51
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von Rudorff GF, Watermann T, Guo XY, Sebastiani D. Conformational Space of a Polyphilic Molecule with a Fluorophilic Side Chain Integrated in a DPPC Bilayer. J Comput Chem 2019; 38:576-583. [PMID: 28211109 DOI: 10.1002/jcc.24711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 12/21/2022]
Abstract
We investigate the conformational space of a polyphilic molecule with hydrophilic, lipophilic and fluorophilic parts inserted as a transmembrane agent into a dipalmitoylphosphatidylcholine bilayer by means of all-atom molecular dynamics simulations. Special focus is put on the competing structural driving forces arising from the hydrophilic, lipophilic and fluorophilic side chains and the aromatic backbone of the polyphile. We observe a significant difference between the lipophilic and the fluorophilic side chains regarding their intramembrane distribution. While the lipophilic groups remain membrane-centered, the fluorophilic parts tend to orient toward the phosphate headgroups. This trend is important for understanding the influence of polyphile agents on the properties of phospholipid membranes. From a fundamental point of view, our computed distribution functions of the side chains are related to the interplay of sterical, enthalpic and entropic driving forces. Our findings illustrate the potential of rationally designed membrane additives which can be exploited to tune the properties of phospholipid membranes. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Guido F von Rudorff
- Department of Physics and Astronomy, University College London, Gower Street, London, United Kingdom.,Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, Halle, 06120, Germany
| | - Tobias Watermann
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, Halle, 06120, Germany
| | - Xiang-Yang Guo
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, Halle, 06120, Germany
| | - Daniel Sebastiani
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, Halle, 06120, Germany
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52
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Maekawa T, Chin H, Nyu T, Sut TN, Ferhan AR, Hayashi T, Cho NJ. Molecular diffusion and nano-mechanical properties of multi-phase supported lipid bilayers. Phys Chem Chem Phys 2019; 21:16686-16693. [DOI: 10.1039/c9cp02085c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Understanding the properties of cell membranes is important in the fields of fundamental and applied biology.
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Affiliation(s)
- Tatsuhiro Maekawa
- Department of Materials Science and Engineering
- School of Materials Chemical Technology
- Tokyo Institute of Technology
- Yokohama
- Japan
| | - Hokyun Chin
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
| | - Takashi Nyu
- Department of Materials Science and Engineering
- School of Materials Chemical Technology
- Tokyo Institute of Technology
- Yokohama
- Japan
| | - Tun Naw Sut
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
| | - Abdul Rahim Ferhan
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
| | - Tomohiro Hayashi
- Department of Materials Science and Engineering
- School of Materials Chemical Technology
- Tokyo Institute of Technology
- Yokohama
- Japan
| | - Nam-Joon Cho
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore
- School of Chemical and Biomedical Engineering
- Nanyang Technological University
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53
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Vatanparast M, Shariatinia Z. Revealing the role of different nitrogen functionalities in the drug delivery performance of graphene quantum dots: a combined density functional theory and molecular dynamics approach. J Mater Chem B 2019; 7:6156-6171. [DOI: 10.1039/c9tb00971j] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The role of different N-functionalities was investigated on the drug delivery performance of N-GQDs. Results suggested that the center N-GQD had a better performance than the pristine and edge N-GQDs.
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Affiliation(s)
- Morteza Vatanparast
- Department of Chemistry
- Amirkabir University of Technology (Tehran Polytechnic)
- Tehran
- Iran
| | - Zahra Shariatinia
- Department of Chemistry
- Amirkabir University of Technology (Tehran Polytechnic)
- Tehran
- Iran
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54
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Williams AT, Donno R, Tirelli N, Dryfe RAW. Biofunctional few-layer metal dichalcogenides and related heterostructures produced by direct aqueous exfoliation using phospholipids. RSC Adv 2019; 9:37061-37066. [PMID: 35539078 PMCID: PMC9075593 DOI: 10.1039/c9ra07764b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/06/2019] [Indexed: 11/21/2022] Open
Abstract
We report a novel, inexpensive and green method for preparing aqueous dispersions of various biofunctional transition-metal dichalcogenides (MoS2, WS2, TiS2 and MoSe2) and their related heterostructures directly via ultrasonic exfoliation mediated by the presence of phospholipids. The dispersions predominantly consist of few-layer flakes coated with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), as confirmed by Raman, photoluminescence and X-ray photoelectron spectroscopies. The phospholipid coating renders the flakes biofunctional, which coupled with the unique properties of transition-metal dichalcogenides and their heterostructures, suggests this method will have great potential in biological applications. We report a method for preparing aqueous dispersions of biofunctional transition-metal dichalcogenides (MoS2, WS2, TiS2 and MoSe2) and their related heterostructures directly via ultrasonic exfoliation mediated by the presence of phospholipids.![]()
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Affiliation(s)
| | - Roberto Donno
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
| | - Nicola Tirelli
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
| | - Robert A. W. Dryfe
- School of Chemistry
- University of Manchester
- Manchester
- UK
- National Graphene Institute
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55
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Sandoval-Altamirano C, Sanchez S, Pizarro N, Morales J, Gunther G. Alkyl-mannoside derivatives: Glycolipids able to form big size aggregates. J PHYS ORG CHEM 2019. [DOI: 10.1002/poc.3822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- C. Sandoval-Altamirano
- Departamento de Química Orgánica y Fisicoquímica; Universidad de Chile, Facultad de Ciencias Químicas y Farmacéuticas; Santiago 1 Chile
| | - S.A. Sanchez
- Departamento de Polímeros; Universidad de Concepción, Facultad de Química; Concepción Chile
| | - N. Pizarro
- Departamento de Ciencias Químicas; Universidad Andrés Bello, Facultad de Ciencias Exactas; Viña del Mar Chile
| | - J. Morales
- Departamento de Ciencias y Tecnología Farmacéuticas; Universidad de Chile, Facultad de Ciencias Químicas y Farmacéuticas; Santiago Chile
| | - G. Gunther
- Departamento de Química Orgánica y Fisicoquímica; Universidad de Chile, Facultad de Ciencias Químicas y Farmacéuticas; Santiago 1 Chile
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56
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Gumí-Audenis B, Illa-Tuset S, Grimaldi N, Pasquina-Lemonche L, Ferrer-Tasies L, Sanz F, Veciana J, Ratera I, Faraudo J, Ventosa N, Giannotti MI. Insights into the structure and nanomechanics of a quatsome membrane by force spectroscopy measurements and molecular simulations. NANOSCALE 2018; 10:23001-23011. [PMID: 30500043 DOI: 10.1039/c8nr07110a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Quatsomes (QS) are unilamellar nanovesicles constituted by quaternary ammonium surfactants and sterols in defined molar ratios. Unlike conventional liposomes, QS are stable upon long storage such as for several years, they show outstanding vesicle-to-vesicle homogeneity regarding size and lamellarity, and they have the structural and physicochemical requirements to be a potential platform for site-specific delivery of hydrophilic and lipophilic molecules. Knowing in detail the structure and mechanical properties of the QS membrane is of great importance for the design of deformable and flexible nanovesicle alternatives, highly pursued in nanomedicine applications such as the transdermal administration route. In this work, we report the first study on the detailed structure of the cholesterol : CTAB QS membrane at the nanoscale, using atomic force microscopy (AFM) and spectroscopy (AFM-FS) in a controlled liquid environment (ionic medium and temperature) to assess the topography of supported QS membranes (SQMs) and to evaluate the local membrane mechanics. We further perform molecular dynamics (MD) simulations to provide an atomistic interpretation of the obtained results. Our results are direct evidence of the bilayer nature of the QS membrane, with characteristics of a fluid-like membrane, compact and homogeneous in composition, and with structural and mechanical properties that depend on the surrounding environment. We show how ions alter the lateral packing, modifying the membrane mechanics. We observe that according to the ionic environment and temperature, different domains may coexist in the QS membranes, ascribed to variations in molecular tilt angles. Our results indicate that QS membrane properties may be easily tuned by altering the lateral interactions with either different environmental ions or counterions.
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Affiliation(s)
- Berta Gumí-Audenis
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
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57
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Otto F, Brezesinski G, van Hoogevest P, Neubert R. Physicochemical characterization of natural phospholipid excipients with varying PC content. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.08.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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58
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Galvanetto N. Single-cell unroofing: probing topology and nanomechanics of native membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2532-2538. [DOI: 10.1016/j.bbamem.2018.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/19/2018] [Accepted: 09/26/2018] [Indexed: 10/28/2022]
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59
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Li Q, Tseng KF, King SJ, Qiu W, Xu J. A fluid membrane enhances the velocity of cargo transport by small teams of kinesin-1. J Chem Phys 2018; 148:123318. [PMID: 29604873 DOI: 10.1063/1.5006806] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Kinesin-1 (hereafter referred to as kinesin) is a major microtubule-based motor protein for plus-end-directed intracellular transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized "motile fraction" to overcome this challenge and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro and employed optical trapping to quantify the transport of membrane-enclosed cargos versus traditional membrane-free cargos under identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins. Importantly, enclosing a cargo in a fluid lipid membrane did not impact single-kinesin transport, indicating that membrane-dependent velocity enhancement for team-based transport arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for fast delivery of cargos in live cells.
