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Xie J, Pink DL, Jayne Lawrence M, Lorenz CD. Digestion of lipid micelles leads to increased membrane permeability. NANOSCALE 2024; 16:2642-2653. [PMID: 38229565 DOI: 10.1039/d3nr05083a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Lipid-based drug carriers are an attractive option to solubilise poorly water soluble therapeutics. Previously, we reported that the digestion of a short tail PC lipid (2C6PC) by the PLA2 enzyme has a significant effect on the structure and stability of the micelles it forms. Here, we studied the interactions of micelles of varying composition representing various degrees of digestion with a model ordered (70 mol% DPPC & 30 mol% cholesterol) and disordered (100% DOPC) lipid membrane. Micelles of all compositions disassociated when interacting with the two different membranes. As the percentage of digestion products (C6FA and C6LYSO) in the micelle increased, the disassociation occurred more rapidly. The C6FA inserts preferentially into both membranes. We find that all micelle components increase the area per lipid, increase the disorder and decrease the thickness of the membranes, and the 2C6PC lipid molecules have the most significant impact. Additionally, there is an increase in permeation of water into the membrane that accompanies the insertion of C6FA into the DOPC membranes. We show that the natural digestion of lipid micelles result in molecular species that can enhance the permeability of lipid membranes that in turn result in an enhanced delivery of drugs.
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Affiliation(s)
- Jun Xie
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
| | - Demi L Pink
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, UK
| | - Christian D Lorenz
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
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2
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Tamai N, Matsuki H, Goto M. Phase Imaging of Phosphatidylcholine Bilayer Membranes by Prodan Fluorescence. MEMBRANES 2022; 12:1219. [PMID: 36557126 PMCID: PMC9784652 DOI: 10.3390/membranes12121219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Prodan (6-propiponyl-2-(N,N-dimethylamino)naphthalene) is well known as a polarity-sensitive fluorescent probe and has a high capability of detecting structural changes occurring within phospholipid bilayer membranes. In this study, we carried out the fluorescence spectroscopic observation of bilayer phase behavior for a series of symmetric saturated diacylphosphatidylcholines (CnPCs) with different acyl-chain length n (n = 12-15 and 19-22) using Prodan as a membrane probe to confirm the availability of Prodan along with the previous results for the CnPC bilayer membranes (n = 16-18). The results were discussed by constructing spectral three-dimensional (3D) imaging plots for visualizing the change in bilayer phase states with temperature or pressure to verify the functionality of this 3D imaging plot. It was found that the Prodan fluorescence technique is applicable to the detection of the changes in the bilayer phase states of all CnPCs with a few exceptions. One of the most crucial exceptions was that Prodan cannot be used for the detection of the bilayer-gel state of the C21PC bilayer membrane. It was also found that it is only to the CnPC bilayer membranes with n = 15-18 that the 3D imaging plot is adequately and accurately applicable as a useful graphical tool for visually detecting the bilayer phase states. This is a disadvantageous feature of this technique brought about by the high sensitivity of Prodan as a membrane probe. Further detailed studies on the molecular behavior of Prodan will enable us to find a more useful way of utilizing this membrane probe.
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Affiliation(s)
| | | | - Masaki Goto
- Correspondence: ; Tel.: +81-88-656-7520; Fax: +81-88-655-3162
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3
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Gasecka P, Balla NK, Sison M, Brasselet S. Lipids-Fluorophores Interactions Probed by Combined Nonlinear Polarized Microscopy. J Phys Chem B 2021; 125:13718-13729. [PMID: 34902969 DOI: 10.1021/acs.jpcb.1c07866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studying the structural dynamics of lipid membranes requires methods that can address both microscopic and macroscopic characteristics. Fluorescence imaging is part of the most used techniques to study membrane properties in various systems from artificial membranes to cells: It benefits from a high sensitivity to local properties such as polarity and molecular orientational order, with a high spatial resolution down to the single-molecule level. The influence of embedded fluorescent lipid probes on the lipid membrane molecules is however poorly known and relies most often on molecular dynamics simulations, due to the challenges faced by experimental approaches to address the molecular-scale dimension of this question. In this work we develop an optical microscopy imaging method to probe the effect of fluorophores embedded in the membrane as lipid probes, on their lipid environment, with a lateral resolution of a few hundreds of nanometers. We combine polarized-nonlinear microscopy contrasts that can independently address the lipid probe, by polarized two-photon fluorescence, and the membrane lipids, by polarized coherent Raman scattering. Using trimethylamino derivative 1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS) as model probes, we show that both probes tend to induce an orientational disorder of their surrounding lipid CH-bonds in 1,2-dipalmitoylphosphatidylcholine (DPPC) lipids environments, while there is no noticeable effect in more disordered 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid membranes.
