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Manoharan V, Rodrigues R, Sadati S, Swann MJ, Freeman N, Du B, Yildirim E, Tamer U, Arvanitis TN, Isakov D, Asadipour A, Charmet J. Platform-agnostic electrochemical sensing app and companion potentiostat. Analyst 2023; 148:4857-4868. [PMID: 37624366 PMCID: PMC10518900 DOI: 10.1039/d2an01350a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 07/11/2023] [Indexed: 08/26/2023]
Abstract
Electrochemical sensing is ubiquitous in a number of fields ranging from biosensing, to environmental monitoring through to food safety and battery or corrosion characterisation. Whereas conventional potentiostats are ideal to develop assays in laboratory settings, they are in general, not well-suited for field work due to their size and power requirements. To address this need, a number of portable battery-operated potentiostats have been proposed over the years. However, most open source solutions do not take full advantage of integrated circuit (IC) potentiostats, a rapidly evolving field. This is partly due to the constraining requirements inherent to the development of dedicated interfaces, such as apps, to address and control a set of common electrochemical sensing parameters. Here we propose the PocketEC, a universal app that has all the functionalities to interface with potentiostat ICs through a user defined property file. The versatility of PocketEC, developed with an assay developer mindset, was demonstrated by interfacing it, via Bluetooth, to the ADuCM355 evaluation board, the open-source DStat potentiostat and the Voyager board, a custom-built, small footprint potentiostat based around the LMP91000 chip. The Voyager board is presented here for the first time. Data obtained using a standard redox probe, Ferrocene Carboxylic Acid (FCA) and a silver ion assay using anodic stripping multi-step amperometry were in good agreement with analogous measurements using a bench top potentiostat. Combined with its Voyager board companion, the PocketEC app can be used directly for a number of wearable or portable electrochemical sensing applications. Importantly, the versatility of the app makes it a candidate of choice for the development of future portable potentiostats. Finally, the app is available to download on the Google Play store and the source codes and design files for the PocketEC app and the Voyager board are shared via Creative Commons license (CC BY-NC 3.0) to promote the development of novel portable or wearable applications based on electrochemical sensing.
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Affiliation(s)
| | - Rui Rodrigues
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
| | - Sara Sadati
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
| | - Marcus J Swann
- 5D Health Protection Group Ltd, Accelerator Building, 1 Daulby Street, Liverpool L7 8XZ, UK
| | - Neville Freeman
- 5D Health Protection Group Ltd, Accelerator Building, 1 Daulby Street, Liverpool L7 8XZ, UK
| | - Bowen Du
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
| | - Ender Yildirim
- Middle East Technical University, Mechanical Engineering Department, 06800, Ankara, Turkey
| | - Ugur Tamer
- Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Ankara, 06330, Turkey
| | - Theodoros N Arvanitis
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
- School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Dmitry Isakov
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
| | - Ali Asadipour
- Computer Science Research Centre, Royal College of Art, London, SW7 2EU, UK.
| | - Jérôme Charmet
- Institute of Digital Healthcare, WMG, University of Warwick, Coventry, CV4 7AL, UK.
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
- HE-Arc Ingénierie, HES-SO University of Applied Sciences and Art of Western Switzerland, 2000 Neuchâtel, Switzerland
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Swann MJ, Freeman NJ, Watson F, Law SJ, Percival SL. A Sensor for Monitoring the Antimicrobial Activity of Wound Dressings for Both Surgical Site Infections (SSIs) and Chronic Wounds. Surg Technol Int 2023; 42:sti42/1692. [PMID: 37493619 DOI: 10.52198/23.sti.42.wh1692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
Antimicrobial impregnated wound dressings are a critical tool for the management, prevention, and control of surgical site infections (SSIs) and infected chronic wounds. However, the sustained therapeutic antimicrobial activity of the dressing when employed for extended periods cannot be readily determined in vivo. Consequently, dressings are changed frequently to ensure that their antimicrobial activity is maintained. Whilst frequent dressing changes allow the wound to be assessed, this is time-consuming and can cause disruption to the wound bed impairing the healing process. Furthermore, this increases medical costs for the patient and hospitals. This paper introduces a novel concept to monitor the therapeutic levels of an antimicrobial component within a wound dressing ensuring the wound dressing remains "fit for purpose" and avoiding indiscriminate use of antiseptics. This could help to inform clinicians whether the antimicrobial is still being delivered at therapeutic levels and as such when to change the dressing ensuring timely positive clinical outcomes. Silver has been used historically as an antimicrobial agent and is ubiquitous in current generations of antimicrobial wound dressings. However, its activity is complex due to the poor solubility of silver ions in the presence of chloride and the effect of complexation by other components in the dressing and wound ecosystem, not least by serum proteins. In this paper, we detail an electrochemical silver sensor (5D patent protected - WO2023275553A1), constructed using a platinum (Pt) nanoband array electrode, and characterise its response to silver ions. This is determined in the presence of bovine serum albumin (BSA) and simulated wound fluid (SWF) containing chloride and rationalised using atomic analysis of the composition of the SWF. The sensor response in SWF is compared with the antimicrobial activity of silver against Pseudomonas aeruginosa in the planktonic and biofilm state, as a function of the amount of silver nitrate added. At low concentrations, silver in SWF has good solubility but reduced antimicrobial effect due to binding of silver by BSA as shown by the sensor response. At intermediate concentrations, above 10ppm, the silver was efficacious on both planktonic microorganisms and biofilm impregnated with microorganisms and readily detected with the sensor. At high concentrations, silver precipitates and both the silver in solution and the sensor response plateaus. The data demonstrates how the sensor correlates with the antimicrobial activity of the silver in vitro and how this could be used to actively monitor antimicrobials in vivo.
