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Sullivan K, Zhang Y, Lopez J, Lowe M, Noy A. Carbon nanotube porin diffusion in mixed composition supported lipid bilayers. Sci Rep 2020; 10:11908. [PMID: 32681044 PMCID: PMC7368039 DOI: 10.1038/s41598-020-68059-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 05/11/2020] [Indexed: 11/30/2022] Open
Abstract
Carbon nanotube porins (CNTPs), short pieces of carbon nanotubes capable of self-inserting into a lipid bilayer, represent a simplified model of biological membrane channels. We have used high-speed atomic force microscopy (HS-AFM) and all-atom molecular dynamics (MD) simulations to study the behavior of CNTPs in a mixed lipid membrane consisting of DOPC lipid with a variable percentage of DMPC lipid added to it. HS-AFM data reveal that the CNTPs undergo diffusive motion in the bilayer plane. Motion trajectories extracted from the HS-AFM movies indicate that CNTPs exhibit diffusion coefficient values broadly similar to values reported for membrane proteins in supported lipid bilayers. The data also indicate that increasing the percentage of DMPC leads to a marked slowing of CNTP diffusion. MD simulations reveal a CNTP-lipid assembly that diffuses in the membrane and show trends that are consistent with the experimental observations.
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Affiliation(s)
- Kylee Sullivan
- Physics Department, Loyola University Maryland, Baltimore, MD, 21210, USA
| | - Yuliang Zhang
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Joseph Lopez
- Physics Department, Loyola University Maryland, Baltimore, MD, 21210, USA
| | - Mary Lowe
- Physics Department, Loyola University Maryland, Baltimore, MD, 21210, USA.
| | - Aleksandr Noy
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA. .,School of Natural Sciences, University of California Merced, Merced, CA, 94343, USA.
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Raudino A, Pannuzzo M. Nucleation theory with delayed interactions: An application to the early stages of the receptor-mediated adhesion/fusion kinetics of lipid vesicles. J Chem Phys 2010; 132:045103. [DOI: 10.1063/1.3290823] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Templating membrane assembly, structure, and dynamics using engineered interfaces. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:839-50. [PMID: 20079336 DOI: 10.1016/j.bbamem.2009.12.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Revised: 12/22/2009] [Accepted: 12/28/2009] [Indexed: 11/20/2022]
Abstract
The physical and chemical properties of biological membranes are intimately linked to their bounding aqueous interfaces. Supported phospholipid bilayers, obtained by surface-assisted rupture, fusion, and spreading of vesicular microphases, offer a unique opportunity, because engineering the substrate allows manipulation of one of the two bilayer interfaces as well. Here, we review a collection of recent efforts, which illustrates deliberate substrate-membrane coupling using structured surfaces exhibiting chemical and topographic patterns. Vesicle fusion on chemically patterned substrates results in co-existing lipid phases, which reflect the underlying pattern of surface energy and wettability. These co-existing bilayer/monolayer morphologies are useful both for fundamental biophysical studies (e.g., studies of membrane asymmetry) as well as for applied work, such as synthesizing large-scale arrays of bilayers or living cells. The use of patterned, static surfaces provides new models to design complex membrane topographies and curvatures. Dynamic switchable-topography surfaces and sacrificial trehalose based-substrates reveal abilities to dynamically introduce membrane curvature and change the nature of the membrane-substrate interface. Taken together, these studies illustrate the importance of controlling interfaces in devising model membrane platforms for fundamental biophysical studies and bioanalytical devices.
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Ye Q, Konradi R, Textor M, Reimhult E. Liposomes tethered to omega-functional PEG brushes and induced formation of PEG brush supported planar lipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:13534-9. [PMID: 19736981 DOI: 10.1021/la902039g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Self-assembly of planar supported lipid bilayers on top of hydrophilic polymer brushes is a desirable alternative to solid supported lipid bilayers and covalently tethered lipid bilayers for applications like sensing on transmembrane proteins which require a large aqueous volume between membrane and substrate. We present a simple dip-and-rinse method to produce poly(ethylene glycol) (PEG) brushes with sparse positively charged hydrophobic tethers, using poly(l-lysine)-graft-poly(ethylene glycol)-quaternary ammonium compound copolymers. The interaction of such polymer coatings with liposomes of different compositions and the conditions for formation of planar lipid bilayers of extraordinarily high fluidity on top of the >10 nm thick reservoir by liposome self-assembly and sequentially triggered rupture are investigated.
