1
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Paez-Perez M, Dent MR, Brooks NJ, Kuimova MK. Viscosity-Sensitive Membrane Dyes as Tools To Estimate the Crystalline Structure of Lipid Bilayers. Anal Chem 2023; 95:12006-12014. [PMID: 37526607 PMCID: PMC10433245 DOI: 10.1021/acs.analchem.3c01747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 07/12/2023] [Indexed: 08/02/2023]
Abstract
Lipid membranes are crucial for cellular integrity and regulation, and tight control of their structural and mechanical properties is vital to ensure that they function properly. Fluorescent probes sensitive to the membrane's microenvironment are useful for investigating lipid membrane properties; however, there is currently a lack of quantitative correlation between the exact parameters of lipid organization and a readout from these dyes. Here, we investigate this relationship for "molecular rotors", or microviscosity sensors, by simultaneously measuring their fluorescence lifetime to determine the membrane viscosity, while using X-ray diffraction to determine the membrane's structural properties. Our results reveal a phase-dependent correlation between the membrane's structural parameters and mechanical properties measured by a BODIPY-based molecular rotor, giving excellent predictive power for the structural descriptors of the lipid bilayer. We also demonstrate that differences in membrane thickness between different lipid phases are not a prerequisite for the formation of lipid microdomains and that this requirement can be disrupted by the presence of line-active molecules. Our results underpin the use of membrane-sensitive dyes as reporters of the structure of lipid membranes.
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Affiliation(s)
- Miguel Paez-Perez
- MSRH, Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, U.K.
| | - Michael R. Dent
- MSRH, Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, U.K.
| | - Nicholas J. Brooks
- MSRH, Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, U.K.
| | - Marina K. Kuimova
- MSRH, Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, U.K.
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2
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Koutsoukos S, Avila J, Brooks NJ, Costa Gomes M, Welton T. Physical properties and nanostructuring of long-chained homobaric imidazolium ionic liquids. Phys Chem Chem Phys 2023; 25:6316-6325. [PMID: 36779289 DOI: 10.1039/d2cp05783b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Understanding the structure-property relationship and nanoscopic behaviour of ionic liquids is of utmost importance for their potential applications. Focusing these studies on sets of homobaric ionic liquids could provide important insight into the effects of specific chemical groups on the overall interaction profile, bringing researchers one step closer to succesfully designing ionic liquids which are tailor-made for specific applications. This work focuses on ionic liquids with 12 total carbons on their side chains, studying both their bulk physical properties (such as densities and viscosities) and their nanostructuring. The results reveal that by keeping the total number of carbons constant, but arranging them differently around the imidazolium ring, either in a linear or in a branched-chain formation, can result in compounds with quite distinct properties. Some of those (such as diffusivity) appear to be more sensitive to symmetry variations, while others (such as density) are not significantly affected. X-ray scattering is used in order to get a clearer understanding of the nanostructuring of the studied compounds and to investigate to what extent the observed macroscopic properties are directly linked to the nanoscale ordering.
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Affiliation(s)
- Spyridon Koutsoukos
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Jocasta Avila
- Laboratoire de Chimie de l'ENS Lyon, CNRS and Université de Lyon, 46 allée d'Italie, 69364 Lyon, France
| | - Nicholas J Brooks
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Margarida Costa Gomes
- Laboratoire de Chimie de l'ENS Lyon, CNRS and Université de Lyon, 46 allée d'Italie, 69364 Lyon, France
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
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3
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Strutt R, Sheffield F, Barlow NE, Flemming AJ, Harling JD, Law RV, Brooks NJ, Barter LMC, Ces O. UV-DIB: label-free permeability determination using droplet interface bilayers. Lab Chip 2022; 22:972-985. [PMID: 35107110 DOI: 10.1039/d1lc01155c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Simple diffusion of molecular entities through a phospholipid bilayer, is a phenomenon of great importance to the pharmaceutical and agricultural industries. Current model lipid systems to probe this typically only employ fluorescence as a readout, thus limiting the range of assessable chemical matter that can be studied. We report a new technology platform, the UV-DIB, which facilitates label free measurement of small molecule translocation rates. This is based upon the coupling of droplet interface bilayer technology with implemented fiber optics to facilitate analysis via ultraviolet spectroscopy, in custom designed PMMA wells. To improve on current DIB technology, the platform was designed to be reusable, with a high sampling rate and a limit of UV detection in the low μM regime. We demonstrate the use of our system to quantify passive diffusion in a reproducible and rapid manner where the system was validated by investigating multiple permeants of varying physicochemical properties across a range of lipid interfaces, each demonstrating differing kinetics. Our system permits the interrogation of structural dependence on the permeation rate of a given compound. We present this ability from two structural perspectives, that of the membrane, and the permeant. We observed a reduction in permeability between pure DOPC and DPhPC interfaces, concurring with literature and demonstrating our ability to study the effects of lipid composition on permeability. In relation to the effects of permeant structure, our device facilitated the rank ordering of various compounds from the xanthine class of compounds, where the structure of each permeant differed by a single group alteration. We found that DIBs were stable up to 5% DMSO, a molecule often used to aid solubilisation of pharmaceutical and agrochemical compounds. The ability of our device to rank-order compounds with such minor structural differences provides a level of precision that is rarely seen in current, industrially applied technologies.
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Affiliation(s)
- Robert Strutt
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Felix Sheffield
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Nathan E Barlow
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Anthony J Flemming
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK
| | - John D Harling
- Medicinal Chemistry, GlaxoSmithKline, Stevenage, SG1 2NY, UK
| | - Robert V Law
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Nicholas J Brooks
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Laura M C Barter
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
| | - Oscar Ces
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, Shepherd's Bush, London, W12 0BZ, UK
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4
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Lopez Mora N, Findlay HE, Brooks NJ, Purushothaman S, Ces O, Booth PJ. The membrane transporter lactose permease increases lipid bilayer bending rigidity. Biophys J 2021; 120:3787-3794. [PMID: 34273316 PMCID: PMC8456183 DOI: 10.1016/j.bpj.2021.06.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 11/26/2022] Open
Abstract
Cellular life relies on membranes, which provide a resilient and adaptive cell boundary. Many essential processes depend upon the ease with which the membrane is able to deform and bend, features that can be characterized by the bending rigidity. Quantitative investigations of such mechanical properties of biological membranes have primarily been undertaken in solely lipid bilayers and frequently in the absence of buffers. In contrast, much less is known about the influence of integral membrane proteins on bending rigidity under physiological conditions. We focus on an exemplar member of the ubiquitous major facilitator superfamily of transporters and assess the influence of lactose permease on the bending rigidity of lipid bilayers. Fluctuation analysis of giant unilamellar vesicles (GUVs) is a useful means to measure bending rigidity. We find that using a hydrogel substrate produces GUVs that are well suited to fluctuation analysis. Moreover, the hydrogel method is amenable to both physiological salt concentrations and anionic lipids, which are important to mimic key aspects of the native lactose permease membrane. Varying the fraction of the anionic lipid in the lipid mixture DOPC/DOPE/DOPG allows us to assess the dependence of membrane bending rigidity on the topology and concentration of an integral membrane protein in the lipid bilayer of GUVs. The bending rigidity gradually increases with the incorporation of lactose permease, but there is no further increase with greater amounts of the protein in the membrane.
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Affiliation(s)
- Nestor Lopez Mora
- Department of Chemistry, Kings College London, London, United Kingdom
| | - Heather E Findlay
- Department of Chemistry, Kings College London, London, United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Sowmya Purushothaman
- Department of Chemistry, Imperial College London, London, United Kingdom; Beyond Meat, El Segundo, California
| | - Oscar Ces
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Paula J Booth
- Department of Chemistry, Kings College London, London, United Kingdom.
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5
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Allen ME, Elani Y, Brooks NJ, Seddon JM. The effect of headgroup methylation on polymorphic phase behaviour in hydrated N-methylated phosphoethanolamine:palmitic acid membranes. Soft Matter 2021; 17:5763-5771. [PMID: 34019613 DOI: 10.1039/d1sm00178g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Mixtures of fatty acids and phospholipids can form hexagonal (HII) and inverse bicontinuous cubic phases, the latter of which are implicated in various cellular processes and have wide-ranging biotechnological applications in protein crystallisation and drug delivery systems. Therefore, it is vitally important to understand the formation conditions of inverse bicontinuous cubic phases and how their properties can be tuned. We have used differential scanning calorimetry and synchrotron-based small angle and wide angle X-ray scattering (SAXS/WAXS) to investigate the polymorphic phase behaviour of palmitic acid/partially-methylated phospholipid mixtures, and how headgroup methylation impacts on inverse bicontinuous cubic phase formation. We find that upon partial methylation of the phospholipid headgroup (1 or 2 methyl substituents) inverse bicontinuous cubic phases are formed (of the Im3m spacegroup), which is not the case with 0 or 3 methyl substituents. This shows how important headgroup methylation is for controlling phase behaviour and how a change in headgroup methylation can be used to controllably tune various inverse bicontinuous phase features such as their lattice parameter and the temperature range of their stability.
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Affiliation(s)
- Matthew E Allen
- Department of Chemistry, Imperial College London, W12 7SL, UK.
| | - Yuval Elani
- Department of Chemical Engineering, Imperial College London, SW7 2AZ, UK
| | | | - John M Seddon
- Department of Chemistry, Imperial College London, W12 7SL, UK.