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Affiliation(s)
- Marcus J Swann
- Centre for Biofilm Science and Technologies (CBST), 5D Bioscience (part of the 5D Health Protection Group Ltd), Liverpool, United Kingdom
| | - Neville J Freeman
- Centre for Biofilm Science and Technologies (CBST), 5D Bioscience (part of the 5D Health Protection Group Ltd), Liverpool, United Kingdom
| | - Fergus Watson
- Centre for Biofilm Science and Technologies (CBST), 5D Bioscience (part of the 5D Health Protection Group Ltd), Liverpool, United Kingdom
| | - Stephen J Law
- Centre for Biofilm Science and Technologies (CBST), 5D Bioscience (part of the 5D Health Protection Group Ltd), Liverpool, United Kingdom
| | - Steven L Percival
- Centre for Biofilm Science and Technologies (CBST), 5D Bioscience (part of the 5D Health Protection Group Ltd), Liverpool, United Kingdom
- University of Manchester, United Kingdom
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Birchenough HL, Swann MJ, Zindy E, Day AJ, Jowitt TA. Enhanced avidin binding to lipid bilayers using PDP-PE lipids with PEG-biotin linkers. Nanoscale Adv 2020; 2:1625-1633. [PMID: 36132312 PMCID: PMC9417969 DOI: 10.1039/d0na00060d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/07/2020] [Indexed: 06/15/2023]
Abstract
Two of the most important aspects of lipid bilayers that have increased their popularity in the field of nanotechnology and biosensors are their fluid nature, which is highly beneficial in ensuring the spatial organization of attached molecules, and the relative ease in which they can be manipulated to change the surface chemistry. Here we have used two different types of functionalized lipids to study the interaction of avidin, which is a common approach to attach further ligands for study. We have tested the commonly used Biotinyl-Cap-PE lipids at different molar percentages and reveal that avidin is not evenly distributed, but forms what looks like clusters even at low percentage occupancy which hampers the level of avidin that can be associated with the surface. We have then successfully employed the novel strategy of using PDP-PE lipids which contain a reducible disulphide to which we added maleamide-PEG-biotin spacers of different lengths. There is a more even distribution of avidin on these layers and thereby increasing the amount and efficiency of avidin association. The reduced levels of avidin that was being associated with the Biotinyl-Cap-PE layers as compared to the PDP-PE lipids could be analysed with QCM-D and interferometry approaches, but it was only with SEEC microscopy that the reason for the reduced occupancy was resolved.
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Affiliation(s)
| | - Marcus J Swann
- Swann Scientific Consulting Ltd 110 Sandy Lane Lymm WA13 9HR UK
| | - Egor Zindy
- Wellcome Trust Centre for Cell-Matrix Research UK
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4
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Falk M, Sultana R, Swann MJ, Mount AR, Freeman NJ. Nanoband array electrode as a platform for high sensitivity enzyme-based glucose biosensing. Bioelectrochemistry 2016; 112:100-5. [PMID: 27118384 DOI: 10.1016/j.bioelechem.2016.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 03/29/2016] [Accepted: 04/08/2016] [Indexed: 02/04/2023]
Abstract
We describe a novel glucose biosensor based on a nanoband array electrode design, manufactured using standard semiconductor processing techniques, and bio-modified with glucose oxidase immobilized at the nanoband electrode surface. The nanoband array architecture allows for efficient diffusion of glucose and oxygen to the electrode, resulting in a thousand-fold improvement in sensitivity and wide linear range compared to a conventional electrode. The electrode constitutes a robust and manufacturable sensing platform.
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Affiliation(s)
- Magnus Falk
- NanoFlex Limited, iTac, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury WA4 4AD, United Kingdom.
| | - Reshma Sultana
- NanoFlex Limited, iTac, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Marcus J Swann
- NanoFlex Limited, iTac, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Andrew R Mount
- EaStCHEM, School of Chemistry, The University of Edinburgh, Joseph Black Building, King's Buildings, Edinburgh, Scotland EH9 3JJ, United Kingdom
| | - Neville J Freeman
- NanoFlex Limited, iTac, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
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Wayment-Steele HK, Jing Y, Swann MJ, Johnson LE, Agnarsson B, Svedhem S, Johal MS, Kunze A. Effects of Al(3+) on Phosphocholine and Phosphoglycerol Containing Solid Supported Lipid Bilayers. Langmuir 2016; 32:1771-1781. [PMID: 26783873 DOI: 10.1021/acs.langmuir.5b03999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Aluminum has attracted great attention recently as it has been suggested by several studies to be associated with increased risks for Alzheimer's and Parkinson's disease. The toxicity of the trivalent ion is assumed to derive from structural changes induced in lipid bilayers upon binding, though the mechanism of this process is still not well understood. In the present study we elucidate the effect of Al(3+) on supported lipid bilayers (SLBs) using fluorescence microscopy, the quartz crystal microbalance with dissipation (QCM-D) technique, dual-polarization interferometry (DPI), and molecular dynamics (MD) simulations. Results from these techniques show that binding of Al(3+) to SLBs containing negatively charged and neutral phospholipids induces irreversible changes such as domain formation. The measured variations in SLB thickness, birefringence, and density indicate a phase transition from a disordered to a densely packed ordered phase.
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Affiliation(s)
- Hannah K Wayment-Steele
- Department of Chemistry, Pomona College , 645 North College Ave., Claremont, California 91711, United States
| | - Yujia Jing
- Department of Applied Physics, Chalmers University of Technology , 412 96 Göteborg, Sweden
| | - Marcus J Swann
- Swann Scientific Consulting Ltd., 110 Sandy Lane, Lymm, Cheshire, U.K
| | - Lewis E Johnson
- Department of Chemistry, Pomona College , 645 North College Ave., Claremont, California 91711, United States
- Department of Chemistry, University of Washington , 109 Bagley Hall, Seattle, Washington 98195, United States
| | - Björn Agnarsson
- Department of Applied Physics, Chalmers University of Technology , 412 96 Göteborg, Sweden
| | - Sofia Svedhem
- Department of Applied Physics, Chalmers University of Technology , 412 96 Göteborg, Sweden
| | - Malkiat S Johal
- Department of Chemistry, Pomona College , 645 North College Ave., Claremont, California 91711, United States
| | - Angelika Kunze
- Department of Applied Physics, Chalmers University of Technology , 412 96 Göteborg, Sweden
- Institute of Physical Chemistry, University of Göttingen , 37077 Göttingen, Germany
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Sola L, Álvarez J, Cretich M, Swann MJ, Chiari M, Hill D. Characterization of porous alumina membranes for efficient, real-time, flow through biosensing. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2014.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Grøftehauge MK, Hajizadeh NR, Swann MJ, Pohl E. Protein-ligand interactions investigated by thermal shift assays (TSA) and dual polarization interferometry (DPI). Acta Crystallogr D Biol Crystallogr 2015; 71:36-44. [PMID: 25615858 PMCID: PMC4304684 DOI: 10.1107/s1399004714016617] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 07/17/2014] [Indexed: 11/10/2022]
Abstract
Over the last decades, a wide range of biophysical techniques investigating protein-ligand interactions have become indispensable tools to complement high-resolution crystal structure determinations. Current approaches in solution range from high-throughput-capable methods such as thermal shift assays (TSA) to highly accurate techniques including microscale thermophoresis (MST) and isothermal titration calorimetry (ITC) that can provide a full thermodynamic description of binding events. Surface-based methods such as surface plasmon resonance (SPR) and dual polarization interferometry (DPI) allow real-time measurements and can provide kinetic parameters as well as binding constants. DPI provides additional spatial information about the binding event. Here, an account is presented of new developments and recent applications of TSA and DPI connected to crystallography.
