amphipathic helix H10 is responsible for peripheral binding of dimeric tubulin to biomimetic "mitochondrial" membranes in a manner that differentiates between the two primary lipid headgroups found in mitochondrial membranes, phosphatidylethanolamine and phosphatidylcholine. The identification of the tubulin dimer orientation and membrane-binding domain represents an essential step toward our understanding of the complex mechanisms by which tubulin interacts with integral proteins of the mitochondrial outer membrane and is important for the structure-inspired design of tubulin-targeting agents.
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Affiliation(s)
- David P Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899;
| | - Sergei Y Noskov
- Center for Molecular Simulations, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N 1N4;
| | - Daniel Jacobs
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Lucie Bergdoll
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Vitalii Silin
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
| | - David L Worcester
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Institute for Stem Cell Biology and Regenerative Medicine, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, Karnataka, India
| | - Hirsh Nanda
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213
| | - 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
| | - Sergey M Bezrukov
- Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
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18
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Ragaliauskas T, Mickevicius M, Rakovska B, Penkauskas T, Vanderah DJ, Heinrich F, Valincius G. Fast formation of low-defect-density tethered bilayers by fusion of multilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:669-678. [PMID: 28088448 DOI: 10.1016/j.bbamem.2017.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/19/2016] [Accepted: 01/10/2017] [Indexed: 10/20/2022]
Abstract
A facile and reproducible preparation of surface-supported lipid bilayers is essential for fundamental membrane research and biotechnological applications. We demonstrate that multilamellar vesicles fuse to molecular-anchor-grafted surfaces yielding low-defect-density, tethered bilayer membranes. Continuous bilayers are formed within 10min, while the electrically insulating bilayers with <0.1μm-2 defect density can be accomplished within 60min. Surface plasmon resonance spectroscopy indicates that an amount of lipid material transferred from vesicles to a surface is inversely proportional to the density of an anchor, while the total amount of lipid that includes tethered and transferred lipid remains constant within 5% standard error. This attests for the formation of intact bilayers independent of the tethering agent density. Neutron reflectometry (NR) revealed the atomic level structural details of the tethered bilayer showing, among other things, that the total thickness of the hydrophobic slab of the construct was 3.2nm and that the molar fraction of cholesterol in lipid content is essentially the same as the molar fraction of cholesterol in the multilamellar liposomes. NR also indicated the formation of an overlayer with an effective thickness of 1.9nm. These overlayers may be easily removed by a single rinse of the tethered construct with 30% ethanol solution. Fast assembly and low residual defect density achievable within an hour of fusion makes our tethered bilayer methodology an attractive platform for biosensing of membrane damaging agents, such as pore forming toxins.
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Affiliation(s)
- Tadas Ragaliauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Mindaugas Mickevicius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Bozena Rakovska
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - Tadas Penkauskas
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania
| | - David J Vanderah
- Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA
| | - Frank Heinrich
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Gintaras Valincius
- Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257 , Lithuania.
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19
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Valiūnienė A, Petrulionienė T, Balevičiūtė I, Mikoliūnaitė L, Valinčius G. Formation of hybrid bilayers on silanized thin-film Ti electrode. Chem Phys Lipids 2016; 202:62-68. [PMID: 27964891 DOI: 10.1016/j.chemphyslip.2016.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/01/2016] [Accepted: 12/05/2016] [Indexed: 11/29/2022]
Abstract
Phospholipid bilayer membranes are essential elements of living organisms as they form boundaries between the intracellular cytoplasm and the extracellular environment, as well as organelles. In this work we report on our attempts to assemble artificial phospholipid bilayer model membranes on Ti surface. To provide hydrophobic cushion for phospholipids, the surface of a thin-film Ti electrode was initially functionalized with trichloro(octadecyl)silane (OTS). Increased hydrophobicity of the solid support allowed vesicle fusion and the formation of a hybrid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer, as probed by the electrochemical impedance spectroscopy (EIS), contact angle measurements (CA) also by the Fourier transform-infrared (FT-IR) spectroscopy, spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). Our study demonstrates the applicability of thin-film Ti electrodes for the formation of hybrid bilayer membranes. These membranes allow functional reconstitution of the pore-forming toxins and provide a bioanalytical platform for the detection of the activity of the cholesterol-dependent cytolysins.
