1
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Martin A, Jemmett PN, Howitt T, Wood MH, Burley AW, Cox LR, Dafforn TR, Welbourn RJL, Campana M, Skoda MW, Thompson JJ, Hussain H, Rawle JL, Carlà F, Nicklin CL, Arnold T, Horswell SL. Effect of Anionic Lipids on Mammalian Plasma Cell Membrane Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:2676-2691. [PMID: 36757323 PMCID: PMC9948536 DOI: 10.1021/acs.langmuir.2c03161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/19/2023] [Indexed: 06/18/2023]
Abstract
The effect of lipid composition on models of the inner leaflet of mammalian cell membranes has been investigated. Grazing incidence X-ray diffraction and X-ray and neutron reflectivity have been used to characterize lipid packing and solvation, while electrochemical and infrared spectroscopic methods have been employed to probe phase behavior in an applied electric field. Introducing a small quantity of the anionic lipid dimyristoylphosphatidylserine (DMPS) into bilayers of zwitterionic dimyristoylphosphatidylethanolamine (DMPE) results in a significant change in the bilayer response to an applied field: the tilt of the hydrocarbon chains increases before returning to the original tilt angle on detachment of the bilayer. Equimolar mixtures, with slightly closer chain packing, exhibit a similar but weaker response. The latter also tend to incorporate more solvent during this electrochemical phase transition, at levels similar to those of pure DMPS. Reflectivity measurements reveal greater solvation of lipid layers for DMPS > 30 mol %, matching the greater propensity for DMPS-rich bilayers to incorporate water. Taken together, the data indicate that the range of 10-35 mol % DMPS provides optimum bilayer properties (in flexibility and function as a barrier), which may explain why the DMPS content of cell membranes tends to be found within this range.
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Affiliation(s)
- Alexandra
L. Martin
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Philip N. Jemmett
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Thomas Howitt
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Mary H. Wood
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Andrew W. Burley
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Liam R. Cox
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Timothy R. Dafforn
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
| | - Rebecca J. L. Welbourn
- ISIS
Pulsed Neutron and Muon Source, Science
and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, OxfordshireOX11 0QX, U.K.
| | - Mario Campana
- ISIS
Pulsed Neutron and Muon Source, Science
and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, OxfordshireOX11 0QX, U.K.
| | - Maximilian W.
A. Skoda
- ISIS
Pulsed Neutron and Muon Source, Science
and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, OxfordshireOX11 0QX, U.K.
| | - Joseph J. Thompson
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
| | - Hadeel Hussain
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
| | - Jonathan L. Rawle
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
| | - Francesco Carlà
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
| | - Christopher L. Nicklin
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
| | - Thomas Arnold
- ISIS
Pulsed Neutron and Muon Source, Science
and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, OxfordshireOX11 0QX, U.K.
- Diamond
Light Source, Harwell Science and Innovation
Campus, Chilton, Didcot, OxfordshireOX11 0DE, U.K.
- European
Spallation Source ERIC PO Box 176, SE-221 00Lund, Sweden
- Department
of Chemistry, University of Bath, Claverton Down, BathBA2 7AY, U.K.
| | - Sarah L. Horswell
- School of
Chemistry and School of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, U.K.
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2
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Jemmett P, Milan DC, Nichols RJ, Howitt T, Martin AL, Arnold T, Rawle JL, Nicklin CL, Dafforn TR, Cox LR, Horswell SL. Influence of the Lipid Backbone on Electrochemical Phase Behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14290-14301. [PMID: 36354380 PMCID: PMC9686133 DOI: 10.1021/acs.langmuir.2c02370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Sphingolipids are an important class of lipids found in mammalian cell membranes with important structural and signaling roles. They differ from another major group of lipids, the glycerophospholipids, in the connection of their hydrocarbon chains to their headgroups. In this study, a combination of electrochemical and structural methods has been used to elucidate the effect of this difference on sphingolipid behavior in an applied electric field. N-Palmitoyl sphingomyelin forms bilayers of similar coverage and thickness to its close analogue di-palmitoyl phosphatidylcholine. Grazing incidence diffraction data show slightly closer packing and a smaller chain tilt angle from the surface normal. Electrochemical IR results at low charge density show that the difference in tilt angle is retained on deposition to form bilayers. The bilayers respond differently to increasing electric field strength: chain tilt angles increase for both molecules, but sphingomyelin chains remain tilted as field strength is further increased. This behavior is correlated with disruption of the hydrogen-bonding network of small groups of sphingomyelin molecules, which may have significance for the behavior of molecules in lipid rafts in the presence of strong fields induced by ion gradients or asymmetric distribution of charged lipids.