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Affiliation(s)
| | - Nelly R. Hajizadeh
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, England
| | - Marcus J. Swann
- Farfield, Biolin Scientific, 62 Wellington Road South, Stockport, Cheshire SK1 3SU, England
| | - Ehmke Pohl
- Chemistry Department and School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, England
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8
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Delivopoulos E, Ouberai MM, Coffey PD, Swann MJ, Shakesheff KM, Welland ME. Serum protein layers on parylene-C and silicon oxide: effect on cell adhesion. Colloids Surf B Biointerfaces 2014; 126:169-77. [PMID: 25555155 PMCID: PMC4342411 DOI: 10.1016/j.colsurfb.2014.12.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 11/17/2022]
Abstract
We studied how cell adhesion is affected by serum protein adsorbed on parylene-C. Serum proteins form distinct layers when adsorbed onto parylene-C or silicon oxide. Biosensing technique elucidates contrasting protein layer densities and thicknesses. Fibronectin supports cell adhesion on both surfaces. Albumin outcompetes fibronectin on parylene-C and vice versa on silicon oxide.
Among the range of materials used in bioengineering, parylene-C has been used in combination with silicon oxide and in presence of the serum proteins, in cell patterning. However, the structural properties of adsorbed serum proteins on these substrates still remain elusive. In this study, we use an optical biosensing technique to decipher the properties of fibronectin (Fn) and serum albumin adsorbed on parylene-C and silicon oxide substrates. Our results show the formation of layers with distinct structural and adhesive properties. Thin, dense layers are formed on parylene-C, whereas thicker, more diffuse layers are formed on silicon oxide. These results suggest that Fn acquires a compact structure on parylene-C and a more extended structure on silicon oxide. Nonetheless, parylene-C and silicon oxide substrates coated with Fn host cell populations that exhibit focal adhesion complexes and good cell attachment. Albumin adopts a deformed structure on parylene-C and a globular structure on silicon oxide, and does not support significant cell attachment on either surface. Interestingly, the co-incubation of Fn and albumin at the ratio found in serum, results in the preferential adsorption of albumin on parylene-C and Fn on silicon oxide. This finding is supported by the exclusive formation of focal adhesion complexes in differentiated mouse embryonic stem cells (CGR8), cultured on Fn/albumin coated silicon oxide, but not on parylene-C. The detailed information provided in this study on the distinct properties of layers of serum proteins on substrates such as parylene-C and silicon oxide is highly significant in developing methods for cell patterning.
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Affiliation(s)
- Evangelos Delivopoulos
- Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FF, UK; School of Systems Engineering, University of Reading, Reading RG6 6AY, UK
| | - Myriam M Ouberai
- Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FF, UK.
| | - Paul D Coffey
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Marcus J Swann
- Farfield, Biolin Scientific, 62 Wellington Road South, Stockport SK1 3SU, Cheshire, UK
| | - Kevin M Shakesheff
- School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Mark E Welland
- Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FF, UK
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Platt GW, Damin F, Swann MJ, Metton I, Skorski G, Cretich M, Chiari M. Allergen immobilisation and signal amplification by quantum dots for use in a biosensor assay of IgE in serum. Biosens Bioelectron 2014; 52:82-8. [DOI: 10.1016/j.bios.2013.08.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 12/01/2022]
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Hirst DJ, Lee TH, Swann MJ, Aguilar MI. Combined mass and structural kinetic analysis of multistate antimicrobial peptide-membrane interactions. Anal Chem 2013; 85:9296-304. [PMID: 23998643 DOI: 10.1021/ac402148v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Kinetic analysis of peptide-membrane interactions generally involves a curve fitting process with no information about what the different curves may physically correspond to. Given the multistep process of peptide-membrane interactions, a computational method that utilizes physical parameters that relate to both peptide binding and membrane structure would provide new insight into this complex process. In this study, kinetic models accounting for two-state and three-state mechanisms were fitted to our previously reported simultaneous real-time measurements of mass and birefringence during the binding and dissociation of the peptide HPA3 (Hirst, D.; Lee, T.-H.; Swann, M.; Unabia, S.; Park, Y.; Hahm, K.-S.; Aguilar, M. Eur. Biophys. J. 2011, 40, 503-514); significantly, the mass and birefringence are constrained by the same set of kinetic constants, allowing the unification of peptide binding patterns with membrane structure changes. For the saturated phospholipid dimyristoyl-phosphatidylcholine (DMPC) the two-state model was sufficient to account for the observed changes in mass and birefringence, whereas for the unsaturated phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) the two-state model was found to be inadequate and a three-state model gave a significantly better fit. The third state of interaction for POPC was found to disrupt the bilayer much more than the previous two states. We propose a hypothesis for the mechanism of membrane permeabilization based on the results featuring a loosely bound first state, a tightly bound second state, and a highly membrane-disrupting third state. The results demonstrate the importance of the difference in membrane fluidity between the gel phase DMPC and the liquid crystal phase POPC for peptide-membrane interactions and establish the combination of DPI and kinetic modeling as a powerful tool for revealing features of peptide-membrane interaction mechanisms, including intermediate states between initial binding and full membrane disruption.
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Affiliation(s)
- Daniel J Hirst
- Department of Biochemistry and Molecular Biology, Monash University , Clayton, Victoria 3800, Australia
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11
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Ouberai MM, Wang J, Swann MJ, Galvagnion C, Guilliams T, Dobson CM, Welland ME. α-Synuclein senses lipid packing defects and induces lateral expansion of lipids leading to membrane remodeling. J Biol Chem 2013; 288:20883-20895. [PMID: 23740253 DOI: 10.1074/jbc.m113.478297] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
There is increasing evidence for the involvement of lipid membranes in both the functional and pathological properties of α-synuclein (α-Syn). Despite many investigations to characterize the binding of α-Syn to membranes, there is still a lack of understanding of the binding mode linking the properties of lipid membranes to α-Syn insertion into these dynamic structures. Using a combination of an optical biosensing technique and in situ atomic force microscopy, we show that the binding strength of α-Syn is related to the specificity of the lipid environment (the lipid chemistry and steric properties within a bilayer structure) and to the ability of the membranes to accommodate and remodel upon the interaction of α-Syn with lipid membranes. We show that this interaction results in the insertion of α-Syn into the region of the headgroups, inducing a lateral expansion of lipid molecules that can progress to further bilayer remodeling, such as membrane thinning and expansion of lipids out of the membrane plane. We provide new insights into the affinity of α-Syn for lipid packing defects found in vesicles of high curvature and in planar membranes with cone-shaped lipids and suggest a comprehensive model of the interaction between α-Syn and lipid bilayers. The ability of α-Syn to sense lipid packing defects and to remodel membrane structure supports its proposed role in vesicle trafficking.