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6
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Salvador-Castell M, Golub M, Erwin N, Demé B, Brooks NJ, Winter R, Peters J, Oger PM. Characterisation of a synthetic Archeal membrane reveals a possible new adaptation route to extreme conditions. Commun Biol 2021; 4:653. [PMID: 34079059 PMCID: PMC8172549 DOI: 10.1038/s42003-021-02178-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 04/29/2021] [Indexed: 02/04/2023] Open
Abstract
It has been proposed that adaptation to high temperature involved the synthesis of monolayer-forming ether phospholipids. Recently, a novel membrane architecture was proposed to explain the membrane stability in polyextremophiles unable to synthesize such lipids, in which apolar polyisoprenoids populate the bilayer midplane and modify its physico-chemistry, extending its stability domain. Here, we have studied the effect of the apolar polyisoprenoid squalane on a model membrane analogue using neutron diffraction, SAXS and fluorescence spectroscopy. We show that squalane resides inside the bilayer midplane, extends its stability domain, reduces its permeability to protons but increases that of water, and induces a negative curvature in the membrane, allowing the transition to novel non-lamellar phases. This membrane architecture can be transposed to early membranes and could help explain their emergence and temperature tolerance if life originated near hydrothermal vents. Transposed to the archaeal bilayer, this membrane architecture could explain the tolerance to high temperature in hyperthermophiles which grow at temperatures over 100 °C while having a membrane bilayer. The induction of a negative curvature to the membrane could also facilitate crucial cell functions that require high bending membranes.
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Affiliation(s)
| | - Maksym Golub
- Université Grenoble Alpes, CNRS, LiPhy, Grenoble, France
- Institut Laue Langevin, Grenoble, France
| | - Nelli Erwin
- Faculty of Chemistry and Chemical Biology, Technische Universität Dortmund, Dortmund, Germany
| | - Bruno Demé
- Institut Laue Langevin, Grenoble, France
| | | | - Roland Winter
- Faculty of Chemistry and Chemical Biology, Technische Universität Dortmund, Dortmund, Germany
| | - Judith Peters
- Université Grenoble Alpes, CNRS, LiPhy, Grenoble, France.
- Institut Laue Langevin, Grenoble, France.
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7
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Páez-Pérez M, López-Duarte I, Vyšniauskas A, Brooks NJ, Kuimova MK. Imaging non-classical mechanical responses of lipid membranes using molecular rotors. Chem Sci 2020; 12:2604-2613. [PMID: 34164028 PMCID: PMC8179291 DOI: 10.1039/d0sc05874b] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Lipid packing in cellular membranes has a direct effect on membrane tension and microviscosity, and plays a central role in cellular adaptation, homeostasis and disease. According to conventional mechanical descriptions, viscosity and tension are directly interconnected, with increased tension leading to decreased membrane microviscosity. However, the intricate molecular interactions that combine to build the structure and function of a cell membrane suggest a more complex relationship between these parameters. In this work, a viscosity-sensitive fluorophore (‘molecular rotor’) is used to map changes in microviscosity in model membranes under conditions of osmotic stress. Our results suggest that the relationship between membrane tension and microviscosity is strongly influenced by the bilayer's lipid composition. In particular, we show that the effects of increasing tension are minimised for membranes that exhibit liquid disordered (Ld) – liquid ordered (Lo) phase coexistence; while, surprisingly, membranes in pure gel and Lo phases exhibit a negative compressibility behaviour, i.e. they soften upon compression. Viscosity-sensitive molecular rotors demonstrate that the non-classical mechanical behaviour of model lipid membranes is able to buffer external stress.![]()
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Affiliation(s)
- Miguel Páez-Pérez
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
| | - Ismael López-Duarte
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK .,Departamento de Química Orgánica, Universidad Autónoma de Madrid Cantoblanco 28049 Madrid Spain
| | - Aurimas Vyšniauskas
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK .,Center of Physical Sciences and Technology Saulėtekio av. 3 Vilnius Lithuania
| | - Nicholas J Brooks
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
| | - Marina K Kuimova
- MSRH, Department of Chemistry, Imperial College London Wood Lane London W12 0BZ UK
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8
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Carter JW, Gonzalez MA, Brooks NJ, Seddon JM, Bresme F. Flip-flop asymmetry of cholesterol in model membranes induced by thermal gradients. Soft Matter 2020; 16:5925-5932. [PMID: 32538402 DOI: 10.1039/d0sm00546k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lipid asymmetry is a crucial property of biological membranes and significantly influences their physical and mechanical properties. It is responsible for maintaining different chemical environments on the external and internal surfaces of cells and organelles and plays a vital role in many biological processes such as cell signalling and budding. In this work we show, using non-equilibrium molecular dynamics (NEMD) simulations, that thermal fields can induce lipid asymmetry in biological membranes. We focus our investigation on cholesterol, an abundant lipid in the plasma membrane, with a rapid flip-flop rate, significantly influencing membrane properties. We demonstrate that thermal fields induce membrane asymmetry with cholesterol showing thermophobic behaviour and therefore accumulating on the cold side of the membrane. This work highlights a possible experimental route to preparing and controlling asymmetry in synthetic membranes.
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Affiliation(s)
- James W Carter
- Department of Chemistry, Imperial College London, MSRH building, 80 Wood Lane, London, W12 0BZ, UK.
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9
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Mann SK, Devgan MK, Franks WT, Huband S, Chan CL, Griffith J, Pugh D, Brooks NJ, Welton T, Pham TN, McQueen LL, Lewandowski JR, Brown SP. MAS NMR Investigation of Molecular Order in an Ionic Liquid Crystal. J Phys Chem B 2020; 124:4975-4988. [PMID: 32412761 PMCID: PMC7341529 DOI: 10.1021/acs.jpcb.0c02328] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure and molecular order in the thermotropic ionic liquid crystal (ILC), [choline][geranate(H)octanoate], an analogue of Choline And GEranate (CAGE), which has potential for use as a broad-spectrum antimicrobial and transdermal and oral delivery agent, were investigated by magic-angle spinning (MAS) nuclear magnetic resonance (NMR), polarizing optical microscopy, small-angle X-ray scattering (SAXS), and mass spectrometry. Mass spectrometry and the 1H NMR chemical shift reveal that CAGE-oct is a dynamic system, with metathesis (the exchange of interacting ions) and hydrogen exchange occurring between hydrogen-bonded/ionic complexes such as [(choline)(geranate)(H)(octanoate)], [(choline)(octanoate)2(H)], and [(choline)(geranate)2(H)]. These clusters, which are shown by mass spectrometry to be significantly more stable than expected for typical electrostatic ion clusters, involve hydrogen bonding between the carboxylic acid, carboxylate, and hydroxyl groups, with rapid hydrogen bond breaking and re-formation observed to average the 1H chemical shifts. The formation of a partial bilayer liquid crystal (LC) phase was identified by SAXS and polarizing optical microscopy at temperatures below ∼293 K. The occurrence of this transition close to room temperature could be utilized as a potential temperature-induced "switch" of the anisotropic properties for particular applications. The presence of an isotropic component of approximately 23% was observed to coexist with the LC phase, as detected by polarizing optical microscopy and quantified by both 1H-13C dipolar-chemical shift correlation (DIPSHIFT) and 1H double-quantum (DQ) MAS NMR experiments. At temperatures above the LC-to-isotropic transition, intermediate-range order (clustering of polar and nonpolar domains), a feature of many ILs, persists. Site-specific order parameters for the LC phase of CAGE-oct were obtained from the MAS NMR measurement of the partially averaged 13C-1H dipolar couplings (DCH) by cross-polarization (CP) build-up curves and DIPSHIFT experiments, and 1H-1H dipolar couplings (DHH) by double-quantum (DQ) build-up curves. The corresponding order parameters, SCH and SHH, are in the range 0-0.2 and are lower compared to those for smectic (i.e., layered) phases of conventional nonionic liquid crystals, resembling those of lamellar phases formed by lyotropic surfactant-solvent systems.
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Affiliation(s)
- Sarah K Mann
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Mohit K Devgan
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - W Trent Franks
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.,Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Steven Huband
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Chi Long Chan
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - Jeraime Griffith
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - David Pugh
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - Tom Welton
- Department of Chemistry, Imperial College London, London SW7 2AZ, U.K
| | - Tran N Pham
- GSK R&D, Stevenage, Hertfordshire SG1 2NY, U.K
| | - Lisa L McQueen
- GSK R&D, Collegeville, Pennsylvania 19426, United States
| | | | - Steven P Brown
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
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10
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Abstract
Dispersions of nonlamellar lipid membrane assemblies are gaining increasing interest for drug delivery and protein therapeutic application. A key bottleneck has been the lack of rational design rules for these systems linking different lipid species and conditions to defined lattice parameters and structures. We have developed robust methods to form cubosomes (nanoparticles with porous internal structures) with water channel diameters of up to 171 Å, which are over 4 times larger than archetypal cubosome structures. The water channel diameter can be tuned via the incorporation of cholesterol and the charged lipid DOPA, DOPG, or DOPS. We have found that large molecules can be incorporated into the porous cubosome structure and that these molecules can interact with the internal cubosome membrane. This offers huge potential for accessible encapsulation and protection of biomolecules and development of confined interfacial reaction environments.
