151
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Kalinowski A, Yaron PN, Qin Z, Shenoy S, Buehler MJ, Lösche M, Dahl KN. Interfacial binding and aggregation of lamin A tail domains associated with Hutchinson-Gilford progeria syndrome. Biophys Chem 2014; 195:43-8. [PMID: 25194277 PMCID: PMC4212650 DOI: 10.1016/j.bpc.2014.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/28/2014] [Accepted: 08/03/2014] [Indexed: 12/16/2022]
Abstract
Hutchinson-Gilford progeria syndrome is a premature aging disorder associated with the expression of ∆50 lamin A (∆50LA), a mutant form of the nuclear structural protein lamin A (LA). ∆50LA is missing 50 amino acids from the tail domain and retains a C-terminal farnesyl group that is cleaved from the wild-type LA. Many of the cellular pathologies of HGPS are thought to be a consequence of protein-membrane association mediated by the retained farnesyl group. To better characterize the protein-membrane interface, we quantified binding of purified recombinant ∆50LA tail domain (∆50LA-TD) to tethered bilayer membranes composed of phosphatidylserine and phosphocholine using surface plasmon resonance. Farnesylated ∆50LA-TD binds to the membrane interface only in the presence of Ca(2+) or Mg(2+) at physiological ionic strength. At extremely low ionic strength, both the farnesylated and non-farnesylated forms of ∆50LA-TD bind to the membrane surface in amounts that exceed those expected for a densely packed protein monolayer. Interestingly, the wild-type LA-TD with no farnesylation also associates with membranes at low ionic strength but forms only a single layer. We suggest that electrostatic interactions are mediated by charge clusters with a net positive charge that we calculate on the surface of the LA-TDs. These studies suggest that the accumulation of ∆50LA at the inner nuclear membrane observed in cells is due to a combination of aggregation and membrane association rather than simple membrane binding; electrostatics plays an important role in mediating this association.
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Affiliation(s)
- Agnieszka Kalinowski
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States
| | - Peter N Yaron
- Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States
| | - Zhao Qin
- Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
| | - Siddharth Shenoy
- Department of Physics, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States
| | - Markus J Buehler
- Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
| | - Mathias Lösche
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States; Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
| | - Kris Noel Dahl
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States.
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152
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Tabaei SR, Jackman JA, Kim SO, Liedberg B, Knoll W, Parikh AN, Cho NJ. Formation of cholesterol-rich supported membranes using solvent-assisted lipid self-assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13345-52. [PMID: 25286344 DOI: 10.1021/la5034433] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
This paper describes the application of a solvent-exchange method to prepare supported membranes containing high fractions of cholesterol (up to ∼57 mol %) in an apparent equilibrium. The method exploits the phenomenon of reverse-phase evaporation, in which the deposition of lipids in alcohol (e.g., isopropanol) is followed by the slow removal of the organic solvent from the water-alcohol mixture. This in turn induces a series of lyotropic phase transitions successively producing inverse-micelles, monomers, micelles, and vesicles in equilibrium with supported bilayers at the contacting solid surface. By using the standard cholesterol depletion by methyl-β-cyclodextrin treatment, a quartz crystal microbalance with dissipation monitoring assay confirms that the cholesterol concentration in the supported membranes is comparable to that in the surrounding bulk phase. A quantitative characterization of the biophysical properties of the resultant bilayer, including lateral diffusion constants and phase separation, using epifluorescence microscopy and atomic force microscopy establishes the formation of laterally contiguous supported lipid bilayers, which break into a characteristic domain-pattern of coexisting phases in a cholesterol concentration-dependent manner. With increasing cholesterol fraction in the supported bilayer, the size of the domains increases, ultimately yielding two-dimensional cholesterol bilayer domains near the solubility limit. A unique feature of the approach is that it enables preparation of supported membranes containing limiting concentrations of cholesterol near the solubility limit under equilibrium conditions, which cannot be obtained using conventional techniques (i.e., vesicle fusion).
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Affiliation(s)
- Seyed R Tabaei
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore
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153
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Saboe PO, Lubner CE, McCool NS, Vargas-Barbosa NM, Yan H, Chan S, Ferlez B, Bazan GC, Golbeck JH, Kumar M. Two-dimensional protein crystals for solar energy conversion. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:7064-9. [PMID: 25155990 DOI: 10.1002/adma.201402375] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/18/2014] [Indexed: 05/03/2023]
Abstract
Two-dimensional photosynthetic protein crystals provide a high density of aligned reaction centers. We reconstitute the robust light harvesting protein Photosystem I into a 2D crystal with lipids and integrate the crystals into a photo-electrochemical device. A 4-fold photocurrent enhancement is measured by incorporating conjugated oligoelectrolytes to form a supporting conductive bilayer in the device which produces a high photocurrent of ∼600 μA per mg PSI deposited.
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Affiliation(s)
- Patrick O Saboe
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
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154
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Nanda H, Heinrich F, Lösche M. Membrane association of the PTEN tumor suppressor: neutron scattering and MD simulations reveal the structure of protein-membrane complexes. Methods 2014; 77-78:136-46. [PMID: 25461777 DOI: 10.1016/j.ymeth.2014.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 12/31/2022] Open
Abstract
Neutron reflection (NR) from planar interfaces is an emerging technology that provides unique and otherwise inaccessible structural information on disordered molecular systems such as membrane proteins associated with fluid bilayers, thus addressing one of the remaining challenges of structural biology. Although intrinsically a low-resolution technique, using structural information from crystallography or NMR allows the construction of NR models that describe the architecture of protein-membrane complexes at high resolution. In addition, a combination of these methods with molecular dynamics (MD) simulations has the potential to reveal the dynamics of protein interactions with the bilayer in atomistic detail. We review recent advances in this area by discussing the application of these techniques to the complex formed by the PTEN phosphatase with the plasma membrane. These studies provide insights in the cellular regulation of PTEN, its interaction with PI(4,5)P2 in the inner plasma membrane and the pathway by which its substrate, PI(3,4,5)P3, accesses the PTEN catalytic site.
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Affiliation(s)
- Hirsh Nanda
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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155
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Barclay TG, Constantopoulos K, Matisons J. Nanotubes Self-Assembled from Amphiphilic Molecules via Helical Intermediates. Chem Rev 2014; 114:10217-91. [DOI: 10.1021/cr400085m] [Citation(s) in RCA: 185] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Thomas G. Barclay
- Flinders Centre for Nanoscale Science & Technology, School of Chemical and Physical Sciences, Flinders University, Adelaide, South Australia 5042, Australia
| | - Kristina Constantopoulos
- Flinders Centre for Nanoscale Science & Technology, School of Chemical and Physical Sciences, Flinders University, Adelaide, South Australia 5042, Australia
| | - Janis Matisons
- Flinders Centre for Nanoscale Science & Technology, School of Chemical and Physical Sciences, Flinders University, Adelaide, South Australia 5042, Australia
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156
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Stereoselective synthesis of perdeuterated phytanic acid, its phospholipid derivatives and their formation into lipid model membranes for neutron reflectivity studies. Chem Phys Lipids 2014; 183:22-33. [DOI: 10.1016/j.chemphyslip.2014.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 04/01/2014] [Accepted: 04/07/2014] [Indexed: 11/23/2022]
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157
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Cranfield CG, Cornell BA, Grage SL, Duckworth P, Carne S, Ulrich AS, Martinac B. Transient potential gradients and impedance measures of tethered bilayer lipid membranes: pore-forming peptide insertion and the effect of electroporation. Biophys J 2014; 106:182-9. [PMID: 24411250 DOI: 10.1016/j.bpj.2013.11.1121] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/13/2013] [Accepted: 11/15/2013] [Indexed: 10/25/2022] Open
Abstract
In this work, we present experimental data, supported by a quantitative model, on the generation and effect of potential gradients across a tethered bilayer lipid membrane (tBLM) with, to the best of our knowledge, novel architecture. A challenge to generating potential gradients across tBLMs arises from the tethering coordination chemistry requiring an inert metal such as gold, resulting in any externally applied voltage source being capacitively coupled to the tBLM. This in turn causes any potential across the tBLM assembly to decay to zero in milliseconds to seconds, depending on the level of membrane conductance. Transient voltages applied to tBLMs by pulsed or ramped direct-current amperometry can, however, provide current-voltage (I/V) data that may be used to measure the voltage dependency of the membrane conductance. We show that potential gradients >~150 mV induce membrane defects that permit the insertion of pore-forming peptides. Further, we report here the novel (to our knowledge) use of real-time modeling of conventional low-voltage alternating-current impedance spectroscopy to identify whether the conduction arising from the insertion of a polypeptide is uniform or heterogeneous on scales of nanometers to micrometers across the membrane. The utility of this tBLM architecture and these techniques is demonstrated by characterizing the resulting conduction properties of the antimicrobial peptide PGLa.