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Affiliation(s)
- Philip
N. Jemmett
- School
of Chemistry, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
| | - David C. Milan
- Department
of Chemistry, University of Liverpool, Crown Street, LiverpoolL69 7ZD, UK
| | - Richard J. Nichols
- Department
of Chemistry, University of Liverpool, Crown Street, LiverpoolL69 7ZD, UK
| | - Thomas Howitt
- School
of Chemistry, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
| | - Alexandra L. Martin
- School
of Chemistry, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
| | - Thomas Arnold
- Diamond
Light Source, Harwell Science and Innovation Campus, Chilton, Didcot, OxfordshireOX11
0DE, UK
- European
Spallation Source ERICPO Box 176, LundSE-221
00, Sweden
- ISIS
Pulsed Neutron and Muon Source, Science and Technology Facilities
Council, Rutherford Appleton Laboratory, Harwell, OxfordshireOX11 0QX, UK
- Department
of Chemistry, University of Bath, Claverton Down, BathBA2 7AY, UK
| | - Jonathan L. Rawle
- Diamond
Light Source, Harwell Science and Innovation Campus, Chilton, Didcot, OxfordshireOX11
0DE, UK
| | - Christopher L. Nicklin
- Diamond
Light Source, Harwell Science and Innovation Campus, Chilton, Didcot, OxfordshireOX11
0DE, UK
| | - Timothy R. Dafforn
- School
of Biosciences, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
| | - Liam R. Cox
- School
of Chemistry, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
| | - Sarah L. Horswell
- School
of Chemistry, University of Birmingham, Edgbaston, BirminghamB15 2TT, UK
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3
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Hybrid bilayer membranes as platforms for biomimicry and catalysis. Nat Rev Chem 2022; 6:862-880. [PMID: 37117701 DOI: 10.1038/s41570-022-00433-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2022] [Indexed: 11/08/2022]
Abstract
Hybrid bilayer membrane (HBM) platforms represent an emerging nanoscale bio-inspired interface that has broad implications in energy catalysis and smart molecular devices. An HBM contains multiple modular components that include an underlying inorganic surface with a biological layer appended on top. The inorganic interface serves as a support with robust mechanical properties that can also be decorated with functional moieties, sensing units and catalytic active sites. The biological layer contains lipids and membrane-bound entities that facilitate or alter the activity and selectivity of the embedded functional motifs. With their structural complexity and functional flexibility, HBMs have been demonstrated to enhance catalytic turnover frequency and regulate product selectivity of the O2 and CO2 reduction reactions, which have applications in fuel cells and electrolysers. HBMs can also steer the mechanistic pathways of proton-coupled electron transfer (PCET) reactions of quinones and metal complexes by tuning electron and proton delivery rates. Beyond energy catalysis, HBMs have been equipped with enzyme mimics and membrane-bound redox agents to recapitulate natural energy transport chains. With channels and carriers incorporated, HBM sensors can quantify transmembrane events. This Review serves to summarize the major accomplishments achieved using HBMs in the past decade.
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Rodríguez-Galván A, Contreras-Torres FF. Scanning Tunneling Microscopy of Biological Structures: An Elusive Goal for Many Years. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3013. [PMID: 36080050 PMCID: PMC9457988 DOI: 10.3390/nano12173013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/29/2022] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
Scanning tunneling microscopy (STM) is a technique that can be used to directly observe individual biomolecules at near-molecular scale. Within this framework, STM is of crucial significance because of its role in the structural analysis, the understanding the imaging formation, and the development of relative techniques. Four decades after its invention, it is pertinent to ask how much of the early dream has come true. In this study, we aim to overview different analyses for DNA, lipids, proteins, and carbohydrates. The relevance of STM imaging is exhibited as an opportunity to assist measurements and biomolecular identification in nanobiotechnology, nanomedicine, biosensing, and other cutting-edge applications. We believe STM research is still an entire science research ecosystem for joining several areas of expertise towards a goal settlement that has been elusive for many years.
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Affiliation(s)
- Andrés Rodríguez-Galván
- Carrera de Biología, Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla 54090, Edo. Mex., Mexico
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5
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Altunayar-Unsalan C, Unsalan O, Mavromoustakos T. Molecular interactions of hesperidin with DMPC/cholesterol bilayers. Chem Biol Interact 2022; 366:110131. [PMID: 36037876 DOI: 10.1016/j.cbi.2022.110131] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 08/05/2022] [Accepted: 08/20/2022] [Indexed: 11/03/2022]
Abstract
Since cell membranes are complex systems, the use of model lipid bilayers is quite important for the study of their interactions with bioactive molecules. Mammalian cell membranes require cholesterol (CHOL) for their structure and function. For this reason, the mixtures of phospholipid and cholesterol are necessary to use in model membrane studies to better simulate the real systems. In the present study, we investigated the effect of the incorporation of hesperidin in model membranes consisting of dimyristoylphosphatidylcholine (DMPC) and CHOL by using differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and atomic force microscopy (AFM). ATR-FTIR results demonstrated that hesperidin increases the fluidity of the DMPC/CHOL binary system. DSC findings indicated that the presence of 5 mol% hesperidin induces a broadening of the main phase transition consisting of three overlapping components. AFM experiments showed that hesperidin increases the thickness of DMPC/CHOL lipid bilayer model membranes. In addition to experimental results, molecular docking studies were conducted with hesperidin and human lanosterol synthase (LS), which is an enzyme found in the final step of cholesterol synthesis, to characterize hesperidin's interactions with its surrounding via its hydroxyl and oxygen groups. Then, hesperidin's ADME/Tox (absorption, distribution, metabolism, excretion and toxicity) profile was computed to see the potential impact on living system. In conclusion, considering the data obtained from experimental studies, this work ensures molecular insights in the interaction between a flavonoid, as an antioxidant drug model, and lipids mimicking those found in mammalian membranes. Moreover, computational studies demonstrated that hesperidin may be a great potential for use as a therapeutic agent for hypercholesterolemia due to its antioxidant property.