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Affiliation(s)
- Paulina Gasecka
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
| | - Naveen K Balla
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
| | - Miguel Sison
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
| | - Sophie Brasselet
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France
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4
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Adrien V, Rayan G, Astafyeva K, Broutin I, Picard M, Fuchs P, Urbach W, Taulier N. How to best estimate the viscosity of lipid bilayers. Biophys Chem 2021; 281:106732. [PMID: 34844029 DOI: 10.1016/j.bpc.2021.106732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/19/2021] [Accepted: 11/19/2021] [Indexed: 11/02/2022]
Abstract
The viscosity of lipid bilayers is a property relevant to biological function, as it affects the diffusion of membrane macromolecules. To determine its value, and hence portray the membrane, various literature-reported techniques lead to significantly different results. Herein we compare the results issuing from two widely used techniques to determine the viscosity of membranes: the Fluorescence Lifetime Imaging Microscopy (FLIM), and Fluorescence Recovery After Photobleaching (FRAP). FLIM relates the time of rotation of a molecular rotor inserted into the membrane to the macroscopic viscosity of a fluid. Whereas FRAP measures molecular diffusion coefficients. This approach is based on a hydrodynamic model connecting the mobility of a membrane inclusion to the viscosity of the membrane. We show that: This article emphasizes the pitfalls to be avoided and the rules to be observed in order to obtain a value of the bilayer viscosity that characterizes the bilayer instead of interactions between the bilayer and the embedded probe.
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Affiliation(s)
- Vladimir Adrien
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France; Université de Paris, CNRS, Laboratoire CiTCoM, 75006 Paris, France; Sorbonne Université, AP-HP Department of Psychiatry, Hôpital Saint-Antoine, Paris, France
| | - Gamal Rayan
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France.
| | - Ksenia Astafyeva
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France
| | - Isabelle Broutin
- Université de Paris, CNRS, Laboratoire CiTCoM, 75006 Paris, France
| | - Martin Picard
- Université de Paris, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, CNRS UMR 7099, F-75005 Paris, France; Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild pour le développement de la recherche Scientifique, F-75005 Paris, France
| | - Patrick Fuchs
- Sorbonne Université, Ecole Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules (LBM), 75005 Paris, France; Université de Paris, UFR Sciences du Vivant, 75013 Paris, France
| | - Wladimir Urbach
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France; Sorbonne Université, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, LIB, F-75006 Paris, France
| | - Nicolas Taulier
- Sorbonne Université, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, LIB, F-75006 Paris, France
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5
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Rybicka-Jasińska K, Espinoza EM, Clark JA, Derr JB, Carlos G, Morales M, Billones MK, O'Mari O, Ågren H, Baryshnikov GV, Vullev VI. Making Nitronaphthalene Fluoresce. J Phys Chem Lett 2021; 12:10295-10303. [PMID: 34653339 PMCID: PMC8800371 DOI: 10.1021/acs.jpclett.1c02155] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nitroaromatic compounds are inherently nonfluorescent, and the subpicosecond lifetimes of the singlet excited states of many small nitrated polycyclic aromatic hydrocarbons, such as nitronaphthalenes, render them unfeasible for photosensitizers and photo-oxidants, despite their immensely beneficial reduction potentials. This article reports up to a 7000-fold increase in the singlet-excited-state lifetime of 1-nitronaphthalene upon attaching an amine or an N-amide to the ring lacking the nitro group. Varying the charge-transfer (CT) character of the excited states and the medium polarity balances the decay rates along the radiative and the two nonradiative pathways and can make these nitronaphthalene derivatives fluoresce. The strong electron-donating amine suppresses intersystem crossing (ISC) but accommodates CT pathways of nonradiate deactivation. Conversely, the N-amide does not induce a pronounced CT character but slows down ISC enough to achieve relatively long lifetimes of the singlet excited state. These paradigms are key for the pursuit of electron-deficient (n-type) organic conjugates with promising optical characteristics.