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Affiliation(s)
- Qiaochu Li
- Department of Physics, University of California, Merced, California 95343, USA
| | - Kuo-Fu Tseng
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Stephen J King
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida 32827, USA
| | - Weihong Qiu
- Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jing Xu
- Department of Physics, University of California, Merced, California 95343, USA
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60
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Mitra S, Ray D, Bhattacharya G, Gupta R, Sen D, Aswal VK, Ghosh SK. Probing the effect of a room temperature ionic liquid on phospholipid membranes in multilamellar vesicles. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 48:119-129. [DOI: 10.1007/s00249-018-1339-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/16/2018] [Accepted: 11/19/2018] [Indexed: 01/12/2023]
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61
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Müller S, Kind M, Gruhle K, Hause G, Meister A, Drescher S. Mixing behaviour of bilayer-forming phosphatidylcholines with single-chain alkyl-branched bolalipids: effect of lateral chain length. Biophys Chem 2018; 244:1-10. [PMID: 30388712 DOI: 10.1016/j.bpc.2018.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 12/17/2022]
Abstract
Liposomes are a promising class of drug delivery vehicles. However, no liposomal formulation has been approved for an oral application so far, due to stability issues of the liposomes in the gastrointestinal tract. Herein, we investigate the miscibility of three novel single-chain alkyl-branched bolalipids PC-C32(1,32Cn)-PC (n = 3, 6, 9) with either saturated or unsaturated phosphatidylcholines by means of differential scanning calorimetry (DSC), transmission electron microscopy (TEM) of stained samples, vitrified specimens, or replica of freeze-fractured samples, and dynamic light scattering (DLS). The novel bolalipids contain lateral alkyl chains of different length in 1- and 32-position of the long membrane-spanning C32 alkyl chain. We will show for the first time that these single-chain alkyl-branched bolalipids show a miscibility with bilayer-forming phospholipids-by maintaining the vesicular aggregate structure-due to the lateral alkyl substituents located next to the phosphocholine headgroup of the bolalipid. We are convinced that these alkyl side chains are able to fill the void volume, which is created when unmodified single-chain bolalipids are inserted in a transmembrane fashion into a phospholipid bilayer. Consequently, the miscibility of our alkyl-chained bolalipids with bilayer-forming phospholipids rose with increasing lengths of the lateral alkyl chain of the bolalipid. Finally, we were successful in preparing liposomes from various bolalipid/phospholipid mixtures, which were stable in size upon storage for at least 21 days. These mixed liposomes (bolasomes) could be used as oral drug delivery systems in the near future.
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Affiliation(s)
- Sindy Müller
- Institute of Pharmacy, Biophysical Pharmacy, Martin Luther University (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, Halle (Saale) 06120, Germany
| | - Maximilian Kind
- Institute of Pharmacy, Biophysical Pharmacy, Martin Luther University (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, Halle (Saale) 06120, Germany
| | - Kai Gruhle
- Institute of Pharmacy, Biophysical Pharmacy, Martin Luther University (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, Halle (Saale) 06120, Germany
| | - Gerd Hause
- Biocenter, MLU Halle-Wittenberg, Weinbergweg 22, Halle (Saale) 06120, Germany
| | - Annette Meister
- HALOmem and Institute of Biochemistry and Biotechnology, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, Halle (Saale) 06120, Germany
| | - Simon Drescher
- Institute of Pharmacy, Biophysical Pharmacy, Martin Luther University (MLU) Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, Halle (Saale) 06120, Germany.
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62
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Chen W, Duša F, Witos J, Ruokonen SK, Wiedmer SK. Determination of the Main Phase Transition Temperature of Phospholipids by Nanoplasmonic Sensing. Sci Rep 2018; 8:14815. [PMID: 30287903 PMCID: PMC6172256 DOI: 10.1038/s41598-018-33107-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 09/20/2018] [Indexed: 01/17/2023] Open
Abstract
Our study demonstrates that nanoplasmonic sensing (NPS) can be utilized for the determination of the phase transition temperature (Tm) of phospholipids. During the phase transition, the lipid bilayer undergoes a conformational change. Therefore, it is presumed that the Tm of phospholipids can be determined by detecting conformational changes in liposomes. The studied lipids included 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). Liposomes in gel phase are immobilized onto silicon dioxide sensors and the sensor cell temperature is increased until passing the Tm of the lipid. The results show that, when the system temperature approaches the Tm, a drop of the NPS signal is observed. The breakpoints in the temperatures are 22.5 °C, 41.0 °C, and 55.5 °C for DMPC, DPPC, and DSPC, respectively. These values are very close to the theoretical Tm values, i.e., 24 °C, 41.4 °C, and 55 °C for DMPC, DPPC, and DSPC, respectively. Our studies prove that the NPS methodology is a simple and valuable tool for the determination of the Tm of phospholipids.
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Affiliation(s)
- Wen Chen
- Department of Chemistry, POB 55, 00014 University of Helsinki, Helsinki, Finland
| | - Filip Duša
- Institute of Analytical Chemistry of the Czech Academy of Sciences, Veveří 97, Brno, 60200, Czech Republic
| | - Joanna Witos
- Department of Bioproducts and Biosystems, POB 16300, 00076 Aalto University, Espoo, Finland
| | | | - Susanne K Wiedmer
- Department of Chemistry, POB 55, 00014 University of Helsinki, Helsinki, Finland.
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63
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Liu X. Interactions of Silver Nanoparticles Formed in Situ on AFM Tips with Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10774-10781. [PMID: 30109936 DOI: 10.1021/acs.langmuir.8b01545] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A facile approach for functionalizing atomic force microscopy (AFM) tips with nanoparticles (NPs) will provide exciting opportunities in the field of tip-enhanced vibrational spectroscopy and in probing the interactions between NPs and biological systems. In this study, through successive exposure to polydopamine and AgNO3 solutions, the apex of AFM tips was functionalized with silver nanoparticles (AgNPs). The AgNP-modified AFM tips were used to measure the interaction forces between AgNPs and supported lipid bilayers (SLBs) formed on mica, as well as to probe the penetration of SLBs by AgNPs, with an emphasis on the effect of human serum albumin (HSA) proteins. AgNPs experienced predominantly repulsive forces when approaching SLBs. The presence of HSA resulted in an enhancement in the repulsive interactions between AgNPs and SLBs, likely through steric repulsion. Finally, the forces required for AgNPs to penetrate SLBs were higher in the presence of HSA probably due to the increase in the effective size of the nanoscale protuberances on the AFM tip stemming from the formation of protein coronas around the AgNPs.
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Affiliation(s)
- Xitong Liu
- Department of Environmental Health and Engineering , Johns Hopkins University , Baltimore , Maryland 21218-2686 , United States
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64
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Vu HT, Hook SM, Siqueira SD, Müllertz A, Rades T, McDowell A. Are phytosomes a superior nanodelivery system for the antioxidant rutin? Int J Pharm 2018; 548:82-91. [DOI: 10.1016/j.ijpharm.2018.06.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 06/17/2018] [Accepted: 06/19/2018] [Indexed: 12/15/2022]
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65
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Interaction of gabaergic ketones with model membranes: A molecular dynamics and experimental approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1563-1570. [DOI: 10.1016/j.bbamem.2018.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 01/28/2023]
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66
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Müller S, Meister A, Otto C, Hause G, Drescher S. Mixing behaviour of asymmetrical glycerol diether bolalipids with saturated and unsaturated phosphatidylcholines. Biophys Chem 2018; 238:39-48. [DOI: 10.1016/j.bpc.2018.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/17/2018] [Accepted: 04/21/2018] [Indexed: 12/17/2022]
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67
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Kakimoto Y, Tachihara Y, Okamoto Y, Miyazawa K, Fukuma T, Tero R. Morphology and Physical Properties of Hydrophilic-Polymer-Modified Lipids in Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7201-7209. [PMID: 29788718 DOI: 10.1021/acs.langmuir.8b00870] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Lipid molecules such as glycolipids that are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying a polyethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0-10 mol % range of PEG-modified lipid concentration ( CPEG). We studied their morphology and fluidity by fluorescence microscopy, the fluorescence recovery after photobleaching method, and atomic force microscopy (AFM). Fluorescence images showed that domains rich in the PEG-modified lipid appeared and SLB fluidity decreased when CPEG ≥ 5%. AFM topographies showed that clusters of the PEG-modified lipid appeared prior to domain formation and the PEG-lipid-rich domains were observed as depressions. Frequency-modulation AFM revealed a force-dependent appearance of the PEG-lipid-rich domain.