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Affiliation(s)
- Cisem Altunayar-Unsalan
- Ege University Central Research Testing and Analysis Laboratory Research and Application Center, 35100, Bornova, Izmir, Turkey.
| | - Ozan Unsalan
- Ege University, Faculty of Science, Department of Physics, 35100, Bornova, Izmir, Turkey.
| | - Thomas Mavromoustakos
- Section of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece.
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6
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Jemmett PN, Milan DC, Nichols RJ, Cox LR, Horswell SL. Effect of Molecular Structure on Electrochemical Phase Behavior of Phospholipid Bilayers on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11887-11899. [PMID: 34590852 DOI: 10.1021/acs.langmuir.1c01975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lipid bilayers form the basis of biological cell membranes, selective and responsive barriers vital to the function of the cell. The structure and function of the bilayer are controlled by interactions between the constituent molecules and so vary with the composition of the membrane. These interactions also influence how a membrane behaves in the presence of electric fields they frequently experience in nature. In this study, we characterize the electrochemical phase behavior of dipalmitoylphosphatidylcholine (DPPC), a glycerophospholipid prevalent in nature and often used in model systems and healthcare applications. DPPC bilayers were formed on Au(111) electrodes using Langmuir-Blodgett and Langmuir-Schaefer deposition and studied with electrochemical methods, atomic force microscopy (AFM) and in situ polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The coverage of the substrate determined with AFM is in accord with that estimated from differential capacitance measurements, and the bilayer thickness is slightly higher than for bilayers of the similar but shorter-chained lipid, dimyristoylphosphatidylcholine (DMPC). DPPC bilayers exhibit similar electrochemical response to DMPC bilayers, but the organization of molecules differs, particularly at negative charge densities. Infrared spectra show that DPPC chains tilt as the charge density on the metal is increased in the negative direction, but, unlike in DMPC, the chains then return to their original tilt angle at the most negative potentials. The onset of the increase in the chain tilt angle coincides with a decrease in solvation around the ester carbonyl groups, and the conformation around the acyl chain linkage differs from that in DMPC. We interpret the differences in behavior between bilayers formed from these structurally similar lipids in terms of stronger dispersion forces between DPPC chains and conclude that relatively subtle changes in molecular structure may have a significant impact on a membrane's response to its environment.
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Affiliation(s)
- Philip N Jemmett
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - David C Milan
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Liam R Cox
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Sarah L Horswell
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
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7
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Cooper TM, Haley JE, Stewart DJ, Long S, Krein DM, Burke AR, Arias E, Moggio I, Turlakov G, Ziolo RF, Biler M, Linares M, Norman P. Nanoscale Organization of a Platinum(II) Acetylide Cholesteric Liquid Crystal Molecular Glass for Photonics Applications. ADVANCED FUNCTIONAL MATERIALS 2020; 30:1910562. [PMID: 32684903 PMCID: PMC7357594 DOI: 10.1002/adfm.201910562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/10/2020] [Accepted: 04/15/2020] [Indexed: 05/22/2023]
Abstract
The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans-Pt(PEt3)2(C≡C-C6H5-C≡N)(C≡C-C6H5-COO-Cholesterol), are described and designated as PE1-CN-Chol. Polarized optical microscopy, differential scanning calorimetry, and wide-angle X-ray scattering experiments show room temperature glassy/crystalline texture with crystal formation upon heating to 165 °C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1-CN-Chol monolayer reveals self-assembly at the solid-liquid interface with an array of two molecules arranged in pairs, oriented head-to-head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials.