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Affiliation(s)
- Charles G Cranfield
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Australia.
| | | | - Stephan L Grage
- Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany
| | | | - Sonia Carne
- Surgical Diagnostics, Roseville, New South Wales, Australia
| | - Anne S Ulrich
- Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Australia
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158
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Gurnev PA, Nestorovich EM. Channel-forming bacterial toxins in biosensing and macromolecule delivery. Toxins (Basel) 2014; 6:2483-540. [PMID: 25153255 PMCID: PMC4147595 DOI: 10.3390/toxins6082483] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/08/2014] [Accepted: 08/08/2014] [Indexed: 12/19/2022] Open
Abstract
To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on "Intracellular Traffic and Transport of Bacterial Protein Toxins", reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, α-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their "second life" in a variety of developing medical and technological applications.
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Affiliation(s)
- Philip A Gurnev
- Physics Department, University of Massachusetts, Amherst, MA 01003, USA.
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159
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Kwon S, Chen ZCY, Noh H, Lee JH, Liu H, Cha JN, Xiang J. Selective functionalization and loading of biomolecules in crystalline silicon nanotube field-effect-transistors. NANOSCALE 2014; 6:7847-7852. [PMID: 24926535 DOI: 10.1039/c4nr01508h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm(2) V(-1) s(-1) in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length.
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Affiliation(s)
- Soonshin Kwon
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA.
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160
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Schuster B, Sleytr UB. Biomimetic interfaces based on S-layer proteins, lipid membranes and functional biomolecules. J R Soc Interface 2014; 11:20140232. [PMID: 24812051 PMCID: PMC4032536 DOI: 10.1098/rsif.2014.0232] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/15/2014] [Indexed: 12/20/2022] Open
Abstract
Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state-of-the-art survey of how S-layer proteins, lipids and polymers may be used as basic building blocks for the assembly of S-layer-supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and, thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas in the (lab-on-a-) biochip technology are combining composite S-layer membrane systems involving specific membrane functions with the silicon world. Thus, it might become possible to create artificial noses or tongues, where many receptor proteins have to be exposed and read out simultaneously. Moreover, S-layer-coated liposomes and emulsomes copying virus envelopes constitute promising nanoformulations for the production of novel targeting, delivery, encapsulation and imaging systems.
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Affiliation(s)
- Bernhard Schuster
- Department of NanoBiotechnology, University of Natural Resources and Life Sciences, Institute for Synthetic Bioarchitectures, Muthgasse 11, 1190 Vienna, Austria
| | - Uwe B. Sleytr
- Department of NanoBiotechnology, University of Natural Resources and Life Sciences, Institute for Biophysics, Muthgasse 11, 1190 Vienna, Austria
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161
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Mathuriya AS, Yakhmi JV. Microbial fuel cells – Applications for generation of electrical power and beyond. Crit Rev Microbiol 2014; 42:127-43. [DOI: 10.3109/1040841x.2014.905513] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - J. V. Yakhmi
- Atomic Energy Education Society, Western Sector, Mumbai, Maharashtra, India
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162
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Silva-López EI, Edens LE, Barden AO, Keller DJ, Brozik JA. Conditions for liposome adsorption and bilayer formation on BSA passivated solid supports. Chem Phys Lipids 2014; 183:91-9. [PMID: 24911903 DOI: 10.1016/j.chemphyslip.2014.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 06/02/2014] [Accepted: 06/04/2014] [Indexed: 12/14/2022]
Abstract
Planar solid supported lipid membranes that include an intervening bovine serum albumen (BSA) cushion can greatly reduce undesirable interactions between reconstituted membrane proteins and the underlying substrate. These hetero-self-assemblies reduce frictional coupling by shielding reconstituted membrane proteins from the strong surface charge of the underlying substrate, thereby preventing them from strongly sticking to the substrate themselves. The motivation for this work is to describe the conditions necessary for liposome adsorption and bilayer formation on these hetero-self-assemblies. Described here are experiments that show that the state of BSA is critically important to whether a lipid bilayer is formed or intact liposomes are adsorbed to the BSA passivated surface. It is shown that a smooth layer of native BSA will readily promote lipid bilayer formation while BSA that has been denatured either chemically or by heat will not. Atomic force microscopy (AFM) and fluorescence microscopy was used to characterize the surfaces of native, heat denatured, and chemically reduced BSA. The mobility of several zwitterionic and negatively charged lipid combinations has been measured using fluorescence recovery after photobleaching (FRAP). From these measurements diffusion constants and percent recoveries have been determined and tabulated. The effect of high concentrations of beta-mercaptoethanol (β-ME) on liposome formation as well as bilayer formation was also explored.
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Affiliation(s)
- Elsa I Silva-López
- Department of Chemistry, Washington State University, PO Box 644630, Pullman, WA 99164-4630, United States
| | - Lance E Edens
- Department of Chemistry and Biological Chemistry, University of New Mexico, Albuquerque, NM 87131-0001, United States
| | - Adam O Barden
- Department of Chemistry, Washington State University, PO Box 644630, Pullman, WA 99164-4630, United States
| | - David J Keller
- Department of Chemistry and Biological Chemistry, University of New Mexico, Albuquerque, NM 87131-0001, United States
| | - James A Brozik
- Department of Chemistry, Washington State University, PO Box 644630, Pullman, WA 99164-4630, United States.
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163
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Wang YY, Pham TD, Zand K, Li J, Burke PJ. Charging the quantum capacitance of graphene with a single biological ion channel. ACS NANO 2014; 8:4228-38. [PMID: 24754625 PMCID: PMC4046776 DOI: 10.1021/nn501376z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 04/22/2014] [Indexed: 05/22/2023]
Abstract
The interaction of cell and organelle membranes (lipid bilayers) with nanoelectronics can enable new technologies to sense and measure electrophysiology in qualitatively new ways. To date, a variety of sensing devices have been demonstrated to measure membrane currents through macroscopic numbers of ion channels. However, nanoelectronic based sensing of single ion channel currents has been a challenge. Here, we report graphene-based field-effect transistors combined with supported lipid bilayers as a platform for measuring, for the first time, individual ion channel activity. We show that the supported lipid bilayers uniformly coat the single layer graphene surface, acting as a biomimetic barrier that insulates (both electrically and chemically) the graphene from the electrolyte environment. Upon introduction of pore-forming membrane proteins such as alamethicin and gramicidin A, current pulses are observed through the lipid bilayers from the graphene to the electrolyte, which charge the quantum capacitance of the graphene. This approach combines nanotechnology with electrophysiology to demonstrate qualitatively new ways of measuring ion channel currents.