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Affiliation(s)
- Qiong Ye
- Swiss Federal Institute of Technology, Laboratory for Surface Science and Technology, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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Meledandri CJ, Perlo J, Farrher E, Brougham DF, Anoardo E. Interpretation of Molecular Dynamics on Different Time Scales in Unilamellar Vesicles Using Field-Cycling NMR Relaxometry. J Phys Chem B 2009; 113:15532-40. [DOI: 10.1021/jp907084s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carla J. Meledandri
- National Institute for Cellular Biotechnology, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and Larte - Famaf. Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (CONICET), Córdoba, Argentina
| | - Josefina Perlo
- National Institute for Cellular Biotechnology, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and Larte - Famaf. Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (CONICET), Córdoba, Argentina
| | - Ezequiel Farrher
- National Institute for Cellular Biotechnology, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and Larte - Famaf. Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (CONICET), Córdoba, Argentina
| | - Dermot F. Brougham
- National Institute for Cellular Biotechnology, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and Larte - Famaf. Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (CONICET), Córdoba, Argentina
| | - Esteban Anoardo
- National Institute for Cellular Biotechnology, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, and Larte - Famaf. Universidad Nacional de Córdoba and Instituto de Física Enrique Gaviola (CONICET), Córdoba, Argentina
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Negishi M, Seto H, Hase M, Yoshikawa K. How does the mobility of phospholipid molecules at a water/oil interface reflect the viscosity of the surrounding oil? LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8431-8434. [PMID: 18646878 DOI: 10.1021/la8015172] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The mobility of phospholipid molecules at a water/oil interface on cell-sized phospholipid-coated microdroplets was investigated through the measurement of diffusion constants by fluorescence recovery after photobleaching. It is found that the diffusion constant of phospholipids showed the relation D approximately (eta water + eta oil) -0.85, where D is the diffusion constant, eta water is the viscosity of water, and eta oil is the viscosity of oil. This observation indicates that the viscosity of the surrounding oil is the primary factor that determines the diffusibility of phospholipids at a water/oil interface.
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Affiliation(s)
- Makiko Negishi
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
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Oliver AE, Kendall EL, Howland MC, Sanii B, Shreve AP, Parikh AN. Protecting, patterning, and scaffolding supported lipid membranes using carbohydrate glasses. LAB ON A CHIP 2008; 8:892-897. [PMID: 18497908 DOI: 10.1039/b800370j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Disaccharides are known to protect sensitive biomolecules against stresses caused by dehydration, both in vivo and in vitro. Here we demonstrate how interfacial accumulation of trehalose can be used to (1) produce rugged supported lipid bilayers capable of near total dehydration; (2) enable spatial patterning of membrane micro-arrays; and (3) form stable bilayers on otherwise lipophobic substrates (e.g., metal transducers) thus affording protecting, patterning, and scaffolding of lipid bilayers.
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Affiliation(s)
- Ann E Oliver
- Department of Applied Science, University of California-Davis, 1 Shields Ave., Davis, CA 95616, USA.