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Affiliation(s)
- Myriam M Ouberai
- From the Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FF, United Kingdom,.
| | - Juan Wang
- the Farfield Group Ltd., Biolin Scientific, Voyager, Chicago Avenue, Manchester M90 3DQ, United Kingdom, and
| | - Marcus J Swann
- the Farfield Group Ltd., Biolin Scientific, Voyager, Chicago Avenue, Manchester M90 3DQ, United Kingdom, and
| | - Celine Galvagnion
- the Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Tim Guilliams
- the Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Christopher M Dobson
- the Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Mark E Welland
- From the Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge CB3 0FF, United Kingdom
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12
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Hunt J, Keeble AH, Dale RE, Corbett MK, Beavil RL, Levitt J, Swann MJ, Suhling K, Ameer-Beg S, Sutton BJ, Beavil AJ. A fluorescent biosensor reveals conformational changes in human immunoglobulin E Fc: implications for mechanisms of receptor binding, inhibition, and allergen recognition. J Biol Chem 2012; 287:17459-17470. [PMID: 22442150 PMCID: PMC3366799 DOI: 10.1074/jbc.m111.331967] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/08/2012] [Indexed: 11/06/2022] Open
Abstract
IgE binding to its high affinity receptor FcεRI on mast cells and basophils is a key step in the mechanism of allergic disease and a target for therapeutic intervention. Early indications that IgE adopts a bent structure in solution have been confirmed by recent x-ray crystallographic studies of IgEFc, which further showed that the bend, contrary to expectation, is enhanced in the crystal structure of the complex with receptor. To investigate the structure of IgEFc and its conformational changes that accompany receptor binding in solution, we created a Förster resonance energy transfer (FRET) biosensor using biologically encoded fluorescent proteins fused to the N- and C-terminal IgEFc domains (Cε2 and Cε4, respectively) together with the theoretical basis for quantitating its behavior. This revealed not only that the IgEFc exists in a bent conformation in solution but also that the bend is indeed enhanced upon FcεRI binding. No change in the degree of bending was seen upon binding to the B cell receptor for IgE, CD23 (FcεRII), but in contrast, binding of the anti-IgE therapeutic antibody omalizumab decreases the extent of the bend, implying a conformational change that opposes FcεRI engagement. HomoFRET measurements further revealed that the (Cε2)(2) and (Cε4)(2) domain pairs behave as rigid units flanking the conformational change in the Cε3 domains. Finally, modeling of the accessible conformations of the two Fab arms in FcεRI-bound IgE revealed a mutual exclusion not seen in IgG and Fab orientations relative to the membrane that may predispose receptor-bound IgE to cross-linking by allergens.
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Affiliation(s)
- James Hunt
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - Anthony H Keeble
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - Robert E Dale
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Melissa K Corbett
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Rebecca L Beavil
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - James Levitt
- The Department of Physics, King's College London, Strand, London WC2R 2LS
| | - Marcus J Swann
- Farfield Group Limited, Voyager, Chicago Avenue, Manchester Airport, Manchester, M90 3DQ, United Kingdom
| | - Klaus Suhling
- The Department of Physics, King's College London, Strand, London WC2R 2LS
| | - Simon Ameer-Beg
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Brian J Sutton
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Andrew J Beavil
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL.
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13
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Coan KED, Swann MJ, Ottl J. Measurement and Differentiation of Ligand-Induced Calmodulin Conformations by Dual Polarization Interferometry. Anal Chem 2012; 84:1586-91. [DOI: 10.1021/ac202844e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kristin E. D. Coan
- Novartis Institutes for BioMedical
Research Basel, CPC/LFP/Label-free Technologies, Novartis Pharma AG, Basel, Switzerland
| | - Marcus J. Swann
- Farfield Group Ltd., West Wing 7, Voyager, Chicago Avenue, Manchester
Airport, Manchester, M90 3DQ, United Kingdom
| | - Johannes Ottl
- Novartis Institutes for BioMedical
Research Basel, CPC/LFP/Label-free Technologies, Novartis Pharma AG, Basel, Switzerland
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14
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Karst JC, Barker R, Devi U, Swann MJ, Davi M, Roser SJ, Ladant D, Chenal A. Identification of a region that assists membrane insertion and translocation of the catalytic domain of Bordetella pertussis CyaA toxin. J Biol Chem 2012; 287:9200-12. [PMID: 22241477 DOI: 10.1074/jbc.m111.316166] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The adenylate cyclase (CyaA) toxin, one of the virulence factors secreted by Bordetella pertussis, the pathogenic bacteria responsible for whooping cough, plays a critical role in the early stages of respiratory tract colonization by this bacterium. The CyaA toxin is able to invade eukaryotic cells by translocating its N-terminal catalytic domain directly across the plasma membrane of the target cells, where, activated by endogenous calmodulin, it produces supraphysiological levels of cAMP. How the catalytic domain is transferred from the hydrophilic extracellular medium into the hydrophobic environment of the membrane and then to the cell cytoplasm remains an unsolved question. In this report, we have characterized the membrane-interacting properties of the CyaA catalytic domain. We showed that a protein covering the catalytic domain (AC384, encompassing residues 1-384 of CyaA) displayed no membrane association propensity. However, a longer polypeptide (AC489), encompassing residues 1-489 of CyaA, exhibited the intrinsic property to bind to membranes and to induce lipid bilayer destabilization. We further showed that deletion of residues 375-485 within CyaA totally abrogated the toxin's ability to increase intracellular cAMP in target cells. These results indicate that, whereas the calmodulin dependent enzymatic domain is restricted to the amino-terminal residues 1-384 of CyaA, the membrane-interacting, translocation-competent domain extends up to residue 489. This thus suggests an important role of the region adjacent to the catalytic domain of CyaA in promoting its interaction with and its translocation across the plasma membrane of target cells.
