1
|
Meredith SA, Kusunoki Y, Connell SD, Morigaki K, Evans SD, Adams PG. Self-Quenching Behavior of a Fluorescent Probe Incorporated within Lipid Membranes Explored Using Electrophoresis and Fluorescence Lifetime Imaging Microscopy. J Phys Chem B 2023; 127:1715-1727. [PMID: 36802586 PMCID: PMC9986866 DOI: 10.1021/acs.jpcb.2c07652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Fluorescent probes are useful in biophysics research to assess the spatial distribution, mobility, and interactions of biomolecules. However, fluorophores can undergo "self-quenching" of their fluorescence intensity at high concentrations. A greater understanding of concentration-quenching effects is important for avoiding artifacts in fluorescence images and relevant to energy transfer processes in photosynthesis. Here, we show that an electrophoresis technique can be used to control the migration of charged fluorophores associated with supported lipid bilayers (SLBs) and that quenching effects can be quantified with fluorescence lifetime imaging microscopy (FLIM). Confined SLBs containing controlled quantities of lipid-linked Texas Red (TR) fluorophores were generated within 100 × 100 μm corral regions on glass substrates. Application of an electric field in-plane with the lipid bilayer induced the migration of negatively charged TR-lipid molecules toward the positive electrode and created a lateral concentration gradient across each corral. The self-quenching of TR was directly observed in FLIM images as a correlation of high concentrations of fluorophores to reductions in their fluorescence lifetime. By varying the initial concentration of TR fluorophores incorporated into the SLBs from 0.3% to 0.8% (mol/mol), the maximum concentration of fluorophores reached during electrophoresis could be modulated from 2% up to 7% (mol/mol), leading to the reduction of fluorescence lifetime down to 30% and quenching of the fluorescence intensity down to 10% of their original levels. As part of this work, we demonstrated a method for converting fluorescence intensity profiles into molecular concentration profiles by correcting for quenching effects. The calculated concentration profiles have a good fit to an exponential growth function, suggesting that TR-lipids can diffuse freely even at high concentrations. Overall, these findings prove that electrophoresis is effective at producing microscale concentration gradients of a molecule-of-interest and that FLIM is an excellent approach to interrogate dynamic changes to molecular interactions via their photophysical state.
Collapse
Affiliation(s)
- Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Yuka Kusunoki
- Graduate School of Agricultural Science, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501, Japan
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe 657-8501, Japan
| | - Stephen D Evans
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U. K.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U. K
| |
Collapse
|
2
|
Broad K, Walker SA, Davidovich I, Witwer K, Talmon Y, Wolfram J. Unraveling multilayered extracellular vesicles: Speculation on cause. J Extracell Vesicles 2023; 12:e12309. [PMID: 36732941 PMCID: PMC9895808 DOI: 10.1002/jev2.12309] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/17/2023] [Accepted: 01/23/2023] [Indexed: 02/04/2023] Open
Abstract
Extracellular vesicles (EVs) are cell-released, heterogenous nanoparticles that play important roles in (patho)physiological processes through intercellular communication. EVs are often depicted as having a single lipid bilayer, but many studies have demonstrated the existence of multilayered EVs. There has been minimal inquiry into differences between unilamellar and multilamellar EVs in terms of biogenesis mechanisms and functional effects. This commentary speculates on potential causes and roles of multilamellar EVs and serves as a call to action for the research community to unravel the complex layers of EVs.
