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Li Z, Ji X, Xie H, Tang BZ. Aggregation-Induced Emission-Active Gels: Fabrications, Functions, and Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100021. [PMID: 34216407 DOI: 10.1002/adma.202100021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 03/14/2021] [Indexed: 05/07/2023]
Abstract
Chromophores that exhibit aggregation-induced emission (i.e., aggregation-induced emission luminogens [AIEgens]) emit intense fluorescence in their aggregated states, but show negligible emission as discrete molecular species in solution due to the changes in restriction and freedom of intramolecular motions. As solvent-swollen quasi-solids with both a compact phase and a free space, gels enable manipulation of intramolecular motions. Thus, AIE-active gels have attracted significant interest owing to their various distinctive properties and promising application potential. Herein, a comprehensive overview of AIE-active gels is provided. The fabrication strategies employed are detailed, and the applications of AIEgens are summarized. In addition, the gel functions arising from the AIE moieties are revealed, along with their structure-property relationships. Furthermore, the applications of AIE-active gels in diverse areas are illustrated. Finally, ongoing challenges and potential means to address them are discussed, along with future perspectives on AIE-active gels, with the overall aim of inspiring research on novel materials and ideas.
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Affiliation(s)
- Zhao Li
- Institute of Engineering Medicine, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, China
| | - Xiaofan Ji
- School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Huilin Xie
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction and Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park Nanshan, Shenzhen, 518055, China
| | - Ben Zhong Tang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction and Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park Nanshan, Shenzhen, 518055, China
- Center for Aggregation-Induced Emission, SCUT-HKUST Joint Research Institutes, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
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Synthesis of sustainable silica xerogels/aerogels using inexpensive steel slag and bean pod ash: A comparison study. ADV POWDER TECHNOL 2020. [DOI: 10.1016/j.apt.2019.12.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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3
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Goodchild JA, Walsh DL, Connell SD. Nanoscale Substrate Roughness Hinders Domain Formation in Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15352-15363. [PMID: 31626551 DOI: 10.1021/acs.langmuir.9b01990] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Supported lipid bilayers are model membranes formed at solid substrate surfaces. This architecture renders the membrane experimentally accessible to surface-sensitive techniques used to study their properties, including atomic force microscopy, optical fluorescence microscopy, quartz crystal microbalance, and X-ray/neutron reflectometry, and allows integration with technology for potential biotechnological applications such as drug screening devices. The experimental technique often dictates substrate choice or treatment, and it is anecdotally recognized that certain substrates are suitable for a particular experiment, but the exact influence of the substrate has not been comprehensively investigated. Here, we study the behavior of a simple model bilayer, phase-separating on a variety of commonly used substrates, including glass, mica, silicon, and quartz, with drastically different results. The distinct micron-scale domains observed on mica, identical to those seen in free-floating giant unilamellar vesicles, are reduced to nanometer-scale domains on glass and quartz. The mechanism for the arrest of domain formation is investigated, and the most likely candidate is nanoscale surface roughness, acting as a drag on the hydrodynamic motion of small domains during phase separation. Evidence was found that the physicochemical properties of the surface have a mediating effect, most likely because of the changes in the lubricating interstitial water layer between the surface and bilayer.
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Affiliation(s)
- James A Goodchild
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
| | - Danielle L Walsh
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
| | - Simon D Connell
- School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , U.K
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Blachon F, Harb F, Munteanu B, Piednoir A, Fulcrand R, Charitat T, Fragneto G, Pierre-Louis O, Tinland B, Rieu JP. Nanoroughness Strongly Impacts Lipid Mobility in Supported Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2444-2453. [PMID: 28219008 DOI: 10.1021/acs.langmuir.6b03276] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In vivo lipid membranes interact with rough supramolecular structures such as protein clusters and fibrils. How these features whose size ranges from a few nanometers to a few tens of nanometers impact lipid and protein mobility is still being investigated. Here, we study supported phospholipid bilayers, a unique biomimetic model, deposited on etched surfaces bearing nanometric corrugations. The surface roughness and mean curvature are carefully characterized by AFM imaging using ultrasharp tips. Neutron specular reflectivity supplements this surface characterization and indicates that the bilayers follow the large-scale corrugations of the substrate. We measure the lateral mobility of lipids in both the fluid and gel phases by fluorescence recovery after patterned photobleaching. Although the mobility is independent of the roughness in the gel phase, it exhibits a 5-fold decrease in the fluid phase when the roughness increases from 0.2 to 10 nm. These results are interpreted with a two-phase model allowing for a strong decrease in the lipid mobility in highly curved or defect-induced gel-like nanoscale regions. This suggests a strong link between membrane curvature and fluidity, which is a key property for various cell functions such as signaling and adhesion.