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Affiliation(s)
- A Valiūnienė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania.
| | - T Petrulionienė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - I Balevičiūtė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - L Mikoliūnaitė
- Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania
| | - G Valinčius
- Department of Chemistry and Bioengineering, Vilnius Gedimino Technical University, Sauletekio al. 11, LT-10223, Vilnius, Lithuania
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20
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Choi Y, Shin SH, Hong S, Kim Y. A combined top-down/bottom-up approach to structuring multi-sensing zones on a thin film and the application to SPR sensors. NANOTECHNOLOGY 2016; 27:345302. [PMID: 27418406 DOI: 10.1088/0957-4484/27/34/345302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The development of a thin film with well-defined metallic micro/nanostructures, diverse surface functionalities, and superior electronic/optical properties has been a great challenge to researchers seeking an efficient method for the detection of various analytes in chemical and biological sensing applications. Herein, we report a facile and effective approach to the fabrication of an ordered gold island pattern on a glass substrate with contrasted chemical functionalities, which can provide spatially separated sensing zones for multi-detection. In the proposed method, the combination between the micro/nano-imprint lithography and sequential self-assembly approaches exhibited synergistic effects that allowed well-defined structuring and easy surface functionalization in separated sensing zones. Via imprint lithography, the uniform gold islands/glass structure was successfully fabricated from a readily available gold-coated glass film. In addition, a sequential self-assembling strategy and specific chemical-substrate interactions, such as thiol-gold and silane-glass, enabled the surfaces of gold islands and exposed portions of the glass substrate with contrasting chemical functionalities-SH-functionalized gold islands and NH2-functionalized glass substrate. A proof-of-concept experiment for the multi-detection of heavy metal ions (Hg(2+) and Cu(2+)) in an aqueous media was also successfully conducted using the dual-functionalized gold islands/glass structure and surface plasmon resonance measurements. The SH groups on the gold islands and the NH2 groups on the glass substrate functioned as spatially separated and selective receptors for Hg(2+) and Cu(2+) ions, respectively. Therefore, both the detection and quantification of Hg(2+) and Cu(2+) ions could be achieved using a single sensing substrate.
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Affiliation(s)
- Youngbo Choi
- Department of Safety Engineering, Chungbuk National University, Chungbuk 28644, Korea
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21
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Preta G, Jankunec M, Heinrich F, Griffin S, Sheldon IM, Valincius G. Tethered bilayer membranes as a complementary tool for functional and structural studies: The pyolysin case. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2070-2080. [PMID: 27211243 DOI: 10.1016/j.bbamem.2016.05.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/27/2016] [Accepted: 05/17/2016] [Indexed: 10/21/2022]
Abstract
We demonstrate the use of tethered bilayer lipid membranes (tBLMs) as an experimental platform for functional and structural studies of membrane associated proteins by electrochemical techniques. The reconstitution of the cholesterol-dependent cytolysin (CDC) pyolysin (PLO) from Trueperella pyogenes into tBLMs was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes of the EIS parameters of the tBLMs upon exposure to PLO solutions were consistent with the dielectric barrier damage occurring through the formation of water-filled pores in membranes. Parallel experiments involving a mutant version of PLO, which is able to bind to the membranes but does not form oligomer pores, strengthen the reliability of this methodology, since no change in the electrochemical impedance was observed. Complementary atomic force microscopy (AFM) and neutron reflectometry (NR) measurements revealed structural details of the membrane bound PLO, consistent with the structural transformations of the membrane bound toxins found for other cholesterol dependent cytolysins. In this work, using the tBLMs platform we also observed a protective effect of the dynamin inhibitor Dynasore against pyolysin as well as pneumolysin. An effect of Dynasore in tBLMs, which was earlier observed in experiments with live cells, confirms the biological relevance of the tBLMs models, as well as demonstrates the potential of the electrochemical impedance spectroscopy to quantify membrane damage by the pore forming toxins. In conclusion, tBLMs are a reliable and complementary method to explore the activity of CDCs in eukaryotic cells and to develop strategies to limit the toxic effects of CDCs.