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Affiliation(s)
- Yung Yu Wang
- Department of Chemical Engineering and Materials Science, Department of Biomedical Engineering, Department of Physics and Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States
| | - Ted D. Pham
- Department of Chemical Engineering and Materials Science, Department of Biomedical Engineering, Department of Physics and Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States
| | - Katayoun Zand
- Department of Chemical Engineering and Materials Science, Department of Biomedical Engineering, Department of Physics and Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States
| | - Jinfeng Li
- Department of Chemical Engineering and Materials Science, Department of Biomedical Engineering, Department of Physics and Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States
| | - Peter J. Burke
- Department of Chemical Engineering and Materials Science, Department of Biomedical Engineering, Department of Physics and Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States
- Address correspondence to
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164
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Singh S, Su Z, Grossutti M, Auzanneau FI. Attempts to prepare tethered bilayer lipid membranes using synthetic thioglycolipid anchors: synthesis of 6″-thiotrisaccharide glycolipid analogues and applications. Carbohydr Res 2014; 390:50-8. [PMID: 24704433 DOI: 10.1016/j.carres.2014.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/07/2014] [Accepted: 03/08/2014] [Indexed: 11/29/2022]
Abstract
The synthesis of the three 6″-deoxy-6″-thio glycolipid analogues β-d-Gal-(1→6)-β-d-Gal-(1→4)-β-d-Glu-(1→OCH2)-[1,2,3]-triazole-1-dodecane, β-d-Gal-(1→4)-β-d-Glu-(1→4)-β-d-Glu-(1→OCH2)-[1,2,3]-triazole-1-dodecane and β-d-Gal-(1→4)-β-d-Glu-(1→4)-β-d-Glu-(1→OCH2)-[1,2,3]-triazole-1-octadecane is presented. Glycosylation at position O-4' of a propargyl cellobioside glycosyl acceptor and position O-6' of a propargyl lactoside glycosyl acceptor with a 6-deoxy-6-thio galactosyl donor gave rise to two unique trisaccharides that in turn underwent copper-catalyzed azide-alkyne cycloadditions with either 1-azidododecane or 1-azidooctadecane. The potential for each of these analogues to function as tethers of lipid bilayers to Au(111) surface was assessed by differential capacitance experiments. A monolayer of the previously described monosaccharide 1-octadecane-4-(6-thio-β-d-galacto-pyranosyloxymethyl)-[1,2,3]-triazole either self-assembled or prepared by Langmuir-Blodgett (LB) transfer was found to support an outer leaflet monolayer (DMPC/cholesterol, 70:30) deposited by Langmuir-Schaefer (LS) touch. The bilayers obtained with this monosaccharide analogue had minimum differential capacitances of 1.0 and 0.9μF/cm(2) when the inner monolayer was prepared by self-assembly and LS touch, respectively. Attempts to produce bilayers using the trisaccharides synthesized here were unsuccessful; we are attributing these unsuccessful results mostly to the high water solubility of trisaccharides combined with the relatively short length of the hydrocarbon chains used in this study.
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Affiliation(s)
- Serena Singh
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Zhangfei Su
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Michael Grossutti
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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165
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Reconstitution of Bacteriorhodopsin into Cyclic Lipid Vesicles. Biosci Biotechnol Biochem 2014; 72:1623-5. [DOI: 10.1271/bbb.80050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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166
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Kim BJ, Um SH, Song WC, Kim YH, Kang MS, Cho JH. Water-gel for gating graphene transistors. NANO LETTERS 2014; 14:2610-2616. [PMID: 24773325 DOI: 10.1021/nl500446s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Water, the primary electrolyte in biology, attracts significant interest as an electrolyte-type dielectric material for transistors compatible with biological systems. Unfortunately, the fluidic nature and low ionic conductivity of water prevents its practical usage in such applications. Here, we describe the development of a solid state, megahertz-operating, water-based gate dielectric system for operating graphene transistors. The new electrolyte systems were prepared by dissolving metal-substituted DNA polyelectrolytes into water. The addition of these biocompatible polyelectrolytes induced hydrogelation to provide solid-state integrity to the system. They also enhanced the ionic conductivities of the electrolytes, which in turn led to the quick formation of an electric double layer at the graphene/electrolyte interface that is beneficial for modulating currents in graphene transistors at high frequencies. At the optimized conditions, the Na-DNA water-gel-gated flexible transistors and inverters were operated at frequencies above 1 MHz and 100 kHz, respectively.
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Affiliation(s)
- Beom Joon Kim
- SKKU Advanced Institute of Nanotechnology (SAINT), ‡School of Chemical Engineering, and §Department of Chemistry, Sungkyunkwan University , Suwon 440-746, Korea
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167
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Brown P, Wood T, Badyal J. Combining plasmachemical emulsion-templating with ATRP to create macroporous lipophilic surfaces. J Colloid Interface Sci 2014; 421:44-8. [DOI: 10.1016/j.jcis.2014.01.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 11/29/2022]
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168
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Tronin A, Nordgren CE, Strzalka JW, Kuzmenko I, Worcester DL, Lauter V, Freites JA, Tobias DJ, Blasie JK. Direct evidence of conformational changes associated with voltage gating in a voltage sensor protein by time-resolved X-ray/neutron interferometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4784-4796. [PMID: 24697545 PMCID: PMC4007984 DOI: 10.1021/la500560w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Indexed: 06/03/2023]
Abstract
The voltage sensor domain (VSD) of voltage-gated cation (e.g., Na(+), K(+)) channels central to neurological signal transmission can function as a distinct module. When linked to an otherwise voltage-insensitive, ion-selective membrane pore, the VSD imparts voltage sensitivity to the channel. Proteins homologous with the VSD have recently been found to function themselves as voltage-gated proton channels or to impart voltage sensitivity to enzymes. Determining the conformational changes associated with voltage gating in the VSD itself in the absence of a pore domain thereby gains importance. We report the direct measurement of changes in the scattering-length density (SLD) profile of the VSD protein, vectorially oriented within a reconstituted phospholipid bilayer membrane, as a function of the transmembrane electric potential by time-resolved X-ray and neutron interferometry. The changes in the experimental SLD profiles for both polarizing and depolarizing potentials with respect to zero potential were found to extend over the entire length of the isolated VSD's profile structure. The characteristics of the changes observed were in qualitative agreement with molecular dynamics simulations of a related membrane system, suggesting an initial interpretation of these changes in terms of the VSD's atomic-level 3-D structure.
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Affiliation(s)
- Andrey
Y. Tronin
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - C. Erik Nordgren
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joseph W. Strzalka
- X-ray
Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Ivan Kuzmenko
- X-ray
Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - David L. Worcester
- Department
of Physiology & Biophysics, University
of California Irvine, Irvine, California 92697, United States
| | - Valeria Lauter
- Spallation
Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - J. Alfredo Freites
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Douglas J. Tobias
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - J. Kent Blasie
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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169
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Thomas M, Corry B, Hilder TA. What have we learnt about the mechanisms of rapid water transport, ion rejection and selectivity in nanopores from molecular simulation? SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:1453-1465. [PMID: 24851242 DOI: 10.1002/smll.201302968] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nanopores have demonstrated an extraordinary ability to allow water molecules to pass through their interiors at rates far exceeding expectations based on continuum theory. Moreover, simulation studies suggest that particular nanoscale pores have the potential to discriminate between water and salts as well as to distinguish between a range of different ion types. Some of the unusual features of transport in these nanopores have been elucidated with molecular dynamics simulation, specifically the spontaneous filling and rapid transport of water, the rejection of ions and the selection between ions. The main focus of this review, however, is the physical mechanisms which act to produce such remarkable behaviour at this scale, drawing on the many studies that have been conducted in the last decade. Since molecular dynamics simulations allow the motion of individual atoms to be followed over time, they have the potential to provide fundamental insight into the reasons why transport in nanoscale pores differs from expectations based on macroscopic theory. Gaining an understanding of the mechanisms of transport in these tiny pores should guide future experiments in this area aimed at developing novel technologies and improving existing membrane separation techniques.
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170
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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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171
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Onaizi SA, Nasser MS, Twaiq F. Lysozyme binding to tethered bilayer lipid membranes prepared by rapid solvent exchange and vesicle fusion methods. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:191-8. [DOI: 10.1007/s00249-014-0955-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/07/2014] [Accepted: 03/13/2014] [Indexed: 11/30/2022]
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172
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Wiedman G, Fuselier T, He J, Searson PC, Hristova K, Wimley WC. Highly efficient macromolecule-sized poration of lipid bilayers by a synthetically evolved peptide. J Am Chem Soc 2014; 136:4724-31. [PMID: 24588399 PMCID: PMC3985440 DOI: 10.1021/ja500462s] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Indexed: 12/30/2022]
Abstract
Peptides that self-assemble, at low concentration, into bilayer-spanning pores which allow the passage of macromolecules would be beneficial in multiple areas of biotechnology. However, there are few, if any, natural or designed peptides that have this property. Here we show that the 26-residue peptide "MelP5", a synthetically evolved gain-of-function variant of the bee venom lytic peptide melittin identified in a high-throughput screen for small molecule leakage, enables the passage of macromolecules across bilayers under conditions where melittin and other pore-forming peptides do not. In surface-supported bilayers, MelP5 forms unusually high conductance, equilibrium pores at peptide:lipid ratios as low as 1:25000. The increase in bilayer conductance due to MelP5 is dramatically higher, per peptide, than the increase due to the parent sequence of melittin or other peptide pore formers. Here we also develop two novel assays for macromolecule leakage from vesicles, and we use them to characterize MelP5 pores in bilayers. We show that MelP5 allows the passage of macromolecules across vesicle membranes at peptide:lipid ratios as low as 1:500, and under conditions where neither osmotic lysis nor gross vesicle destabilization occur. The macromolecule-sized, equilibrium pores formed by MelP5 are unique as neither melittin nor other pore-forming peptides release macromolecules significantly under the same conditions. MelP5 thus appears to belong to a novel functional class of peptide that could form the foundation of multiple potential biotechnological applications.