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Affiliation(s)
- Johanna C Karst
- Institut Pasteur, CNRS UMR 3528, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, Paris, France
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15
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Boudjemline A, Saridakis E, Swann MJ, Govada L, Mavridis IM, Chayen NE. Use of Dual Polarization Interferometry as a Diagnostic Tool for Protein Crystallization. Anal Chem 2011; 83:7881-7. [DOI: 10.1021/ac2017844] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Emmanuel Saridakis
- Institute of Physical Chemistry, National Centre for Scientific Research “DEMOKRITOS”, Athens 15310, Greece
| | | | - Lata Govada
- Biomolecular Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, SW7 2AZ, U.K
| | - Irene M. Mavridis
- Institute of Physical Chemistry, National Centre for Scientific Research “DEMOKRITOS”, Athens 15310, Greece
| | - Naomi E. Chayen
- Biomolecular Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, SW7 2AZ, U.K
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16
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Baumann MK, Swann MJ, Textor M, Reimhult E. Pleckstrin Homology-Phospholipase C-δ1 Interaction with Phosphatidylinositol 4,5-Bisphosphate Containing Supported Lipid Bilayers Monitored in Situ with Dual Polarization Interferometry. Anal Chem 2011; 83:6267-74. [DOI: 10.1021/ac2009178] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martina K. Baumann
- Department of Materials, Laboratory for Surface Science and Technology (LSST), ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
| | - Marcus J. Swann
- Farfield Group, Farfield House, Southmere Court, Electra Way, Crewe Business Park, Crewe CW1 6GU, United Kingdom
| | - Marcus Textor
- Department of Materials, Laboratory for Surface Science and Technology (LSST), ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
| | - Erik Reimhult
- Department of Materials, Laboratory for Surface Science and Technology (LSST), ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna, Muthgasse 11, A-1190 Vienna, Austria
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17
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Hirst DJ, Lee TH, Swann MJ, Unabia S, Park Y, Hahm KS, Aguilar MI. Effect of acyl chain structure and bilayer phase state on binding and penetration of a supported lipid bilayer by HPA3. Eur Biophys J 2011; 40:503-14. [PMID: 21222117 DOI: 10.1007/s00249-010-0664-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 12/22/2010] [Indexed: 10/18/2022]
Abstract
The effect of acyl chain structure and bilayer phase state on binding and penetration by the peptide HPA3 was studied using dual polarisation interferometry. This peptide is an analogue of Hp(2-20) derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1) which has been shown to have antimicrobial and cell-penetrating properties. The binding of HPA3 to zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitolyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and negatively charged membranes composed of DMPC and 1,2-dimyristoyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (DMPG) or POPC and 1-palmitolyl-2-oleyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (POPG) was determined using dual polarisation interferometry (DPI). Mass and birefringence were measured in real time, enabling the creation of birefringence-mass plots for detailed analysis of the changes in lipid bilayer order during the peptide-binding process. HPA3 bound to all four lipids and the binding progressed as a single phase for the saturated gel phase bilayers DMPC and DMPC-DMPG. However, the binding process involved two or more phases, with penetration of the unsaturated fluid phase POPC and POPC-POPG bilayers. Structural changes in the saturated bilayer were partially reversible whereas binding to the unsaturated bilayer resulted in irreversible changes in membrane structure. These results demonstrate that more disordered unsaturated bilayers are more susceptible to further disorganisation and have a lower capacity to recover from peptide-induced structural changes than saturated ordered bilayers. In addition, this study further establishes DPI as powerful tool for analysis of multiphase peptide-insertion processes associated with complex structural changes in the liquid-crystalline membrane.
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Affiliation(s)
- Daniel J Hirst
- Department of Biochemistry & Molecular Biology, Monash University, Clayton, VIC 3800, Australia
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18
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Moore JD, Perez-Pardo MA, Popplewell JF, Spencer SJ, Ray S, Swann MJ, Shard AG, Jones W, Hills A, Bracewell DG. Chemical and biological characterisation of a sensor surface for bioprocess monitoring. Biosens Bioelectron 2010; 26:2940-7. [PMID: 21195603 DOI: 10.1016/j.bios.2010.11.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 11/19/2010] [Accepted: 11/26/2010] [Indexed: 11/25/2022]
Abstract
This paper describes the step-wise fabrication and characterisation of a multi-layer dual polarization interferometry (DPI) based biosensor utilising Protein G (ProG) as the bio-recognition layer for the detection of a fragment antibody (Fab'). The biosensor is capable of monitoring the concentration of Fab' product within the extracellular medium of a fed-batch fermentation after leakage from Escherichia coli (E.coli). The activity, stability and functionality of each sensor layer were analysed in situ using DPI, whilst the chemical identity and homogeneity of the chemical layers were assessed ex situ using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Two different biotin linkers were found to produce hugely differing surfaces after the capture of NeutrAvidin™ (NA) and biotinylated Protein G (b-ProG). The hydrophilic (PEG)(4)-biotin linker resulted in a surface where the b-ProG layer was deposited and organised above the NA layer producing an active and stable surface, whilst the hydrophobic LC-biotin linker generated a surface where the b-ProG layer was buried within the NA layer leading to variable surfaces and poor binding of the Fab' target. The biosensor has a detection limit of 1.7 μg/ml with a dynamic range covering two orders of magnitude. The sensor can detect the onset of Fab' leakage as early as 2h following product induction, with high signal-to-noise ratios and little interference from extracellular components. Leakage of Fab' followed a biphasic profile, switching to a more rapid rate 20 h after induction, indicating accelerated product loss and the need for cultivation harvest.
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Affiliation(s)
- Jonathan D Moore
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
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19
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Wang J, Coffey PD, Swann MJ, Yang F, Lu JR, Yang X. Optical extinction combined with phase measurements for probing DNA-small-molecule interactions using an evanescent waveguide biosensor. Anal Chem 2010; 82:5455-62. [PMID: 20524624 DOI: 10.1021/ac9027164] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We demonstrate the use of both optical extinction and phase measurements for probing the interactions between DNA and small molecules by dual polarization interferometry. On binding to DNA at the interface, mitoxantrone (MTX) and methylene blue (MB) induced reversible concentration-dependent optical extinction due to light absorption, which clearly revealed the association and dissociation of small molecules with DNA in real time. The binding constants of MTX-DNA and MB-DNA determined from the masses derived from optical extinction are 1.8 x 10(5) and 4.2 x 10(4) M(-1), respectively, and shown to be buffer salt concentration-dependent. Apart from optical extinction, phase measurements reflected the overall change of the interaction; namely, a combined result of the binding of small molecules and any changes in DNA structure. The masses derived from phase could be very different from those derived from optical extinction. The structural changes detected by phase measurements showed a contraction and densification of DNA upon intercalation by MTX or MB. The combination of optical extinction and phase measurements allows a detailed understanding of the interaction process.