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Affiliation(s)
- Hanna M G Barriga
- Department of Chemistry , Imperial College London , Molecular Sciences Research Hub, White City Campus, Wood Lane , London W12 0BZ , U.K
| | - Oscar Ces
- Department of Chemistry , Imperial College London , Molecular Sciences Research Hub, White City Campus, Wood Lane , London W12 0BZ , U.K
| | - Robert V Law
- Department of Chemistry , Imperial College London , Molecular Sciences Research Hub, White City Campus, Wood Lane , London W12 0BZ , U.K
| | - John M Seddon
- Department of Chemistry , Imperial College London , Molecular Sciences Research Hub, White City Campus, Wood Lane , London W12 0BZ , U.K
| | - Nicholas J Brooks
- Department of Chemistry , Imperial College London , Molecular Sciences Research Hub, White City Campus, Wood Lane , London W12 0BZ , U.K
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11
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Salvador-Castell M, Brooks NJ, Peters J, Oger P. Induction of non-lamellar phases in archaeal lipids at high temperature and high hydrostatic pressure by apolar polyisoprenoids. Biochim Biophys Acta Biomembr 2019; 1862:183130. [PMID: 31734311 DOI: 10.1016/j.bbamem.2019.183130] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/01/2022]
Abstract
It is now well established that cell membranes are much more than a barrier that separate the cytoplasm from the outside world. Regarding membrane's lipids and their self-assembling, the system is highly complex, for example, the cell membrane needs to adopt different curvatures to be functional. This is possible thanks to the presence of non-lamellar-forming lipids, which tend to curve the membrane. Here, we present the effect of squalane, an apolar isoprenoid molecule, on an archaea-like lipid membrane. The presence of this molecule provokes negative membrane curvature and forces lipids to self-assemble under inverted cubic and inverted hexagonal phases. Such non-lamellar phases are highly stable under a broad range of external extreme conditions, e.g. temperatures and high hydrostatic pressures, confirming that such apolar lipids could be included in the architecture of membranes arising from cells living under extreme environments.
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Affiliation(s)
| | - Nicholas J Brooks
- Imperial College London, South Kensington Campus, London SW7 2AZ, England, United Kingdom of Great Britain and Northern Ireland
| | - Judith Peters
- Université Grenoble Alpes, LiPhy, CNRS, 38000 Grenoble, France; Institut Laue Langevin, 38000 Grenoble, France
| | - Philippe Oger
- Université de Lyon, INSA de Lyon, CNRS, UMR 5240, 69211 Villeurbanne, France.
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12
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Tyler AII, Greenfield JL, Seddon JM, Brooks NJ, Purushothaman S. Coupling Phase Behavior of Fatty Acid Containing Membranes to Membrane Bio-Mechanics. Front Cell Dev Biol 2019; 7:187. [PMID: 31616666 PMCID: PMC6763698 DOI: 10.3389/fcell.2019.00187] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 08/22/2019] [Indexed: 12/15/2022] Open
Abstract
Biological membranes constantly modulate their fluidity for proper functioning of the cell. Modulation of membrane properties via regulation of fatty acid composition has gained a renewed interest owing to its relevance in endocytosis, endoplasmic reticulum membrane homeostasis, and adaptation mechanisms in the deep sea. Endowed with significant degrees of freedom, the presence of free fatty acids can alter the curvature of membranes which in turn can alter the response of curvature sensing proteins, thus defining adaptive ways to reconfigure membranes. Most significantly, recent experiments demonstrated that polyunsaturated lipids facilitate membrane bending and fission by endocytic proteins – the first step in the biogenesis of synaptic vesicles. Despite the vital roles of fatty acids, a systematic study relating the interactions between fatty acids and membrane and the consequent effect on the bio-mechanics of membranes under the influence of fatty acids has been sparse. Of specific interest is the vast disparity in the properties of cis and trans fatty acids, that only differ in the orientation of the double bond and yet have entirely unique and opposing chemical properties. Here we demonstrate a combined X-ray diffraction and membrane fluctuation analysis method to couple the structural properties to the biophysical properties of fatty acid-laden membranes to address current gaps in our understanding. By systematically doping pure dioleoyl phosphatidylcholine (DOPC) membranes with cis fatty acid and trans fatty acid we demonstrate that the presence of fatty acids doesn’t always fluidize the membrane. Rather, an intricate balance between the curvature, molecular interactions, as well as the amount of specific fatty acid dictates the fluidity of membranes. Lower concentrations are dominated by the nature of interactions between the phospholipid and the fatty acids. Trans fatty acid increases the rigidity while decreasing the area per lipid similar to the properties depicted by the addition of saturated fatty acids to lipidic membranes. Cis fatty acid however displays the accepted view of having a fluidizing effect at small concentrations. At higher concentrations curvature frustration dominates, leading to increased rigidity irrespective of the type of fatty acid. These results are consistent with theoretical predictions as detailed in the manuscript.
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Affiliation(s)
- Arwen I I Tyler
- Department of Chemistry, Imperial College London, London, United Kingdom.,School of Food Science and Nutrition, University of Leeds, Leeds, United Kingdom
| | - Jake L Greenfield
- Department of Chemistry, Imperial College London, London, United Kingdom.,Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - John M Seddon
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Sowmya Purushothaman
- Department of Material Science, University of California, Davis, Davis, CA, United States.,Cavendish Laboratory, Cambridge, United Kingdom
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13
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Woodcock EM, Girvan P, Eckert J, Lopez-Duarte I, Kubánková M, van Loon JJWA, Brooks NJ, Kuimova MK. Measuring Intracellular Viscosity in Conditions of Hypergravity. Biophys J 2019; 116:1984-1993. [PMID: 31053255 DOI: 10.1016/j.bpj.2019.03.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/28/2019] [Accepted: 03/19/2019] [Indexed: 12/12/2022] Open
Abstract
Gravity-sensitive cellular responses are regularly observed in both specialized and nonspecialized cells. One potential mechanism for this sensitivity is a changing viscosity of the intracellular organelles. Here, we report a novel, to our knowledge, viscosity-sensitive molecular rotor based on mesosubstituted boron-dipyrrin used to investigate the response of viscosity of cellular membranes to hypergravity conditions created at the large diameter centrifuge at the European Space Agency Technology Centre. Mouse osteoblastic (MC3T3-E1) and endothelial (human umbilical vein endothelial cell) cell lines were tested, and an increase in viscosity was found with increasing hypergravity loading. This response is thought to be primarily biologically driven, with the potential for a small, instantaneous physical mechanism also contributing to the observed effect. This work provides the first, to our knowledge, quantitative data for cellular viscosity changes under hypergravity, up to 15 × g.
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Affiliation(s)
- Emma M Woodcock
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom; Institute of Chemical Biology, Imperial College London, South Kensington, London, United Kingdom
| | - Paul Girvan
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom; Institute of Chemical Biology, Imperial College London, South Kensington, London, United Kingdom
| | - Julia Eckert
- Department of Physics, School of Science, Technische Universität Dresden, Dresden, Germany; European Space Agency Technology Centre, TEC-MMG LIS Lab, Noordwijk, the Netherlands
| | - Ismael Lopez-Duarte
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom
| | - Markéta Kubánková
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom
| | - Jack J W A van Loon
- European Space Agency Technology Centre, TEC-MMG LIS Lab, Noordwijk, the Netherlands; Department of Oral and Maxillofacial Surgery/Oral Pathology, Dutch Experiment Support Centre, Academic Centre for Dentistry Amsterdam, VU University Medical Centre, Amsterdam, the Netherlands
| | - Nicholas J Brooks
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom; Institute of Chemical Biology, Imperial College London, South Kensington, London, United Kingdom.
| | - Marina K Kuimova
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom; Institute of Chemical Biology, Imperial College London, South Kensington, London, United Kingdom.
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14
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Weber CC, Brooks NJ, Castiglione F, Mauri M, Simonutti R, Mele A, Welton T. On the structural origin of free volume in 1-alkyl-3-methylimidazolium ionic liquid mixtures: a SAXS and 129Xe NMR study. Phys Chem Chem Phys 2019; 21:5999-6010. [PMID: 30809621 DOI: 10.1039/c9cp00587k] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquid (IL) mixtures enable the design of fluids with finely tuned structural and physicochemical properties for myriad applications. In order to rationally develop and design IL mixtures with the desired properties, a thorough understanding of the structural origins of their physicochemical properties and the thermodynamics of mixing needs to be developed. To elucidate the structural origins of the excess molar volume within IL mixtures containing ions with different alkyl chain lengths, 3 IL mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs have been explored in a joint small angle X-ray scattering (SAXS) and 129Xe NMR study. The apolar domains of the IL mixtures were shown to possess similar dimensions to the largest alkyl chain of the mixture with the size evolution determined by whether the shorter alkyl chain was able to interact with the apolar domain. 129Xe NMR results illustrated that the origin of excess molar volume in these mixtures was due to fluctuations within these apolar domains arising from alkyl chain mismatch, with the formation of a greater number of smaller voids within the IL structure. These results indicate that free volume effects for these types of mixtures can be predicted from simple considerations of IL structure and that the structural basis for the formation of excess molar volume in these mixtures is substantially different to IL mixtures formed of different types of ions.