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Affiliation(s)
- Gregory Wiedman
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Taylor Fuselier
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Jing He
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Peter C. Searson
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kalina Hristova
- Department
of Materials Science and Engineering, Johns
Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for Nanobiotechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - William C. Wimley
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
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173
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Martinac B, Nomura T, Chi G, Petrov E, Rohde PR, Battle AR, Foo A, Constantine M, Rothnagel R, Carne S, Deplazes E, Cornell B, Cranfield CG, Hankamer B, Landsberg MJ. Bacterial mechanosensitive channels: models for studying mechanosensory transduction. Antioxid Redox Signal 2014; 20:952-69. [PMID: 23834368 DOI: 10.1089/ars.2013.5471] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SIGNIFICANCE Sensations of touch and hearing are manifestations of mechanical contact and air pressure acting on touch receptors and hair cells of the inner ear, respectively. In bacteria, osmotic pressure exerts a significant mechanical force on their cellular membrane. Bacteria have evolved mechanosensitive (MS) channels to cope with excessive turgor pressure resulting from a hypo-osmotic shock. MS channel opening allows the expulsion of osmolytes and water, thereby restoring normal cellular turgor and preventing cell lysis. RECENT ADVANCES As biological force-sensing systems, MS channels have been identified as the best examples of membrane proteins coupling molecular dynamics to cellular mechanics. The bacterial MS channel of large conductance (MscL) and MS channel of small conductance (MscS) have been subjected to extensive biophysical, biochemical, genetic, and structural analyses. These studies have established MscL and MscS as model systems for mechanosensory transduction. CRITICAL ISSUES In recent years, MS ion channels in mammalian cells have moved into focus of mechanotransduction research, accompanied by an increased awareness of the role they may play in the pathophysiology of diseases, including cardiac hypertrophy, muscular dystrophy, or Xerocytosis. FUTURE DIRECTIONS A recent exciting development includes the molecular identification of Piezo proteins, which function as nonselective cation channels in mechanosensory transduction associated with senses of touch and pain. Since research on Piezo channels is very young, applying lessons learned from studies of bacterial MS channels to establishing the mechanism by which the Piezo channels are mechanically activated remains one of the future challenges toward a better understanding of the role that MS channels play in mechanobiology.
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Affiliation(s)
- Boris Martinac
- 1 Molecular Cardiology and Biophysics Division/Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute , Darlinghurst, Australia
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174
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Heinrich F, Nanda H, Goh HZ, Bachert C, Lösche M, Linstedt AD. Myristoylation restricts orientation of the GRASP domain on membranes and promotes membrane tethering. J Biol Chem 2014; 289:9683-91. [PMID: 24505136 DOI: 10.1074/jbc.m113.543561] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian Golgi reassembly stacking protein (GRASP) proteins are Golgi-localized homotypic membrane tethers that organize Golgi stacks into a long, contiguous ribbon-like structure. It is unknown how GRASPs undergo trans pairing given that cis interactions between the proteins in the plane of the membrane are intrinsically favored. To test the hypothesis that myristoylation of the self-interacting GRASP domain restricts its orientation on the membrane to favor trans pairing, we established an in vitro assay that recapitulates GRASP-dependent membrane tethering and used neutron reflection under similar conditions to determine the orientation of the GRASP domain. In vivo, the membrane association of GRASP proteins is conferred by the simultaneous insertion of an N-terminal myristic acid and binding to a Golgi-associated binding partner. In our assay, the latter contact was replaced using a C-terminal hexa-His moiety, which bound to Ni(2+)-conjugated lipids incorporated into a substrate-supported bilayer lipid membrane. Nonmyristoylated protein lacked a fixed orientation on the membrane and inefficiently tethered liposomes. In contrast, myristoylated GRASP promoted tethering and exhibited a unique membrane complex. Thus, myristoylation restricts the membrane orientation of the GRASP domain favoring interactions in trans for membrane tethering.
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175
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Sugawara M, Shoji A, Sakamoto M. Pore-forming compounds as signal transduction elements for highly sensitive biosensing. ANAL SCI 2014; 30:119-28. [PMID: 24420253 DOI: 10.2116/analsci.30.119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pore-forming compounds are attracting much attention due to the signal transduction ability for the development of highly sensitive biosensing. In this review, we describe an overview of the recent advances made by our group in the design of molecular sensing interfaces of spherical and planar lipid bilayers and natural bilayers. The potential uses of pore-forming compounds, such as gramicidin and MCM-41, in lipid bilayers and natural glutamate receptor channels in biomembrane are presented.
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Affiliation(s)
- Masao Sugawara
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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176
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Markowski T, Drescher S, Meister A, Blume A, Dobner B. Structure–property relationships in a series of diglycerol tetraether model lipids and their lyotropic assemblies: the effect of branching topology and chirality. Org Biomol Chem 2014; 12:3649-62. [DOI: 10.1039/c4ob00048j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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177
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Drescher S, Dobner B. Synthesis of Novel Asymmetrical Single-Chain Phosphoglycol-Based Bolaamphiphiles. SYNTHETIC COMMUN 2013. [DOI: 10.1080/00397911.2013.825806] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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178
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Czogalla A, Grzybek M, Jones W, Coskun U. Validity and applicability of membrane model systems for studying interactions of peripheral membrane proteins with lipids. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:1049-59. [PMID: 24374254 DOI: 10.1016/j.bbalip.2013.12.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/12/2013] [Accepted: 12/17/2013] [Indexed: 12/11/2022]
Abstract
The cell membrane serves, at the same time, both as a barrier that segregates as well as a functional layer that facilitates selective communication. It is characterized as much by the complexity of its components as by the myriad of signaling process that it supports. And, herein lays the problems in its study and understanding of its behavior - it has a complex and dynamic nature that is further entangled by the fact that many events are both temporal and transient in their nature. Model membrane systems that bypass cellular complexity and compositional diversity have tremendously accelerated our understanding of the mechanisms and biological consequences of lipid-lipid and protein-lipid interactions. Concurrently, in some cases, the validity and applicability of model membrane systems are tarnished by inherent methodical limitations as well as undefined quality criteria. In this review we introduce membrane model systems widely used to study protein-lipid interactions in the context of key parameters of the membrane that govern lipid availability for peripheral membrane proteins. This article is part of a Special Issue entitled Tools to study lipid functions.
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Affiliation(s)
- Aleksander Czogalla
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany.
| | - Michał Grzybek
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany
| | - Walis Jones
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany
| | - Unal Coskun
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany.
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179
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Wilkop TE, Sanborn J, Oliver AE, Hanson JM, Parikh AN. On-Demand Self-Assembly of Supported Membranes Using Sacrificial, Anhydrobiotic Sugar Coats. J Am Chem Soc 2013; 136:60-3. [DOI: 10.1021/ja410866w] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Thomas E. Wilkop
- Department
of Biomedical Engineering, University of California, Davis, California, 95616 United States
| | - Jeremy Sanborn
- Applied
Science Graduate Group, University of California, Davis, California, 95616 United States
| | - Ann E. Oliver
- Department
of Biomedical Engineering, University of California, Davis, California, 95616 United States
| | - Joshua M. Hanson
- Biophysics
Graduate Group, University of California, Davis, California, 95616 United States
| | - Atul N. Parikh
- Department
of Biomedical Engineering, University of California, Davis, California, 95616 United States
- Applied
Science Graduate Group, University of California, Davis, California, 95616 United States
- Biophysics
Graduate Group, University of California, Davis, California, 95616 United States
- Department of Chemical Engineering & Materials Science, University of California, Davis, California, 95616 United States
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180
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Weng B, Morrin A, Shepherd R, Crowley K, Killard AJ, Innis PC, Wallace GG. Wholly printed polypyrrole nanoparticle-based biosensors on flexible substrate. J Mater Chem B 2013; 2:793-799. [PMID: 32261311 DOI: 10.1039/c3tb21378a] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Printing has been widely used in the sensor industry for its speed, low cost and production scalability. In this work we present a wholly-printed polypyrrole (PPy) based biosensor produced by inkjet printing bioinks composed of dispersions of PPy nanoparticles and enzymes onto screen-printed carbon electrodes. Two enzymes, horseradish peroxidase (HRP) or glucose oxidase (GoD) were incorporated into the PPy nanoparticle dispersions to impart biosensing functionality and selectivity into the conducting polymer ink. Further functionality was also introduced by deposition of a permselective ethyl cellulose (EC) membrane using inkjet printing. Cyclic voltammetry (CV) and chrono-amperometry were used to characterize the response of the PPy biosensors to H2O2 and glucose. Results demonstrated the possibility of PPy based biosensor fabrication using the rapid and low cost technique of inkjet printing. The detection range of H2O2 was found to be 10 μM-10 mM and for glucose was 1-5 mM.