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Affiliation(s)
- Florence Blachon
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Frédéric Harb
- Doctoral School for Science and Technology, Platform for Research in NanoSciences and Nanotechnology, Campus Pierre Gemayel, Lebanese University , Fanar-Metn BP 90239 Beirut, Lebanon
| | - Bogdan Munteanu
- CNRS, INSA de Lyon, LaMCoS, UMR5259, Université de Lyon , 69621 Lyon, France
| | - Agnès Piednoir
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Rémy Fulcrand
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Thierry Charitat
- Université de Strasbourg, Institut Charles Sadron , UPR22, CNRS, 67034 Strasbourg Cedex 2, France
| | - Giovanna Fragneto
- Institut Laue-Langevin , 71 Avenue des Martyrs, F-38042 Grenoble, France
| | - Olivier Pierre-Louis
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Bernard Tinland
- CINaM-CNRS, Aix-Marseille Université , UMR7325, 13288 Marseille, France
| | - Jean-Paul Rieu
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
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5
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Bruzas I, Unser S, Yazdi S, Ringe E, Sagle L. Ultrasensitive Plasmonic Platform for Label-Free Detection of Membrane-Associated Species. Anal Chem 2016; 88:7968-74. [PMID: 27436204 DOI: 10.1021/acs.analchem.6b00801] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lipid membranes and membrane proteins are important biosensing targets, motivating the development of label-free methods with improved sensitivity. Silica-coated metal nanoparticles allow these systems to be combined with supported lipid bilayers for sensing membrane proteins through localized surface plasmon resonance (LSPR). However, the small sensing volume of LSPR makes the thickness of the silica layer critical for performance. Here, we develop a simple, inexpensive, and rapid sol-gel method for preparing thin conformal, continuous silica films and demonstrate its applicability using gold nanodisk arrays with LSPRs in the near-infrared range. Silica layers as thin as ∼5 nm are observed using cross-sectional scanning transmission electron microscopy. The loss in sensitivity due to the thin silica coating was found to be only 16%, and the biosensing capabilities of the substrates were assessed through the binding of cholera toxin B to GM1 lipids. This sensor platform should prove useful in the rapid, multiplexed detection and screening of membrane-associated biological targets.