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Affiliation(s)
- Thomas M Cooper
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - Joy E Haley
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - David J Stewart
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - Stephanie Long
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - Douglas M Krein
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - Aaron R Burke
- Materials and Manufacturing Directorate Air Force Research Laboratory Wright-Patterson Air Force Base Dayton OH 45433 USA
| | - Eduardo Arias
- Centro de Investigación en Química Aplicada (CIQA) Boulevard Enrique Reyna 140 Saltillo 25294 México
| | - Ivana Moggio
- Centro de Investigación en Química Aplicada (CIQA) Boulevard Enrique Reyna 140 Saltillo 25294 México
| | - Gleb Turlakov
- Centro de Investigación en Química Aplicada (CIQA) Boulevard Enrique Reyna 140 Saltillo 25294 México
| | - Ronald F Ziolo
- Centro de Investigación en Química Aplicada (CIQA) Boulevard Enrique Reyna 140 Saltillo 25294 México
| | - Michal Biler
- Department of Theoretical Chemistry and Biology School of Engineering Sciences in Chemistry, Biotechnology and Health KTH Royal Institute of Technology Stockholm SE-106 91 Sweden
| | - Mathieu Linares
- Department of Theoretical Chemistry and Biology School of Engineering Sciences in Chemistry, Biotechnology and Health KTH Royal Institute of Technology Stockholm SE-106 91 Sweden
| | - Patrick Norman
- Department of Theoretical Chemistry and Biology School of Engineering Sciences in Chemistry, Biotechnology and Health KTH Royal Institute of Technology Stockholm SE-106 91 Sweden
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8
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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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10
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Juhaniewicz-Dębińska J, Tymecka D, Sęk S. Lipopeptide-induced changes in permeability of solid supported bilayers composed of bacterial membrane lipids. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2017.12.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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11
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Konarzewska D, Juhaniewicz J, Güzeloğlu A, Sęk S. Characterization of planar biomimetic lipid films composed of phosphatidylethanolamines and phosphatidylglycerols from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:475-483. [DOI: 10.1016/j.bbamem.2017.01.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 01/03/2017] [Accepted: 01/05/2017] [Indexed: 01/27/2023]
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12
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Shimizu H, Matsunaga S, Yamada T, Kobayashi T, Kawai M. Formation of Ordered Phospholipid Monolayer on a Hydrophilically Modified Au(111) Substrate. ACS NANO 2016; 10:7811-7820. [PMID: 27494363 DOI: 10.1021/acsnano.6b03421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The molecular arrangement of phospholipid molecules was investigated on a hydrophilically modified gold surface within an aqueous solution by scanning tunneling microscopy. By suspending phospholipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC) nanoparticles in the aqueous electrolyte surrounding a hydrophilically modified gold (111) substrate with 3-mercaptopropionic acid (SH-C2H4-COOH, 3-MPA), well-ordered adlattices of POPC were observed. Traces of particle fusion were visualized before formation of the adlattice. Addition of cholesterol to the suspension seems to facilitate accommodation of POPC on this surface. The observed unit cells of POPC adlattices had dimensions of 0.5 nm × 1.9-2.5 nm. By high-resolution imaging, each unit cell was discerned to be occupied by one upright POPC molecule. The POPC + cholesterol suspension also leads to formation of a flat integrated POPC layer, which may be a lipid bilayer covering the surface.
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Affiliation(s)
- Hiroaki Shimizu
- RIKEN , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Advanced Materials Science, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Soichiro Matsunaga
- RIKEN , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Advanced Materials Science, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Taro Yamada
- RIKEN , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | | | - Maki Kawai
- RIKEN , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Advanced Materials Science, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
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13
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Wu HL, Tsao HK, Sheng YJ. Dynamic and mechanical properties of supported lipid bilayers. J Chem Phys 2016; 144:154904. [DOI: 10.1063/1.4947038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Hsing-Lun Wu
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, Department of Physics, National Central University, Jhongli 320, Taiwan
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
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14
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Karan S, Berndt R. Generation of spin in single cholesterol molecules on gold. Phys Chem Chem Phys 2016; 18:9334-7. [PMID: 26948454 DOI: 10.1039/c5cp07410j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Compact islands of cholesterol on Au(111) were investigated with scanning tunneling microscopy at ∼5 K. Single molecules have been switched among several states, three of which exhibit a sharp spectroscopic feature at the Fermi level. This feature signals the presence of a localized spin and suggests that the molecule may be controllably switched between paramagnetic and diamagnetic states.
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Affiliation(s)
- Sujoy Karan
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.
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15
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Two-dimensional self-assembly of melem and melemium cations at pH-controlled aqueous solution–Au(111) interfaces under electrochemical control. Front Chem Sci Eng 2016. [DOI: 10.1007/s11705-016-1564-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Pawłowski J, Juhaniewicz J, Güzeloğlu A, Sęk S. Mechanism of Lipid Vesicles Spreading and Bilayer Formation on a Au(111) Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:11012-9. [PMID: 26010469 DOI: 10.1021/acs.langmuir.5b01331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Spreading of small unilamellar vesicles on solid surfaces is one of the most common ways to obtain supported lipid bilayers. Although the method has been used successfully for many years, the details of this process are still the subject of intense debate. Particularly controversial is the mechanism of bilayer formation on metallic surfaces like gold. In this work, we have employed scanning probe microscopy techniques to evaluate the details of lipid vesicles spreading and formation of the lipid bilayer on a Au(111) surface in a phosphate-buffered saline solution. Nanoscale imaging revealed that the mechanism of this process differs significantly from that usually assumed for hydrophilic surfaces such as mica, glass, and silicon oxide. Formation of the bilayer on gold involves several steps. Initially, the vesicles accumulate on a gold surface and release lipid molecules that adsorb on a Au(111) surface, giving rise to the appearance of highly ordered stripelike domains. The latter serve as a template for the buildup of a hemimicellar film, which contributes to the increased hydrophilicity of the external surface and facilitates further adsorption and rupture of the vesicles. As a result, the bilayer is spread over a hemimicellar film, and then it is followed by slow fusion between coupled layers leading to formation of a single bilayer supported on a gold surface. We believe that the results presented in this work may provide some new insights into the area of research related to supported lipid bilayers.