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Affiliation(s)
- Bo Weng
- Chongqing Key Lab for Advanced Materials & Clean Energies of Techonologies, Institute for Clean Energy and Advanced Materials, Southwest University, 2 Tiansheng Rd, Beibei, Chongqing, China 400715
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181
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Mayer M, Yang J. Engineered ion channels as emerging tools for chemical biology. Acc Chem Res 2013; 46:2998-3008. [PMID: 23932142 DOI: 10.1021/ar400129t] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Over the last 25 years, researchers have developed exogenously expressed, genetically engineered, semi-synthetic, and entirely synthetic ion channels. These structures have sufficient fidelity to serve as unique tools that can reveal information about living organisms. One of the most exciting success stories is optogenetics: the use of light-gated channels to trigger action potentials in specific neurons combined with studies of the response from networks of cells or entire live animals. Despite this breakthrough, the use of molecularly engineered ion channels for studies of biological systems is still in its infancy. Historically, researchers studied ion channels in the context of their own function in single cells or in multicellular signaling and regulation. Only recently have researchers considered ion channels and pore-forming peptides as responsive tools to report on the chemical and physical changes produced by other biochemical processes and reactions. This emerging class of molecular probes has a number of useful characteristics. For instance, these structures can greatly amplify the signal of chemical changes: the binding of one molecule to a ligand-gated ion channel can result in flux of millions of ions across a cell membrane. In addition, gating occurs on sub-microsecond time scales, resulting in fast response times. Moreover, the signal is complementary to existing techniques because the output is ionic current rather than fluorescence or radioactivity. And finally, ion channels are also localized at the membrane of cells where essential processes such as signaling and regulation take place. This Account highlights examples, mostly from our own work, of uses of ion channels and pore-forming peptides such as gramicidin in chemical biology. We discuss various strategies for preparing synthetically tailored ion channels that range from de novo designed synthetic molecules to genetically engineered or simply exogenously expressed or reconstituted wild-type channels. Next we consider aspects of experimental design by comparing various membrane environments or systems that make it possible to quantify the response of ion channels to biochemical processes of interest. We present applications of ion channels to answer questions in chemical biology, and propose potential future developments and applications of these single molecule probes. Finally we discuss the hurdles that impede the routine use of ion channel probes in biochemistry and cell biology laboratories and developments and strategies that could overcome these problems. Optogenetics has facilitated breakthroughs in neuroscience, and these results give a dramatic idea of what may lie ahead for designed ion channels as a functional class of molecular probes. If researchers can improve molecular engineering to increase ion channel versatility and can overcome the barriers to collaborating across disciplines, we conclude that these structures could have tremendous potential as novel tools for chemical biology studies.
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Affiliation(s)
- Michael Mayer
- Department of Chemical Engineering and Department of Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109-2110, United States
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, California 92093-0358, United States
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182
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Futaki S, Noshiro D, Kiwada T, Asami K. Extramembrane control of ion channel peptide assemblies, using alamethicin as an example. Acc Chem Res 2013; 46:2924-33. [PMID: 23680081 DOI: 10.1021/ar400051f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ion channels allow the influx and efflux of specific ions through a plasma membrane. Many ion channels can sense, for example, the membrane potential (the voltage gaps between the inside and the outside of the membrane), specific ligands such as neurotransmitters, and mechanical tension within the membrane. They modulate cell function in response to these stimuli. Researchers have focused on developing peptide- and non-peptide-based model systems to elucidate ion-channel protein functions and to create artificial sensing systems. In this Account, we employed a typical peptide that forms ion channels,alamethicin, as a model to evaluate our methodologies for controlling the assembly states of channel-forming molecules in membranes. As alamethicin self-assembles in membranes, it prompts channel formation, but number of peptide molecules in these channels is not constant. Using planar-lipid bilayer methods, we monitored the association states of alamethicin in real time. Many ligand-gated, natural-ion channel proteins have large extramembrane domains. As these proteins interact with specific ligands, those conformational alterations in the extramembrane domains are transmitted to the transmembrane, pore-forming domains to open and close the channels. We hypothesized that if we conjugated suitable extramembrane segments to alamethicin, ligand binding to the extramembrane segments could alter the structure of the extramembrane domains and influence the association states or association numbers of alamethicin in the membranes. We could then assess those changes by using single-channel current recording. We found that we could modulate channel assembly and eventual ion flux with attached leucine-zipper extramembrane peptide segments. Using conformationally switchable leucine-zipper extramembrane segments that respond to Fe(3+), we fabricated an artificial Fe(3+)-sensitive ion channel; a decrease in the helical content of the extramembrane segment led to an increase in the channel current. When we added a calmodulin C-terminus segment, we formed a channel that was sensitive to Ca(2+). This result demonstrated that we could prepare artificial channels that were sensitive to specific ligands by adding appropriate extramembrane segments from natural protein motifs that respond to external stimuli. In conclusion, our research points to the possibility of creating tailored sensor or signal transduction systems through the conjugation of a conformationally switchable extramembrane peptide/protein segment to a suitable transmembrane peptide segment.
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Affiliation(s)
- Shiroh Futaki
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Daisuke Noshiro
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tatsuto Kiwada
- Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Koji Asami
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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183
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Budvytyte R, Pleckaityte M, Zvirbliene A, Vanderah DJ, Valincius G. Reconstitution of cholesterol-dependent vaginolysin into tethered phospholipid bilayers: implications for bioanalysis. PLoS One 2013; 8:e82536. [PMID: 24349307 PMCID: PMC3862629 DOI: 10.1371/journal.pone.0082536] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/24/2013] [Indexed: 11/18/2022] Open
Abstract
Functional reconstitution of the cholesterol-dependent cytolysin vaginolysin (VLY) from Gardnerella vaginalis into artificial tethered bilayer membranes (tBLMs) has been accomplished. The reconstitution of VLY was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes of the EIS parameters of the tBLMs upon exposure to VLY solutions were consistent with the formation of water-filled pores in the membranes. It was found that reconstitution of VLY is a strictly cholesterol-dependent, irreversible process. At a constant cholesterol concentration reconstitution of VLY occurred in a concentration-dependent manner, thus allowing the monitoring of VLY concentration and activity in vitro and opening possibilities for tBLM utilization in bioanalysis. EIS methodology allowed us to detect VLY down to 0.5 nM (28 ng/mL) concentration. Inactivation of VLY by certain amino acid substitutions led to noticeably lesser tBLM damage. Pre-incubation of VLY with the neutralizing monoclonal antibody 9B4 inactivated the VLY membrane damage in a concentration-dependent manner, while the non-neutralizing antibody 21A5 exhibited no effect. These findings demonstrate the biological relevance of the interaction between VLY and the tBLM. The membrane-damaging interaction between VLY and tBLM was observed in the absence of the human CD59 receptor, known to strongly facilitate the hemolytic activity of VLY. Taken together, our study demonstrates the applicability of tBLMs as a bioanalytical platform for the detection of the activity of VLY and possibly other cholesterol-dependent cytolysins.