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Affiliation(s)
- Cameron C Weber
- School of Science, Auckland University of Technology, Auckland, New Zealand
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15
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Khan H, Seddon JM, Law RV, Brooks NJ, Robles E, Cabral JT, Ces O. Effect of glycerol with sodium chloride on the Krafft point of sodium dodecyl sulfate using surface tension. J Colloid Interface Sci 2019; 538:75-82. [DOI: 10.1016/j.jcis.2018.11.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/02/2018] [Accepted: 11/07/2018] [Indexed: 10/27/2022]
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16
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Brady RA, Kaufhold WT, Brooks NJ, Foderà V, Di Michele L. Flexibility defines structure in crystals of amphiphilic DNA nanostars. J Phys Condens Matter 2019; 31:074003. [PMID: 30523829 DOI: 10.1088/1361-648x/aaf4a1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
DNA nanostructures with programmable shape and interactions can be used as building blocks for the self-assembly of crystalline materials with prescribed nanoscale features, holding a vast technological potential. Structural rigidity and bond directionality have been recognised as key design features for DNA motifs to sustain long-range order in 3D, but the practical challenges associated with prescribing building-block geometry with sufficient accuracy have limited the variety of available designs. We have recently introduced a novel platform for the one-pot preparation of crystalline DNA frameworks supported by a combination of Watson-Crick base pairing and hydrophobic forces (Brady et al 2017 Nano Lett. 17 3276-81). Here we use small angle x-ray scattering and coarse-grained molecular simulations to demonstrate that, as opposed to available all-DNA approaches, amphiphilic motifs do not rely on structural rigidity to support long-range order. Instead, the flexibility of amphiphilic DNA building-blocks is a crucial feature for successful crystallisation.
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Affiliation(s)
- Ryan A Brady
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
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17
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Girvan P, Teng X, Brooks NJ, Baldwin GS, Ying L. Redox Kinetics of the Amyloid-Beta-Copper Complex and Its Biological Implications. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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18
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Menny A, Serna M, Boyd CM, Gardner S, Joseph AP, Morgan BP, Topf M, Brooks NJ, Bubeck D. CryoEM reveals how the complement membrane attack complex ruptures lipid bilayers. Nat Commun 2018; 9:5316. [PMID: 30552328 PMCID: PMC6294249 DOI: 10.1038/s41467-018-07653-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/12/2018] [Indexed: 01/08/2023] Open
Abstract
The membrane attack complex (MAC) is one of the immune system's first responders. Complement proteins assemble on target membranes to form pores that lyse pathogens and impact tissue homeostasis of self-cells. How MAC disrupts the membrane barrier remains unclear. Here we use electron cryo-microscopy and flicker spectroscopy to show that MAC interacts with lipid bilayers in two distinct ways. Whereas C6 and C7 associate with the outer leaflet and reduce the energy for membrane bending, C8 and C9 traverse the bilayer increasing membrane rigidity. CryoEM reconstructions reveal plasticity of the MAC pore and demonstrate how C5b6 acts as a platform, directing assembly of a giant β-barrel whose structure is supported by a glycan scaffold. Our work provides a structural basis for understanding how β-pore forming proteins breach the membrane and reveals a mechanism for how MAC kills pathogens and regulates cell functions.
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Affiliation(s)
- Anaïs Menny
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Marina Serna
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
- Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro, 3.28029, Madrid, Spain
| | - Courtney M Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, OX11 0FA, UK
| | - B Paul Morgan
- Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK.
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19
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Trantidou T, Friddin MS, Gan KB, Han L, Bolognesi G, Brooks NJ, Ces O. Mask-Free Laser Lithography for Rapid and Low-Cost Microfluidic Device Fabrication. Anal Chem 2018; 90:13915-13921. [DOI: 10.1021/acs.analchem.8b03169] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Tatiana Trantidou
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
- Institute of Chemical Biology, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
| | - Mark S. Friddin
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
- Institute of Chemical Biology, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
| | - Kin B. Gan
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
| | - Luyao Han
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
| | - Guido Bolognesi
- Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU, U.K
| | - Nicholas J. Brooks
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
- Institute of Chemical Biology, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
| | - Oscar Ces
- Department of Chemistry, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
- Institute of Chemical Biology, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K
- FABRICELL, Imperial College, London SW7 2AZ, U.K
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20
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Brady RA, Brooks NJ, Foderà V, Cicuta P, Di Michele L. Amphiphilic-DNA Platform for the Design of Crystalline Frameworks with Programmable Structure and Functionality. J Am Chem Soc 2018; 140:15384-15392. [PMID: 30351920 DOI: 10.1021/jacs.8b09143] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The reliable preparation of functional, ordered, nanostructured frameworks would be a game changer for many emerging technologies, from energy storage to nanomedicine. Underpinned by the excellent molecular recognition of nucleic acids, along with their facile synthesis and breadth of available functionalizations, DNA nanotechnology is widely acknowledged as a prime route for the rational design of nanostructured materials. Yet, the preparation of crystalline DNA frameworks with programmable structure and functionality remains a challenge. Here we demonstrate the potential of simple amphiphilic DNA motifs, dubbed "C-stars", as a versatile platform for the design of programmable DNA crystals. In contrast to all-DNA materials, in which structure depends on the precise molecular details of individual building blocks, the self-assembly of C-stars is controlled uniquely by their topology and symmetry. Exploiting this robust self-assembly principle, we design a range of topologically identical, but structurally and chemically distinct C-stars that following a one-pot reaction self-assemble into highly porous, functional, crystalline frameworks. Simple design variations allow us to fine-tune the lattice parameter and thus control the partitioning of macromolecules within the frameworks, embed responsive motifs that can induce isothermal disassembly, and include chemical moieties to capture target proteins specifically and reversibly.
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Affiliation(s)
- Ryan A Brady
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry , Imperial College London , London SW7 2AZ , United Kingdom
| | - Vito Foderà
- Department of Pharmacy , University of Copenhagen , Universitetsparken 2 , 2100 Copenhagen , Denmark
| | - Pietro Cicuta
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , United Kingdom
| | - Lorenzo Di Michele
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , United Kingdom
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21
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Girvan P, Teng X, Brooks NJ, Baldwin GS, Ying L. Redox Kinetics of the Amyloid-β-Cu Complex and Its Biological Implications. Biochemistry 2018; 57:6228-6233. [DOI: 10.1021/acs.biochem.8b00133] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Holme M, Rana S, Barriga HMG, Kauscher U, Brooks NJ, Stevens MM. A Robust Liposomal Platform for Direct Colorimetric Detection of Sphingomyelinase Enzyme and Inhibitors. ACS Nano 2018; 12:8197-8207. [PMID: 30080036 PMCID: PMC6117748 DOI: 10.1021/acsnano.8b03308] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/20/2018] [Indexed: 05/23/2023]
Abstract
The enzyme sphingomyelinase (SMase) is an important biomarker for several diseases such as Niemann Pick's, atherosclerosis, multiple sclerosis, and HIV. We present a two-component colorimetric SMase activity assay that is more sensitive and much faster than currently available commercial assays. Herein, SMase-triggered release of cysteine from a sphingomyelin (SM)-based liposome formulation with 60 mol % cholesterol causes gold nanoparticle (AuNP) aggregation, enabling colorimetric detection of SMase activities as low as 0.02 mU/mL, corresponding to 1.4 pM concentration. While the lipid composition offers a stable, nonleaky liposome platform with minimal background signal, high specificity toward SMase avoids cross-reactivity of other similar phospholipases. Notably, use of an SM-based liposome formulation accurately mimics the natural in vivo substrate: the cell membrane. We studied the physical rearrangement process of the lipid membrane during SMase-mediated hydrolysis of SM to ceramide using small- and wide-angle X-ray scattering. A change in lipid phase from a liquid to gel state bilayer with increasing concentration of ceramide accounts for the observed increase in membrane permeability and consequent release of encapsulated cysteine. We further demonstrated the effectiveness of the sensor in colorimetric screening of small-molecule drug candidates, paving the way for the identification of novel SMase inhibitors in minutes. Taken together, the simplicity, speed, sensitivity, and naked-eye readout of this assay offer huge potential in point-of-care diagnostics and high-throughput drug screening.
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Affiliation(s)
- Margaret
N. Holme
- Department
of Materials, Imperial College London, London, SW7 2AZ, U.K.
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London, SW7 2AZ, U.K.
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Subinoy Rana
- Department
of Materials, Imperial College London, London, SW7 2AZ, U.K.
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London, SW7 2AZ, U.K.
- School
of Engineering, Newcastle University, Newcastle upon Tyne, NE1
7RU, U.K.
| | - Hanna M. G. Barriga
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Ulrike Kauscher
- Department
of Materials, Imperial College London, London, SW7 2AZ, U.K.
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London, SW7 2AZ, U.K.
| | | | - Molly M. Stevens
- Department
of Materials, Imperial College London, London, SW7 2AZ, U.K.
- Department of Bioengineering and Institute of Biomedical
Engineering, Imperial College London, London, SW7 2AZ, U.K.
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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23
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Brooker HR, Gyamfi IA, Wieckowska A, Brooks NJ, Mulvihill DP, Geeves MA. A novel live-cell imaging system reveals a reversible hydrostatic pressure impact on cell-cycle progression. J Cell Sci 2018; 131:jcs.212167. [PMID: 29930079 PMCID: PMC6104828 DOI: 10.1242/jcs.212167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 06/04/2018] [Indexed: 11/20/2022] Open
Abstract
Life is dependent upon the ability of a cell to rapidly respond to changes in the environment. Small perturbations in local environments change the ability of molecules to interact and, hence, communicate. Hydrostatic pressure provides a rapid non-invasive, fully reversible method for modulating affinities between molecules both in vivo and in vitro. We have developed a simple fluorescence imaging chamber that allows intracellular protein dynamics and molecular events to be followed at pressures <200 bar in living cells. By using yeast, we investigated the impact of hydrostatic pressure upon cell growth and cell-cycle progression. While 100 bar has no effect upon viability, it induces a delay in chromosome segregation, resulting in the accumulation of long undivided cells that are also bent, consistent with disruption of the cytoskeletons. This delay is independent of stress signalling and induces synchronisation of cell-cycle progression. Equivalent effects were observed in Candida albicans, with pressure inducing a reversible cell-cycle delay and hyphal growth. We present a simple novel non-invasive fluorescence microscopy-based approach to transiently impact molecular dynamics in order to visualise, dissect and study signalling pathways and cellular processes in living cells. Summary: Development of a simple fluorescence imaging chamber allowing observation of intracellular protein dynamics and molecular events in living cells at pressure up to 200 bar.