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Affiliation(s)
- Yasuhiro Kakimoto
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Yoshihiro Tachihara
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Yoshiaki Okamoto
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Keisuke Miyazawa
- Division of Electrical Engineering and Computer Science , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Takeshi Fukuma
- Division of Electrical Engineering and Computer Science , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
- Nano Life Science Institute (WPI-NanoLSI) , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Ryugo Tero
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
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68
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Liu D, Lipponen K, Quan P, Wan X, Zhang H, Mäkilä E, Salonen J, Kostiainen R, Hirvonen J, Kotiaho T, Santos HA. Impact of Pore Size and Surface Chemistry of Porous Silicon Particles and Structure of Phospholipids on Their Interactions. ACS Biomater Sci Eng 2018; 4:2308-2313. [PMID: 30159385 PMCID: PMC6108535 DOI: 10.1021/acsbiomaterials.8b00343] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/14/2018] [Indexed: 02/06/2023]
Abstract
![]()
By exploiting its porous structure
and high loading capacity, porous
silicon (PSi) is a promising biomaterial to fabricate protocells and
biomimetic reactors. Here, we have evaluated the impact of physicochemical
properties of PSi particles [thermally oxidized PSi, TOPSi; annealed
TOPSi, AnnTOPSi; (3-aminopropyl) triethoxysilane functionalized thermally
carbonized PSi, APTES-TCPSi; and thermally hydrocarbonized PSi, THCPSi]
on their surface interactions with different phospholipids. All of
the four phospholipids were similarly adsorbed by the surface of PSi
particles, except for TOPSi. Among four PSi particles, TOPSi with
hydrophilic surface and smaller pore size showed the weakest adsorption
toward phosphatidylcholines. By increasing the pore size from roughly
12.5 to 18.0 nm (TOPSi vs AnnTOPSi), the quantity of phosphatidylcholines
adsorbed by TOPSi was enhanced to the same level of hydrophilic APTES-TCPSi
and hydrophobic THCPSi. The 1,2-dioleoyl-sn-glycero-3-phosphocholine
(DOPC) exhibited the highest release ratio of phospholipids from all
four PSi particles, and phosphatidylserine (DPPS) showed the lowest
release ratio of phospholipids from PSi particles, except for TOPSi,
which adsorbed less phospholipids due to the small pore size. There
is consistency in the release extent of phospholipids from PSi particles
and the isosteric heat of adsorption. Overall, our study demonstrates
the importance of pore size and surface chemistry of PSi particles
as well as the structure of phospholipids on their interactions. The
obtained information can be employed to guide the selection of PSi
particles and phospholipids to fabricate highly ordered structures,
for example, protocells, or biomimetic reactors.
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Affiliation(s)
- Dongfei Liu
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland.,Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
| | - Katriina Lipponen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
| | - Peng Quan
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland.,Department of Pharmaceutical Science, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Xiaocao Wan
- Department of Pharmaceutical Science, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Hongbo Zhang
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland.,Department of Pharmaceutical Science, Åbo Akademi University, Turku FI-20520, Finland
| | - Ermei Mäkilä
- Laboratory of Industrial Physics, Department of Physics and Astronomy, University of Turku, Turku FI-20014, Finland
| | - Jarno Salonen
- Laboratory of Industrial Physics, Department of Physics and Astronomy, University of Turku, Turku FI-20014, Finland
| | - Risto Kostiainen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
| | - Jouni Hirvonen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
| | - Tapio Kotiaho
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland.,Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
| | - Hélder A Santos
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland.,Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, Helsinki Institute of Life Science, HiLIFE, and Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki FI-00014, Finland
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69
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Poursoroush A, Sperotto MM, Laradji M. Phase behavior of supported lipid bilayers: A systematic study by coarse-grained molecular dynamics simulations. J Chem Phys 2018; 146:154902. [PMID: 28433014 DOI: 10.1063/1.4981008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Solid-supported lipid bilayers are utilized by experimental scientists as models for biological membranes because of their stability. However, compared to free standing bilayers, their close proximity to the substrate may affect their phase behavior. As this is still poorly understood, and few computational studies have been performed on such systems thus far, here we present the results from a systematic study based on molecular dynamics simulations of an implicit-solvent model for solid-supported lipid bilayers with varying lipid-substrate interactions. The attractive interaction between the substrate and the lipid head groups that are closest to the substrate leads to an increased translocation of the lipids from the distal to the proximal bilayer-leaflet. This thereby leads to a transbilayer imbalance of the lipid density, with the lipid density of the proximal leaflet higher than that of the distal leaflet. Consequently, the order parameter of the proximal leaflet is found to be higher than that of the distal leaflet, the higher the strength of lipid interaction is, the stronger the effect. The proximal leaflet exhibits gel and fluid phases with an abrupt melting transition between the two phases. In contrast, below the melting temperature of the proximal leaflet, the distal leaflet is inhomogeneous with coexisting gel and fluid domains. The size of the fluid domains increases with increasing the strength of the lipid interaction. At low temperatures, the inhomogeneity of the distal leaflet is due to its reduced lipid density.
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Affiliation(s)
- Asma Poursoroush
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, USA
| | - Maria Maddalena Sperotto
- DTU Bioinformatics, Department of Bio and Health Informatics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Mohamed Laradji
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, USA
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70
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O'Leary EI, Jiang Z, Strub MP, Lee JC. Effects of phosphatidylcholine membrane fluidity on the conformation and aggregation of N-terminally acetylated α-synuclein. J Biol Chem 2018; 293:11195-11205. [PMID: 29853639 DOI: 10.1074/jbc.ra118.002780] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/22/2018] [Indexed: 12/15/2022] Open
Abstract
Membrane association of α-synuclein (α-syn), a neuronal protein associated with Parkinson's disease (PD), is involved in α-syn function and pathology. Most previous studies on α-syn-membrane interactions have not used the physiologically relevant N-terminally acetylated (N-acetyl) α-syn form nor the most naturally abundant cellular lipid, i.e. phosphatidylcholine (PC). Here, we report on how PC membrane fluidity affects the conformation and aggregation propensity of N-acetyl α-syn. It is well established that upon membrane binding, α-syn adopts an α-helical structure. Using CD spectroscopy, we show that N-acetyl α-syn transitions from α-helical to disordered at the lipid melting temperature (Tm ). We found that this fluidity sensing is a robust characteristic, unaffected by acyl chain length (Tm = 34-55 °C) and preserved in its homologs β- and γ-syn. Interestingly, both N-acetyl α-syn membrane binding and amyloid formation trended with lipid order (1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) > 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin/cholesterol (2:2:1) ≥ DOPC), with gel-phase vesicles shortening aggregation kinetics and promoting fibril formation compared to fluid membranes. Furthermore, we found that acetylation enhances binding to PC micelles and small unilamellar vesicles with high curvature (r ∼16-20 nm) and that DPPC binding is reduced in the presence of cholesterol. These results confirmed that the exposure of hydrocarbon chains (i.e. packing defects) is essential for binding to zwitterionic gel membranes. Collectively, our in vitro results suggest that N-acetyl α-syn localizes to highly curved, ordered membranes inside a cell. We propose that age-related changes in membrane fluidity can promote the formation of amyloid fibrils, insoluble materials associated with PD.
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Affiliation(s)
- Emma I O'Leary
- From the Laboratory of Protein Conformation and Dynamics and
| | - Zhiping Jiang
- From the Laboratory of Protein Conformation and Dynamics and
| | - Marie-Paule Strub
- the Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Jennifer C Lee
- From the Laboratory of Protein Conformation and Dynamics and
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71
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Sych T, Mély Y, Römer W. Lipid self-assembly and lectin-induced reorganization of the plasma membrane. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170117. [PMID: 29632269 PMCID: PMC5904303 DOI: 10.1098/rstb.2017.0117] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2018] [Indexed: 01/10/2023] Open
Abstract
The plasma membrane represents an outstanding example of self-organization in biology. It plays a vital role in protecting the integrity of the cell interior and regulates meticulously the import and export of diverse substances. Its major building blocks are proteins and lipids, which self-assemble to a fluid lipid bilayer driven mainly by hydrophobic forces. Even if the plasma membrane appears-globally speaking-homogeneous at physiological temperatures, the existence of specialized nano- to micrometre-sized domains of raft-type character within cellular and synthetic membrane systems has been reported. It is hypothesized that these domains are the origin of a plethora of cellular processes, such as signalling or vesicular trafficking. This review intends to highlight the driving forces of lipid self-assembly into a bilayer membrane and the formation of small, transient domains within the plasma membrane. The mechanisms of self-assembly depend on several factors, such as the lipid composition of the membrane and the geometry of lipids. Moreover, the dynamics and organization of glycosphingolipids into nanometre-sized clusters will be discussed, also in the context of multivalent lectins, which cluster several glycosphingolipid receptor molecules and thus create an asymmetric stress between the two membrane leaflets, leading to tubular plasma membrane invaginations.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Taras Sych
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch Cedex, France
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch Cedex, France
| | - Winfried Römer
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
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72
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Xiang S, Sarem M, Shah S, Shastri VP. Liposomal Treatment of Cancer Cells Modulates Uptake Pathway of Polymeric Nanoparticles by Altering Membrane Stiffness. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1704245. [PMID: 29460335 DOI: 10.1002/smll.201704245] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/03/2018] [Indexed: 06/08/2023]
Abstract
Nanomedicines can be taken up by cells via nonspecific and dynamin-dependent (energy-dependent) clathrin and caveolae-mediated endocytosis. While significant effort has focused on targeting pathway-specific transporters, the role of nanobiophysics in the cell lipid bilayer nanoparticle uptake pathway remains largely unexplored. In this study, it is demonstrated that stiffness of lipid bilayer is a key determinant of uptake of liposomes by mammalian cells. Dynamin-mediated endocytosis (DME) of liposomes is found to correlate with its phase behavior, with transition toward solid phase promoting DME, and transition toward fluidic phase resulting in dynamin-independent endocytosis. Since liposomes can transfer lipids to cell membrane, it is sought to engineer the biophysical properties of the membrane of breast epithelial tumor cells (MD-MBA-231) by treatment with phosphatidylcholine liposomes, and elucidate its effect on the uptake of polymeric nanoparticles. Analysis of the giant plasma membrane vesicles derived from treated cells using flicker spectroscopy reveals that liposome treatment alters membrane stiffness and DME of nanoparticles. Since liposomes have a history of use in drug delivery, localized priming of tumors with liposomes may present a hitherto unexploited means of targeting tumors based on biophysical interactions.