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Affiliation(s)
- Rima Budvytyte
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
- Bio Complexity Department, The Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark
| | - Milda Pleckaityte
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Aurelija Zvirbliene
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - David J. Vanderah
- Biomolecular Structure and Function Group, National Institute of Standards and Technology at Institute of Bioscience and Biotechnology Research, Rockville, Maryland, United States of America
| | - Gintaras Valincius
- Department of Bioelectrochemistry and Biospectroscopy, Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
- * E-mail:
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184
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Cortie MB, Nafea EH, Chen H, Valenzuela SM, Ting SS, Sonvico F, Milthorpe B. Nanomedical research in Australia and New Zealand. Nanomedicine (Lond) 2013; 8:1999-2006. [PMID: 24279489 DOI: 10.2217/nnm.13.179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Although Australia and New Zealand have a combined population of less than 30 million, they have an active and interlinked community of nanomedical researchers. This report provides a synopsis and update on this network with a view to identifying the main topics of interest and their likely future trajectories. In addition, our report may also serve to alert others to opportunities for joint projects. Australian and New Zealand researchers are engaged in most of the possible nanomedical topics, but the majority of interest is focused on drug and nucleic acid delivery using nanoparticles or nanoporous constructs. There are, however, smaller programs directed at hyperthermal therapy and radiotherapy, various kinds of diagnostic tests and regenerative technologies.
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Affiliation(s)
- Michael B Cortie
- Institute for Nanoscale Technology, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Sydney, Australia
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185
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Minner DE, Herring VL, Siegel AP, Kimble-Hill A, Johnson MA, Naumann CA. Iterative layer-by-layer assembly of polymer-tethered multi-bilayers using maleimide–thiol coupling chemistry. SOFT MATTER 2013; 9:9643-9650. [PMID: 26029773 DOI: 10.1039/c3sm51446c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The current study reports on the layer-by-layer assembly of a polymer-tethered lipid multi-bilayer stack using the iterative addition and roll out of giant unilamellar vesicles (GUVs) containing constituents with thiol and maleimide functional groups, respectively. Confocal microscopy and photobleaching experiments confirm stack integrity and stability over time, as well as the lateral fluidity of individual bilayers within the stacks. Complementary wide-field single molecule fluorescence microscopy and atomic force microscopy experiments show that increasing bilayer-substrate distances are associated with changes in lipid lateral mobility and bilayer morphology. Importantly, the described iterative approach can be employed to assemble multi-bilayer stacks with more than two bilayers, thus further reducing the influence of the underlying solid substrate on membrane behavior. Furthermore, the presence of lipopolymers within the multi-bilayer stacks results in fascinating membrane dynamics and organization properties, with interesting parallels to those found in plasma membranes. In that sense, the described multi-bilayer architecture represents an attractive model membrane platform for a variety of different biophysical studies.
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Affiliation(s)
- Daniel E Minner
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202-3274, USA
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186
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Tronin A, Chen CH, Gupta S, Worcester D, Lauter V, Strzalka J, Kuzmenko I, Blasie JK. Structural changes in single membranes in response to an applied transmembrane electric potential revealed by time-resolved neutron/X-ray interferometry. Chem Phys 2013; 422. [PMID: 24222930 DOI: 10.1016/j.chemphys.2013.01.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The profile structure of a hybrid lipid bilayer, tethered to the surface of an inorganic substrate and fully hydrated with a bulk aqueous medium in an electrochemical cell, was investigated as a function of the applied transbilayer electric potential via time-resolved neutron reflectivity, enhanced by interferometry. Significant, and fully reversible structural changes were observed in the distal half (with respect to the substrate surface) of the hybrid bilayer comprised of a zwitterionic phospholipid in response to a +100mV potential with respect to 0mV. These arise presumably due to reorientation of the electric dipole present in the polar headgroup of the phospholipid and its resulting effect on the thickness of the phospholipid's hydrocarbon chain layer within the hybrid bilayer's profile structure. The profile structure of the voltage-sensor domain from a voltage-gated ion channel protein within a phospholipid bilayer membrane, tethered to the surface of an inorganic substrate and fully hydrated with a bulk aqueous medium in an electrochemical cell, was also investigated as a function of the applied transmembrane electric potential via time-resolved X-ray reflectivity, enhanced by interferometry. Significant, fully-reversible, and different structural changes in the protein were detected in response to ±100mV potentials with respect to 0mV. The approach employed is that typical of transient spectroscopy, shown here to be applicable to both neutron and X-ray reflectivity of thin films.
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Affiliation(s)
- A Tronin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
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187
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Siontorou CG, Batzias FA. A methodological combined framework for roadmapping biosensor research: a fault tree analysis approach within a strategic technology evaluation frame. Crit Rev Biotechnol 2013; 34:31-55. [PMID: 23919240 DOI: 10.3109/07388551.2013.790339] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Biosensor technology began in the 1960s to revolutionize instrumentation and measurement. Despite the glucose sensor market success that revolutionized medical diagnostics, and artificial pancreas promise currently the approval stage, the industry is reluctant to capitalize on other relevant university-produced knowledge and innovation. On the other hand, the scientific literature is extensive and persisting, while the number of university-hosted biosensor groups is growing. Considering the limited marketability of biosensors compared to the available research output, the biosensor field has been used by the present authors as a suitable paradigm for developing a methodological combined framework for "roadmapping" university research output in this discipline. This framework adopts the basic principles of the Analytic Hierarchy Process (AHP), replacing the lower level of technology alternatives with internal barriers (drawbacks, limitations, disadvantages), modeled through fault tree analysis (FTA) relying on fuzzy reasoning to count for uncertainty. The proposed methodology is validated retrospectively using ion selective field effect transistor (ISFET) - based biosensors as a case example, and then implemented prospectively membrane biosensors, putting an emphasis on the manufacturability issues. The analysis performed the trajectory of membrane platforms differently than the available market roadmaps that, considering the vast industrial experience in tailoring and handling crystallic forms, suggest the technology path of biomimetic and synthetic materials. The results presented herein indicate that future trajectories lie along with nanotechnology, and especially nanofabrication and nano-bioinformatics, and focused, more on the science-path, that is, on controlling the natural process of self-assembly and the thermodynamics of bioelement-lipid interaction. This retained the nature-derived sensitivity of the biosensor platform, pointing out the differences between the scope of academic research and the market viewpoint.
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Affiliation(s)
- Christina G Siontorou
- Department of Industrial Management and Technology, University of Piraeus , Karaoli and Dimitriou, Piraeus , Greece
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188
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Budvytyte R, Valincius G, Niaura G, Voiciuk V, Mickevicius M, Stauffer H, Goh HZ, Shekhar P, Heinrich F, Shenoy S, Lösche M, Vanderah DJ. Structure and properties of tethered bilayer lipid membranes with unsaturated anchor molecules. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8645-56. [PMID: 23745652 PMCID: PMC3753044 DOI: 10.1021/la401132c] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The self-assembled monolayers (SAMs) of new lipidic anchor molecule HC18 [Z-20-(Z-octadec-9-enyloxy)-3,6,9,12,15,18,22-heptaoxatetracont-31-ene-1-thiol] and mixed HC18/β-mercaptoethanol (βME) SAMs were studied by spectroscopic ellipsometry, contact angle measurements, reflection-absorption infrared spectroscopy, and electrochemical impedance spectroscopy (EIS) and were evaluated in tethered bilayer lipid membranes (tBLMs). Our data indicate that HC18, containing a double bond in the alkyl segments, forms highly disordered SAMs up to anchor/βME molar fraction ratios of 80/20 and result in tBLMs that exhibit higher lipid diffusion coefficients relative to those of previous anchor compounds with saturated alkyl chains, as determined by fluorescence correlation spectroscopy. EIS data shows the HC18 tBLMs, completed by rapid solvent exchange or vesicle fusion, form more easily than with saturated lipidic anchors, exhibit excellent electrical insulating properties indicating low defect densities, and readily incorporate the pore-forming toxin α-hemolysin. Neutron reflectivity measurements on HC18 tBLMs confirm the formation of complete tBLMs, even at low tether compositions and high ionic lipid compositions. Our data indicate that HC18 results in tBLMs with improved physical properties for the incorporation of integral membrane proteins (IMPs) and that 80% HC18 tBLMs appear to be optimal for practical applications such as biosensors where high electrical insulation and IMP/peptide reconstitution are imperative.