Collapse
Affiliation(s)
- Kelly Broad
- Department of Biochemistry and Molecular BiologyDepartment of Physiology and Biomedical EngineeringDepartment of TransplantationMayo ClinicJacksonvilleFloridaUSA
- Skaggs Graduate School of Chemical and Biological SciencesUniversity of Florida Scripps Biomedical ResearchJupiterFloridaUSA
| | - Sierra A. Walker
- Department of Biochemistry and Molecular BiologyDepartment of Physiology and Biomedical EngineeringDepartment of TransplantationMayo ClinicJacksonvilleFloridaUSA
| | - Irina Davidovich
- Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute (RBNI)Technion‐Israel Institute of TechnologyHaifaIsrael
| | - Kenneth Witwer
- Department of Molecular and Comparative PathobiologyThe Johns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of NeurologyThe Johns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Yeshayahu Talmon
- Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute (RBNI)Technion‐Israel Institute of TechnologyHaifaIsrael
| | - Joy Wolfram
- School of Chemical EngineeringThe University of QueenslandBrisbaneQueenslandAustralia
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQueenslandAustralia
- Department of NanomedicineHouston Methodist Research InstituteHoustonTexasUSA
| |
Collapse
|
3
|
Kocherginsky N. Biomimetic Membranes without Proteins but with Aqueous Nanochannels and Facilitated Transport. Minireview. MEMBRANES AND MEMBRANE TECHNOLOGIES 2021. [PMCID: PMC8675542 DOI: 10.1134/s251775162106010x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- N. Kocherginsky
- NEXT-ChemX, Department of Chemistry, University of Illinois, 61801 Urbana, Illinois USA
| |
Collapse
|
4
|
Meredith SA, Yoneda T, Hancock AM, Connell SD, Evans SD, Morigaki K, Adams PG. Model Lipid Membranes Assembled from Natural Plant Thylakoids into 2D Microarray Patterns as a Platform to Assess the Organization and Photophysics of Light-Harvesting Proteins. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006608. [PMID: 33690933 DOI: 10.1002/smll.202006608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/14/2021] [Indexed: 06/12/2023]
Abstract
Natural photosynthetic "thylakoid" membranes found in green plants contain a large network of light-harvesting (LH) protein complexes. Rearrangement of this photosynthetic machinery, laterally within stacked membranes called "grana", alters protein-protein interactions leading to changes in the energy balance within the system. Preparation of an experimentally accessible model system that allows the detailed investigation of these complex interactions can be achieved by interfacing thylakoid membranes and synthetic lipids into a template comprised of polymerized lipids in a 2D microarray pattern on glass surfaces. This paper uses this system to interrogate the behavior of LH proteins at the micro- and nanoscale and assesses the efficacy of this model. A combination of fluorescence lifetime imaging and atomic force microscopy reveals the differences in photophysical state and lateral organization between native thylakoid and hybrid membranes, the mechanism of LH protein incorporation into the developing hybrid membranes, and the nanoscale structure of the system. The resulting model system within each corral is a high-quality supported lipid bilayer that incorporates laterally mobile LH proteins. Photosynthetic activity is assessed in the hybrid membranes versus proteoliposomes, revealing that commonly used photochemical assays to test the electron transfer activity of photosystem II may actually produce false-positive results.
Collapse
Affiliation(s)
- Sophie A Meredith
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Takuro Yoneda
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe, 657-8501, Japan
| | - Ashley M Hancock
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Simon D Connell
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Stephen D Evans
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe, 657-8501, Japan
| | - Peter G Adams
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| |
Collapse
|
5
|
Structure, Formation, and Biological Interactions of Supported Lipid Bilayers (SLB) Incorporating Lipopolysaccharide. COATINGS 2020. [DOI: 10.3390/coatings10100981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Biomimetic membrane systems play a crucial role in the field of biosensor engineering. Over the years, significant progress has been achieved creating artificial membranes by various strategies from vesicle fusion to Langmuir transfer approaches to meet an ever-growing demand for supported lipid bilayers on various substrates such as glass, mica, gold, polymer cushions, and many more. This paper reviews the diversity seen in the preparation of biologically relevant model lipid membranes which includes monolayers and bilayers of phospholipid and other crucial components such as proteins, characterization techniques, changes in the physical properties of the membranes during molecular interactions and the dynamics of the lipid membrane with biologically active molecules with special emphasis on lipopolysaccharides (LPS).
Collapse
|
6
|
Hancock AM, Meredith SA, Connell SD, Jeuken LJC, Adams PG. Proteoliposomes as energy transferring nanomaterials: enhancing the spectral range of light-harvesting proteins using lipid-linked chromophores. NANOSCALE 2019; 11:16284-16292. [PMID: 31465048 DOI: 10.1039/c9nr04653d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bio-hybrid nanomaterials have great potential for combining the most desirable aspects of biomolecules and the contemporary concepts of nanotechnology to create highly efficient light-harvesting materials. Light-harvesting proteins are optimized to absorb and transfer solar energy with remarkable efficiency but have a spectral range that is limited by their natural pigment complement. Herein, we present the development of model membranes ("proteoliposomes") in which the absorption range of the membrane protein Light-Harvesting Complex II (LHCII) is effectively enhanced by the addition of lipid-tethered Texas Red (TR) chromophores. Energy transfer from TR to LHCII is observed with up to 94% efficiency and increased LHCII fluorescence of up to three-fold when excited in the region of lowest natural absorption. The new self-assembly procedure offers the modularity to control the concentrations incorporated of TR and LHCII, allowing energy transfer and fluorescence to be tuned. Fluorescence Lifetime Imaging Microscopy provides single-proteoliposome-level quantification of energy transfer efficiency and confirms that functionality is retained on surfaces. Designer proteoliposomes could act as a controllable light-harvesting nanomaterial and are a promising step in the development of bio-hybrid light-harvesting systems.