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Affiliation(s)
- Jan Pawłowski
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw , Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Joanna Juhaniewicz
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw , Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Alişan Güzeloğlu
- 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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17
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Matyszewska D, Brzezińska K, Juhaniewicz J, Bilewicz R. pH dependence of daunorubicin interactions with model DMPC:Cholesterol membranes. Colloids Surf B Biointerfaces 2015. [DOI: 10.1016/j.colsurfb.2015.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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18
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Peng PY, Chiang PC, Chao L. Mobile lipid bilayers on gold surfaces through structure-induced lipid vesicle rupture. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3904-3911. [PMID: 25746237 DOI: 10.1021/la504532a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Forming fluid supported lipid bilayers (SLBs) on a gold surface can enable various lipid-membrane-associated biomolecular interactions to be investigated by several surface sensing techniques, such as surface plasmon resonance and scanning tunneling microscopy. However, forming fluid SLBs on a gold surface through lipid vesicle deposition continues to pose a challenge. In this study, we constructed nanograting structures on a gold surface to induce lipid vesicle rupture for forming a mobile layer of SLBs. Observations based on fluorescence recovery after photobleaching showed that SLBs on the prepared grating supports had some fluidity, while SLBs on the planar support had no fluidity. The anisotropic fluorescence intensity recovery shape changes observed in the SLBs on the grating support suggested that a second layer of SLBs partially formed on top of the first layer in contact with the gold surface and extended along the grating structure. Comparisons of the relative amounts of second bilayer and the fluorescence recovery fractions on supports with various grating edge densities suggested that the second layer formed at the edge regions and that the coverage ratio was directly proportional to the grating edge density. All of these results showed that the grating edges could serve as vesicle-rupture-inducing sites for the formation of a mobile second SLB on a gold surface. The formation of the second layer of SLBs at the edge regions but not in the flat regions enabled us to determine the second layer locations and provided us with an opportunity to pattern mobile lipid bilayers on gold surfaces by controlling the edge locations.
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Affiliation(s)
- Po-Yu Peng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Po-Chieh Chiang
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Ling Chao
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
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19
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Matyszewska D, Sek S, Jabłonowska E, Pałys B, Pawlowski J, Bilewicz R, Konrad F, Osornio YM, Landau EM. Dependence of interfacial film organization on lipid molecular structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:11329-11339. [PMID: 25229461 DOI: 10.1021/la502092g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Combination of surface analytical techniques was employed to investigate the interfacial behavior of the two designed lipids-N-stearoylglycine (1) and its bulky neutral headgroup-containing derivative N-stearoylvaline ethyl ester (2)-at the air-solution interface and as transferred layers on different substrates. Formation of monolayers at the air-water interface was monitored on pure water and on aqueous solutions of different pH. Crystallization effects were visualized at pure water by recording the hystereses in the Langmuir-Blodgett (LB) isotherms and by transferring the layers onto mica, gold (111), and ITO (indium-tin oxide on glass) electrodes. Subphase pH affects the morphology and patch formation in monolayers of 1, as evidenced by BAM measurements. At pH 8.2, formation of well-ordered crystallites is observed, which upon compression elongate according to predominantly 1-D growth mechanism to form a dense layer of crystallites. This effect is not observed in monolayers of 2, whose headgroup is not protonated. The orientation of layers of 1 transferred to the solid supports is also pH dependent, and their stability can be related to formation of a hydrogen-bonded networks. AFM images of 1 exhibited platelets of multilayer phase. The IR spectra of the ITO substrates covered by 1 indicated formation of hydrogen bonds between the amide groups. The nature of the adsorption layer and its organization as a function of potential were studied in-depth by EC STM using Au(111) as the substrate. A model showing the arrangement of hydrogen bonds between adsorbed molecules is presented and related to the observed organization of the layer.
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Affiliation(s)
- Dorota Matyszewska
- Faculty of Chemistry, University of Warsaw , Pasteura 1, 02-093 Warsaw, Poland
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20
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Grossutti M, Seenath R, Conlon S, Leitch JJ, Li J, Lipkowski J. Spectroscopic and permeation studies of phospholipid bilayers supported by a soft hydrogel scaffold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:10862-10870. [PMID: 25147944 DOI: 10.1021/la502925p] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Polarized attenuated total reflection infrared (ATR-IR) spectroscopy, fluorescence microscopy, and fluorescence spectroscopy were used to characterize a lipid coating composed of 70 mol % 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 30 mol % cholesterol, supported on a spherical hydrogel scaffold. The fluorescence microscopy images show an association between the lipid coating and the hydrogel scaffold. Fluorescence permeability measurements revealed that the phospholipid coating acts as a permeability barrier, exhibiting characteristics of a lamellar bilayer coating structure. Variable evanescent wave penetration depth ATR-IR spectroscopy studies validated the determination of quantitative molecular orientation information for a lipid coating supported on a spherical scaffold. These polarized ATR-IR studies measured an average DMPC acyl chain tilt angle of ∼21-25°, with respect to the surface normal.