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Affiliation(s)
- Rima Budvytyte
- Institute of Biochemistry, Vilnius University, Vilnius, LT-08662, Lithuania
| | - Gintaras Valincius
- Institute of Biochemistry, Vilnius University, Vilnius, LT-08662, Lithuania
| | - Gediminas Niaura
- Institute of Biochemistry, Vilnius University, Vilnius, LT-08662, Lithuania
| | - Vladislava Voiciuk
- Institute of Biochemistry, Vilnius University, Vilnius, LT-08662, Lithuania
| | | | - Hilary Stauffer
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Hood College, Frederick, MD 21701
| | - Haw-Zan Goh
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213
| | | | - Frank Heinrich
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Siddharth Shenoy
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Mathias Lösche
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - David J. Vanderah
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
- Institute for Bioscience and Biotechnology Research, Rockville, MD 20850
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189
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Synergizing nucleic acid aptamers with 1-dimensional nanostructures as label-free field-effect transistor biosensors. Biosens Bioelectron 2013; 50:278-93. [PMID: 23872609 DOI: 10.1016/j.bios.2013.06.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/06/2013] [Accepted: 06/17/2013] [Indexed: 01/04/2023]
Abstract
Since the introduction by Gold et al. in 1990, nucleic acid aptamers had evolved to become a true contender in biosensors for protein and cell detections. Aptamers are short strands of synthetically designed DNA or RNA oligonucleotides that can be self-assembled into unique 3-dimensional structures and can bind to different proteins, cells or even small molecules at a high level of specificity and affinity. In recent years, there had been many reports in literature in using aptamers in place of conventional antibodies as capture biomolecules on the surface. This is mainly due to the better thermal stability properties and ease in production. Consequently, also these characteristics allowed the aptamers to find use in field effect transistors (FETs) based upon 1D nanostructured (1D-NS) as label-free biosensing. In terms of designing label-free platforms for biosensors applications, 1D-NS FET had been an attractive option due to reported high sensitivities toward protein targets arising from the large surface area for detection as well as to their label-free nature. Since the first aptamer-based 1D-NS FET biosensor had surfaced in 2005, there had been many more improvements in the overall design and sensitivity in recent years. In this review, the latest developments in synergizing these two interesting areas of research (aptamers and 1D-NS FET) will be discussed for a range of different nanowire types as well as for the detection results.
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190
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Park M, Tsai SL, Chen W. Microbial biosensors: engineered microorganisms as the sensing machinery. SENSORS 2013; 13:5777-95. [PMID: 23648649 PMCID: PMC3690029 DOI: 10.3390/s130505777] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/18/2013] [Accepted: 05/03/2013] [Indexed: 01/10/2023]
Abstract
Whole-cell biosensors are a good alternative to enzyme-based biosensors since they offer the benefits of low cost and improved stability. In recent years, live cells have been employed as biosensors for a wide range of targets. In this review, we will focus on the use of microorganisms that are genetically modified with the desirable outputs in order to improve the biosensor performance. Different methodologies based on genetic/protein engineering and synthetic biology to construct microorganisms with the required signal outputs, sensitivity, and selectivity will be discussed.
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Affiliation(s)
- Miso Park
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA; E-Mail:
| | - Shen-Long Tsai
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan; E-Mail:
| | - Wilfred Chen
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-302-831-6327; Fax: +1-302-831-1048
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191
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Impedance and dielectric characterizations of ionic partitioning in interfaces that membranous, biomimetic and gold surfaces form with electrolytes. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.03.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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192
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Tsuji Y, Kawano R, Osaki T, Kamiya K, Miki N, Takeuchi S. Droplet-based lipid bilayer system integrated with microfluidic channels for solution exchange. LAB ON A CHIP 2013; 13:1476-81. [PMID: 23450304 DOI: 10.1039/c3lc41359d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This paper proposes a solution exchange of a droplet-based lipid bilayer system, in which the inner solution of a droplet is replaced for the purpose of efficient ion channel analyses. In our previous report, we successfully recorded the channel conductance of alpha-hemolysin in a bilayer lipid membrane using a droplet contact method that can create a spontaneous lipid bilayer at the interface of contacting droplets; this method is widely used as highly efficient method for preparing planar lipid membranes. When only pipetting droplets of the solution, this method is highly efficient for preparing lipid membranes. However, the drawback of droplet-based systems is their inability to exchange the solution within the droplets. To study the effect of inhibitors and promoters of ion channels in drug discovery, it would be beneficial to conduct a solution exchange of droplets to introduce membrane proteins and to apply or wash-out the chemicals. In this study, we propose a droplet contact method that allows for the solution exchange of droplets via microfluidic channels. We experimentally and numerically investigated the bilayer stability with respect to exchanging flow rates, and then demonstrated a binding assay of an alpha-hemolysin using one of its blockers. The solution exchange in this system was conducted in less than 20 s without rupturing the membrane. We believe that the proposed system will enhance the efficiency of ion channel analyses.
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Affiliation(s)
- Yutaro Tsuji
- Kanagawa Academy of Science and Technology (KAST), KSP EAST 303, 3-2-1, Sakado, Kawasaki, Kanagawa, Japan
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193
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Gui AL, Yau HM, Thomas DS, Chockalingam M, Harper JB, Gooding JJ. Using supramolecular binding motifs to provide precise control over the ratio and distribution of species in multiple component films grafted on surfaces: demonstration using electrochemical assembly from aryl diazonium salts. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4772-4781. [PMID: 23527551 DOI: 10.1021/la400358e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Supramolecular interactions between two surface modification species are explored to control the ratio and distribution of these species on the resultant surface. A binary mixture of aryl diazonium salts bearing oppositely charged para-substituents (either -SO3(-) or -N(+)(Me)3), which also reduce at different potentials, has been examined on glassy carbon surfaces using cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Striking features were observed: (1) the two aryl diazonium salts in the mixed solution undergo reductive adsorption at the same potential which is distinctively less negative than the potential required for the reduction of either of the two aryl diazonium salts alone; (2) the surface ratio of the two phenyl derivatives is consistently 1:1 regardless of the ratio of the two aryl diazonium salts in the modification solutions. Homogeneous distribution of the two oppositely charged phenyl species on the modified surface has also been suggested by XPS survey spectra. Diffusion coefficient measurements by DOSY NMR and DFT based computation have indicated the association of the two aryl diazonium species in the solution, which has led to changes in the molecular orbital energies of the two species. This study highlights the potential of using intermolecular interactions to control the assembly of multicomponent thin layers.
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Affiliation(s)
- Alicia L Gui
- School of Chemistry and Australian Centre for NanoMedicine, The University of New South Wales, Sydney, NSW 2052, Australia
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194
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Budvytyte R, Mickevicius M, Vanderah DJ, Heinrich F, Valincius G. Modification of tethered bilayers by phospholipid exchange with vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4320-4327. [PMID: 23445262 DOI: 10.1021/la304613a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Phosphatidylcholine and cholesterol exchange between vesicles and planar tethered bilayer lipid membranes (tBLMs) was demonstrated from electrochemical impedance spectroscopy (EIS), fluorescence microscopy (FM), and neutron reflectometry (NR) data. Cholesterol is incorporated into the tBLMs, as determined by the functional reconstitution of the pore forming toxin α-hemolysin (EIS data), attaining cholesterol concentrations nearly equal to that in the donor vesicles. Using fluorescently labeled lipids and cholesterol, FM indicates that the vesicle-tBLM exchange is homogeneous for the lipids but not for cholesterol. NR data with perdeuterated lipids indicates lipid exchange asymmetry with two lipids exchanged in the outer leaflet for every lipid in the inner leaflet. NR and EIS data further show different exchange rates for cholesterol (t1/2 < 60 min) and phosphatidylcholine (t1/2 > 4 h). This work lays the foundation for the preparation of robust, lower defect, more biologically relevant tBLMs by essentially combining the two methods of tBLM formation-rapid solvent exchange and vesicle fusion.
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Affiliation(s)
- Rima Budvytyte
- Institute of Biochemistry, Vilnius University, Vilnius, Lithuania
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195
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Regulation of the membrane insertion and conductance activity of the metamorphic chloride intracellular channel protein CLIC1 by cholesterol. PLoS One 2013; 8:e56948. [PMID: 23457643 PMCID: PMC3572944 DOI: 10.1371/journal.pone.0056948] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 01/16/2013] [Indexed: 02/02/2023] Open
Abstract
The Chloride Intracellular ion channel protein CLIC1 has the ability to spontaneously insert into lipid membranes from a soluble, globular state. The precise mechanism of how this occurs and what regulates this insertion is still largely unknown, although factors such as pH and redox environment are known contributors. In the current study, we demonstrate that the presence and concentration of cholesterol in the membrane regulates the spontaneous insertion of CLIC1 into the membrane as well as its ion channel activity. The study employed pressure versus area change measurements of Langmuir lipid monolayer films; and impedance spectroscopy measurements using tethered bilayer membranes to monitor membrane conductance during and following the addition of CLIC1 protein. The observed cholesterol dependent behaviour of CLIC1 is highly reminiscent of the cholesterol-dependent-cytolysin family of bacterial pore-forming proteins, suggesting common regulatory mechanisms for spontaneous protein insertion into the membrane bilayer.