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Affiliation(s)
| | - Eli M Espinoza
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - John A Clark
- Department of Bioengineering, University of California, Riverside, California 92521, United States
| | - James B Derr
- Department of Biochemistry, University of California, Riverside, California 92521, United States
| | - Gregory Carlos
- Department of Biology, University of California, Riverside, California 92521, United States
| | - Maryann Morales
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Mimi Karen Billones
- Department of Biology, University of California, Riverside, California 92521, United States
| | - Omar O'Mari
- Department of Bioengineering, University of California, Riverside, California 92521, United States
| | - Hans Ågren
- Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden
| | - Glib V Baryshnikov
- Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, SE-60174 Norrköping, Sweden
| | - Valentine I Vullev
- Department of Bioengineering, University of California, Riverside, California 92521, United States
- Department of Chemistry, University of California, Riverside, California 92521, United States
- Department of Biochemistry, University of California, Riverside, California 92521, United States
- Materials Science and Engineering Program, University of California, Riverside, California 92521, United States
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6
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Yee SM, Gillams RJ, McLain SE, Lorenz CD. Effects of lipid heterogeneity on model human brain lipid membranes. SOFT MATTER 2021; 17:126-135. [PMID: 33155582 DOI: 10.1039/d0sm01766c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cell membranes naturally contain a heterogeneous lipid distribution. However, homogeneous bilayers are commonly preferred and utilised in computer simulations due to their relative simplicity, and the availability of lipid force field parameters. Recently, experimental lipidomics data for the human brain cell membranes under healthy and Alzheimer's disease (AD) conditions were investigated, since disruption to the lipid composition has been implicated in neurodegenerative disorders, including AD [R. B. Chan et al., J. Biol. Chem., 2012, 287, 2678-2688]. In order to observe the effects of lipid complexity on the various bilayer properties, molecular dynamics simulations were used to study four membranes with increasing heterogeneity: a pure POPC membrane, a POPC and cholesterol membrane in a 1 : 1 ratio (POPC-CHOL), and to our knowledge, the first realistic models of a healthy brain membrane and an Alzheimer's diseased brain membrane. Numerous structural, interfacial, and dynamical properties, including the area per lipid, interdigitation, dipole potential, and lateral diffusion of the two simple models, POPC and POPC-CHOL, were analysed and compared to those of the complex brain models consisting of 27 lipid components. As the membranes gain heterogeneity, a number of alterations were found in the structural and dynamical properties, and more significant differences were observed in the lateral diffusion. Additionally, we observed snorkeling behaviour of the lipid tails that may play a role in the permeation of small molecules across biological membranes. In this work, atomistic description of realistic brain membrane models is provided, which can add insight towards the permeability and transport pathways of small molecules across these membrane barriers.
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Affiliation(s)
- Sze May Yee
- Department of Physics, King's College London, London WC2R 2LS, UK.
| | - Richard J Gillams
- School of Electronics and Computer Science, and Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Sylvia E McLain
- Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9RH, UK
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7
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Suhaj A, Gowland D, Bonini N, Owen DM, Lorenz CD. Laurdan and Di-4-ANEPPDHQ Influence the Properties of Lipid Membranes: A Classical Molecular Dynamics and Fluorescence Study. J Phys Chem B 2020; 124:11419-11430. [PMID: 33275430 DOI: 10.1021/acs.jpcb.0c09496] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Environmentally sensitive (ES) dyes have been used for many decades to study the lipid order of cell membranes, as different lipid phases play a crucial role in a wide variety of cell processes. Yet, the understanding of how ES dyes behave, interact, and affect membranes at the atomistic scale is lacking, partially due to the lack of molecular dynamics (MD) models of these dyes. Here, we present ground- and excited-state MD models of commonly used ES dyes, Laurdan and di-4-ANEPPDHQ, and use MD simulations to study the behavior of these dyes in a disordered and an ordered membrane. We also investigate the effect that these two dyes have on the hydration and lipid order of the membranes, where we see a significant effect on the hydration of lipids proximal to the dyes. These findings are combined with experimental fluorescence experiments of ordered and disordered vesicles and live HeLa cells stained by the aforementioned dyes, where the generalized polarization (GP) values were measured at different concentrations of the dyes. We observe a small but significant decrease of GP at higher Laurdan concentrations in vesicles, while the same effect is not observed in cell membranes. The opposite effect is observed with di-4-ANEPPDHQ where no significant change in GP is seen for vesicles but a very substantial and significant decrease is seen in cell membranes. Together, our results show the profound effect that ES dyes have on membranes, and the presented MD models will be important for further understanding of these effects.