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Affiliation(s)
- Michael Grossutti
- Department of Chemistry, University of Guelph , Guelph, Ontario N1G 2W1, Canada
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21
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Hibino M, Tsuchiya H. Self-assembled monolayers of cholesterol and cholesteryl esters on graphite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6852-6857. [PMID: 24853476 DOI: 10.1021/la500944t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The molecular arrangements of self-assembled monolayers (SAMs) of cholesterol, cholesteryl laurate, and cholesteryl stearate adsorbed on a graphite surface were studied using scanning tunneling microscopy (STM) at the liquid-solid interface. The STM images of the SAMs showed two-dimensional periodic arrays of bright regions that corresponded to the sterol rings. However, individual sterol rings could not be observed in the bright regions in the STM images of the cholesterol monolayers. Nevertheless, by comparing the STM images and the crystallographic data, it is concluded that the cholesterol molecules are arranged in pairs oriented head-to-head owing to the hydrogen bonds between the hydroxyl groups. These dimers, in turn, are oriented parallel to each other, owing to the interactions between the sterol rings. The STM images of cholesteryl ester monolayers had molecular resolution and showed pairs of cholesteryl ester molecules oriented in an antiparallel manner, with their fatty acid chains located in the central regions. Furthermore, the fatty acid chains of cholesteryl stearate were observed to be oriented in the (1120) zigzag direction of the graphite lattice, whereas those of cholesteryl laurate were oriented in the (1010) armchair direction. These observations reveal that the interactions between the fatty acid chains affect the structure of the SAMs. The molecular arrangements also depend on the lengths of the fatty acid chains of the cholesterol esters and hence on the interactions between the alkyl chains and the graphite surface. The self-assembly at the liquid-solid interface is therefore controlled by the interactions between sterol rings, between alkyl chains, and between alkyl chains and the substrate.
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Affiliation(s)
- Masahiro Hibino
- Department of Applied Science, Muroran Institute of Technology , 27-1 Mizumoto-cho, Muroran 050-8585, Japan
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22
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Lipid bilayers supported on bare and modified gold – Formation, characterization and relevance of lipid rafts. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.07.117] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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23
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Li Y, Liu C, Xie Y, Li X, Fan X, Yuan L, Zeng Q. Single-molecule observation of the K(+)-induced switching of valinomycin within a template network. Chem Commun (Camb) 2014; 49:9021-3. [PMID: 23977669 DOI: 10.1039/c3cc44978e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The K(+)-induced switching of valinomycin has been studied using a molecular template formed by an aromatic oligoamide macrocycle at the liquid/solid interface by scanning tunneling microscopy (STM). Individual valinomycin and its K(+) complex can be identified and resolved in the molecular template, and the high-resolution STM images of valinomycin and its K(+) complex show triangle-like and cyclic structural characteristics, respectively.
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Affiliation(s)
- Yibao Li
- Key Laboratory of Organo-pharmaceutical Chemistry, Gannan Normal University, Ganzhou 341000, P. R. China.
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24
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Uchida T, Osawa M, Lipkowski J. SEIRAS studies of water structure at the gold electrode surface in the presence of supported lipid bilayer. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2013.10.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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25
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Biomimetic Membrane Supported at a Metal Electrode Surface. ADVANCES IN PLANAR LIPID BILAYERS AND LIPOSOMES 2014. [DOI: 10.1016/b978-0-12-418698-9.00001-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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26
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Claridge SA, Thomas JC, Silverman MA, Schwartz JJ, Yang Y, Wang C, Weiss PS. Differentiating amino acid residues and side chain orientations in peptides using scanning tunneling microscopy. J Am Chem Soc 2013; 135:18528-35. [PMID: 24219245 PMCID: PMC4117194 DOI: 10.1021/ja408550a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Single-molecule measurements of complex biological structures such as proteins are an attractive route for determining structures of the large number of important biomolecules that have proved refractory to analysis through standard techniques such as X-ray crystallography and nuclear magnetic resonance. We use a custom-built low-current scanning tunneling microscope to image peptide structures at the single-molecule scale in a model peptide that forms β sheets, a structural motif common in protein misfolding diseases. We successfully differentiate between histidine and alanine amino acid residues, and further differentiate side chain orientations in individual histidine residues, by correlating features in scanning tunneling microscope images with those in energy-optimized models. Beta sheets containing histidine residues are used as a model system due to the role histidine plays in transition metal binding associated with amyloid oligomerization in Alzheimer's and other diseases. Such measurements are a first step toward analyzing peptide and protein structures at the single-molecule level.