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Affiliation(s)
- Ian Bruzas
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Sarah Unser
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
| | - Sadegh Yazdi
- Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, MS-325, Houston, Texas 77005, United States
| | - Emilie Ringe
- Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, MS-325, Houston, Texas 77005, United States
| | - Laura Sagle
- Department of Chemistry, College of Arts and Sciences, University of Cincinnati , 301 West Clifton Court, Cincinnati, Ohio 45221-0172, United States
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Duro N, Gjika M, Siddiqui A, Scott HL, Varma S. POPC Bilayers Supported on Nanoporous Substrates: Specific Effects of Silica-Type Surface Hydroxylation and Charge Density. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:6766-6774. [PMID: 27283467 DOI: 10.1021/acs.langmuir.6b01155] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent advances in nanotechnology bring to the forefront a new class of extrinsic constraints for remodeling lipid bilayers. In this next-generation technology, membranes are supported over nanoporous substrates. The nanometer-sized pores in the substrate are too small for bilayers to follow the substrate topology; consequently, the bilayers hang over the pores. Experiments demonstrate that nanoporous substrates remodel lipid bilayers differently from continuous substrates. The underlying molecular mechanisms, however, remain largely undetermined. Here we use molecular dynamics (MD) simulations to probe the effects of silica-type hydroxylation and charge densities on adsorbed palmitoyl-oleoylphosphatidylcholine (POPC) bilayers. We find that a 50% porous substrate decorated with a surface density of 4.6 hydroxyls/nm(2) adsorbs a POPC bilayer at a distance of 4.5 Å, a result consistent with neutron reflectivity experiments conducted on topologically similar silica constructs under highly acidic conditions. Although such an adsorption distance suggests that the interaction between the bilayer and the substrate will be buffered by water molecules, we find that the substrate does interact directly with the bilayer. The substrate modifies several properties of the bilayer-it dampens transverse lipid fluctuations, reduces lipid diffusion rates, and modifies transverse charge densities significantly. Additionally, it affects lipid properties differently in the two leaflets. Compared to substrates functionalized with sparser surface hydroxylation densities, this substrate adheres to bilayers at smaller distances and also remodels POPC more extensively, suggesting a direct correspondence between substrate hydrophilicity and membrane properties. A partial deprotonation of surface hydroxyls, as expected of a silica substrate under mildly acidic conditions, however, produces an inverse effect: it increases the substrate-bilayer distance, which we attribute to the formation of an electric double layer over the negatively charged substrate, and restores, at least partially, leaflet asymmetry and headgroup orientations. Overall, this study highlights the intrinsic complexity of lipid-substrate interactions and suggests the prospect of making two surface attributes-dipole densities and charge densities-work antagonistically toward remodeling lipid bilayer properties.
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Affiliation(s)
- Nalvi Duro
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida , Tampa, Florida 33620, United States
| | - Marion Gjika
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida , Tampa, Florida 33620, United States
| | - Ahnaf Siddiqui
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida , Tampa, Florida 33620, United States
| | - H Larry Scott
- Department of Physics, Illinois Institute of Technology , Chicago, Illinois 60616, United States
| | - Sameer Varma
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida , Tampa, Florida 33620, United States
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7
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Metal ion binding to phospholipid bilayers evaluated by microaffinity chromatography. J Chromatogr A 2016; 1451:75-82. [DOI: 10.1016/j.chroma.2016.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 02/01/2023]
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8
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Redondo-Morata L, Giannotti MI, Sanz F. AFM-based force-clamp monitors lipid bilayer failure kinetics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:6403-6410. [PMID: 22443887 DOI: 10.1021/la3005147] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The lipid bilayer rupture phenomenon is here explored by means of atomic force microscopy (AFM)-based force clamp, for the first time to our knowledge, to evaluate how lipid membranes respond when compressed under an external constant force, in the range of nanonewtons. Using this method, we were able to directly quantify the kinetics of the membrane rupture event and the associated energy barriers, for both single supported bilayers and multibilayers, in contradistinction to the classic studies performed at constant velocity. Moreover, the affected area of the membrane during the rupture process was calculated using an elastic deformation model. The elucidated information not only contributes to a better understanding of such relevant process, but also proves the suitability of AFM-based force clamp to study model structures as lipid bilayers. These findings on the kinetics of lipid bilayers rupture could be extended and applied to the study of other molecular thin films. Furthermore, systems of higher complexity such as models mimicking cell membranes could be studied by means of AFM-based force-clamp technique.