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Affiliation(s)
- Holly R Brooker
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | - Irene A Gyamfi
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | | | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | | | - Michael A Geeves
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
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24
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Bolognesi G, Friddin MS, Salehi-Reyhani A, Barlow NE, Brooks NJ, Ces O, Elani Y. Sculpting and fusing biomimetic vesicle networks using optical tweezers. Nat Commun 2018; 9:1882. [PMID: 29760422 PMCID: PMC5951844 DOI: 10.1038/s41467-018-04282-w] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 04/10/2018] [Indexed: 11/16/2022] Open
Abstract
Constructing higher-order vesicle assemblies has discipline-spanning potential from responsive soft-matter materials to artificial cell networks in synthetic biology. This potential is ultimately derived from the ability to compartmentalise and order chemical species in space. To unlock such applications, spatial organisation of vesicles in relation to one another must be controlled, and techniques to deliver cargo to compartments developed. Herein, we use optical tweezers to assemble, reconfigure and dismantle networks of cell-sized vesicles that, in different experimental scenarios, we engineer to exhibit several interesting properties. Vesicles are connected through double-bilayer junctions formed via electrostatically controlled adhesion. Chemically distinct vesicles are linked across length scales, from several nanometres to hundreds of micrometres, by axon-like tethers. In the former regime, patterning membranes with proteins and nanoparticles facilitates material exchange between compartments and enables laser-triggered vesicle merging. This allows us to mix and dilute content, and to initiate protein expression by delivering biomolecular reaction components. Assembly of higher-order artificial vesicles can unlock new applications. Here, the authors use optical tweezers to construct user-defined 2D and 3D architectures of chemically distinct vesicles and demonstrate inter-vesicle communication and light-enabled compartment merging.
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Affiliation(s)
- Guido Bolognesi
- Department of Chemical Engineering, Loughborough University, Loughborough, LE11 3TU, UK
| | - Mark S Friddin
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nathan E Barlow
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
| | - Yuval Elani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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25
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Karamdad K, Hindley JW, Bolognesi G, Friddin MS, Law RV, Brooks NJ, Ces O, Elani Y. Engineering thermoresponsive phase separated vesicles formed via emulsion phase transfer as a content-release platform. Chem Sci 2018; 9:4851-4858. [PMID: 29910937 PMCID: PMC5982195 DOI: 10.1039/c7sc04309k] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 04/22/2018] [Indexed: 01/20/2023] Open
Abstract
Elucidation of cholesterol insertion efficiency into phase-transfer vesicles enables the rational design of phase-separated membranes as thermally-responsive platforms for artificial cell construction.
Giant unilamellar vesicles (GUVs) are a well-established tool for the study of membrane biophysics and are increasingly used as artificial cell models and functional units in biotechnology. This trend is driven by the development of emulsion-based generation methods such as Emulsion Phase Transfer (EPT), which facilitates the encapsulation of almost any water-soluble compounds (including biomolecules) regardless of size or charge, is compatible with droplet microfluidics, and allows GUVs with asymmetric bilayers to be assembled. However, the ability to control the composition of membranes formed via EPT remains an open question; this is key as composition gives rise to an array of biophysical phenomena which can be used to add functionality to membranes. Here, we evaluate the use of GUVs constructed via this method as a platform for phase behaviour studies and take advantage of composition-dependent features to engineer thermally-responsive GUVs. For the first time, we generate ternary GUVs (DOPC/DPPC/cholesterol) using EPT, and by compensating for the lower cholesterol incorporation efficiencies, show that these possess the full range of phase behaviour displayed by electroformed GUVs. As a demonstration of the fine control afforded by this approach, we demonstrate release of dye and peptide cargo when ternary GUVs are heated through the immiscibility transition temperature, and show that release temperature can be tuned by changing vesicle composition. We show that GUVs can be individually addressed and release triggered using a laser beam. Our findings validate EPT as a suitable method for generating phase separated vesicles and provide a valuable proof-of-concept for engineering content release functionality into individually addressable vesicles, which could have a host of applications in the development of smart synthetic biosystems.
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Affiliation(s)
- Kaiser Karamdad
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
| | - James W Hindley
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
| | - Guido Bolognesi
- Department of Chemical Engineering , Loughborough University , Loughborough , LE11 3TU , UK
| | - Mark S Friddin
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ;
| | - Robert V Law
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
| | - Nicholas J Brooks
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
| | - Oscar Ces
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK.,FABRICELL , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
| | - Yuval Elani
- Department of Chemistry , Imperial College London , Exhibition Road , London , SW7 2AZ , UK . ; .,Institute of Chemical Biology , Imperial College London , Exhibition Road , London , SW7 2AZ , UK.,FABRICELL , Imperial College London , Exhibition Road , London , SW7 2AZ , UK
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26
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Miller RM, Cabral JT, Robles ESJ, Brooks NJ, Ces O. Crystallisation of sodium dodecyl sulfate–water micellar solutions with structurally similar additives: counterion variation. CrystEngComm 2018. [DOI: 10.1039/c8ce00452h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Kinetic and morphological insight into the crystallisation of micellar SDS–H2O solutions using small quantities of structurally similar additives.
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Affiliation(s)
| | - João T. Cabral
- Department of Chemical Engineering
- Imperial College London
- London SW7 2AZ
- UK
| | - Eric S. J. Robles
- The Procter & Gamble Company
- Newcastle Innovation Centre
- Newcastle-Upon-Tyne NE12 9TS
- UK
| | | | - Oscar Ces
- Department of Chemistry and Institute of Chemical Biology-CDT
- UK
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27
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Barlow NE, Bolognesi G, Haylock S, Flemming AJ, Brooks NJ, Barter LMC, Ces O. Rheological Droplet Interface Bilayers (rheo-DIBs): Probing the Unstirred Water Layer Effect on Membrane Permeability via Spinning Disk Induced Shear Stress. Sci Rep 2017; 7:17551. [PMID: 29242597 PMCID: PMC5730560 DOI: 10.1038/s41598-017-17883-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 12/01/2017] [Indexed: 12/27/2022] Open
Abstract
A new rheological droplet interface bilayer (rheo-DIB) device is presented as a tool to apply shear stress on biological lipid membranes. Despite their exciting potential for affecting high-throughput membrane translocation studies, permeability assays conducted using DIBs have neglected the effect of the unstirred water layer (UWL). However as demonstrated in this study, neglecting this phenomenon can cause significant underestimates in membrane permeability measurements which in turn limits their ability to predict key processes such as drug translocation rates across lipid membranes. With the use of the rheo-DIB chip, the effective bilayer permeability can be modulated by applying shear stress to the droplet interfaces, inducing flow parallel to the DIB membranes. By analysing the relation between the effective membrane permeability and the applied stress, both the intrinsic membrane permeability and UWL thickness can be determined for the first time using this model membrane approach, thereby unlocking the potential of DIBs for undertaking diffusion assays. The results are also validated with numerical simulations.
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Affiliation(s)
- Nathan E Barlow
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Guido Bolognesi
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
| | - Stuart Haylock
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Anthony J Flemming
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Laura M C Barter
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK.
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK.
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Cornell CE, McCarthy NLC, Levental KR, Levental I, Brooks NJ, Keller SL. n-Alcohol Length Governs Shift in L o-L d Mixing Temperatures in Synthetic and Cell-Derived Membranes. Biophys J 2017; 113:1200-1211. [PMID: 28801104 PMCID: PMC5607138 DOI: 10.1016/j.bpj.2017.06.066] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/07/2017] [Accepted: 06/29/2017] [Indexed: 11/30/2022] Open
Abstract
A persistent challenge in membrane biophysics has been to quantitatively predict how membrane physical properties change upon addition of new amphiphiles (e.g., lipids, alcohols, peptides, or proteins) in order to assess whether the changes are large enough to plausibly result in biological ramifications. Because of their roles as general anesthetics, n-alcohols are perhaps the best-studied amphiphiles of this class. When n-alcohols are added to model and cell membranes, changes in membrane parameters tend to be modest. One striking exception is found in the large decrease in liquid-liquid miscibility transition temperatures (Tmix) observed when short-chain n-alcohols are incorporated into giant plasma membrane vesicles (GPMVs). Coexisting liquid-ordered and liquid-disordered phases are observed at temperatures below Tmix in GPMVs as well as in giant unilamellar vesicles (GUVs) composed of ternary mixtures of a lipid with a low melting temperature, a lipid with a high melting temperature, and cholesterol. Here, we find that when GUVs of canonical ternary mixtures are formed in aqueous solutions of short-chain n-alcohols (n ≤ 10), Tmix increases relative to GUVs in water. This shift is in the opposite direction from that reported for cell-derived GPMVs. The increase in Tmix is robust across GUVs of several types of lipids, ratios of lipids, types of short-chain n-alcohols, and concentrations of n-alcohols. However, as chain lengths of n-alcohols increase, nonmonotonic shifts in Tmix are observed. Alcohols with chain lengths of 10–14 carbons decrease Tmix in ternary GUVs of dioleoyl-PC/dipalmitoyl-PC/cholesterol, whereas 16 carbons increase Tmix again. Gray et al. observed a similar influence of the length of n-alcohols on the direction of the shift in Tmix. These results are consistent with a scenario in which the relative partitioning of n-alcohols between liquid-ordered and liquid-disordered phases evolves as the chain length of the n-alcohol increases.