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196
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Hassler BL, Worden RM, Mason AJ. A protein-based electrochemical biosensor array platform for integrated microsystems. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2013; 7:43-51. [PMID: 23853278 DOI: 10.1109/tbcas.2012.2195661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This paper elucidates challenges in integrating different classes of proteins into a microsystem and presents an electrochemical array strategy for heterogeneous protein-based biosensors. The overlapping requirements and limitations imposed by biointerface formation, electrochemical characterization, and microsystem fabrication are identified. A planar electrode array is presented that synergistically resolves these requirements using thin film Au and Ag/AgCl electrodes on a dielectric substrate. Using molecular self-assembly, electrodes were modified by nano-structures of two diverse proteins, alkali ion-channel protein and alcohol dehydrogenase enzyme. Electrochemical impedance spectroscopy and cyclic voltammetry measurements were performed to characterize sensor response to alkali ion and alcohol, respectively. This work demonstrates the viability of the electrochemical microsystem platform for heterogeneous protein-based biosensor interfaces.
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197
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Haque F, Li J, Wu HC, Liang XJ, Guo P. Solid-State and Biological Nanopore for Real-Time Sensing of Single Chemical and Sequencing of DNA. NANO TODAY 2013; 8:56-74. [PMID: 23504223 PMCID: PMC3596169 DOI: 10.1016/j.nantod.2012.12.008] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Sensitivity and specificity are two most important factors to take into account for molecule sensing, chemical detection and disease diagnosis. A perfect sensitivity is to reach the level where a single molecule can be detected. An ideal specificity is to reach the level where the substance can be detected in the presence of many contaminants. The rapidly progressing nanopore technology is approaching this threshold. A wide assortment of biomotors and cellular pores in living organisms perform diverse biological functions. The elegant design of these transportation machineries has inspired the development of single molecule detection based on modulations of the individual current blockage events. The dynamic growth of nanotechnology and nanobiotechnology has stimulated rapid advances in the study of nanopore based instrumentation over the last decade, and inspired great interest in sensing of single molecules including ions, nucleotides, enantiomers, drugs, and polymers such as PEG, RNA, DNA, and polypeptides. This sensing technology has been extended to medical diagnostics and third generation high throughput DNA sequencing. This review covers current nanopore detection platforms including both biological pores and solid state counterparts. Several biological nanopores have been studied over the years, but this review will focus on the three best characterized systems including α-hemolysin and MspA, both containing a smaller channel for the detection of single-strand DNA, as well as bacteriophage phi29 DNA packaging motor connector that contains a larger channel for the passing of double stranded DNA. The advantage and disadvantage of each system are compared; their current and potential applications in nanomedicine, biotechnology, and nanotechnology are discussed.
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Affiliation(s)
- Farzin Haque
- Nanobiotechnology Center, Markey Cancer Center and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Jinghong Li
- Department of Chemistry, Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Beijing 100084, China
| | - Hai-Chen Wu
- Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Xing-Jie Liang
- Laboratory of Nanomedicine and Nanosafety, CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, China
| | - Peixuan Guo
- Nanobiotechnology Center, Markey Cancer Center and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA
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198
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Dong W, Luo J, He H, Jiang L. A reinforced composite structure composed of polydiacetylene assemblies deposited on polystyrene microspheres and its application to H5N1 virus detection. Int J Nanomedicine 2013; 8:221-32. [PMID: 23403826 PMCID: PMC3565586 DOI: 10.2147/ijn.s39676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In this study, we immobilized polydiacetylene vesicles (PDAVs) onto the surface of polystyrene (PS) microspheres (1 μm in diameter) by using both electrical charge and conjugated forces to form a reinforced composite structure. These reinforced complexes could be easily washed, separated by centrifugation, and resuspended by gentle agitation. After passing through a narrow 200 μm-diameter channel, the composite structures maintained their original shape, demonstrating their resilience and potential for use in microfluidic technologies. The number of PDAVs in the composite structure could be mediated by changing the extent of layer deposition, which affected the sensitivity of detection. It showed that PDAVs did not change their blue color after addition of detecting probes such as anti-H5N1, which was of great importance in the fabrication and modification of stable color-changeable biosensors based on PDAVs. By conjugating anti-H5N1 antibodies to the PS@PDAV via N -hydroxysuccinimide and 1-ethyl3-(3-dimethylaminopropyl) carbodiimide chemistry, a stable blue complex, anti-H5N1 microsphere (PS@PDAV-anti-H5N1) was formed. A target antigen of H5N1 (HAQ [H5N1 strain A/ environment/Qinghai/1/2008{H5N1} in clade 0]) was detected by PS@PDAV-anti-H5N1. At an optimal PDAV deposition level of three layers, the limit of detection was determined to be approximately 3 0 ng/mL of HAQ by using optical spectrum measurement and visual inspection, meeting the needs of fast and simple color-changeable detection. However, a much lower limitation of detection (1 ng/mL) was able to be obtained using laser-scanning confocal microscopy, which could be compared with the results obtained with other sophisticated equipment.
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Affiliation(s)
- Wenjie Dong
- Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of China
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199
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Zhong L, Tu R, Gilchrist ML. Tether-supported biomembranes with α-helical peptide-based anchoring constructs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:299-307. [PMID: 23190371 PMCID: PMC3542394 DOI: 10.1021/la303628n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The strict requirement of constructing a native lipid environment to preserve the structure and functionality of membrane proteins is the starting constraint when building biomaterials and sensor systems from these biomolecules. To enhance the viability of supported biomembranes systems and build new ligand display interfaces, we apply rationally designed peptides partitioned into the lipid bilayer interface. Peptides designed to form membrane-spanning α-helical anchoring domains are synthesized using solid-phase peptide synthesis. K(3)A(4)L(2)A(7)L(2)A(3)K(2)-FITC is synthesized on the 100 mg scale for use as a biomembrane anchoring molecule, where orthogonal side-chain modifications allow us to introduce probes enabling peptide localization within supported bilayers. The peptides are found to form α-helical domains within liposomes as assessed with circular dichroism spectroscopy. These peptides are designed to be incorporated into lipid bilayers supported by microspheres and serve as biomembrane anchoring moieties to amino-terminated surfaces. Here, the silica bead surface (4.7 μm diameter) is activated with homobifunctional NHS-PEG(3000)-NHS as "polymer cushion" spacers. This tethering to a subset of the K(3)A(4)L(2)A(7)L(2)A(3)K(2)-FITC molecules present in the bilayer is achieved by the fusion of liposomes followed by coupling of the peptide amino groups to the NHS presented from the silica microsphere surfaces. The biomembrane distributions of tethered and untethered K(3)A(4)L(2)A(7)L(2)A(3)K(2)-FITC are probed with confocal microscopy and are found to give 3D reconstructions consistent with largely homogeneous supported biomembranes. The fluidity of the untethered fraction of peptides within supported membranes is quantified using the fluorescence recovery after photobleaching (FRAP) technique. The presence of the PEG(3000) polymer cushion facilitated a 28.9% increase in peptide diffusivity over untethered bilayers at the lowest peptide to lipid ratio we examined. We show that rationally designed peptide-based anchors can be used to tether lipid bilayers, creating a polymer-cushioned lipid microenvironment on surfaces with high lateral mobility and facilitating the development of a new platform for ligand displays.
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Affiliation(s)
- Lina Zhong
- Department of Chemical Engineering, The Grove School of Engineering, The City College of New York, 140 Street @ Convent Ave, New York NY 10031
| | - Raymond Tu
- Department of Chemical Engineering, The Grove School of Engineering, The City College of New York, 140 Street @ Convent Ave, New York NY 10031
| | - M. Lane Gilchrist
- Department of Chemical Engineering, The Grove School of Engineering, The City College of New York, 140 Street @ Convent Ave, New York NY 10031
- Department of Biomedical Engineering, The Grove School of Engineering, The City College of New York, 140 Street @ Convent Ave, New York NY 10031
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200
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Application of Infrared Spectroscopy for Structural Analysis of Planar Lipid Bilayers Under Electrochemical Control. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-411515-6.00002-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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