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Affiliation(s)
- Shelley A. Claridge
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
| | - John C. Thomas
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
| | - Miles A. Silverman
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
| | - Jeffrey J. Schwartz
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
| | - Yanlian Yang
- National Center for Nanoscience and Technology, Beijing 100190, PR China
| | - Chen Wang
- National Center for Nanoscience and Technology, Beijing 100190, PR China
| | - Paul S. Weiss
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095-7227, United States
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27
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Agmo Hernández V. The theory of metal electronucleation applied to the study of fundamental properties of liposomes. J Solid State Electrochem 2012. [DOI: 10.1007/s10008-012-1874-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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28
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Xu LP, Liu Y, Zhang X. Interfacial self-assembly of amino acids and peptides: scanning tunneling microscopy investigation. NANOSCALE 2011; 3:4901-4915. [PMID: 22057641 DOI: 10.1039/c1nr11070e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Proteins play important roles in human daily life. To take advantage of the lessons learned from nature, it is essential to investigate the self-assembly of subunits of proteins, i.e., amino acids and polypeptides. Due to its high resolution and versatility of working environment, scanning tunneling microscopy (STM) has become a powerful tool for studying interfacial molecular assembly structures. This review is intended to reflect the progress in studying interfacial self-assembly of amino acids and peptides by STM. In particular, we focus on environment-induced polymorphism, chiral recognition, and coadsorption behavior with molecular templates. These studies would be highly beneficial to research endeavors exploring the mechanism and nanoscale-controlling molecular assemblies of amino acids and polypeptides on surfaces, understanding the origin of life, unravelling the essence of disease at the molecular level and deeming what is necessary for the "bottom-up" nanofabrication of molecular devices and biosensors being constructed with useful properties and desired performance.
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Affiliation(s)
- Li-Ping Xu
- Research Center for Bioengineering and Sensing Technology, University of Science & Technology Beijing, Beijing, 100083, PR China.
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29
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Kycia AH, Wang J, Merrill AR, Lipkowski J. Atomic force microscopy studies of a floating-bilayer lipid membrane on a Au(111) surface modified with a hydrophilic monolayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10867-77. [PMID: 21766864 DOI: 10.1021/la2016269] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The surface of a gold electrode was functionalized with a hydrophilic monolayer of 1-thio-β-D-glucose formed by spontaneous self-assembly. The Langmuir-Blodgett/Langmuir-Schaefer (LB/LS) method was then used to assemble a bilayer onto the modified Au(111) surface. The bilayer lipid membrane (BLM) was separated from the Au(111) electrode surface by incorporating the monosialoganglioside GM1 into the inner leaflet of a bilayer composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and cholesterol. To make the inner leaflet, monolayers of GM1/DMPC/cholesterol with mole ratios of 1:6:3, 2:5:3, and 3:4:3 were used. The outer leaflet was composed of a 7:3 mole ratio of DMPC/cholesterol. Because of the amphiphilic properties of GM1, the hydrophobic acyl chains were incorporated into the BLM, whereas the large hydrophilic carbohydrate headgroups were physically adsorbed to the Au(111) electrode surface, creating a "floating" BLM (fBLM). This model contained a water-rich reservoir between the BLM and the gold surface. In addition, because of the bilayer being physically adsorbed onto the support, the fluidity of the BLM was maintained. The compression isotherms were measured at the air/water interface to determine the phase behavior and optimal transfer conditions. The images acquired using atomic force microscopy (AFM) and the force-distance measurements showed that the structure of the fBLM evolved with increasing GM1 content from 10 to 30 mol %, undergoing a transition from a corrugated to a homogeneous phase. This change was associated with a significant increase in bilayer thickness (from ∼5.3 to 7.3 nm). The highest-quality fBLM was produced with 30 mol % GM1.
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Affiliation(s)
- Annia H Kycia
- Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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30
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Agmo Hernández V, Karlsson G, Edwards K. Intrinsic heterogeneity in liposome suspensions caused by the dynamic spontaneous formation of hydrophobic active sites in lipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:4873-4883. [PMID: 21391645 DOI: 10.1021/la1049919] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The spontaneous, dynamic formation of hydrophobic active sites in lipid bilayer membranes is studied and characterized. It is shown that the rates of formation and consumption of these active sites control at least two important properties of liposomes: their affinity for hydrophobic surfaces and the rate by which they spontaneously release encapsulated molecules. The adhesion and spreading of liposomes onto hydrophobic polystyrene nanoparticles and the spontaneous leakage of an encapsulated fluorescent dye were monitored for different liposome compositions employing Cryo-TEM, DLS, and fluorescence measurements. It was observed that an apparently homogeneous, monodisperse liposome suspension behaves as if composed by two different populations: a fast leaking population that presents affinity for the hydrophobic substrate employed, and a slow leaking population that does not attach immediately to it. The results reported here suggest that the proportion of liposomes in each population changes over time until a dynamic equilibrium is reached. It is shown that this phenomenon can lead to irreproducibility in, for example, spontaneous leakage experiments, as extruded liposomes leak much faster just after preparation than 24 h afterward. Our findings account for discrepancies in several experimental results reported in the literature. To our knowledge, this is the first systematic study addressing the issue of an existing intrinsic heterogeneity of liposome suspensions.
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Affiliation(s)
- Víctor Agmo Hernández
- Department of Physical and Analytical Chemistry, Uppsala University, Husargatan 3, Box 579, 75123, Uppsala, Sweden.