Collapse
Affiliation(s)
- Ashley M Hancock
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Lars J C Jeuken
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK and School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
7
|
Adams PG, Vasilev C, Hunter CN, Johnson MP. Correlated fluorescence quenching and topographic mapping of Light-Harvesting Complex II within surface-assembled aggregates and lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2018; 1859:1075-1085. [PMID: 29928860 PMCID: PMC6135645 DOI: 10.1016/j.bbabio.2018.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/11/2018] [Accepted: 06/15/2018] [Indexed: 01/30/2023]
Abstract
Light-Harvesting Complex II (LHCII) is a chlorophyll-protein antenna complex that efficiently absorbs solar energy and transfers electronic excited states to photosystems I and II. Under excess light intensity LHCII can adopt a photoprotective state in which excitation energy is safely dissipated as heat, a process known as Non-Photochemical Quenching (NPQ). In vivo NPQ is triggered by combinatorial factors including transmembrane ΔpH, PsbS protein and LHCII-bound zeaxanthin, leading to dramatically shortened LHCII fluorescence lifetimes. In vitro, LHCII in detergent solution or in proteoliposomes can reversibly adopt an NPQ-like state, via manipulation of detergent/protein ratio, lipid/protein ratio, pH or pressure. Previous spectroscopic investigations revealed changes in exciton dynamics and protein conformation that accompany quenching, however, LHCII-LHCII interactions have not been extensively studied. Here, we correlated fluorescence lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM) of trimeric LHCII adsorbed to mica substrates and manipulated the environment to cause varying degrees of quenching. AFM showed that LHCII self-assembled onto mica forming 2D-aggregates (25-150 nm width). FLIM determined that LHCII in these aggregates were in a quenched state, with much lower fluorescence lifetimes (~0.25 ns) compared to free LHCII in solution (2.2-3.9 ns). LHCII-LHCII interactions were disrupted by thylakoid lipids or phospholipids, leading to intermediate fluorescent lifetimes (0.6-0.9 ns). To our knowledge, this is the first in vitro correlation of nanoscale membrane imaging with LHCII quenching. Our findings suggest that lipids could play a key role in modulating the extent of LHCII-LHCII interactions within the thylakoid membrane and so the propensity for NPQ activation.
Collapse
Affiliation(s)
- Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| |
Collapse
|
8
|
Lee K, Zhang L, Yi Y, Wang X, Yu Y. Rupture of Lipid Membranes Induced by Amphiphilic Janus Nanoparticles. ACS NANO 2018; 12:3646-3657. [PMID: 29617553 DOI: 10.1021/acsnano.8b00759] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The surface coatings of nanoparticles determine their interaction with biomembranes, but studies have been limited almost exclusively to nanoparticles with a uniform surface chemistry. Although nanoparticles are increasingly made with complex surface chemistries to achieve multifunctionalities, our understanding of how a heterogeneous surface coating affects particle-biomembrane interaction has been lagging far behind. Here we report an investigation of this question in an experimental system consisting of amphiphilic "two-faced" Janus nanoparticles and supported lipid membranes. We show that amphiphilic Janus nanoparticles at picomolar concentrations induce defects in zwitterionic lipid bilayers. In addition to revealing the various effects of hydrophobicity and charge in particle-bilayer interactions, we demonstrate that the Janus geometry-the spatial segregation of hydrophobicity and charges on particle surface-causes nanoparticles to bind more strongly to bilayers and induce defects more effectively than particles with uniformly mixed surface functionalities. We combine experiments with computational simulation to further elucidate how amphiphilic Janus nanoparticles extract lipids to rupture intact lipid bilayers. This study provides direct evidence that the spatial arrangement of surface functionalities on a nanoparticle, rather than just its overall surface chemistry, plays a crucial role in determining how it interacts with biological membranes.