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Affiliation(s)
- Juan Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
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20
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Saridakis E, Boudjemline A, Swann MJ, Mavridis IM, Chayen NE. Dual polarization interferometry in macromolecular crystallisation diagnostics. Acta Crystallogr A 2010. [DOI: 10.1107/s010876731009330x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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21
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Lee TH, Hall KN, Swann MJ, Popplewell JF, Unabia S, Park Y, Hahm KS, Aguilar MI. The membrane insertion of helical antimicrobial peptides from the N-terminus of Helicobacter pylori ribosomal protein L1. Biochim Biophys Acta 2010; 1798:544-57. [PMID: 20100457 DOI: 10.1016/j.bbamem.2010.01.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 01/14/2010] [Accepted: 01/20/2010] [Indexed: 01/08/2023]
Abstract
The interaction of two helical antimicrobial peptides, HPA3 and HPA3P with planar supported lipid membranes was quantitatively analysed using two complementary optical biosensors. The peptides are analogues of Hp(2-20) derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1). The binding of these two peptide analogues to zwitterionic dimyristoyl-phosphatidylcholine (DMPC) and negatively charged membranes composed of DMPC/dimyristoylphosphatidylglycerol (DMPG) (4:1) was determined using surface plasmon resonance (SPR) and dual polarisation interferometry (DPI). Using SPR analysis, it was shown that the proline substitution in HPA3P resulted in much lower binding for both zwitterionic and anionic membranes than HPA3. Structural changes in the planar DMPC and DMPC/DMPG (4:1) bilayers induced by the binding of both Hp(2-20) analogues were then resolved in real-time with DPI. The overall process of peptide-induced changes in membrane structure was analysed by the real-time changes in bound peptide mass as a function of bilayer birefringence. The insertion of both HPA3 and HPA3P into the supported lipid bilayers resulted in a decrease in birefringence with increasing amounts of bound peptide which reflects a decrease in the order of the bilayer. The binding of HPA3 to each membrane was associated with a higher level of bound peptide and greater membrane lipid disordering and a faster and higher degree of insertion into the membrane than HPA3P. Furthermore, the binding of both HPA3 and HPA3P to negatively charged DMPC/DMPG bilayers also leads to a greater disruption of the lipid ordering. These results demonstrate the geometrical changes in the membrane upon peptide insertion and the extent of membrane structural changes can be obtained quantitatively. Moreover, monitoring the effect of peptides on a structurally characterised bilayer has provided further insight into the role of membrane structure changes in the molecular basis of peptide selectivity and activity and may assist in defining the mode of antimicrobial action.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, Clayton, Vic, 3800, Australia
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22
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Sanghera N, Swann MJ, Ronan G, Pinheiro TJ. Insight into early events in the aggregation of the prion protein on lipid membranes. Biochimica et Biophysica Acta (BBA) - Biomembranes 2009; 1788:2245-51. [DOI: 10.1016/j.bbamem.2009.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 08/06/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
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23
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Popplewell JF, Swann MJ, Ahmed Y, Turnbull JE, Fernig DG. Fabrication of carbohydrate surfaces by using nonderivatised oligosaccharides, and their application to measuring the assembly of sugar-protein complexes. Chembiochem 2009; 10:1218-26. [PMID: 19360804 DOI: 10.1002/cbic.200800696] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This way up. Dual polarisation interferometry was used to design and characterise a surface on which the orientation and density of immobilised carbohydrates was suitable for studying their interactions with proteins. Lactoferrin was shown to adopt two orientations: "end-on" or "side-on", while for FGF-2 a single monolayer of protein was observed. The new surface can be used to elucidate the binding of proteins to carbohydrates and the geometry of the complexes, a frequently controversial area. Surface-based tools, such as microarrays and optical biosensors, are being increasingly applied to the analysis of carbohydrate-protein interactions. A key to these developments is the presentation of the carbohydrate to the protein target. Dual polarisation interferometry (DPI) is a surface-based technique that permits the real-time measurement of the changes in thickness, refractive index and mass of adsorbates 100 nm thick or less on the surface of a functionalised waveguide. DPI has been used to design and characterise a surface on which the orientation and density of the immobilised carbohydrates is suitable for studying their interactions with proteins and where nonspecific binding is reduced to less than 5 % of total binding. A thiol-functionalised surface was derivatised with a heterobifunctional crosslinker to yield a hydrazide surface. This was treated with oligosaccharides, derived from keratan sulfate (KS) chondroitin sulfate (CS) and heparin, that possess a reducing end. To block the unreacted hydrazide groups, the surface was treated with an aldehyde-functionalised PEG. The heparin DP-10 surfaces were then used to determine the performance of the immobilised DP-10 with respect to binding of two well-characterised proteins, lactoferrin (Lf) and fibroblast growth factor-2. The results show that Lf could adopt two different orientations, at high protein loadings the protein layer thickness corresponded to an "end-on" orientation of Lf, whilst rinsing with buffer saw the Lf molecules adopt a "side-on" configuration. In the case of FGF-2, a single monolayer of protein bound to DP-10 was observed. These results demonstrate that the new surface can be used to resolve key questions relating to the binding of proteins to carbohydrates, including, when used in DPI, the resolution of the geometry of complexes, an area that is frequently controversial.
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24
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Abstract
An optical sensor for quantitative analysis of ultrathin films and adsorbed layers is described. Quantification of both layer thickness and refractive index (density) can be made for in situ and ex-situ coated films. With the use of two polarizations, in situ measurements are made via one path length in a young's interferometer arrangement while ex-situ measurements use multiple path lengths. The multiple path length young's interferometer arrangement is embodied in a solid state waveguide configuration called the multiple path length dual polarization interferometer (MPL-DPI). The technique is demonstrated with ultrathin layers of poly(methylmethacrylate) and human serum albumin.
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Affiliation(s)
- Paul D Coffey
- School of Physics and Astronomy, The University of Manchester, Manchester, UK
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25
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Devi U, Gostock M, Popplewell JF, Swann MJ. Characterization of the Dynamic Structural Changes of Melittin - Lipid Bilayer Interactions. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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26
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Karim K, Taylor JD, Cullen DC, Swann MJ, Freeman NJ. Measurement of Conformational Changes in the Structure of Transglutaminase on Binding Calcium Ions Using Optical Evanescent Dual Polarisation Interferometry. Anal Chem 2007; 79:3023-31. [PMID: 17367112 DOI: 10.1021/ac051254b] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The conformational changes occurring when the protein transglutaminase binds calcium ions have been studied using the optical evanescent technique of dual polarization interferometry (DPI) implemented via a dual slab waveguide structure. Immobilized transglutaminase layers of 4-5 nm in thickness were obtained, which when challenged with calcium ions underwent a contraction of approximately 0.5 nm (depending on the concentration of calcium) and an increase in refractive index of approximately 1 x 10-2. The affinity constant for the calcium binding was found to be in the range of 0.95 +/- 0.2 mM. The results reported are in good agreement with those found in the literature obtained by other techniques. It has also been shown that the structural changes occurring during the binding event are considerably larger than the mass changes that take place; thus, DPI offers a potentially valuable method to study real-time structural changes occurring to proteins when they bind metal ions.