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Affiliation(s)
- Giulio Preta
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
| | - Marija Jankunec
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
| | - Frank Heinrich
- NIST Center for Neutron Research, Gaithersburg, MD 20899, USA
| | - Sholeem Griffin
- Institute of Life Science, Swansea University Medical School, Swansea SA2 8PP, United Kingdom
| | - Iain Martin Sheldon
- Institute of Life Science, Swansea University Medical School, Swansea SA2 8PP, United Kingdom
| | - Gintaras Valincius
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania.
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22
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Eicher-Lorka O, Charkova T, Matijoška A, Kuodis Z, Urbelis G, Penkauskas T, Mickevičius M, Bulovas A, Valinčius G. Cholesterol-based tethers and markers for model membranes investigation. Chem Phys Lipids 2016; 195:71-86. [PMID: 26772524 DOI: 10.1016/j.chemphyslip.2015.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/16/2015] [Accepted: 12/30/2015] [Indexed: 11/16/2022]
Abstract
A series of new bifunctional cholesterol compounds for tethered bilayer membrane (tBLM) systems were synthesized and tested. The compounds containing cyclic disulfide group may be used as molecular anchors for phospholipid bilayers. Anchoring occurs through the insertion of the cholesterol moiety into the hydrophobic slab of the phospholipid layer, while the surface density of anchor molecules may be adjusted using disulfides terminated spacers. Five ethylene oxide segments between the disulfide group and the cholesteryl provide hydration of the layer separating solid support and model membrane. Another group of cholesterol derivatives described in this work contains either fluorescence probe or electroactive functional groups. We demonstrated the practical utility of these compounds for visualization of cholesterol extraction from and loading to tBLMs. We demonstrated that electroactive group containing cholesterol derivatives can be reconstituted either into vesicles or tBLMs. In both cases an electrochemical signal can be generated on electrodes from these probes. In general, the newly synthesized compound may be utilized in a variety of applications involving tethered bilayer systems and vesicles.
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Affiliation(s)
- O Eicher-Lorka
- Institute of Chemistry, Center for Physical Sciences and Technology, A. Goštauto St. 9, LT-01108 Vilnius, Lithuania.
| | - T Charkova
- Institute of Chemistry, Center for Physical Sciences and Technology, A. Goštauto St. 9, LT-01108 Vilnius, Lithuania
| | - A Matijoška
- Institute of Chemistry, Center for Physical Sciences and Technology, A. Goštauto St. 9, LT-01108 Vilnius, Lithuania
| | - Z Kuodis
- Institute of Chemistry, Center for Physical Sciences and Technology, A. Goštauto St. 9, LT-01108 Vilnius, Lithuania
| | - G Urbelis
- Institute of Chemistry, Center for Physical Sciences and Technology, A. Goštauto St. 9, LT-01108 Vilnius, Lithuania
| | - T Penkauskas
- Institute of Biochemistry, Vilnius University, Mokslininkų St. 12, LT-08662 Vilnius, Lithuania
| | - M Mickevičius
- Institute of Biochemistry, Vilnius University, Mokslininkų St. 12, LT-08662 Vilnius, Lithuania
| | - A Bulovas
- Institute of Biochemistry, Vilnius University, Mokslininkų St. 12, LT-08662 Vilnius, Lithuania
| | - G Valinčius
- Institute of Biochemistry, Vilnius University, Mokslininkų St. 12, LT-08662 Vilnius, Lithuania
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