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Affiliation(s)
- Adam Suhaj
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Duncan Gowland
- Theory & Simulation of Condensed Matter Group, Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Nicola Bonini
- Theory & Simulation of Condensed Matter Group, Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Dylan M Owen
- Institute of Immunology and Immunotherapy, Department of Mathematics and Centre of Membrane Proteins and Receptors, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Christian D Lorenz
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London WC2R 2LS, United Kingdom
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8
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Kaur B, Kaur G, Chaudhary GR, Sharma VK, Srinivasan H, Mitra S, Sharma A, Gawali SL, Hassan P. An investigation of morphological, microscopic dynamics, fluidity, and physicochemical variations in Cu-decorated metallosomes with cholesterol. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Filipe HAL, Moreno MJ, Loura LMS. The Secret Lives of Fluorescent Membrane Probes as Revealed by Molecular Dynamics Simulations. Molecules 2020; 25:E3424. [PMID: 32731549 PMCID: PMC7435664 DOI: 10.3390/molecules25153424] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/23/2020] [Accepted: 07/25/2020] [Indexed: 12/15/2022] Open
Abstract
Fluorescent probes have been employed for more than half a century to study the structure and dynamics of model and biological membranes, using spectroscopic and/or microscopic experimental approaches. While their utilization has led to tremendous progress in our knowledge of membrane biophysics and physiology, in some respects the behavior of bilayer-inserted membrane probes has long remained inscrutable. The location, orientation and interaction of fluorophores with lipid and/or water molecules are often not well known, and they are crucial for understanding what the probe is actually reporting. Moreover, because the probe is an extraneous inclusion, it may perturb the properties of the host membrane system, altering the very properties it is supposed to measure. For these reasons, the need for independent methodologies to assess the behavior of bilayer-inserted fluorescence probes has been recognized for a long time. Because of recent improvements in computational tools, molecular dynamics (MD) simulations have become a popular means of obtaining this important information. The present review addresses MD studies of all major classes of fluorescent membrane probes, focusing in the period between 2011 and 2020, during which such work has undergone a dramatic surge in both the number of studies and the variety of probes and properties accessed.
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Affiliation(s)
- Hugo A. L. Filipe
- Chemistry Department, Coimbra Chemistry Center, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Maria João Moreno
- Coimbra Chemistry Center and CNC—Center for Neuroscience and Cell Biology, Chemistry Department, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Luís M. S. Loura
- Coimbra Chemistry Center and CNC—Center for Neuroscience and Cell Biology, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
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10
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Lubart Q, Hannestad JK, Pace H, Fjällborg D, Westerlund F, Esbjörner EK, Bally M. Lipid vesicle composition influences the incorporation and fluorescence properties of the lipophilic sulphonated carbocyanine dye SP-DiO. Phys Chem Chem Phys 2020; 22:8781-8790. [DOI: 10.1039/c9cp04158c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lipid membrane composition influences insertion efficiency and photophysical properties of lipophilic membrane-inserting dyes.