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Affiliation(s)
- K Karim
- Cranfield Health, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK
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27
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Popplewell JF, Swann MJ, Freeman NJ, McDonnell C, Ford RC. Quantifying the effects of melittin on liposomes. Biochim Biophys Acta 2006; 1768:13-20. [PMID: 17092481 DOI: 10.1016/j.bbamem.2006.05.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 05/12/2006] [Accepted: 05/19/2006] [Indexed: 11/19/2022]
Abstract
Melittin, the soluble peptide of bee venom, has been demonstrated to induce lysis of phospholipid liposomes. We have investigated the dependence of the lytic activity of melittin on lipid composition. The lysis of liposomes, measured by following their mass and dimensions when immobilised on a solid substrate, was close to zero when the negatively charged lipids phosphatidyl glycerol or phosphatidyl serine were used as the phospholipid component of the liposome. Whilst there was significant binding of melittin to the liposomes, there was little net change in their diameter with melittin binding reversed upon salt injection. For the zwitterionic phosphatidyl choline the lytic ability of melittin is dependent on the degree of acyl chain unsaturation, with melittin able to induce lysis of liposomes in the liquid crystalline state, whilst those in the gel state showed strong resistance to lysis. By directly measuring the dimensions and mass changes of liposomes on exposure to melittin using Dual Polarisation Interferometry, rather than following the florescence of entrapped dyes we attained further information about the initial stages of melittin binding to liposomes.
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Affiliation(s)
- J F Popplewell
- Farfield Scientific Ltd, Farfield House, Southmere Court, Electra Way, Crewe Business Park, Crewe CW1 6GU2, UK
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28
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Terry CJ, Popplewell JF, Swann MJ, Freeman NJ, Fernig DG. Characterisation of membrane mimetics on a dual polarisation interferometer. Biosens Bioelectron 2006; 22:627-32. [PMID: 16530399 DOI: 10.1016/j.bios.2006.01.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 01/26/2006] [Accepted: 01/26/2006] [Indexed: 10/24/2022]
Abstract
Dual polarisation interferometry (DPI) has been used to characterise the formation of hybrid bilayer membranes (HBM) on a silicon-oxynitride surface. This technique allows the simultaneous determination of multiple physical properties of an HBM, as the HBM is being formed in a single experiment: mass, thickness in the z-direction (normal to the surface), tilt angle of the first layer and refractive index. Decanoic acid was covalently attached to an amine modified silicon-oxynitride sensor chip surface via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride condensation reaction. The decanoic acid layer was 0.92+/-0.12 nm thick, indicating a tilt angle of 57 degrees from surface normal, and possessed a mass of 1.05+/-0.10 ng mm(-2) and a refractive index (RI) of 1.450+/-0.020. Phospholipid vesicles made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) were injected over the fatty acid surface to form an HBM. The DPPC HBM was 4.32+/-0.68 nm thick, with a total mass of 3.18+/-0.60 ng mm(-2) and a RI of 1.404+/-0.007. The DMPC HBM was 2.12+/-0.34 nm thick, with a total mass of 2.25+/-0.51 ng mm(-2), and a RI of 1.435+/-0.007. DPI thus provides an insight into HBM formation and differences between the structural organisation of HBMs of different composition.
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Affiliation(s)
- Carla J Terry
- School of Biological Sciences, Biosciences Building, Crown Street, University of Liverpool, Liverpool L69 7ZB, UK.
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29
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Abstract
A new optical biosensor is described based on a dual waveguide interferometric technique. By addressing the waveguide structure with alternate polarisations the optogeometrical properties (density and thickness) of adsorbed protein layers at the sensor (solid)-liquid interface have been determined. Differences in the waveguide mode dispersion between the transverse electric (TE) and transverse magnetic (TM) modes allow unique solutions for adlayer thickness and refractive index to be determined at all stages during the formation process. The technique has been verified using standard protein systems and by comparing the data with published work using X-ray crystallography and neutron reflection techniques. The data obtained was found to be in excellent agreement with previously reported X-ray experiments given that typical film thicknesses for streptavidin layers were in the range 5.5-6.5 nm compared with the short axis crystal structure of between 4.8 and 5.6 nm. The precision of the measurements taken was of the order of 40 pm with respect to adsorbed adlayer thicknesses. This biosensor approach provides measurements of both thickness and density of adlayers to a high precision, simultaneously and in real time enabling detail of the structure and function of proteins to be elucidated. From such data it is possible to obtain information on the orientation, distortion and efficiency of immobilisation procedures as well as the interaction event of interest. The technique is expected to find utility with those interested in protein structure and function. This is an area of growing importance within the life sciences as the demand for quantitative analytical techniques increases with the growth in "proteomics".
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Affiliation(s)
- Graham H Cross
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
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30
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Swann MJ, Peel LL, Carrington S, Freeman NJ. Dual-polarization interferometry: an analytical technique to measure changes in protein structure in real time, to determine the stoichiometry of binding events, and to differentiate between specific and nonspecific interactions. Anal Biochem 2004; 329:190-8. [PMID: 15158477 DOI: 10.1016/j.ab.2004.02.019] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Indexed: 11/18/2022]
Abstract
The study of solution-phase interactions between small molecules and immobilized proteins is of intense interest, especially to the pharmaceutical industry. An optical sensing technique, dual polarization interferometry, has been employed for the detailed study of a model protein system, namely, d-biotin interactions with streptavidin immobilized on a solid surface. Changes in thickness and density of an immobilized streptavidin layer as a result of the binding of d-biotin have been directly measured in solution and in real time. The results obtained from this approach are in excellent agreement with X-ray crystallographic data for the structural changes expected in the streptavidin-D-biotin system. The mass changes measured on binding d-biotin also agree closely with anticipated binding capacity values. Determination of the density changes occurring in the protein adlayer provides a means for differentiation between specific and nonspecific interactions.