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Affiliation(s)
- Shengnan Xiang
- Institute for Macromolecular Chemistry, University of Freiburg, 79104, Freiburg, Germany
| | - Melika Sarem
- Institute for Macromolecular Chemistry, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany
- Helmholtz Virtual Institute on Multifunctional Biomaterials for Medicine, Kantstr. 55, 14513, Teltow, Germany
| | - Samveg Shah
- Institute for Macromolecular Chemistry, University of Freiburg, 79104, Freiburg, Germany
| | - V Prasad Shastri
- Institute for Macromolecular Chemistry, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany
- Helmholtz Virtual Institute on Multifunctional Biomaterials for Medicine, Kantstr. 55, 14513, Teltow, Germany
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73
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Duan Y, Liu Y, Li J, Wang H, Wen S. Investigation on the Nanomechanics of Liposome Adsorption on Titanium Alloys: Temperature and Loading Effects. Polymers (Basel) 2018; 10:polym10040383. [PMID: 30966418 PMCID: PMC6415199 DOI: 10.3390/polym10040383] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/27/2018] [Accepted: 03/29/2018] [Indexed: 01/08/2023] Open
Abstract
The mechanical properties of liposomes, determined by the lipid phase state at ambient temperature, have a close relationship with their physiological activities. Here, atomic force microscopy (AFM) was used to produce images and perform force measurements on titanium alloys at two adsorbed temperatures. The mechanical properties were evaluated under repeated loading and unloading, suggesting a better reversibility and resistance of gel phase liposomes. The liquid phase liposomes were irreversibly damaged during the first approach while the gel phase liposomes could bear more iterations, resulting from water flow reversibly going across the membranes. The statistical data offered strong evidence that the lipid membranes in the gel phase are robust enough to resist the tip penetration, mainly due to their orderly organization and strong hydrophobic interactions between lipid molecules. This work regarding the mechanical properties of liposomes with different phases provides guidance for future clinical applications, such as artificial joints.
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Affiliation(s)
- Yiqin Duan
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
| | - Yuhong Liu
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
| | - Jinjin Li
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
| | - Hongdong Wang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
| | - Shizhu Wen
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
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74
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Bhojoo U, Chen M, Zou S. Temperature induced lipid membrane restructuring and changes in nanomechanics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:700-709. [DOI: 10.1016/j.bbamem.2017.12.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/17/2017] [Accepted: 12/08/2017] [Indexed: 11/26/2022]
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75
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Atukorale PU, Guven ZP, Bekdemir A, Carney RP, Van Lehn RC, Yun DS, Jacob Silva PH, Demurtas D, Yang YS, Alexander-Katz A, Stellacci F, Irvine DJ. Structure-Property Relationships of Amphiphilic Nanoparticles That Penetrate or Fuse Lipid Membranes. Bioconjug Chem 2018; 29:1131-1140. [PMID: 29465986 PMCID: PMC6311100 DOI: 10.1021/acs.bioconjchem.7b00777] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The development of synthetic nanomaterials that could embed within, penetrate, or induce fusion between membranes without permanent disruption would have great significance for biomedical applications. Here we describe structure-function relationships of highly water-soluble gold nanoparticles comprised of an ∼1.5-5 nm diameter metal core coated by an amphiphilic organic ligand shell, which exhibit membrane embedding and fusion activity mediated by the surface ligands. Using an environment-sensitive dye anchored within the ligand shell as a sensor of membrane embedding, we demonstrate that particles with core sizes of ∼2-3 nm are capable of embedding within and penetrating fluid bilayers. At the nanoscale, these particles also promote spontaneous fusion of liposomes or spontaneously embed within intact liposomal vesicles. These studies provide nanoparticle design and selection principles that could be used in drug delivery applications, as membrane stains, or for the creation of novel organic/inorganic nanomaterial self-assemblies.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Darrell J Irvine
- Ragon Institute of MGH, MIT, and Harvard, Cambridge , Massachusetts 02139 , United States.,Howard Hughes Medical Institute, Chevy Chase , Maryland 20815 , United States
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76
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Cholesterol induced asymmetry in DOPC bilayers probed by AFM force spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:953-959. [PMID: 29408513 DOI: 10.1016/j.bbamem.2018.01.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 01/24/2018] [Accepted: 01/28/2018] [Indexed: 11/21/2022]
Abstract
Cholesterol induced mechanical effects on artificial lipid bilayers are well known and have been thoroughly investigated by AFM force spectroscopy. However, dynamics of cholesterol impingement into bilayers at various cholesterol concentrations and their effects have not been clearly understood. In this paper we present, the effect of cholesterol as a function of its concentration in a simple single component dioleoylphosphatidylcholine (DOPC) bilayer. The nature of measured breakthrough forces on a bilayer with the addition of cholesterol, suggested that it is not just responsible to increase the mechanical stability but also introduces irregularities across the leaflets of the bilayer. This cholesterol induced asymmetry across the (in the inner and outer leaflets) bilayer is related to the phenomena of interleaflet coupling and is a function of cholesterol concentration probed by AFM can provide an unprecedented direction on mechanical properties of lipid membrane as it can be directly correlated to biophysical properties of a cell membrane.
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77
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Williams AT, Donno R, Tirelli N, Dryfe RA. Phospholipid-mediated exfoliation as a facile preparation method for graphene suspensions. RSC Adv 2018; 8:19220-19225. [PMID: 35539657 PMCID: PMC9080625 DOI: 10.1039/c8ra03365j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/16/2018] [Indexed: 11/25/2022] Open
Abstract
This paper deals with simple, inexpensive and ‘green’ methods of production for graphene in colloidal dispersion. Herein, we report on such a method by preparing aqueous graphene dispersions via ultrasonic exfoliation in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The product predominantly consists of few-layer graphene flakes coated by DOPC with a lateral size of a few tens to hundreds of nm, as confirmed by Raman and X-ray photoelectron spectroscopies, thermogravimetric analysis (TGA), dynamic light scattering (DLS) and atomic force microscopy (AFM). The novelty of this method lies in its dependence on a typical soft matter property: the fluidity of the hydrophobic chains. Stiffer phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, which possesses two palmitoyl chains) or 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (POPC, one palmitoyl, one oleyl chain) are ineffective at dispersing graphene; however, in the presence of cholesterol these phospholipids also become effective mediators. The phospholipid coating renders the flakes compatible with biological environments. A simple, inexpensive and ‘green’ method of production for graphene in colloidal dispersion.![]()
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Affiliation(s)
| | - Roberto Donno
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
| | - Nicola Tirelli
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
- NorthWest Centre for Advanced Drug Delivery
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78
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Gumí-Audenis B, Costa L, Redondo-Morata L, Milhiet PE, Sanz F, Felici R, Giannotti MI, Carlà F. In-plane molecular organization of hydrated single lipid bilayers: DPPC:cholesterol. NANOSCALE 2017; 10:87-92. [PMID: 29210438 DOI: 10.1039/c7nr07510c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding the physical properties of cholesterol-phospholipid systems is essential to gain a better knowledge of the function of each membrane constituent. We present a novel, simple and user-friendly setup that allows for the straightforward grazing incidence X-ray diffraction characterization of hydrated individual supported lipid bilayers. This configuration minimizes the scattering from the liquid and allows the detection of the extremely weak diffracted signal of the membrane, enabling the differentiation of the coexisting domains in DPPC:cholesterol single bilayers.
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79
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Jing H, Das S. Electric double layer electrostatics of lipid-bilayer-encapsulated nanoparticles: Toward a better understanding of protocell electrostatics. Electrophoresis 2017; 39:752-759. [PMID: 29235657 DOI: 10.1002/elps.201700286] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/08/2017] [Accepted: 11/08/2017] [Indexed: 11/09/2022]
Abstract
Lipid-bilayer-encapsulated nanoparticles (LBLENPs) or NP-supported LBL systems, such as protocells (which are lipid bilayer encapsulated mesoporous silica nanoparticles or MSNPs) have received extensive attention for applications like targeted drug and gene deliveries, multimodal diagnostics, characterization of membrane-geometry sensitive molecules, etc. Very often electrostatic-mediated interactions have been hypothesized to play key roles in the functioning of these LBLENPs. Despite that, very little has been done to theoretically quantify the fundamental electric double layer (EDL) electrostatics of such LBLENPs. In this study, we develop an EDL theory to describe the electrostatics of such LBLENPs. We show that the electrostatics is a manifestation of the charged/dielectric nature of the NP, LBL structure and charging, and the ionic environment in which the LBLENPs are present. We also establish that for certain conditions of charging of the NP one witnesses a most remarkable charge inversion like electrostatics within the LBL membrane or the NP itself. We anticipate that our findings will provide an extremely useful platform for better understanding the fabrication and functioning of such LBLENPs and discuss examples where our theory can be useful.