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Affiliation(s)
- Caitlin E Cornell
- University of Washington, Department of Chemistry, Seattle, Washington
| | | | - Kandice R Levental
- Department of Integrative Biology and Pharmacology, McGovern Medical School at The University of Texas Medical Center, Houston, Texas
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, McGovern Medical School at The University of Texas Medical Center, Houston, Texas
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Sarah L Keller
- University of Washington, Department of Chemistry, Seattle, Washington.
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Trantidou T, Friddin M, Elani Y, Brooks NJ, Law RV, Seddon JM, Ces O. Engineering Compartmentalized Biomimetic Micro- and Nanocontainers. ACS Nano 2017; 11:6549-6565. [PMID: 28658575 DOI: 10.1021/acsnano.7b03245] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Compartmentalization of biological content and function is a key architectural feature in biology, where membrane bound micro- and nanocompartments are used for performing a host of highly specialized and tightly regulated biological functions. The benefit of compartmentalization as a design principle is behind its ubiquity in cells and has led to it being a central engineering theme in construction of artificial cell-like systems. In this review, we discuss the attractions of designing compartmentalized membrane-bound constructs and review a range of biomimetic membrane architectures that span length scales, focusing on lipid-based structures but also addressing polymer-based and hybrid approaches. These include nested vesicles, multicompartment vesicles, large-scale vesicle networks, as well as droplet interface bilayers, and double-emulsion multiphase systems (multisomes). We outline key examples of how such structures have been functionalized with biological and synthetic machinery, for example, to manufacture and deliver drugs and metabolic compounds, to replicate intracellular signaling cascades, and to demonstrate collective behaviors as minimal tissue constructs. Particular emphasis is placed on the applications of these architectures and the state-of-the-art microfluidic engineering required to fabricate, functionalize, and precisely assemble them. Finally, we outline the future directions of these technologies and highlight how they could be applied to engineer the next generation of cell models, therapeutic agents, and microreactors, together with the diverse applications in the emerging field of bottom-up synthetic biology.
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Affiliation(s)
- Tatiana Trantidou
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Mark Friddin
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Yuval Elani
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Robert V Law
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - John M Seddon
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Oscar Ces
- Department of Chemistry and ‡Institute of Chemical Biology, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
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Brooks NJ, Castiglione F, Doherty CM, Dolan A, Hill AJ, Hunt PA, Matthews RP, Mauri M, Mele A, Simonutti R, Villar-Garcia IJ, Weber CC, Welton T. Linking the structures, free volumes, and properties of ionic liquid mixtures. Chem Sci 2017; 8:6359-6374. [PMID: 29619199 PMCID: PMC5859882 DOI: 10.1039/c7sc01407d] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/11/2017] [Indexed: 11/21/2022] Open
Abstract
The formation of ionic liquid (IL) mixtures has been proposed as an approach to rationally fine-tune the physicochemical properties of ILs for a variety of applications. However, the effects of forming such mixtures on the resultant properties of the liquids are only beginning to be understood. Towards a more complete understanding of both the thermodynamics of mixing ILs and the effect of mixing these liquids on their structures and physicochemical properties, the spatial arrangement and free volume of IL mixtures containing the common [C4C1im]+ cation and different anions have been systematically explored using small angle X-ray scattering (SAXS), positron annihilation lifetime spectroscopy (PALS) and 129Xe NMR techniques. Anion size has the greatest effect on the spatial arrangement of the ILs and their mixtures in terms of the size of the non-polar domains and inter-ion distances. It was found that differences in coulombic attraction between oppositely charged ions arising from the distribution of charge density amongst the atoms of the anion also significantly influences these inter-ion distances. PALS and 129Xe NMR results pertaining to the free volume of these mixtures were found to strongly correlate with each other despite the vastly different timescales of these techniques. Furthermore, the excess free volumes calculated from each of these measurements were in excellent agreement with the excess volumes of mixing measured for the IL mixtures investigated. The correspondence of these techniques indicates that the static and dynamic free volume of these liquid mixtures are strongly linked. Consequently, fluxional processes such as hydrogen bonding do not significantly contribute to the free volumes of these liquids compared to the spatial arrangement of ions arising from their size, shape and coulombic attraction. Given the relationship between free volume and transport properties such as viscosity and conductivity, these results provide a link between the structures of IL mixtures, the thermodynamics of mixing and their physicochemical properties.
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Affiliation(s)
- Nicholas J Brooks
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Franca Castiglione
- Department of Chemistry , Materials and Chemical Engineering "Giulio Natta" , Politecnico di Milano , Piazza L. da Vinci 32 , 20133 Milan , Italy
| | - Cara M Doherty
- CSIRO Manufacturing , Private Bag 10 , Clayton South , Victoria 3169 , Australia
| | - Andrew Dolan
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Anita J Hill
- CSIRO Manufacturing , Private Bag 10 , Clayton South , Victoria 3169 , Australia
| | - Patricia A Hunt
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Richard P Matthews
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
| | - Michele Mauri
- Dipartimento di Scienza dei Materiali , Università of Milano-Bicocca , via Cozzi 55 , 20125 Milano , Italy
| | - Andrea Mele
- Department of Chemistry , Materials and Chemical Engineering "Giulio Natta" , Politecnico di Milano , Piazza L. da Vinci 32 , 20133 Milan , Italy
| | - Roberto Simonutti
- Dipartimento di Scienza dei Materiali , Università of Milano-Bicocca , via Cozzi 55 , 20125 Milano , Italy
| | - Ignacio J Villar-Garcia
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK . .,Photoactivated Processes Unit , IMDEA Energy Institute , Móstoles Technology Park, Avenida Ramón de la Sagra, 3 , 28935 Móstole , Madrid , Spain
| | - Cameron C Weber
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK . .,School of Science , Auckland University of Technology , Auckland 1010 , New Zealand
| | - Tom Welton
- Department of Chemistry , Imperial College London , London , SW7 2AZ , UK .
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31
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Abstract
Many emerging technologies require materials with well-defined three-dimensional nanoscale architectures. Production of these structures is currently underpinned by self-assembling amphiphilic macromolecules or engineered all-DNA building blocks. Both of these approaches produce restricted ranges of crystal geometries due to synthetic amphiphiles' simple shape and limited specificity, or the technical difficulties in designing space-filling DNA motifs with targeted shapes. We have overcome these limitations with amphiphilic DNA nanostructures, or "C-Stars", that combine the design freedom and facile functionalization of DNA-based materials with robust hydrophobic interactions. C-Stars self-assemble into single crystals exceeding 40 μm in size with lattice parameters exceeding 20 nm.
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Affiliation(s)
- Ryan A Brady
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, U.K
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London , London SW7 2AZ, U.K
| | - Pietro Cicuta
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, U.K
| | - Lorenzo Di Michele
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, U.K
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32
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Barlow NE, Smpokou E, Friddin MS, Macey R, Gould IR, Turnbull C, Flemming AJ, Brooks NJ, Ces O, Barter LMC. Engineering plant membranes using droplet interface bilayers. Biomicrofluidics 2017; 11:024107. [PMID: 28396711 PMCID: PMC5367087 DOI: 10.1063/1.4979045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 03/08/2017] [Indexed: 05/31/2023]
Abstract
Droplet interface bilayers (DIBs) have become widely recognised as a robust platform for constructing model membranes and are emerging as a key technology for the bottom-up assembly of synthetic cell-like and tissue-like structures. DIBs are formed when lipid-monolayer coated water droplets are brought together inside a well of oil, which is excluded from the interface as the DIB forms. The unique features of the system, compared to traditional approaches (e.g., supported lipid bilayers, black lipid membranes, and liposomes), is the ability to engineer multi-layered bilayer networks by connecting multiple droplets together in 3D, and the capability to impart bilayer asymmetry freely within these droplet architectures by supplying droplets with different lipids. Yet despite these achievements, one potential limitation of the technology is that DIBs formed from biologically relevant components have not been well studied. This could limit the reach of the platform to biological systems where bilayer composition and asymmetry are understood to play a key role. Herein, we address this issue by reporting the assembly of asymmetric DIBs designed to replicate the plasma membrane compositions of three different plant species; Arabidopsis thaliana, tobacco, and oats, by engineering vesicles with different amounts of plant phospholipids, sterols and cerebrosides for the first time. We show that vesicles made from our plant lipid formulations are stable and can be used to assemble asymmetric plant DIBs. We verify this using a bilayer permeation assay, from which we extract values for absolute effective bilayer permeation and bilayer stability. Our results confirm that stable DIBs can be assembled from our plant membrane mimics and could lead to new approaches for assembling model systems to study membrane translocation and to screen new agrochemicals in plants.
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Affiliation(s)
| | | | | | | | | | - C Turnbull
- Department of Life Sciences, Imperial College London , Sir Alexander Fleming Building, South Kensington SW7 2AZ, United Kingdom
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33
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de Bruin A, Friddin MS, Elani Y, Brooks NJ, Law R, Seddon JM, Ces O. A transparent 3D printed device for assembling droplet hydrogel bilayers (DHBs). RSC Adv 2017. [DOI: 10.1039/c7ra09406j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We report a new approach for assembling droplet hydrogel bilayers (DHBs) using a transparent 3D printed device.