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Pucadyil TJ, Chattopadhyay A. Confocal Fluorescence Recovery After Photobleaching of Green Fluorescent Protein in Solution. J Fluoresc 2006; 16:87-94. [PMID: 16397826 DOI: 10.1007/s10895-005-0019-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Accepted: 09/27/2005] [Indexed: 10/25/2022]
Abstract
Fluorescence recovery after photobleaching (FRAP) is one of the most widely used approaches to quantitatively estimate diffusion characteristics of molecules in solution and cellular systems. In general, comparison of the diffusion times (t (1/2)) from a FRAP experiment provides qualitative estimates of diffusion rates. However, obtaining consistent and reliable quantitative estimates of mobility of molecules using FRAP is hindered by the lack of appropriate standards for calibrating the FRAP set-up (microscope configuration and data fitting algorithms) used in a given experiment. In comparison with other fluorescent markers, the green fluorescent proteins (GFP) possess characteristics that are ideal for use in such experiments. We have monitored the mobility of pure enhanced green fluorescent protein (EGFP) in a viscous solution by confocal FRAP experiments. Our experimentally determined diffusion coefficient of EGFP in a glycerol-water mixture is in excellent agreement with the value predicted for GFP in a solution of comparable viscosity, calculated using the Stokes-Einstein equation. The agreement in the experimentally determined diffusion coefficient and that predicted from theoretical framework improves significantly when one takes into account the effective size of the bleached spot in such experiments. Our results therefore validate the use of GFP as a convenient standard for FRAP experiments. Importantly, we present a simple method to correct for artifacts in the accurate determination of diffusion coefficient of molecules measured using FRAP arising due to the underestimation in the effective size of the bleached spot.
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Affiliation(s)
- Thomas J Pucadyil
- Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
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Menger FM, Chlebowski ME, Galloway AL, Lu H, Seredyuk VA, Sorrells JL, Zhang H. A tribute to the phospholipid. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:10336-41. [PMID: 16262289 DOI: 10.1021/la0508691] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Fredric M Menger
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
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Howland MC, Sapuri-Butti AR, Dixit SS, Dattelbaum AM, Shreve AP, Parikh AN. Phospholipid morphologies on photochemically patterned silane monolayers. J Am Chem Soc 2005; 127:6752-65. [PMID: 15869298 DOI: 10.1021/ja043439q] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have studied the spreading of phospholipid vesicles on photochemically patterned n-octadecylsiloxane monolayers using epifluorescence and imaging ellipsometry measurements. Self-assembled monolayers of n-octadecylsiloxanes were patterned using short-wavelength ultraviolet radiation and a photomask to produce periodic arrays of patterned hydrophilic domains separated from hydrophobic surroundings. Exposing these patterned surfaces to a solution of small unilamellar vesicles of phospholipids and their mixtures resulted in a complex lipid layer morphology epitaxially reflecting the underlying pattern of hydrophilicity. The hydrophilic square regions of the photopatterned OTS monolayer reflected lipid bilayer formation, and the hydrophobic OTS residues supported lipid monolayers. We further observed the existence of a boundary region composed of a nonfluid lipid phase and a lipid-free moat at the interface between the lipid monolayer and bilayer morphologies spontaneously corralling the fluid bilayers. The outer-edge of the boundary region was found to be accessible for subsequent adsorption by proteins (e.g., streptavidin and BSA), but the inner-edge closer to the bilayer remained resistant to adsorption by protein or vesicles. Mechanistic implications of our results in terms of the effects of substrate topochemical character are discussed. Furthermore, our results provide a basis for the construction of complex biomembrane models, which exhibit fluidity barriers and differentiate membrane properties based on correspondence between lipid leaflets. We also envisage the use of this construct where two-dimensionally fluid, low-defect lipid layers serve as sacrificial resists for the deposition of protein and other material patterns.
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Affiliation(s)
- Michael C Howland
- Department of Applied Science, University of California, Davis, CA 95616, USA
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Ng CC, Cheng YL, Pennefather PS. Properties of a self-assembled phospholipid membrane supported on lipobeads. Biophys J 2005; 87:323-31. [PMID: 15240467 PMCID: PMC1304353 DOI: 10.1529/biophysj.103.030627] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The overall objective of our work was to make a hydrogel-supported phospholipid bilayer that models a cytoskeleton-supported cell membrane and provides a platform for studying membrane biology. Previously, we demonstrated that a pre-Lipobead, consisting of phospholipids covalently attached to the surface of a hydrogel, could give rise to a Lipobead when incubated with liposomes because the attached phospholipids promote self-assembly of a phospholipid membrane on the pre-Lipobead. We now report the properties of that Lipobead membrane. The lateral diffusion coefficient of fluorescently labeled phosphatidylcholine analogs in the membrane was measured by fluorescence recovery after photobleaching and was found to decrease as the surface anchor density and hydrogel crosslinking density increased. Results from the quenching of phosphatidylcholine analogs suggest that the phospholipid membrane of the Lipobead was composed mostly of a semipermeable lipid bilayer. However, the diffusional barrier properties of the Lipobead membrane were demonstrated by the entrapment of 1.5-3.0 K dextran molecules in the hydrogel core after liposome fusion. This hydrogel-supported bilayer membrane preparation shows promise as a new platform for studying membrane biology and for high throughput drug screening.
