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Matjaž MG, Mravljak J, Rogač MB, Šentjurc M, Gašperlin M, Pobirk AZ. Microstructure evaluation of dermally applicable liquid crystals as a function of water content and temperature: Can electron paramagnetic resonance provide complementary data? Int J Pharm 2017; 533:431-444. [DOI: 10.1016/j.ijpharm.2017.05.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/22/2017] [Accepted: 05/16/2017] [Indexed: 10/19/2022]
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Faller R. Molecular modeling of lipid probes and their influence on the membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2353-2361. [PMID: 26891817 DOI: 10.1016/j.bbamem.2016.02.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 02/08/2016] [Accepted: 02/09/2016] [Indexed: 01/03/2023]
Abstract
In this review a number of Molecular Dynamics simulation studies are discussed which focus on the understanding of the behavior of lipid probes in biomembranes. Experiments often use specialized probe moieties or molecules to report on the behavior of a membrane and try to gain information on the membrane as a whole from the probe lipids as these probes are the only things an experiment sees. Probes can be used to make NMR, EPR and fluorescence accessible to the membrane and use fluorescent or spin-active moieties for this purpose. Clearly membranes with and without probes are not identical which makes it worthwhile to elucidate the differences between them with detailed atomistic simulations. In almost all cases these differences are confined to the local neighborhood of the probe molecules which are sparsely used and generally present as single molecules. In general, the behavior of the bulk membrane lipids can be qualitatively understood from the probes but in most cases their properties cannot be directly quantitatively deduced from the probe behavior. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Roland Faller
- Department of Chemical Engineering & Materials Science, University of California-Davis, Davis, CA 95616, USA.
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Maniruzzaman M, Snowden MJ, Bradely MS, Douroumis D. Studies of intermolecular interactions in solid dispersions using advanced surface chemical analysis. RSC Adv 2015. [DOI: 10.1039/c5ra13176f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The aim of this study is to utilise an advanced surface chemical analysis based on X-ray photoelectron spectroscopy (XPS) to determine and characterise drug/polymer interactions in solid dispersions manufactured via hot melt extrusion (HME).
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Affiliation(s)
- M. Maniruzzaman
- Faculty of Engineering and Science
- University of Greenwich
- Chatham Maritime
- UK
| | - Martin J. Snowden
- Faculty of Engineering and Science
- University of Greenwich
- Chatham Maritime
- UK
| | - Mike S. Bradely
- Faculty of Engineering and Science
- University of Greenwich
- Chatham Maritime
- UK
| | - D. Douroumis
- Faculty of Engineering and Science
- University of Greenwich
- Chatham Maritime
- UK
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Urbančič I, Ljubetič A, Arsov Z, Strancar J. Coexistence of probe conformations in lipid phases-a polarized fluorescence microspectroscopy study. Biophys J 2014; 105:919-27. [PMID: 23972844 DOI: 10.1016/j.bpj.2013.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/04/2013] [Accepted: 07/08/2013] [Indexed: 01/14/2023] Open
Abstract
Several well-established fluorescence methods depend on environment-sensitive probes that report about molecular properties of their local environment. For reliable interpretation of experiments, careful characterization of probes' behavior is required. In this study, bleaching-corrected polarized fluorescence microspectroscopy with nanometer spectral peak position resolution was applied to characterize conformations of two alkyl chain-labeled 7-nitro-2-1,3-benzoxadiazol-4-yl phospholipids in three model membranes, representing the three main lipid phases. The combination of polarized and spectral detection revealed two main probe conformations with their preferential fluorophore dipole orientations roughly parallel and perpendicular to membrane normal. Their peak positions were separated by 2-6 nm because of different local polarities and depended on lipid environment. The relative populations of conformations, estimated by a numerical model, indicated a specific sensitivity of the two probes to molecular packing with cholesterol. The coexistence of probe conformations could be further exploited to investigate membrane organization below microscopy spatial resolution, such as lipid rafts. With the addition of polarized excitation or detection to any environment-sensitive fluorescence imaging technique, the conformational analysis can be directly applied to explore local membrane complexity.