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Affiliation(s)
- Lorena Redondo-Morata
- Institute for Bioengineering of Catalonia (IBEC), 15-21 Baldiri I Reixac, 08028 Barcelona, Spain
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9
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Moya-Ortega MD, Alvarez-Lorenzo C, Concheiro A, Loftsson T. Cyclodextrin-based nanogels for pharmaceutical and biomedical applications. Int J Pharm 2012; 428:152-63. [PMID: 22388054 DOI: 10.1016/j.ijpharm.2012.02.038] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/22/2012] [Accepted: 02/23/2012] [Indexed: 11/18/2022]
Abstract
Hydrophilic nanogels combine the advantages of hydrogels with certain advantages that are inherent in their nanoscale size. Similar to macrogels, nanogels can contain and protect drugs and regulate their release by incorporating high-affinity functional groups, stimuli-responsive conformations and biodegradable bonds into the polymer network. Similar to nanoparticles, nanogels can easily be administered in liquid form for parenteral drug delivery. The nanoscale size of nanogels gives them a high specific surface area that is available for further bioconjugation of active targeting agents. Biodistribution and drug release can be modulated through size adjustments. The incorporation of hydrophilic cyclodextrin (CD) moieties into the polymeric network of the nanogels provides them with a drug loading and release mechanism that is based on the formation of inclusion complexes without decreasing the hydrophilicity of the network. The covalent attachment of CD molecules to the chemically crosslinked networks may enable the CDs to display fully their ability to form complexes, while simultaneously preventing drug release upon media dilution. The preparation, characterization and advantages for pharmaceutical and biomedical applications of CD-based nanogels are reviewed in this article.
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Affiliation(s)
- Maria D Moya-Ortega
- Faculty of Pharmaceutical Sciences, University of Iceland, Hofsvallagata 53, IS-107 Reykjavik, Iceland
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10
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Satriano C, Fragalà ME. Lipid vesicle adsorption on micropore arrays prepared by colloidal lithography-based deposition approaches. RSC Adv 2012. [DOI: 10.1039/c2ra20163a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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11
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Mulligan K, Jakubek ZJ, Johnston LJ. Supported lipid bilayers on biocompatible polysaccharide multilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14352-14359. [PMID: 22013993 DOI: 10.1021/la203207p] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Formation of supported lipid bilayers on soft polymer cushions is a useful approach to decouple the membrane from the substrate for applications involving membrane proteins. We prepared biocompatible polymer cushions by the layer-by-layer assembly of two polysaccharide polyelectrolytes, chitosan (CHI) and hyaluronic acid, on glass and silicon substrates. (CHI/HA)(5) films were characterized by atomic force microscopy, giving an average thickness of 57 nm and roughness of 25 nm in aqueous solution at pH 6.5. Formation of zwitterionic lipid bilayers by the vesicle fusion method was attempted using DOPC vesicles at pH 4 and 6.5 on (CHI/HA)(5) films. At higher pH adsorbed lipids had low mobility and large immobile lipid fractions; a combination of fluorescence and AFM indicated that this was attributable to formation of poor quality membranes with defects and pinned lipids rather than to a layer of surface-adsorbed vesicles. By contrast, more uniform bilayers with mobile lipids were produced at pH 4. Fluorescence recovery after photobleaching gave diffusion coefficients that were similar to those for bilayers on PEG cushions and considerably higher than those measured on other polyelectrolyte films. The results suggest that the polymer surface charge is more important than the surface roughness in controlling formation of mobile supported bilayers. These results demonstrate that polysaccharides provide a useful alternative to other polymer cushions, particularly for applications where biocompatibility is important.
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Affiliation(s)
- Kirk Mulligan
- Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
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12
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Tero R, Sazaki G, Ujihara T, Urisu T. Anomalous diffusion in supported lipid bilayers induced by oxide surface nanostructures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9662-9665. [PMID: 21761843 DOI: 10.1021/la201474h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Hierarchic structure and anomalous diffusion on submicrometer scale were introduced into an artificial cell membrane, and the spatiotemporal dependence of lipid diffusion was visualized on nanostructured oxide surfaces. We observed the lipid diffusion in supported lipid bilayers (SLBs) on step-and-terrace TiO(2)(100) and amorphous SiO(2)/Si surfaces by single molecule tracking (SMT) method. The SMT at the time resolution of 500 μs to 30 ms achieved observation of the lipid diffusion over the spatial and temporal ranges of 100 nm/millisecond to 1 μm/second. The temporal dependence of the diffusion coefficient in the SLB on TiO(2)(100) showed that the crossover from anomalous diffusion to random diffusion occurred around 10 ms. The surface fine architecture on substrates will be applicable to induce hierarchic structures on the order of 100 nm or less, which correspond to the microcompartment size in vivo.