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Affiliation(s)
- Charlene C Ng
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
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Turnheim K, Gruber J, Wachter C, Ruiz-Gutiérrez V. Membrane phospholipid composition affects function of potassium channels from rabbit colon epithelium. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:C83-90. [PMID: 10409111 DOI: 10.1152/ajpcell.1999.277.1.c83] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the effects of membrane phospholipids on the function of high-conductance, Ca(2+)-activated K(+) channels from the basolateral cell membrane of rabbit distal colon epithelium by reconstituting these channels into planar bilayers consisting of different 1:1 mixtures of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI). At low ambient K(+) concentrations single-channel conductance is higher in PE/PS and PE/PI bilayers than in PE/PC bilayers. At high K(+) concentrations this difference in channel conductance is abolished. Introducing the negatively charged SDS into PE/PC bilayers increases channel conductance, whereas the positively charged dodecyltrimethylammonium has the opposite effect. All these findings are consistent with modulation of channel current by the charge of the lipid membrane surrounding the channel. But the K(+) that permeates the channel senses only a small fraction of the full membrane surface potential of the charged phospholipid bilayers, equivalent to separation of the conduction pathway from the charged phospholipid head groups by 20 A. This distance appears to insulate the channel entrance from the bilayer surface potential, suggesting large dimensions of the channel-forming protein. In addition, in PE/PC and PE/PI bilayers, but not in PE/PS bilayers, the open-state probability of the channel decreases with time ("channel rundown"), indicating that phospholipid properties other than surface charge are required to maintain channel fluctuations.
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Affiliation(s)
- K Turnheim
- Pharmakologisches Institut, Universität Wien, A-1090 Vienna, Austria.
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Fulbright RM, Axelrod D, Dunham WR, Marcelo CL. Fatty acid alteration and the lateral diffusion of lipids in the plasma membrane of keratinocytes. Exp Cell Res 1997; 233:128-34. [PMID: 9184082 DOI: 10.1006/excr.1997.3553] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The fluorescent probe diI was used to study the lateral mobility of lipids in in vitro strains of living adult human keratinocytes grown in four different media. One medium was essential fatty acid deficient (EFAD) and low in calcium ion, a medium known to yield cells that proliferate rapidly and contain lipid with extremely low levels of essential fatty acids. Two other media were supplemented with essential fatty acids (FAS), media that are known to result in cells that grow more slowly and have normalized fatty acid proportions. A fourth medium consisted of 1 microM all-trans-retinoic acid added to the fatty acid-supplemented medium (FAS-RA), a medium known to produce cells that are highly proliferative, with a growth rate greater than that of the FAS strains and similar to that of the EFAD strains. The keratinocytes grown in these four media were studied using the fluorescence recovery after photobleaching (FRAP) technique to determine the lateral diffusion rate of diI in the plasma membranes. Our results showed a positive correlation between growth rate and diffusion coefficient (D): the diffusion coefficient of diI was higher in the EFAD or FAS-RA cells than in the FAS cells. The measurement of D among the FAS cells fell into two groups. One group was similar to the single group seen in the EFAD cells, but the other group was composed of much lower D values. The other FRAP parameters (mobile fraction and bleach depth) were larger in the "slow" group than in the "fast" group. This trend of negative correlation between these parameters and D was also found within the fast group. These results are interpreted in terms of possible changes in membrane structure or morphology that might be indirectly associated with the fatty acid alterations, including the possible presence of areas in senescing keratinocytes where plasma membranes collapse to form an interacting system of lipid bilayers.
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Affiliation(s)
- R M Fulbright
- Biophysics Research Division, University of Michigan, Ann Arbor 48109-1055, USA
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