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Affiliation(s)
- Haoyuan Jing
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
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80
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Kojima T. Combined Reflectometric Interference Spectroscopy and Quartz Crystal Microbalance Detect Differential Adsorption of Lipid Vesicles with Different Phase Transition Temperatures on SiO2, TiO2, and Au Surfaces. Anal Chem 2017; 89:13596-13602. [DOI: 10.1021/acs.analchem.7b04105] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Taisuke Kojima
- Department of Biomedical Engineering, Georgia Institute of Technology, 950 Atlantic Drive NW, Atlanta, Georgia 30332, United States
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81
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Porfire A, Muntean DM, Rus L, Sylvester B, Tomuţă I. A quality by design approach for the development of lyophilized liposomes with simvastatin. Saudi Pharm J 2017; 25:981-992. [PMID: 29158704 PMCID: PMC5681309 DOI: 10.1016/j.jsps.2017.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023] Open
Abstract
Lyophilization is used to ensure an increased shelf-life of liposomes, by preserving them in dry state, more stable than the aqueous dispersions. When stored as aqueous systems, the encapsulated drugs are released and the liposomes might aggregate or fuse. The aim of this study was to develop and optimize a lyophilized formulation of simvastatin (SIM) loaded into long circulating liposomes using the Quality by Design (QbD) approach. Pharmaceutical development by QbD aims to identify characteristics that are critical for the final product quality, and to establish how the critical process parameters can be varied to consistently produce a product with the desired characteristics. In the case of lyophilized liposomes, the choice of the optimum formulation and technological parameters has to be done, in order to protect the integrity of the liposomal membrane during lyophilization. Thus, the influence of several risk factors (3 formulation factors: PEG proportion, cholesterol concentration, the cryoprotectant to phospholipids molar ratio, and 2 process parameters: the number of extrusions through 100 nm polycarbonate membranes and the freezing conditions prior lyophilization) over the critical quality attributes (CQAs) of lyophilized long circulating liposomes with simvastatin (lyo-LCL-SIM), i.e. the size, the encapsulated SIM concentration, the encapsulated SIM retention, the Tm change and the residual moisture content, was investigated within the current study using the design of experiments tool of QbD. Moreover, the design space for lyo-LCL-SIM was determined, in which the established quality requirements of the product are met, provided that the risk factors vary within the established limits.
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Affiliation(s)
- Alina Porfire
- Iuliu Hatieganu University of Medicine and Pharmacy, Dept. of Pharmaceutical Technology and Biopharmaceutics, Cluj-Napoca, Romania
| | - Dana Maria Muntean
- Iuliu Hatieganu University of Medicine and Pharmacy, Dept. of Pharmaceutical Technology and Biopharmaceutics, Cluj-Napoca, Romania
| | - Lucia Rus
- Iuliu Hatieganu University of Medicine and Pharmacy, Dept. of Drug Analysis, Cluj-Napoca, Romania
| | - Bianca Sylvester
- Iuliu Hatieganu University of Medicine and Pharmacy, Dept. of Pharmaceutical Technology and Biopharmaceutics, Cluj-Napoca, Romania
| | - Ioan Tomuţă
- Iuliu Hatieganu University of Medicine and Pharmacy, Dept. of Pharmaceutical Technology and Biopharmaceutics, Cluj-Napoca, Romania
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82
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Grzyb J, Gieczewska K, Łabuz J, Sztatelman O. Detailed characterization of Synechocystis PCC 6803 ferredoxin:NADP + oxidoreductase interaction with model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:281-291. [PMID: 29038021 DOI: 10.1016/j.bbamem.2017.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 10/08/2017] [Accepted: 10/10/2017] [Indexed: 11/15/2022]
Abstract
Direct interaction of ferredoxin:NADP+ oxidoreductase (FNR) with thylakoid membranes was postulated as a part of the cyclic electron flow mechanism. In vitro binding of FNR to digalactosyldiacylglycerol and monogalactosyldiacylglycerol membranes was also shown. In this paper we deal with the latter interaction in more detail describing the effect for two FNR forms of Synechocystis PCC 6803. The so-called short FNR (sFNR) is homologous to FNR from higher plant chloroplasts. The long FNR (lFNR) form contains an additional domain, responsible for the interaction with phycobilisomes. We compare the binding of both sFNR and lFNR forms to native and non-native lipids. We also include factors which could modulate this process: pH change, temperature change, presence of ferredoxin, NADP+ and NADPH and heavy metals. For the lFNR, we also include phycobilisomes as a modulating factor. The membrane binding is generally faster at lower pH. The sFNR was binding faster than lFNR. Ferredoxin isoforms with higher midpoint potential, as well as NADPH and NADP+, weakened the binding. Charged lipids and high phosphate promoted the binding. Heavy metal ions decreased the rate of membrane binding only when FNR was preincubated with them before injection beneath the monolayer. FNR binding was limited to surface lipid groups and did not influence hydrophobic chain packing. Taken together, FNR interaction with lipids appears to be non-specific, with an electrostatic component. This suggests that the direct FNR interaction with lipids is most likely not a factor in directing electron transfer, but should be taken into account during in vitro studies.
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Affiliation(s)
- Joanna Grzyb
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, F. Joliot Curie 14a, PL-50383 Wroclaw, Poland; Laboratory of Biological Physics, Institute of Physics Polish Academy of Sciences, Aleja Lotników 32/46, PL-02668 Warsaw, Poland.
| | - Katarzyna Gieczewska
- Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, PL-02096 Warsaw, Poland; Department of Biophysics, Institute of Physics, Maria Sklodowska-Curie University, M. Sklodowska-Curie sq. 5, PL-20031 Lublin, Poland
| | - Justyna Łabuz
- Laboratory of Photobiology, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7A, PL-30387 Krakow, Poland
| | - Olga Sztatelman
- Department of Plant Biochemistry, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, PL-02106 Warszawa, Poland
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83
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Micklavzina BL, Longo ML. Characterization of Repulsive Forces and Surface Deformation in Thin Micellar Films via AFM. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10483-10491. [PMID: 28903007 DOI: 10.1021/acs.langmuir.7b02508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Here we examine how the force on an atomic force microscope (AFM) tip varies as it approaches micellar surfactant films, and use this information to discern the film's surface structure and Young's modulus. Rows of wormlike hemimicelles were created at a graphite interface using 10 mM sodium dodecyl sulfate (SDS). We found that the repulsive force on a silicon nitride tip as it approached the surface was exponential, with a decay length of 2.0 ± 0.1 nm. The addition of Na2SO4 was found to cause a change in this behavior, with a clear split into two exponential regions at concentrations above 1 mM. We also observed that the range of these forces increased with added salt from ∼15 nm in pure SDS to ∼20 nm at a Na2SO4 concentration of 1.34 mM. These forces were inconsistent with electrostatic repulsion, and were determined to be steric in nature. We show that the behavior at higher salt concentrations is consistent with the theory of polyelectrolyte brushes in the osmotic regime. From this, we hypothesize the presence of micellar brushes at the surface that behave similarly to adsorbed polymer chains. In addition, the Young's modulus of the film was taken from data near the interface using Sneddon's model, and found to be 80 ± 40 MPa. Similar experiments were performed with 10 mM dodecylamine hydrochloride (DAH) solutions in the presence of added magnesium chloride. The decay length for the pure DAH solution was found to be 2.6 ± 0.3 nm, and the addition of 1.34 mM of MgCl2 caused this to increase to 3.7 ± 0.3 nm. No decay length splitting was observed for DAH. We conclude that the behavior at the surface resembles that of an uncharged polymer brush, as the ionic and surface charge densities are much lower for DAH than for SDS.
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Affiliation(s)
- Benjamin L Micklavzina
- Department of Materials Science and Engineering, University of California Davis , Davis, California 95616, United States
| | - Marjorie L Longo
- Department of Chemical Engineering, University of California Davis , Davis, California 95616, United States
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84
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Bodescu MA, Rosenkötter F, Fritz J. Time lapse AFM on vesicle formation from mixed lipid bilayers induced by the membrane-active peptide melittin. SOFT MATTER 2017; 13:6845-6851. [PMID: 28829104 DOI: 10.1039/c7sm01095h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Melittin is a model system for the action of antimicrobial peptides which are potential candidates for novel antibiotics. We investigated the membrane lysis effect of melittin on phase-separated supported lipid bilayers (DOPC-DPPC) by atomic force microscopy. AFM images show that the peptide first forms defects at the interface between the two lipid phases and then degrades preferentially the liquid-phase DOPC-enriched domains. Vesicular structures of 10-20 nm radius were observed to form, suggesting a mixed carpet-toroidal model mechanism for the resolved action of melittin.
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Affiliation(s)
- M A Bodescu
- Jacobs University Bremen, Department of Physics & Earth Sciences, Campus Ring 1, 28759 Bremen, Germany.