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Affiliation(s)
- Ryugo Tero
- Division of Biomolecular Sensing, Institute for Molecular Science, Okazaki 444-8585, Japan.
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Huckabay HA, Dunn RC. Hydration effects on membrane structure probed by single molecule orientations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2658-2666. [PMID: 21319764 DOI: 10.1021/la104792w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Single molecule fluorescence measurements are used to probe the structural changes in glass-supported DPPC bilayers as a function of relative humidity (RH). Defocused polarized total internal reflection fluorescence microscopy is employed to determine the three-dimensional orientation of the fluorescent lipid analogue BODIPY-PC, doped into DPPC membranes in trace amounts. Supported DPPC bilayers formed using vesicle fusion and Langmuir-Blodgett/Langmuir-Schäfer (LB/LS) transfer are compared and show similar trends as a function of relative humidity. Population histograms of the emission dipole tilt angle reveal bimodal distributions as observed previously for BODIPY-PC in DPPC. These distributions are dominated by large populations of BODIPY-PC molecules with emission dipoles oriented parallel (≥81°) and normal (≤10°) to the membrane plane, with less than 25% oriented at intermediate tilts. As the relative humidity is increased from 13% to 95%, the population of molecules oriented normal to the surface decreases with a concomitant increase in those oriented parallel to the surface. The close agreement in trends observed for bilayers formed from vesicle fusion and LB/LS transfer supports the assignment of an equivalent surface pressure of 23 mN/m for bilayers formed from vesicle fusion. At each RH condition, a small population of BODIPY-PC dye molecules are laterally mobile in both bilayer preparations. This population exponentially increases with RH but never exceeds 6% of the total population. Interestingly, even under conditions where there is little lateral diffusion, fluctuations in the single molecule orientations can be observed which suggests there is appreciable freedom in the acyl chain region. Dynamic measurements of single molecule orientation changes, therefore, provide a new view into membrane properties at the single molecule level.
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Affiliation(s)
- Heath A Huckabay
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas , 2030 Becker Drive, Lawrence, Kansas 66047, United States
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14
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Nellis BA, Satcher JH, Risbud SH. Phospholipid bilayer formation on a variety of nanoporous oxide and organic xerogel films. Acta Biomater 2011; 7:380-6. [PMID: 20674809 DOI: 10.1016/j.actbio.2010.07.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/22/2010] [Accepted: 07/23/2010] [Indexed: 10/19/2022]
Abstract
Lipid bilayers supported by nanoporous xerogel materials are being explored as models for cell membranes. In order to better understand and characterize the nature of the surface-bilayer interactions, several oxide and organic nanoporous xerogel films (alumina, titania, iron oxide, phloroglucinol-formaldehyde, resorcinol-formaldehyde and cellulose acetate) have been investigated as a scaffold for vesicle-fused 1,2-dioleoyl-glycero-3-phosphocholine (DOPC) lipid bilayer formation and mobility. The surface topography of the different substrates was analyzed using contact and tapping-mode atomic force microscopy and the surface energy of the substrates was determined using contact angle goniometry. Lipid bilayer formation has been observed with fluorescence microscopy and lateral lipid diffusion coefficients have been determined using fluorescence recovery after photobleaching. Titania xerogel films were found to be a robust and convenient support for formation of a two-phase DOPC/1,2-distearoyl-glycero-3-phosphocholine bilayer and domains were observed with this system. It was found that the cellulose acetate xerogel film support produced the slowest lipid lateral diffusion.