Collapse
Affiliation(s)
- Kwahun Lee
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Liuyang Zhang
- State Key Laboratory for Manufacturing Systems Engineering , Xi'an Jiaotong University , Xi'an , Shaanxi 710049 , China
| | - Yi Yi
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Xianqiao Wang
- College of Engineering , University of Georgia , Athens , Georgia 30602 , United States
| | - Yan Yu
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| |
Collapse
|
9
|
Colorimetric analysis of lipopolysaccharides based on its self-assembly to inhibit ion transport. Anal Chim Acta 2017; 992:85-93. [DOI: 10.1016/j.aca.2017.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 09/02/2017] [Accepted: 09/03/2017] [Indexed: 11/22/2022]
|
10
|
Zhu Y, Moran-Mirabal J. Micropatterning of Phase-Segregated Supported Lipid Bilayers and Binary Lipid Phases through Polymer Stencil Lift-Off. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11021-11028. [PMID: 27700106 DOI: 10.1021/acs.langmuir.6b02346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Supported lipid bilayers (SLBs) provide an excellent model system for studying structural and functional characteristics of biomembranes. Patterning model membranes on solid supports has elicited much interest because lipid bilayer arrays at cellular or subcellular scales provide attractive platforms for reconstituting tissue-like conditions for cell culture, and for creating simplified physiological environments to study biological processes. Phase-segregated SLB patterns can be especially useful for such studies, as the selective functionalization of the lipid phases with different lipids, receptors, or proteins can be achieved to mimic the key features of plasma membrane. However, it remains challenging to pattern phase-segregated lipid bilayers and to spatially control the lipid phases at the micron scale. Current methods to achieve this involve multiple surface modification and patterning steps, elaborate techniques such as microfluidic, microcontact printing, or electrochemical control, among others. To overcome the complexity in producing phase-segregated patterns, we have developed simple and rapid strategies to pattern SLBs with phase separation utilizing the polymer stencil lift-off (PSLO) technique. PSLO is a powerful technique for SLB patterning, since it allows the faithful pattern transfer of micron-sized lipid domains onto solid surfaces under aqueous conditions, which eliminates the need for controlled humidity and reduces the risk of bilayer disruption through drying. By integrating postetching substrate cleaning and a blocking treatment, well-defined homogeneous and phase-segregated SLB patterns were achieved with lipid mobility that matches that of SLBs formed on clean SiO2 wafer substrates. A two-step incubation method was also developed for patterning binary lipid phases, which allowed precise control of their position and geometries. The created phase-segregated SLB patterns were used to study lipid phase behavior within confined areas, and quantitative analysis showed that smaller pattern sizes resulted in smaller gel phase domains, which also covered a smaller fraction of the total patterned SLB area. This was attributed to the decreased mobility of the bottom leaflet of the SLB, which lies in close proximity to the substrate, and the resulting hindered exchange of lipid molecules between the bottom and upper leaflets through the SLB boundary. By further integration with functional groups, the phase-segregated lipid bilayer patterns might find relevant application in tissue engineering, biophysical studies of biomolecular and cellular interactions, and biosensing platforms.
Collapse
Affiliation(s)
- Yujie Zhu
- Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S4L8, Canada
| | - Jose Moran-Mirabal
- Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S4L8, Canada
| |
Collapse
|
11
|
Stromberg LR, Hengartner NW, Swingle KL, Moxley RA, Graves SW, Montaño GA, Mukundan H. Membrane Insertion for the Detection of Lipopolysaccharides: Exploring the Dynamics of Amphiphile-in-Lipid Assays. PLoS One 2016; 11:e0156295. [PMID: 27227979 PMCID: PMC4881986 DOI: 10.1371/journal.pone.0156295] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/12/2016] [Indexed: 12/27/2022] Open
Abstract
Shiga toxin-producing Escherichia coli is an important cause of foodborne illness, with cases attributable to beef, fresh produce and other sources. Many serotypes of the pathogen cause disease, and differentiating one serotype from another requires specific identification of the O antigen located on the lipopolysaccharide (LPS) molecule. The amphiphilic structure of LPS poses a challenge when using classical detection methods, which do not take into account its lipoglycan biochemistry. Typically, detection of LPS requires heat or chemical treatment of samples and relies on bioactivity assays for the conserved lipid A portion of the molecule. Our goal was to develop assays to facilitate the direct and discriminative detection of the entire LPS molecule and its O antigen in complex matrices using minimal sample processing. To perform serogroup identification of LPS, we used a method called membrane insertion on a waveguide biosensor, and tested three serogroups of LPS. The membrane insertion technique allows for the hydrophobic association of LPS with a lipid bilayer, where the exposed O antigen can be targeted for specific detection. Samples of beef lysate were spiked with LPS to perform O antigen specific detection of LPS from E. coli O157. To validate assay performance, we evaluated the biophysical interactions of LPS with lipid bilayers both in- and outside of a flow cell using fluorescence microscopy and fluorescently doped lipids. Our results indicate that membrane insertion allows for the qualitative and reliable identification of amphiphilic LPS in complex samples like beef homogenates. We also demonstrated that LPS-induced hole formation does not occur under the conditions of the membrane insertion assays. Together, these findings describe for the first time the serogroup-specific detection of amphiphilic LPS in complex samples using a membrane insertion assay, and highlight the importance of LPS molecular conformations in detection architectures.
Collapse
Affiliation(s)
- Loreen R. Stromberg
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico, United States of America
- Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
- The New Mexico Consortium, Los Alamos, New Mexico, United States of America
| | - Nicolas W. Hengartner
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Kirstie L. Swingle
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Rodney A. Moxley
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Steven W. Graves
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico, United States of America
- The New Mexico Consortium, Los Alamos, New Mexico, United States of America
| | - Gabriel A. Montaño
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Harshini Mukundan
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico, United States of America
- Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
- The New Mexico Consortium, Los Alamos, New Mexico, United States of America
| |
Collapse
|