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85
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Manca ML, Manconi M, Zaru M, Valenti D, Peris JE, Matricardi P, Maccioni AM, Fadda AM. Glycerosomes: Investigation of role of 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC) on the assembling and skin delivery performances. Int J Pharm 2017; 532:401-407. [PMID: 28917990 DOI: 10.1016/j.ijpharm.2017.09.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/07/2017] [Accepted: 09/12/2017] [Indexed: 10/18/2022]
Abstract
Glycerosomes were formulated using 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC), diclofenac sodium salt and 10, 20 or 30% glycerol in the water phase, while corresponding liposomes were prepared with the same amount of DMPC and diclofenac, without glycerol. The aim of the present work was to evaluate the effect of the used phospholipid on vesicle features and ability to favour diclofenac skin deposition by comparing these results with those found in previous works performed using hydrogenated soy phosphatidylcholine (P90H) and dipalmitoylphosphatidylcholine (DPPC). Liposomes and glycerosomes were multilamellar, liposomes being smaller (72±6nm). Interactions among glycerol, phospholipids and drug led to the formation of a non-rigid bilayer structure and a variation of the main transition temperature, which shifted to lower temperature. The addition of glycerol led to the formation of more viscous systems (from ∼2.5mPa/s for basic liposomes to ∼5mPa/s for glycerosomes), which improved spread ability of the formulations on the skin.Results obtained in vitro were promising using glycerosomes, irrespective of the amount of glycerol used: the amount of drug, which accumulated into and permeated through the different skin strata, was high and comparable with that obtained using P90H, suggesting that glycerosomes may represent an efficient carrier for both local effect or systemic absorption.
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Affiliation(s)
- Maria Letizia Manca
- Dept. Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, University of Cagliari, 09124 Cagliari, Italy
| | - Maria Manconi
- Dept. Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, University of Cagliari, 09124 Cagliari, Italy.
| | - Marco Zaru
- Icnodermsrl, Sardegna Ricerche Ed.5, 09010 Pula, Cagliari, Italy
| | - Donatella Valenti
- Dept. Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, University of Cagliari, 09124 Cagliari, Italy
| | - Jose Esteban Peris
- Dept. Farmacia y Tecnologia Farmaceutica, University of Valencia, 46100-Burjassot, Valencia, Spain
| | - Pietro Matricardi
- Dept. di Chimica e Tecnologia Farmaceutica, Sapienza, University of Roma, Roma, Italy
| | - Anna Maria Maccioni
- Dept. Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, University of Cagliari, 09124 Cagliari, Italy
| | - Anna Maria Fadda
- Dept. Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, University of Cagliari, 09124 Cagliari, Italy
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86
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Peschel C, Brehm M, Sebastiani D. Polyphilic Interactions as Structural Driving Force Investigated by Molecular Dynamics Simulation (Project 7). Polymers (Basel) 2017; 9:E445. [PMID: 30965747 PMCID: PMC6418726 DOI: 10.3390/polym9090445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 11/16/2022] Open
Abstract
We investigated the effect of fluorinated molecules on dipalmitoylphosphatidylcholine (DPPC) bilayers by force-field molecular dynamics simulations. In the first step, we developed all-atom force-field parameters for additive molecules in membranes to enable an accurate description of those systems. On the basis of this force field, we performed extensive simulations of various bilayer systems containing different additives. The additive molecules were chosen to be of different size and shape, and they included small molecules such as perfluorinated alcohols, but also more complex molecules. From these simulations, we investigated the structural and dynamic effects of the additives on the membrane properties, as well as the behavior of the additive molecules themselves. Our results are in good agreement with other theoretical and experimental studies, and they contribute to a microscopic understanding of interactions, which might be used to specifically tune membrane properties by additives in the future.
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Affiliation(s)
- Christopher Peschel
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle, Germany.
| | - Martin Brehm
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle, Germany.
| | - Daniel Sebastiani
- Institute of Chemistry, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle, Germany.
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87
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Tiefenboeck P, Kim JA, Trunk F, Eicher T, Russo E, Teijeira A, Halin C, Leroux JC. Microinjection for the ex Vivo Modification of Cells with Artificial Organelles. ACS NANO 2017; 11:7758-7769. [PMID: 28777538 DOI: 10.1021/acsnano.7b01404] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Microinjection is extensively used across fields to deliver material intracellularly. Here we address the fundamental aspects of introducing exogenous organelles into cells to endow them with artificial functions. Nanocarriers encapsulating biologically active cargo or extreme intraluminal pH were injected directly into the cytosol of cells, where they bypassed subcellular processing pathways and remained intact for several days. Nanocarriers' size was found to dictate their intracellular distribution pattern upon injection, with larger vesicles adopting polarized agglomerated distributions and smaller colloids spreading evenly in the cytosol. This in turn determined the symmetry or asymmetry of their dilution following cell division, ultimately affecting the intracellular dose at a cell population level. As an example of microinjection's applicability, a cell type relevant for cell-based therapies (dendritic cells) was injected with vesicles, and its migratory properties were studied in a co-culture system mimicking lymphatic capillaries.
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Affiliation(s)
- Peter Tiefenboeck
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Jong Ah Kim
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Ferdinand Trunk
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Tamara Eicher
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Erica Russo
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Alvaro Teijeira
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Cornelia Halin
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
| | - Jean-Christophe Leroux
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich , 8093 Zürich, Switzerland
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88
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Piantanida L, Bolt HL, Rozatian N, Cobb SL, Voïtchovsky K. Ions Modulate Stress-Induced Nanotexture in Supported Fluid Lipid Bilayers. Biophys J 2017; 113:426-439. [PMID: 28746853 PMCID: PMC5529180 DOI: 10.1016/j.bpj.2017.05.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 05/22/2017] [Accepted: 05/30/2017] [Indexed: 12/13/2022] Open
Abstract
Most plasma membranes comprise a large number of different molecules including lipids and proteins. In the standard fluid mosaic model, the membrane function is effected by proteins whereas lipids are largely passive and serve solely in the membrane cohesion. Here we show, using supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers in different saline solutions, that ions can locally induce ordering of the lipid molecules within the otherwise fluid bilayer when the latter is supported. This nanoordering exhibits a characteristic length scale of ∼20 nm, and manifests itself clearly when mechanical stress is applied to the membrane. Atomic force microscopy (AFM) measurements in aqueous solutions containing NaCl, KCl, CaCl2, and Tris buffer show that the magnitude of the effect is strongly ion-specific, with Ca2+ and Tris, respectively, promoting and reducing stress-induced nanotexturing of the membrane. The AFM results are complemented by fluorescence recovery after photobleaching experiments, which reveal an inverse correlation between the tendency for molecular nanoordering and the diffusion coefficient within the bilayer. Control AFM experiments on other lipids and at different temperatures support the hypothesis that the nanotexturing is induced by reversible, localized gel-like solidification of the membrane. These results suggest that supported fluid phospholipid bilayers are not homogenous at the nanoscale, but specific ions are able to locally alter molecular organization and mobility, and spatially modulate the membrane’s properties on a length scale of ∼20 nm. To illustrate this point, AFM was used to follow the adsorption of the membrane-penetrating antimicrobial peptide Temporin L in different solutions. The results confirm that the peptides do not absorb randomly, but follow the ion-induced spatial modulation of the membrane. Our results suggest that ionic effects have a significant impact for passively modulating the local properties of biological membranes, when in contact with a support such as the cytoskeleton.
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Affiliation(s)
- Luca Piantanida
- Department of Physics, Durham University, Durham, United Kingdom
| | - Hannah L Bolt
- Department of Chemistry, Durham University, Durham, United Kingdom
| | - Neshat Rozatian
- Department of Chemistry, Durham University, Durham, United Kingdom
| | - Steven L Cobb
- Department of Chemistry, Durham University, Durham, United Kingdom
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89
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Thermal Response Analysis of Phospholipid Bilayers Using Ellipsometric Techniques. BIOSENSORS-BASEL 2017; 7:bios7030034. [PMID: 28820461 PMCID: PMC5618040 DOI: 10.3390/bios7030034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 12/29/2022]
Abstract
Biomimetic planar artificial membranes have been widely studied due to their multiple applications in several research fields. Their humectation and thermal response are crucial for reaching stability; these characteristics are related to the molecular organization inside the bilayer, which is affected by the aliphatic chain length, saturations, and molecule polarity, among others. Bilayer stability becomes a fundamental factor when technological devices are developed—like biosensors—based on those systems. Thermal studies were performed for different types of phosphatidylcholine (PC) molecules: two pure PC bilayers and four binary PC mixtures. These analyses were carried out through the detection of slight changes in their optical and structural parameters via Ellipsometry and Surface Plasmon Resonance (SPR) techniques. Phospholipid bilayers were prepared by Langmuir-Blodgett technique and deposited over a hydrophilic silicon wafer. Their molecular inclination degree, mobility, and stability of the different phases were detected and analyzed through bilayer thickness changes and their optical phase-amplitude response. Results show that certain binary lipid mixtures—with differences in its aliphatic chain length—present a co-existence of two thermal responses due to non-ideal mixing.