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31
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Wang Y, Niu L, Li Y, Mao X, Yang Y, Wang C. Single molecule studies of cyclic peptides using molecular matrix at liquid/solid interface by scanning tunneling microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:16305-16311. [PMID: 20593799 DOI: 10.1021/la101467s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report in this work the single molecule studies of cyclic peptide, cyclosporine A (CsA), using a molecular network formed by star-shaped oligofluorene (StOF-COOH(3)) at the liquid/solid interface by scanning tunneling microscopy (STM). Individual cyclosporine A can be identified and resolved in the molecular network, and the high-resolution STM images of CsA show polygon-like characteristics with a diameter of approximately 1.7 nm. Furthermore, the complex of CsA and Mg(2+) has also been observed to adsorb inside of the molecular matrix. The STM results reveal two adsorption characteristics for the CsA-Mg(2+) complex, which is suggestive of asymmetrical configurations of the complex. The difference in binding energy between the two observed adsorption configurations is estimated to be 1.88 kJ·mol(-1). These results help set the stage for studying the fine structures and functions of various cyclic peptides at the liquid/solid interface.
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Affiliation(s)
- Yibing Wang
- National Center for Nanoscience and Technology, Beijing 100190, PR China
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32
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Abstract
This article describes efforts to build a model biological membrane at a surface of a gold electrode. In this architecture, the membrane may be exposed to static electric fields on the order of 10(7) to 10(8) V m(-1). These fields are comparable in magnitude to the static electric field acting on a natural biological membrane. The field may be conveniently used to manipulate organic molecules within the membrane. By turning a knob on the control instrument one can deposit or lift the membrane from the gold surface. Electrochemical techniques can be used to control the physical state of the film while the infrared reflection absorption spectroscopy (IRRAS), surface imaging by STM and AFM and neutron scattering techniques can be employed to study conformational changes of organic molecules and their ordering within the membrane. This is shown on examples of membranes built of a simple zwitterionic phospholipid such as 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and a mixed membrane composed of DMPC and cholesterol. The results illustrate the tremendous effect of cholesterol on the membrane structure. Two methods of membrane deposition at the electrode surface, namely by unilamellar vesicles fusion and using the Langmuir-Blodgett technique, are compared. Applications of these model systems to study interactions of small antibiotic peptides with lipids are discussed.
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Affiliation(s)
- Jacek Lipkowski
- Department of Chemistry, University of Guelph, Guelph, Ontario, CanadaN1G 2W1.
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33
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Matsunaga S, Matsunaga T, Iwamoto K, Yamada T, Shibayama M, Kawai M, Kobayashi T. Visualization of phospholipid particle fusion induced by duramycin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8200-8207. [PMID: 19432393 DOI: 10.1021/la900616c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We visualized nanometer-scale phospholipid particle fusion by scanning tunneling microscopy (STM) on an alkanethiol-modified gold substrate, induced by duramycin, a tetracyclic antibiotic peptide with 19 amino residues. Ultrasonic homogenization generated a suspension mainly consisting of minimal lipid particles (MLP) from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in a phosphate buffer solution, confirmed by dynamic light scattering (DLS). In situ STM discerned individual MLP as particles (diameter approximately 8 nm) spread on Au(111), modified with alkanethiol, within the suspension. The MLP became fragile by the presence of duramycin, and the MLP were easily scratched by the scanning tip into multilayers along the surface. This process of particle fusion on the gold surface coincides with the aggregation of MLP in the suspension, observed by DLS. It was demonstrated that STM is capable of discerning and monitoring the nanometer-scale features of phospholipid particles altered by antibiotics with biochemical impact. STM might allow in situ, real-space, nanometer-scale observations of minute particles composed of phospholipids within the real cells with the highest magnification ratio.
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Affiliation(s)
- Soichiro Matsunaga
- Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, 277-8561, Japan
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34
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Chen M, Li M, Brosseau CL, Lipkowski J. AFM studies of the effect of temperature and electric field on the structure of a DMPC-cholesterol bilayer supported on a Au(111) electrode surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:1028-1037. [PMID: 19113809 DOI: 10.1021/la802839f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Atomic force microscopy (AFM) was used to characterize a phospholipid bilayer composed of 70 mol % 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 30 mol % cholesterol, at a Au(111) electrode surface. Results indicate that addition of cholesterol relaxes membrane elastic stress, increases membrane thickness, and reduces defect density. The thickness and thermotropic properties of the mixed DMPC-cholesterol bilayer supported at the gold electrode surface are quite similar to the properties of the mixed membrane in unilamellar vesicles. The stability of the supported membrane at potentials negative to the potential of zero charge E(pzc) was investigated. This study demonstrates that the bilayer supported at the gold electrode surface is stable provided the applied potential (E - E(pzc)) is less than -0.3 V. At larger polarizations, swelling of the membrane is observed. Polarizations larger than -1 V cause electrodewetting of the bilayer from the gold surface. At these negative potentials, the bilayer remains in close proximity to the metal surface, separated from it by a approximately 2 nm thick layer of electrolyte.
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Affiliation(s)
- Maohui Chen
- Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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35
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Hernández VA, Milchev A, Scholz F. Study of the temporal distribution of the adhesion-spreading events of liposomes on a mercury electrode. J Solid State Electrochem 2009. [DOI: 10.1007/s10008-008-0770-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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