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Affiliation(s)
- Marcus J Swann
- Farfield Sensors Ltd., Salford University Business Park, Leslie Hough Way, Salford, Greater Manchester M6 6AJ, UK
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31
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Lu JR, Swann MJ, Peel LL, Freeman NJ. Lysozyme adsorption studies at the silica/water interface using dual polarization interferometry. Langmuir 2004; 20:1827-1832. [PMID: 15801450 DOI: 10.1021/la0360299] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lysozyme adsorption at the silica/water interface has been studied using a new analytical technique called dual polarization interferometry. This laboratory-based technique allows the build up or removal of molecular layers adsorbing or reacting on a lightly doped silicon dioxide (silica) surface to be measured in terms of thickness and refractive index changes with time. Lysozyme adsorption was studied at a range of concentrations from 0.03 to 4.0 g dm(-3) and at both pH 4 and pH 7. Adsorbed layers ranging from 14 to 43 +/- 1 A in thickness and 0.21 to 2.36 +/- 0.05 mg m(-2) in mass coverage were observed at pH 4 with increasing lysozyme concentration, indicating a strong deformation of the monolayer over the low concentration range and the formation of an almost complete sideways-on bilayer toward the high concentration of 4 g dm(-3). At pH 7, the thickness of adsorbed layers varied from 16 to 54 +/- 1 A with significantly higher surface coverage (0.74 to 3.29 +/- 0.05 mg m(-2)), again indicating structural deformation during the initial monolayer formation, followed by a gradual transition to bilayer adsorption over the high concentration end. The pH recycling performed at a fixed lysozyme concentration of 1.0 g dm(-3) indicated a broadly reversible adsorption regardless of whether the pH was cycled from pH 7 to pH 4 and back again or vice versa. These observations are in good agreement with earlier studies undertaken using neutron reflection although the fine details of molecular orientations in the layers differ subtly.
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Affiliation(s)
- Jian R Lu
- Biological Physics Group, Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, United Kingdom
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Hillman AR, Swann MJ, Bruckenstein S. General appraoch to the interpretation of electrochemical quartz crystal microbalance data. 1. Cyclic voltammetry: kinetic subtleties in the electrochemical doping of polybithiophene films. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100161a056] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Glidle A, Bailey L, Hadyoon CS, Hillman AR, Jackson A, Ryder KS, Saville PM, Swann MJ, Webster JR, Wilson RW, Cooper JM. Temporal and spatial profiling of the modification of an electroactive polymeric interface using neutron reflectivity. Anal Chem 2001; 73:5596-606. [PMID: 11816593 DOI: 10.1021/ac0104882] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electropolymerized films of the functionalized pyrrole, pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), were reacted with a solution-phase nucleophile, ferrocene ethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymer membrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reaction profile within the electrodeposited polymer membrane after nucleophilic substitution is presented. This was achieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained from XPS, FT-IR, and electrochemical measurements. The results presented illustrate how, for a partially reacted film resulting from a short reaction time, the extent of reaction with ferrocene ethylamine is not homogeneous throughout the thickness of the film, but occurs predominantly at the polymer/solution interface. We show that the progress of the reaction within the polymer film is limited by the transport of reacting species in the dense regions of the membrane that are furthest from the solution interface. The data do not fit an alternative model in which there is spatially homogeneous progression of the reaction front throughout the bulk of the thin film polymer. Guided by the neutron reflectivity measurements, suitable modifications were made to the electrodeposition method to prepare films whose architecture resulted in faster rates of reaction.
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Affiliation(s)
- A Glidle
- Department of Electronics, Glasgow University, UK
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Abstract
Thin polymeric films have been deposited as upper cladding layers on a new integrated optical interferometer fabricated from layers of silicon oxynitride on a silicon wafer. The evanescent field of the probing waveguide mode transduces refractive index changes in the polymer layer into the measured phase changes in the device. Real-time measurement of index change and its sign is obtained. Upon exposure to humid air, we record water sorption by films of poly(vinyl pyrrolidone) by a rapid positive index change for void-space filling followed by a slow negative index change for swelling. Sorption of water vapor into a thin film of the viscous liquid polymer polyethylenimine shows only swelling mode behaviour and a simple constitutive model can be applied to give the fractional water occupied volume.
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Affiliation(s)
- G H Cross
- University of Durham, Department of Physics, South Road, Durham, UK DH1 3LE
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Hillman AR, Saville PM, Glidle A, Richardson RM, Roser SJ, Swann MJ, Webster JRP. Neutron Reflectivity Determination of Buried Electroactive Interface Structure: PBT/PPy and PBT/PXV Bilayers. J Am Chem Soc 1998. [DOI: 10.1021/ja970301h] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Robert Hillman
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - Paul M. Saville
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - Andrew Glidle
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - Robert M. Richardson
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - Stephen J. Roser
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - Marcus J. Swann
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
| | - John R. P. Webster
- Contribution from the Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K., Bioelectronics, Glasgow University, Glasgow G12 8QQ, U.K., School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K., School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K
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Swann MJ, Glidle A, Cui L, Barker JR, Cooper JM. The determination of gaseous molecular density using a hybrid vapour sensor. Chem Commun (Camb) 1998. [DOI: 10.1039/a808060g] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Swann MJ, Bloor D, Haruyama T, Aizawa M. The role of polypyrrole as charge transfer mediator and immobilization matrix for d-fructose dehydrogenase in a fructose sensor. Biosens Bioelectron 1997. [DOI: 10.1016/s0956-5663(97)00087-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Brooke GM, Drury CJ, Bloor D, Swann MJ. Poly(4,5,6,7-tetrafluorobenzo[c]thiophene) and related oligomers: a class of manipulable conjugated materials. Part 1.—Syntheses. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/jm9950501317] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Christensen PA, Hamnett A, Hillman AR, Swann MJ, Higgins SJ. An in situ Fourier-transform infrared study of the electroreduction of polybithiophene. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/ft9938900921] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hillman AR, Loveday DC, Swann MJ, Bruckenstein S, Wilde CP. Transport of neutral species in electroactive polymer films. ACTA ACUST UNITED AC 1991. [DOI: 10.1039/ft9918702047] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Carr MW, Hillman A, Lubetkin SD, Swann MJ. Detection of electrolytically generated bubbles using an electrochemical quartz crystal microbalance. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0022-0728(89)80261-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hillman AR, Loveday DC, Swann MJ, Eales RM, Hamnett A, Higgins SJ, Bruckenstein S, Wilde CP. Charge transport in electroactive polymer films. ACTA ACUST UNITED AC 1989. [DOI: 10.1039/dc9898800151] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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