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90
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Ferhan AR, Ma GJ, Jackman JA, Sut TN, Park JH, Cho NJ. Probing the Interaction of Dielectric Nanoparticles with Supported Lipid Membrane Coatings on Nanoplasmonic Arrays. SENSORS (BASEL, SWITZERLAND) 2017; 17:E1484. [PMID: 28644423 PMCID: PMC5539686 DOI: 10.3390/s17071484] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 06/20/2017] [Accepted: 06/20/2017] [Indexed: 12/16/2022]
Abstract
The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been only very limited investigation of the interactions between solution-phase nanomaterials and supported lipid membranes. Herein, we established a surface-based localized surface plasmon resonance (LSPR) sensing platform for probing the interaction of dielectric nanoparticles with supported lipid bilayer (SLB)-coated, plasmonic nanodisk arrays. A key emphasis was placed on controlling membrane functionality by tuning the membrane surface charge vis-à-vis lipid composition. The optical sensing properties of the bare and SLB-coated sensor surfaces were quantitatively compared, and provided an experimental approach to evaluate nanoparticle-membrane interactions across different SLB platforms. While the interaction of negatively-charged silica nanoparticles (SiNPs) with a zwitterionic SLB resulted in monotonic adsorption, a stronger interaction with a positively-charged SLB resulted in adsorption and lipid transfer from the SLB to the SiNP surface, in turn influencing the LSPR measurement responses based on the changing spatial proximity of transferred lipids relative to the sensor surface. Precoating SiNPs with bovine serum albumin (BSA) suppressed lipid transfer, resulting in monotonic adsorption onto both zwitterionic and positively-charged SLBs. Collectively, our findings contribute a quantitative understanding of how supported lipid membrane coatings influence the sensing performance of nanoplasmonic arrays, and demonstrate how the high surface sensitivity of nanoplasmonic sensors is well-suited for detecting the complex interactions between nanoparticles and lipid membranes.
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Affiliation(s)
- Abdul Rahim Ferhan
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
| | - Gamaliel Junren Ma
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
| | - Joshua A Jackman
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
| | - Tun Naw Sut
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
| | - Jae Hyeon Park
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
| | - Nam-Joon Cho
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
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91
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Effect of Statins on the Nanomechanical Properties of Supported Lipid Bilayers. Biophys J 2017; 111:363-372. [PMID: 27463138 DOI: 10.1016/j.bpj.2016.06.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 05/25/2016] [Accepted: 06/15/2016] [Indexed: 11/23/2022] Open
Abstract
Many drugs and other xenobiotics may reach systemic concentrations where they interact not only with the proteins that are their therapeutic targets but also modify the physicochemical properties of the cell membrane, which may lead to altered function of many transmembrane proteins beyond the intended targets. These changes in bilayer properties may contribute to nonspecific, promiscuous changes in membrane protein and cell function because membrane proteins are energetically coupled to their host lipid bilayer. It is thus important, for both pharmaceutical and biophysical reasons, to understand the bilayer-modifying effect of amphiphiles (including therapeutic agents). Here we use atomic force microscopy topography imaging and nanomechanical mapping to monitor the effect of statins, a family of hypolipidemic drugs, on synthetic lipid membranes. Our results reveal that statins alter the nanomechanical stability of the bilayers and increase their elastic moduli depending on the lipid bilayer order. Our results also suggest that statins increase bilayer heterogeneity, which may indicate that statins form nanometer-sized aggregates in the membrane. This is further evidence that changes in bilayer nanoscale mechanical properties may be a signature of lipid bilayer-mediated effects of amphiphilic drugs.
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92
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Shabardina V, Kramer C, Gerdes B, Braunger J, Cordes A, Schäfer J, Mey I, Grill D, Gerke V, Steinem C. Mode of Ezrin-Membrane Interaction as a Function of PIP2 Binding and Pseudophosphorylation. Biophys J 2017; 110:2710-2719. [PMID: 27332129 DOI: 10.1016/j.bpj.2016.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/14/2016] [Accepted: 05/05/2016] [Indexed: 12/28/2022] Open
Abstract
Ezrin, a protein of the ezrin, radixin, moesin (ERM) family, provides a regulated linkage between the plasma membrane and the cytoskeleton. The hallmark of this linkage is the activation of ezrin by phosphatidylinositol-4,5-bisphosphate (PIP2) binding and a threonine phosphorylation at position 567. To analyze the influence of these activating factors on the organization of ezrin on lipid membranes and the proposed concomitant oligomer-monomer transition, we made use of supported lipid bilayers in conjunction with atomic force microscopy and fluorescence microscopy. Bilayers doped with either PIP2 as the natural receptor lipid of ezrin or a Ni-nitrilotriacetic acid-equipped lipid to bind the proteins via their His6-tags to the lipid membrane were used to bind two different ezrin variants: ezrin wild-type and ezrin T567D mimicking the phosphorylated state. Using a combination of reflectometric interference spectroscopy, atomic force microscopy, and Förster resonance energy transfer experiments, we show that only the ezrin T567D mutant, upon binding to PIP2-containing bilayers, undergoes a remarkable conformational change, which we attribute to an opening of the conformation resulting in monomeric protein on the lipid bilayer.
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Affiliation(s)
- Victoria Shabardina
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Corinna Kramer
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Benjamin Gerdes
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Julia Braunger
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Andrea Cordes
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Jonas Schäfer
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - David Grill
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany.
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany; Göttingen Center for Molecular Biosciences, Göttingen, Germany.
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93
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Stelter D, Keyes T. Enhanced Sampling of Phase Transitions in Coarse-Grained Lipid Bilayers. J Phys Chem B 2017; 121:5770-5780. [PMID: 28530813 DOI: 10.1021/acs.jpcb.6b11711] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Freezing and melting of dipalmitoylphosphatidylcholine (DPPC) bilayers are simulated in both the explicit (Wet) and implicit solvent (Dry) coarse-grained MARTINI force fields with enhanced sampling, via the isobaric, molecular dynamics version of the generalized replica exchange method (gREM). Phase transitions are described with the entropic viewpoint, based upon the statistical temperature as a function of enthalpy, TS(H) = 1/(dS(H)/dH), where S is the configurational entropy. Bilayer thickness, area per lipid, and the second-rank order parameter (P2) are calculated vs temperature in the transition range. In a 32-lipid Wet MARTINI system, transitions in the lipid and water subsystems are strongly coupled, giving rise to considerable structure in TS(H) and the need to specify the state of the water when reporting a lipid transition temperature. For gel lipid + liquid water → fluid lipid + liquid water, we find 292.4 K. The small system is influenced by finite-size effects, but it is argued that the entropic approach is well suited to revealing them, which will be particularly relevant for studies of finite nanosystems where there is no thermodynamic limit. In a 390-lipid Dry MARTINI system, two-dimensional analogues of the topographies of coexisting states ("subphases") seen in pure fluids are found. They are not seen in the 32-lipid Wet or Dry system, but the Dry lipids show a new type of state with gel in one leaflet and tilted gel in the other. Dry bilayer transition temperatures are 333.3 K (390 lipids) and 338 K (32 lipids), indicating that the 32-lipid system is not too small for a qualitative study of the transition. Physical arguments are given for Dry lipid system size dependence and for the difference between Wet and Dry systems.
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Affiliation(s)
- David Stelter
- Department of Chemistry, Boston University , Boston, Massachusetts 02215, United States
| | - Tom Keyes
- Department of Chemistry, Boston University , Boston, Massachusetts 02215, United States
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94
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Et-Thakafy O, Delorme N, Gaillard C, Mériadec C, Artzner F, Lopez C, Guyomarc'h F. Mechanical Properties of Membranes Composed of Gel-Phase or Fluid-Phase Phospholipids Probed on Liposomes by Atomic Force Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5117-5126. [PMID: 28475345 DOI: 10.1021/acs.langmuir.7b00363] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In many liposome applications, the nanomechanical properties of the membrane envelope are essential to ensure, e.g., physical stability, protection, or penetration into tissues. Of all factors, the lipid composition and its phase behavior are susceptible to tune the mechanical properties of membranes. To investigate this, small unilamellar vesicles (SUV; diameter < 200 nm), referred to as liposomes, were produced using either unsaturated 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or saturated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in aqueous buffer at pH 6.7. The respective melting temperatures of these phospholipids were -20 and 41 °C. X-ray diffraction analysis confirmed that at 20 °C DOPC was in the fluid phase and DPPC was in the gel phase. After adsorption of the liposomes onto flat silicon substrates, atomic force microscopy (AFM) was used to image and probe the mechanical properties of the liposome membrane. The resulting force-distance curves were treated using an analytical model based on the shell theory to yield the Young's modulus (E) and the bending rigidity (kC) of the curved membranes. The mechanical investigation showed that DPPC membranes were much stiffer (E = 116 ± 45 MPa) than those of DOPC (E = 13 ± 9 MPa) at 20 °C. The study demonstrates that the employed methodology allows discrimination of the respective properties of gel- or fluid-phase membranes when in the shape of liposomes. It opens perspectives to map the mechanical properties of liposomes containing both fluid and gel phases or of biological systems.