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Affiliation(s)
| | - Mark S. Friddin
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
| | - Yuval Elani
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
| | - Nicholas J. Brooks
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
| | - Robert V. Law
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
| | - John M. Seddon
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
| | - Oscar Ces
- Department of Chemistry
- Imperial College London
- London
- UK
- Institute of Chemical Biology
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34
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Karamdad K, Law RV, Seddon JM, Brooks NJ, Ces O. Studying the effects of asymmetry on the bending rigidity of lipid membranes formed by microfluidics. Chem Commun (Camb) 2016; 52:5277-80. [PMID: 27001410 DOI: 10.1039/c5cc10307j] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this article we detail a robust high-throughput microfluidic platform capable of fabricating either symmetric or asymmetric giant unilamellar vesicles (GUVs) and characterise the mechanical properties of their membranes.
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Affiliation(s)
- K Karamdad
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - R V Law
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - J M Seddon
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - N J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - O Ces
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
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35
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Abstract
We present a simple method for the multiplexed formation of droplet interface bilayers (DIBs) using a mechanically operated linear acrylic chamber array. To demonstrate the functionality of the chip design, a lipid membrane permeability assay is performed. We show that multiple, symmetric DIBs can be created and separated using this robust low-cost approach.
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Affiliation(s)
- Nathan E Barlow
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
| | - Guido Bolognesi
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
| | - Anthony J Flemming
- Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK.
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
| | - Laura M C Barter
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ, UK.
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36
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Chan CL, Bolognesi G, Bhandarkar A, Friddin MS, Brooks NJ, Seddon JM, Law RV, Barter LMC, Ces O. DROPLAY: laser writing of functional patterns within biological microdroplet displays. Lab Chip 2016; 16:4621-4627. [PMID: 27797387 DOI: 10.1039/c6lc01219a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this study, we introduce an optofluidic method for the rapid construction of large-area cell-sized droplet assemblies with user-defined, re-writable, two-dimensional patterns of functional droplets. Light responsive water-in-oil droplets capable of releasing fluorescent dye molecules upon exposure were generated and self-assembled into arrays inside a microfluidic device. This biological architecture was exploited by the scanning laser of a confocal microscope to 'write' user defined patterns of differentiated (fluorescent) droplets in a network of originally undifferentiated (non-fluorescent) droplets. As a result, long lasting images were produced on a droplet fabric with droplets acting as pixels of a biological monitor, which can be erased and re-written on-demand. Regio-specific light-induced droplet differentiation within a large population of droplets provides a new paradigm for the rapid construction of bio-synthetic systems with potential as tissue mimics and biological display materials.
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Affiliation(s)
- Chi Long Chan
- Department of Chemistry, Imperial College London, London, UK.
| | - Guido Bolognesi
- Department of Chemistry, Imperial College London, London, UK.
| | - Archis Bhandarkar
- Department of Biological Engineering, Massachusetts Institute of Technology, USA
| | - Mark S Friddin
- Department of Chemistry, Imperial College London, London, UK.
| | | | - John M Seddon
- Department of Chemistry, Imperial College London, London, UK.
| | - Robert V Law
- Department of Chemistry, Imperial College London, London, UK.
| | | | - Oscar Ces
- Department of Chemistry, Imperial College London, London, UK.
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37
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Friddin MS, Bolognesi G, Elani Y, Brooks NJ, Law RV, Seddon JM, Neil MAA, Ces O. Optically assembled droplet interface bilayer (OptiDIB) networks from cell-sized microdroplets. Soft Matter 2016; 12:7731-7734. [PMID: 27722718 DOI: 10.1039/c6sm01357k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a new platform technology to systematically assemble droplet interface bilayer (DIB) networks in user-defined 3D architectures from cell-sized droplets using optical tweezers. Our OptiDIB platform is the first demonstration of optical trapping to precisely construct 3D DIB networks, paving the way for the development of a new generation of modular bio-systems.
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Affiliation(s)
- Mark S Friddin
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Guido Bolognesi
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK.
| | - Yuval Elani
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Robert V Law
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - John M Seddon
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Mark A A Neil
- Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK and Photonics Group, Department of Physics, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK. and Institute of Chemical Biology, Imperial College London, Exhibition Road South Kensington, London, SW7 2AZ, UK
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Machta BB, Gray E, Nouri M, McCarthy NLC, Gray EM, Miller AL, Brooks NJ, Veatch SL. Conditions that Stabilize Membrane Domains Also Antagonize n-Alcohol Anesthesia. Biophys J 2016; 111:537-545. [PMID: 27508437 PMCID: PMC4982967 DOI: 10.1016/j.bpj.2016.06.039] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/24/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022] Open
Abstract
Diverse molecules induce general anesthesia with potency strongly correlated with both their hydrophobicity and their effects on certain ion channels. We recently observed that several n-alcohol anesthetics inhibit heterogeneity in plasma-membrane-derived vesicles by lowering the critical temperature (Tc) for phase separation. Here, we exploit conditions that stabilize membrane heterogeneity to further test the correlation between the anesthetic potency of n-alcohols and effects on Tc. First, we show that hexadecanol acts oppositely to n-alcohol anesthetics on membrane mixing and antagonizes ethanol-induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described "intoxication reversers" raise Tc and counter ethanol's effects in vesicles, mimicking the findings of previous electrophysiological and behavioral measurements. Third, we find that elevated hydrostatic pressure, long known to reverse anesthesia, also raises Tc in vesicles with a magnitude that counters the effect of butanol at relevant concentrations and pressures. Taken together, these results demonstrate that ΔTc predicts anesthetic potency for n-alcohols better than hydrophobicity in a range of contexts, supporting a mechanistic role for membrane heterogeneity in general anesthesia.
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Affiliation(s)
| | | | | | - Nicola L C McCarthy
- Department of Chemistry, Imperial College London, South Kensington Campus, London, United Kingdom
| | | | - Ann L Miller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, South Kensington Campus, London, United Kingdom
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39
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Furse S, Brooks NJ, Woscholski R, Gaffney PR, Templer RH. Pressure-dependent inverse bicontinuous cubic phase formation in a phosphatidylinositol 4-phosphate/phosphatidylcholine system. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.cdc.2016.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Brooks NJ, Cates ME, Clegg PS, Lips A, Poon WCK, Seddon JM. Soft interfacial materials: from fundamentals to formulation. Philos Trans A Math Phys Eng Sci 2016; 374:rsta.2015.0135. [PMID: 27298436 PMCID: PMC4920283 DOI: 10.1098/rsta.2015.0135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/25/2016] [Indexed: 05/22/2023]
Abstract
This article is part of the themed issue ‘Soft interfacial materials: from fundamentals to formulation’.
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Affiliation(s)
- N J Brooks
- Department of Chemistry, Imperial College of Science Technology and Medicine, London SW7 2AZ, UK
| | - M E Cates
- DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
| | - P S Clegg
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - A Lips
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - W C K Poon
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - J M Seddon
- Department of Chemistry, Imperial College of Science Technology and Medicine, London SW7 2AZ, UK
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Dent MR, López-Duarte I, Dickson CJ, Geoghegan ND, Cooper JM, Gould IR, Krams R, Bull JA, Brooks NJ, Kuimova MK. Imaging phase separation in model lipid membranes through the use of BODIPY based molecular rotors. Phys Chem Chem Phys 2016; 17:18393-402. [PMID: 26104504 DOI: 10.1039/c5cp01937k] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In order to fully understand the dynamics of processes within biological lipid membranes, it is necessary to possess an intimate knowledge of the physical state and ordering of lipids within the membrane. Here we report the use of three molecular rotors based on meso-substituted boron-dipyrrin (BODIPY) in combination with fluorescence lifetime spectroscopy to investigate the viscosity and phase behaviour of model lipid bilayers. In phase-separated giant unilamellar vesicles, we visualise both liquid-ordered (Lo) and liquid-disordered (Ld) phases using fluorescence lifetime imaging microscopy (FLIM), determining their associated viscosity values, and investigate the effect of composition on the viscosity of these phases. Additionally, we use molecular dynamics simulations to investigate the orientation of the BODIPY probes within the bilayer, as well as using molecular dynamics simulations and fluorescence correlation spectroscopy (FCS) to compare diffusion coefficients with those predicted from the fluorescence lifetimes of the probes.
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Affiliation(s)
- Michael R Dent
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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42
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Zhang Y, Carter JW, Lervik A, Brooks NJ, Seddon JM, Bresme F. Structural organization of sterol molecules in DPPC bilayers: a coarse-grained molecular dynamics investigation. Soft Matter 2016; 12:2108-2117. [PMID: 26758699 DOI: 10.1039/c5sm03051j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the structural organization of cholesterol (CHOL) analogues in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using coarse-grained molecular dynamics simulations and the MARTINI forcefield. Different sterol molecules are modelled by increasing (CHOLL) or decreasing (CHOLS) the diameter of the sterol beads employed in the MARTINI model of CHOL. At high sterol concentrations, (xsterol = 0.5), typical of liquid ordered phases, we find that the sterol arrangement and sterol-DPPC interactions strongly depend on the sterol size. Smaller sterols (CHOLS and CHOL) form linear clusters, while the larger sterols (CHOLL) arrange themselves into disc shaped clusters. By combining structural and dynamical properties we also investigate the So→ Ld transition for the CHOLL and CHOLS sterols. We show that small changes in the sterol size significantly affect the stability of the gel phase with the gel phase stabilized by the small sterols, but destabilized by large sterols. The general dependence of the phase behaviour of the membrane with sterol content is reminiscent of the one observed in naturally occurring membranes. The relevance of our results to understand current cholesterol-bilayer structural models is discussed.