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Affiliation(s)
- Iztok Urbančič
- Laboratory of Biophysics, Condensed Matter Physics Department, Jožef Stefan Institute, Ljubljana, Slovenia
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Kyrychenko A, Ladokhin AS. Molecular dynamics simulations of depth distribution of spin-labeled phospholipids within lipid bilayer. J Phys Chem B 2013; 117:5875-85. [PMID: 23614631 DOI: 10.1021/jp4026706] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spin-labeled lipids are commonly used as fluorescence quenchers in studies of membrane penetration of dye-labeled proteins and peptides using depth-dependent quenching. Accurate calculations of depth of the fluorophore rely on the use of several spin labels placed in the membrane at various positions. The depth of the quenchers (spin probes) has to be determined independently; however, experimental determination of transverse distributions of spin probe depths is difficult. In this Article, we use molecular dynamics (MD) simulations to study the membrane behavior and depth distributions of spin-labeled phospholipids in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer. To probe different depths within the bilayer, a series containing five Doxyl-labeled lipids (n-Doxyl PC) has been studied, in which a spin moiety was covalently attached to nth carbon atoms (where n = 5, 7, 10, 12, and 14) of the sn-2 stearoyl chain of the host phospholipid. Our results demonstrate that the chain-attached spin labels are broadly distributed across the model membrane and their environment is characterized by a high degree of mobility and structural heterogeneity. Despite the high thermal disorder, the depth distributions of the Doxyl labels were found to correlate well with their attachment positions, indicating that the distribution of the spin label within the model membrane is dictated by the depth of the nth lipid carbon atom and not by intrinsic properties of the label. In contrast, a much broader and heterogeneous distribution was observed for a headgroup-attached Tempo spin label of Tempo-PC lipids. MD simulations reveal that, due to the hydrophobic nature, a Tempo moiety favors partitioning from the headgroup region deeper into the membrane. Depending on the concentration of Tempo-PC lipids, the probable depth of the Tempo moiety could span a range from 14.4 to 18.2 Å from the membrane center. Comparison of the MD-estimated immersion depths of Tempo and n-Doxyl labels with their suggested experimental depth positions allows us to review critically the possible sources of error in depth-dependent fluorescence quenching studies.
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Affiliation(s)
- Alexander Kyrychenko
- Department of Biochemistry and Molecular Biology, Kansas University Medical Center, Kansas City, Kansas 66160-7421, USA.
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Vartorelli MR, Garay AS, Rodrigues DE. Spin-labeled Stearic Acid Behavior and Perturbations on the Structure of a Gel-Phase-Lipid Bilayer in Water: 5-, 12- and 16-SASL. J Phys Chem B 2008; 112:16830-42. [DOI: 10.1021/jp806476a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martín R. Vartorelli
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and INTEC (UNL-CONICET), C.C. 242, Ciudad Universitaria, C.P. S3000ZAA, Santa Fe, Argentina
| | - Alberto S. Garay
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and INTEC (UNL-CONICET), C.C. 242, Ciudad Universitaria, C.P. S3000ZAA, Santa Fe, Argentina
| | - Daniel E. Rodrigues
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and INTEC (UNL-CONICET), C.C. 242, Ciudad Universitaria, C.P. S3000ZAA, Santa Fe, Argentina
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Stimson L, Dong L, Karttunen M, Wisniewska A, Dutka M, Róg T. Stearic Acid Spin Labels in Lipid Bilayers: Insight through Atomistic Simulations. J Phys Chem B 2007; 111:12447-53. [DOI: 10.1021/jp0746796] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lorna Stimson
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
| | - Lei Dong
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
| | - Mikko Karttunen
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
| | - Anna Wisniewska
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
| | - Małgorzata Dutka
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
| | - Tomasz Róg
- Laboratory of Physics, Helsinki University of Technology, Finland, Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada, Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland, and Biophysics and Statistical Mechanics Group, Department of Electrical and Communication Engineering, Helsinki University of Technology, Finland
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