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Affiliation(s)
- Quentin Lubart
- Division of Biological Physics
- Department of Physics
- Chalmers University of Technology
- 41296 Gothenburg
- Sweden
| | - Jonas K. Hannestad
- Division of Biological Physics
- Department of Physics
- Chalmers University of Technology
- 41296 Gothenburg
- Sweden
| | - Hudson Pace
- Department of Integrative Medical Biology
- Umeå University
- 90185 Umeå
- Sweden
| | - Daniel Fjällborg
- Division of Biological Physics
- Department of Physics
- Chalmers University of Technology
- 41296 Gothenburg
- Sweden
| | - Fredrik Westerlund
- Division of Chemical Biology
- Department of Biology and Biological Engineering
- Chalmers University of Technology
- 41296 Gothenburg
- Sweden
| | - Elin K. Esbjörner
- Division of Chemical Biology
- Department of Biology and Biological Engineering
- Chalmers University of Technology
- 41296 Gothenburg
- Sweden
| | - Marta Bally
- Department of Clinical Microbiology & Wallenberg Centre for Molecular Medicine
- Umeå University
- 90185 Umeå
- Sweden
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Smith P, Ziolek RM, Gazzarrini E, Owen DM, Lorenz CD. On the interaction of hyaluronic acid with synovial fluid lipid membranes. Phys Chem Chem Phys 2019; 21:9845-9857. [PMID: 31032510 DOI: 10.1039/c9cp01532a] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
All-atom molecular dynamics simulations have been used to investigate the adsorption of low molecular weight hyaluronic acid to lipid membranes. We have determined the interactions that govern the adsorption of three different molecular weight hyaluronic acid molecules (0.4, 3.8 & 15.2 kDa) to lipid bilayers that are representative of the surface-active phospholipid bilayers found in synovial joints. We have found that both direct hydrogen bonds and water-mediated interactions with the lipid headgroups play a key role in the binding of hyaluronic acid to the lipid bilayer. The water-mediated interactions become increasingly important in stabilising the adsorbed hyaluronic acid molecules as the molecular weight of hyaluronic acid increases. We also observe a redistribution of ions around bound hyaluronic acid molecules and the associated lipid headgroups, and that the degree of redistribution increases with the molecular weight of hyaluronic acid. By comparing this behaviour to that observed in simulations of the charge-neutral polysaccharide dextran (MW ∼ 15 kDa), we show that this charge redistribution leads to an increased alignment of the lipid headgroups with the membrane normal, and therefore to more direct and water-mediated interactions between hyaluronic acid and the lipid membrane. These findings provide a detailed understanding of the general structure of hyaluronic acid-lipid complexes that have recently been presented experimentally, as well as a potential mechanism for their enhanced tribological properties.
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Affiliation(s)
- Paul Smith
- Biological Physics & Soft Matter Group, Department of Physics, King's College London, London, UK.
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12
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Steinmark IE, James AL, Chung PH, Morton PE, Parsons M, Dreiss CA, Lorenz CD, Yahioglu G, Suhling K. Targeted fluorescence lifetime probes reveal responsive organelle viscosity and membrane fluidity. PLoS One 2019; 14:e0211165. [PMID: 30763333 PMCID: PMC6375549 DOI: 10.1371/journal.pone.0211165] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/08/2019] [Indexed: 11/19/2022] Open
Abstract
The only way to visually observe cellular viscosity, which can greatly influence biological reactions and has been linked to several human diseases, is through viscosity imaging. Imaging cellular viscosity has allowed the mapping of viscosity in cells, and the next frontier is targeted viscosity imaging of organelles and their microenvironments. Here we present a fluorescent molecular rotor/FLIM framework to image both organellar viscosity and membrane fluidity, using a combination of chemical targeting and organelle extraction. For demonstration, we image matrix viscosity and membrane fluidity of mitochondria, which have been linked to human diseases, including Alzheimer's Disease and Leigh's syndrome. We find that both are highly dynamic and responsive to small environmental and physiological changes, even under non-pathological conditions. This shows that neither viscosity nor fluidity can be assumed to be fixed and underlines the need for single-cell, and now even single-organelle, imaging.
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Affiliation(s)
| | - Arjuna L. James
- Department of Physics, King’s College London, London, United Kingdom
| | - Pei-Hua Chung
- Department of Physics, King’s College London, London, United Kingdom
| | - Penny E. Morton
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Maddy Parsons
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Cécile A. Dreiss
- Institute of Pharmaceutical Science, King’s College London, London, United Kingdom
| | | | - Gokhan Yahioglu
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Klaus Suhling
- Department of Physics, King’s College London, London, United Kingdom
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