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Affiliation(s)
- Yawen Zhang
- Department of Chemistry, Imperial College London, UK.
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Martin HP, Brooks NJ, Seddon JM, Luckham PF, Terrill NJ, Kowalski AJ, Cabral JT. Microfluidic processing of concentrated surfactant mixtures: online SAXS, microscopy and rheology. Soft Matter 2016; 12:1750-1758. [PMID: 26739043 DOI: 10.1039/c5sm02689j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the effect of microfluidic flow on the microstructure and dynamics of a model surfactant mixture, combining synchrotron Small Angle X-ray Scattering (SAXS), microscopy and rheology. A system comprising a single-chain cationic surfactant, hexadecyl trimethyl ammonium chloride (C16TAC), a short-chain alcohol (1-pentanol) and water was selected for the study due to its flow responsiveness and industrial relevance. Model flow fields, including sequential contraction-expansion (extensional) and rotational flows, were investigated and the fluid response in terms of the lamellar d-spacing, orientation and birefringence was monitored in situ, as well as the recovery processes after cessation of flow. Extensional flows are found to result in considerable d-spacing increase (from approx 59 Å to 65 Å). However, under continuous flow, swelling decreases with increasing flow velocity, eventually approaching the equilibrium values at velocities ≃2 cm s(-1). Through individual constrictions we observe the alignment of lamellae along the flow velocity, accompanied by increasing birefringence, followed by an orientation flip whereby lamellae exit perpendicularly to the flow direction. The resulting microstructures are mapped quantitatively onto the flow field in 2D with 200 μm spatial resolution. Rotational flows alone do not result in appreciable changes in lamellar spacing and flow type and magnitude evidently impact the fluid microstructure under flow, as well as upon relaxation. The findings are correlated with rheological properties measured ex situ to provide a mechanistic understanding of the effect of flow imposed by tubular processing units in the phase behavior and performance of a model surfactant system with ubiquitous applications in personal care and coating industries.
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Affiliation(s)
- Hazel P Martin
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
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44
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McCarthy NLC, Ces O, Law RV, Seddon JM, Brooks NJ. Separation of liquid domains in model membranes induced with high hydrostatic pressure. Chem Commun (Camb) 2016; 51:8675-8. [PMID: 25907808 DOI: 10.1039/c5cc02134k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have imaged the formation of membrane microdomains immediately after their induction using a novel technology platform coupling high hydrostatic pressure to fluorescence microscopy. After formation, the ordered domains are small and highly dynamic. This will enhance links between model lipid assemblies and dynamic processes in cellular membranes.
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Affiliation(s)
- Nicola L C McCarthy
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
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Dent MR, López-Duarte I, Dickson CJ, Chairatana P, Anderson HL, Gould IR, Wylie D, Vyšniauskas A, Brooks NJ, Kuimova MK. Imaging plasma membrane phase behaviour in live cells using a thiophene-based molecular rotor. Chem Commun (Camb) 2016; 52:13269-13272. [DOI: 10.1039/c6cc05954f] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A thiophene-based molecular rotor was used to probe ordering and viscosity within artificial lipid bilayers and live cell plasma membranes.
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Affiliation(s)
| | - Ismael López-Duarte
- Department of Chemistry
- Imperial College London
- London
- UK
- Department of Chemistry
| | - Callum J. Dickson
- Computer-Aided Drug Discovery
- Global Discovery Chemistry
- Novartis Institutes for BioMedical Research
- Cambridge
- USA
| | - Phoom Chairatana
- Department of Chemistry
- Chemistry Research Laboratory
- Oxford University
- Oxford
- UK
| | - Harry L. Anderson
- Department of Chemistry
- Chemistry Research Laboratory
- Oxford University
- Oxford
- UK
| | - Ian R. Gould
- Department of Chemistry
- Imperial College London
- London
- UK
| | - Douglas Wylie
- Department of Chemistry
- Imperial College London
- London
- UK
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Carreras P, Elani Y, Law RV, Brooks NJ, Seddon JM, Ces O. A microfluidic platform for size-dependent generation of droplet interface bilayer networks on rails. Biomicrofluidics 2015; 9:064121. [PMID: 26759638 PMCID: PMC4698115 DOI: 10.1063/1.4938731] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/14/2015] [Indexed: 05/30/2023]
Abstract
Droplet interface bilayer (DIB) networks are emerging as a cornerstone technology for the bottom up construction of cell-like and tissue-like structures and bio-devices. They are an exciting and versatile model-membrane platform, seeing increasing use in the disciplines of synthetic biology, chemical biology, and membrane biophysics. DIBs are formed when lipid-coated water-in-oil droplets are brought together-oil is excluded from the interface, resulting in a bilayer. Perhaps the greatest feature of the DIB platform is the ability to generate bilayer networks by connecting multiple droplets together, which can in turn be used in applications ranging from tissue mimics, multicellular models, and bio-devices. For such applications, the construction and release of DIB networks of defined size and composition on-demand is crucial. We have developed a droplet-based microfluidic method for the generation of different sized DIB networks (300-1500 pl droplets) on-chip. We do this by employing a droplet-on-rails strategy where droplets are guided down designated paths of a chip with the aid of microfabricated grooves or "rails," and droplets of set sizes are selectively directed to specific rails using auxiliary flows. In this way we can uniquely produce parallel bilayer networks of defined sizes. By trapping several droplets in a rail, extended DIB networks containing up to 20 sequential bilayers could be constructed. The trapped DIB arrays can be composed of different lipid types and can be released on-demand and regenerated within seconds. We show that chemical signals can be propagated across the bio-network by transplanting enzymatic reaction cascades for inter-droplet communication.
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Affiliation(s)
- P Carreras
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Y Elani
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - R V Law
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - N J Brooks
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - J M Seddon
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - O Ces
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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47
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Affiliation(s)
- Sowmya Purushothaman
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Pietro Cicuta
- Cavendish
Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K
| | - Oscar Ces
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Nicholas J. Brooks
- Department
of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
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Tyler AII, Barriga HMG, Parsons ES, McCarthy NLC, Ces O, Law RV, Seddon JM, Brooks NJ. Electrostatic swelling of bicontinuous cubic lipid phases. Soft Matter 2015; 11:3279-86. [PMID: 25790335 DOI: 10.1039/c5sm00311c] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Lipid bicontinuous cubic phases have attracted enormous interest as bio-compatible scaffolds for use in a wide range of applications including membrane protein crystallisation, drug delivery and biosensing. One of the major bottlenecks that has hindered exploitation of these structures is an inability to create targeted highly swollen bicontinuous cubic structures with large and tunable pore sizes. In contrast, cubic structures found in vivo have periodicities approaching the micron scale. We have been able to engineer and control highly swollen bicontinuous cubic phases of spacegroup Im3m containing only lipids by (a) increasing the bilayer stiffness by adding cholesterol and (b) inducing electrostatic repulsion across the water channels by addition of anionic lipids to monoolein. By controlling the composition of the ternary mixtures we have been able to achieve lattice parameters up to 470 Å, which is 5 times that observed in pure monoolein and nearly twice the size of any lipidic cubic phase reported previously. These lattice parameters significantly exceed the predicted maximum swelling for bicontinuous cubic lipid structures, which suggest that thermal fluctuations should destroy such phases for lattice parameters larger than 300 Å.
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Affiliation(s)
- Arwen I I Tyler
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
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Barriga HMG, Parsons ES, McCarthy NLC, Ces O, Seddon JM, Law RV, Brooks NJ. Pressure-temperature phase behavior of mixtures of natural sphingomyelin and ceramide extracts. Langmuir 2015; 31:3678-3686. [PMID: 25742392 DOI: 10.1021/la504935c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ceramides are a group of sphingolipids that act as highly important signaling molecules in a variety of cellular processes including differentiation and apoptosis. The predominant in vivo synthetic pathway for ceramide formation is via sphingomyelinase catalyzed hydrolysis of sphingomyelin. The biochemistry of this essential pathway has been studied in detail; however, there is currently a lack of information on the structural behavior of sphingomyelin- and ceramide-rich model membrane systems, which is essential for developing a bottom-up understanding of ceramide signaling and platform formation. We have studied the lyotropic phase behavior of sphingomyelin-ceramide mixtures in excess water as a function of temperature (30-70 °C) and pressure (1-200 MPa) by small- and wide-angle X-ray scattering. At low ceramide concentrations the mixtures form the ripple gel phase (P(β)') below the gel transition temperature for sphingomyelin, and this observation has been confirmed by atomic force microscopy. Formation of the ripple gel phase can also be induced at higher temperatures via the application of hydrostatic pressure. At high ceramide concentration an inverse hexagonal phase (HII) is formed coexisting with a cubic phase.
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Affiliation(s)
- Hanna M G Barriga
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Edward S Parsons
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Nicola L C McCarthy
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Oscar Ces
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - John M Seddon
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Robert V Law
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
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50
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Elani Y, Purushothaman S, Booth PJ, Seddon JM, Brooks NJ, Law RV, Ces O. Measurements of the effect of membrane asymmetry on the mechanical properties of lipid bilayers. Chem Commun (Camb) 2015; 51:6976-9. [PMID: 25797170 DOI: 10.1039/c5cc00712g] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We detail an approach for constructing asymmetric membranes and characterising their mechanical properties, leading to the first measurement of the effect of asymmetry on lipid bilayer mechanics. Our results demonstrate that asymmetry induces a significant increase in rigidity compared to symmetric membranes. Given that all biological membranes are asymmetric our findings have profound implications for the role of this phenomenon in biology.
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Affiliation(s)
- Yuval Elani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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