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Affiliation(s)
| | - Nicolas Delorme
- UMR CNRS 6283 Institut des Molécules et Matériaux du Mans, Université du Maine, Université Bretagne-Loire, 72000 Le Mans, France
| | - Cédric Gaillard
- UR BIA 1268 Biopolymères Interactions Assemblages, INRA, 44316 Nantes, France
| | - Cristelle Mériadec
- Institut de Physique de Rennes, UMR 6251, CNRS, Université de Rennes 1, 263 Av. Général Leclerc, 35042 Rennes, France
| | - Franck Artzner
- Institut de Physique de Rennes, UMR 6251, CNRS, Université de Rennes 1, 263 Av. Général Leclerc, 35042 Rennes, France
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95
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Liascukiene I, El Kirat K, Beauvais M, Asadauskas SJ, Lambert JF, Landoulsi J. Lipid Layers on Nanoscale Surface Topography: Stability and Effect on Protein Adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4414-4425. [PMID: 28380299 DOI: 10.1021/acs.langmuir.7b00431] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Herein, we report the coating of a surface with a random nanoscale topography with a lipid film formed by an anchoring stearic acid (SA) monolayer and phospholipid (DPPC) layers. For this purpose, different procedures were used for phospholipid coating, including adsorption from solution, drop deposition, and spin-coating. Our results reveal that the morphology of the obtained lipid films is strongly influenced by the topography of the underlying substrate but also impacted by other factors, including the coating procedure and surface wettability (modulated by the presence of SA). These coated surfaces showed a remarkable antifouling behavior toward proteins, with different yields of repellency (Yrp) depending on the amount/organization of DPPC on the nanostructured substrate. The interaction between the proteins and phospholipids involves a partial detachement of the film. The use of characterization techniques with different charcateristics (accuracy, selectivity, analysis depth) did not reveal any obvious vertical heterogenity of the probed interface, indicating that the lipid film acts as a nonfouling coating on the whole surface, including the outermost part (nanoprotrusions) and deeper regions (valleys).
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Affiliation(s)
- Irma Liascukiene
- Sorbonne Universités, UPMC Univ Paris 06 , F-75005 Paris, France
- CNRS, UMR 7197 , Laboratoire de Réactivité de Surface, F-75005 Paris, France
- State Research Institute Center for Physical Sciences and Technology , Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
| | - Karim El Kirat
- Laboratoire de Biomécanique & Bioingénierie, CNRS, UMR 7338, Université de Technologie de Compiègne , BP 20529, F-60205 Compiègne Cedex, France
| | - Mathieu Beauvais
- Alcatel-Lucent Bell Labs France , 7 route de Villejust, 91620 Nozay, France
| | - Svajus J Asadauskas
- State Research Institute Center for Physical Sciences and Technology , Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
| | - Jean-François Lambert
- Sorbonne Universités, UPMC Univ Paris 06 , F-75005 Paris, France
- CNRS, UMR 7197 , Laboratoire de Réactivité de Surface, F-75005 Paris, France
| | - Jessem Landoulsi
- Sorbonne Universités, UPMC Univ Paris 06 , F-75005 Paris, France
- CNRS, UMR 7197 , Laboratoire de Réactivité de Surface, F-75005 Paris, France
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96
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Haghiralsadat F, Amoabediny G, Sheikhha MH, Zandieh-Doulabi B, Naderinezhad S, Helder MN, Forouzanfar T. New liposomal doxorubicin nanoformulation for osteosarcoma: Drug release kinetic study based on thermo and pH sensitivity. Chem Biol Drug Des 2017; 90:368-379. [PMID: 28120466 DOI: 10.1111/cbdd.12953] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/05/2016] [Accepted: 01/05/2017] [Indexed: 11/27/2022]
Abstract
A novel approach was developed for the preparation of stealth controlled-release liposomal doxorubicin. Various liposomal formulations were prepared by employing both thin film and pH gradient hydration techniques. The optimum formulation contained phospholipid and cholesterol in 1:0.43 molar ratios in the presence of 3% DSPE-mPEG (2000). The liposomal formulation was evaluated by determining mean size of vesicle, encapsulation efficiency, polydispersity index, zeta potentials, carrier's functionalization, and surface morphology. The vesicle size, encapsulation efficiency, polydispersity index, and zeta potentials of purposed formula were 93.61 nm, 82.8%, 0.14, and -23, respectively. Vesicles were round-shaped and smooth-surfaced entities with sharp boundaries. In addition, two colorimetric methods for cytotoxicity assay were compared and the IC50 (the half maximal inhibitory concentration) of both methods for encapsulated doxorubicin was determined to be 0.1 μg/ml. The results of kinetic drug release were investigated at several different temperatures and pH levels, which showed that purposed formulation was thermo and pH sensitive.
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Affiliation(s)
- Fateme Haghiralsadat
- Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran.,Department of Nano Biotechnology, Research Center for New Technologies in Life Science Engineering, University of Tehran, Tehran, Iran
| | - Ghasem Amoabediny
- Department of Nano Biotechnology, Research Center for New Technologies in Life Science Engineering, University of Tehran, Tehran, Iran.,Department of Biotechnology and Pharmaceutical Engineering, School of Engineering, University of Tehran, Tehran, Iran.,Department of Oral & Maxillofacial Surgery, VU University Medical Center, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Mohammad Hasan Sheikhha
- Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.,Biotechnology Research Center, International Campus, Shahid Sadoughi University of Medical Science, Yazd, Iran
| | - Behrouz Zandieh-Doulabi
- Department of Orthopedic Surgery, VU University Medical Center, MOVE Research Institute, Amsterdam, Netherlands.,Oral Cell Biology and Functional Anatomy, VU University, Amsterdam, North Holland, Netherlands
| | - Samira Naderinezhad
- Department of Nano Biotechnology, Research Center for New Technologies in Life Science Engineering, University of Tehran, Tehran, Iran.,Department of Biotechnology and Pharmaceutical Engineering, School of Engineering, University of Tehran, Tehran, Iran
| | - Marco N Helder
- Department of Oral & Maxillofacial Surgery, VU University Medical Center, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.,Department of Orthopedic Surgery, VU University Medical Center, MOVE Research Institute, Amsterdam, Netherlands
| | - Tymour Forouzanfar
- Department of Oral & Maxillofacial Surgery, VU University Medical Center, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
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97
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Shafikov MZ, Suleymanova AF, Kozhevnikov DN, König B. Tuning the Excimer Emission of Amphiphilic Platinum(II) Complexes Mediated by Phospholipid Vesicles. Inorg Chem 2017; 56:4885-4897. [DOI: 10.1021/acs.inorgchem.6b03100] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marsel Z. Shafikov
- Ural Federal University, Mira 19, Ekaterinburg, 620002, Russia
- I. Postovsky Institute of Organic Synthesis, Ekaterinburg, 620990, Russia
| | | | | | - Burkhard König
- Institut für Organische Chemie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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98
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Almonte L, Colchero J. True non-contact atomic force microscopy imaging of heterogeneous biological samples in liquids: topography and material contrast. NANOSCALE 2017; 9:2903-2915. [PMID: 28181615 DOI: 10.1039/c6nr07967a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The present work analyses how the tip-sample interaction signals critically determine the operation of an Atomic Force Microscope (AFM) set-up immersed in liquid. On heterogeneous samples, the conservative tip-sample interaction may vary significantly from point to point - in particular from attractive to repulsive - rendering correct feedback very challenging. Lipid membranes prepared on a mica substrate are analyzed as reference samples which are locally heterogeneous (material contrast). The AFM set-up is operated dynamically at low oscillation amplitude and all available experimental data signals - the normal force, as well as the amplitude and frequency - are recorded simultaneously. From the analysis of how the dissipation (oscillation amplitude) and the conservative interaction (normal force and resonance frequency) vary with the tip-sample distance we conclude that dissipation is the only appropriate feedback source for stable and correct topographic imaging. The normal force and phase then carry information about the sample composition ("chemical contrast"). Dynamic AFM allows imaging in a non-contact regime where essentially no forces are applied, rendering dynamic AFM a truly non-invasive technique.
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Affiliation(s)
- Lisa Almonte
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química (Campus Espinardo), Universidad de Murcia, E-30100 Murcia, Spain.
| | - Jaime Colchero
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química (Campus Espinardo), Universidad de Murcia, E-30100 Murcia, Spain.
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99
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Sannigrahi A, Maity P, Karmakar S, Chattopadhyay K. Interaction of KMP-11 with Phospholipid Membranes and Its Implications in Leishmaniasis: Effects of Single Tryptophan Mutations and Cholesterol. J Phys Chem B 2017; 121:1824-1834. [DOI: 10.1021/acs.jpcb.6b11948] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Achinta Sannigrahi
- Structural Biology & Bio-Informatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mallick Road, Kolkata 700032, India
| | - Pabitra Maity
- Department
of Physics, Jadavpur University, 188, Raja S. C. Mallick Road, Kolkata 700032, India
| | - Sanat Karmakar
- Department
of Physics, Jadavpur University, 188, Raja S. C. Mallick Road, Kolkata 700032, India
| | - Krishnananda Chattopadhyay
- Structural Biology & Bio-Informatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mallick Road, Kolkata 700032, India
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100
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Sánchez-Borzone ME, Mariani ME, Miguel V, Gleiser RM, Odhav B, Venugopala KN, García DA. Membrane effects of dihydropyrimidine analogues with larvicidal activity. Colloids Surf B Biointerfaces 2017; 150:106-113. [DOI: 10.1016/j.colsurfb.2016.11.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 11/18/2016] [Accepted: 11/22/2016] [Indexed: 10/20/2022]
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