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15
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Garcia-Manyes S, Redondo-Morata L, Oncins G, Sanz F. Nanomechanics of Lipid Bilayers: Heads or Tails? J Am Chem Soc 2010; 132:12874-86. [DOI: 10.1021/ja1002185] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sergi Garcia-Manyes
- Department of Biological Sciences, Columbia University, New York, 10027, New York, Departament de Química Física, Universitat de Barcelona, 08028, Spain, Institut de Bioenginyeria de Catalunya, Barcelona, 08028, Spain, Serveis Cientificotècnics, Universitat de Barcelona, 08028, Spain, and CIBER-BBN, Zaragoza 50018, Spain
| | - Lorena Redondo-Morata
- Department of Biological Sciences, Columbia University, New York, 10027, New York, Departament de Química Física, Universitat de Barcelona, 08028, Spain, Institut de Bioenginyeria de Catalunya, Barcelona, 08028, Spain, Serveis Cientificotècnics, Universitat de Barcelona, 08028, Spain, and CIBER-BBN, Zaragoza 50018, Spain
| | - Gerard Oncins
- Department of Biological Sciences, Columbia University, New York, 10027, New York, Departament de Química Física, Universitat de Barcelona, 08028, Spain, Institut de Bioenginyeria de Catalunya, Barcelona, 08028, Spain, Serveis Cientificotècnics, Universitat de Barcelona, 08028, Spain, and CIBER-BBN, Zaragoza 50018, Spain
| | - Fausto Sanz
- Department of Biological Sciences, Columbia University, New York, 10027, New York, Departament de Química Física, Universitat de Barcelona, 08028, Spain, Institut de Bioenginyeria de Catalunya, Barcelona, 08028, Spain, Serveis Cientificotècnics, Universitat de Barcelona, 08028, Spain, and CIBER-BBN, Zaragoza 50018, Spain
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16
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Goksu EI, Longo ML. Ternary lipid bilayers containing cholesterol in a high curvature silica xerogel environment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8614-24. [PMID: 20143868 DOI: 10.1021/la9046885] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The phase behavior of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) (1/1 mol ratio)/cholesterol (0-60 mol %) supported lipid bilayers agreed with a DOPC/DSPC/cholesterol ternary phase diagram by Zhao et al. when a mica support was used (Zhao, J.; Wu, J.; Heberle, F. A.; Mills, T. T.; Klawitter, P.; Huang, G.; Costanza, G.; Feigenson, G. W. Biochim. Biophys. Acta, Biomembr. 2007, 1768, 2764-2776). However, when a silica xerogel support was used, the phase behavior deviated from the phase diagram. Specifically, miscibility and trend lines of DSPC-rich domain area fraction, domain shape, and domain size versus cholesterol, obtained by analysis of fluorescence and atomic force microscopy (AFM) images, were as expected for mica-supported lipid bilayers, but were substantially stretched to higher cholesterol concentrations for silica xerogel-supported lipid bilayers. In addition, this behavior was found in three other ternary lipid compositions substituting slightly shorter acyl chain lengths in comparison to DSPC or a saturated lipid versus unsaturated DOPC. Qualitative comparison of domain characteristics of DOPC/DSPC/cholesterol (0 and 15 mol %) bilayers supported by silica xerogel, mica, borosilicate glass, and quartz showed that the networked surface layer of high curvature (0.04 nm(-1)) silica beads was the dominant influence as opposed to the surface chemistry. Based upon the literature, we postulate two curvature-based mechanisms that explain our results. In the first mechanism, cholesterol was transferred from the higher curvature supported lipid bilayer to the lower curvature vesicles in the medium during the vesicle fusion and thermal cooling step, resulting in a lowered cholesterol concentration of the supported lipid bilayer. In the second mechanism, high curvature promoted sustained lipid demixing as the cholesterol concentration was increased, thus creating a new phase diagram in which coexisting phases persist to a higher cholesterol concentration. These results suggest that a surface layer of high curvature features can be used to observe and study curvature-induced intrabilayer transport or demixing over large areas and that curvature can play an important role in sorting and localization of biomembrane components.
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Affiliation(s)
- Emel I Goksu
- Department of Chemical Engineering & Materials Science, University of California, Davis, California 95616, USA
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What Is the Difference Between a Supported and a Free Bilayer? Insights from Molecular Modeling on Different Scales. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1554-4516(10)11007-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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