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Huang Y, Fuller G, Chandran Suja V. Physicochemical characteristics of droplet interface bilayers. Adv Colloid Interface Sci 2022; 304:102666. [PMID: 35429720 DOI: 10.1016/j.cis.2022.102666] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 11/01/2022]
Abstract
Droplet interface bilayer (DIB) is a lipid bilayer formed when two lipid monolayer-coated aqueous droplets are brought in contact within an oil phase. DIBs, especially post functionalization, are a facile model system to study the biophysics of the cell membrane. Continued advances in enhancing and functionalizing DIBs to be a faithful cell membrane mimetic requires a deep understanding of the physicochemical characteristics of droplet interface bilayers. In this review, we provide a comprehensive overview of the current scientific understanding of DIB characteristics starting with the key experimental frameworks for DIB generation, visualization and functionalization. Subsequently we report experimentally measured physical, electrical and transport characteristics of DIBs across physiologically relevant lipids. Advances in simulations and mathematical modelling of DIBs are also discussed, with an emphasis on revealing principles governing the key physicochemical characteristics. Finally, we conclude the review with important outstanding questions in the field.
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2
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Kato S, Garenne D, Noireaux V, Maeda YT. Phase Separation and Protein Partitioning in Compartmentalized Cell-Free Expression Reactions. Biomacromolecules 2021; 22:3451-3459. [PMID: 34258998 DOI: 10.1021/acs.biomac.1c00546] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Liquid-liquid phase separation (LLPS) is important to control a wide range of reactions from gene expression to protein degradation in a cell-sized space. To bring a better understanding of the compatibility of such phase-separated structures with protein synthesis, we study emergent LLPS in a cell-free transcription-translation (TXTL) reaction. When the TXTL reaction composed of many proteins is concentrated, the uniformly mixed state becomes unstable, and membrane-less phases form spontaneously. This LLPS droplet formation is induced when the TXTL reaction is enclosed in water-in-oil emulsion droplets, in which water evaporates from the surface. As the emulsion droplets shrink, smaller LLPS droplets appear inside the emulsion droplets and coalesce into large phase-separated domains that partition the localization of synthesized reporter proteins. The presence of PEG in the TXTL reaction is important not only for versatile cell-free protein synthesis but also for the formation of two large domains capable of protein partitioning. Our results may shed light on the dynamic interplay of LLPS formation and cell-free protein synthesis toward the construction of synthetic organelles.
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Affiliation(s)
- Shuzo Kato
- Department of Physics, Kyushu University, Motooka 744, Fukuoka 819-0395, Japan
| | - David Garenne
- School of Physics and Astronomy, University of Minnesota, 115 Union Street Se, Minneapolis, Minnesota 55455, United States
| | - Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, 115 Union Street Se, Minneapolis, Minnesota 55455, United States
| | - Yusuke T Maeda
- Department of Physics, Kyushu University, Motooka 744, Fukuoka 819-0395, Japan
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3
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Czekalska MA, Jacobs AMJ, Toprakcioglu Z, Kong L, Baumann KN, Gang H, Zubaite G, Ye R, Mu B, Levin A, Huck WTS, Knowles TPJ. One-Step Generation of Multisomes from Lipid-Stabilized Double Emulsions. ACS APPLIED MATERIALS & INTERFACES 2021; 13:6739-6747. [PMID: 33522221 DOI: 10.1021/acsami.0c16019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Multisomes are multicompartmental structures formed by a lipid-stabilized network of aqueous droplets, which are contained by an outer oil phase. These biomimetic structures are emerging as a versatile platform for soft matter and synthetic biology applications. While several methods for producing multisomes have been described, including microfluidic techniques, approaches for generating biocompatible, monodisperse multisomes in a reproducible manner remain challenging to implement due to low throughput and complex device fabrication. Here, we report on a robust method for the dynamically controlled generation of multisomes with controllable sizes and high monodispersity from lipid-based double emulsions. The described microfluidic approach entails the use of three different phases forming a water/oil/water (W/O/W) double emulsion stabilized by lipid layers. We employ a gradient of glycerol concentration between the inner core and outer phase to drive the directed osmosis, allowing the swelling of lamellar lipid layers resulting in the formation of small aqueous daughter droplets at the interface of the inner aqueous core. By adding increasing concentrations of glycerol to the outer aqueous phase and subsequently varying the osmotic gradient, we show that key structural parameters, including the size of the internal droplets, can be specifically controlled. Finally, we show that this approach can be used to generate multisomes encapsulating small-molecule cargo, with potential applications in synthetic biology, drug delivery, and as carriers for active materials in the food and cosmetics industries.
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Affiliation(s)
- Magdalena A Czekalska
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw 01-224, Poland
| | - Anne M J Jacobs
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Zenon Toprakcioglu
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
| | - Lingling Kong
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
- State Key Laboratory of Bioreactor Engineering and Applied Chemistry Institute, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Kevin N Baumann
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
| | - Hongze Gang
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
- State Key Laboratory of Bioreactor Engineering and Applied Chemistry Institute, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Greta Zubaite
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
| | - Ruqiang Ye
- State Key Laboratory of Bioreactor Engineering and Applied Chemistry Institute, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Bozhong Mu
- State Key Laboratory of Bioreactor Engineering and Applied Chemistry Institute, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
- Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai 200237, China
| | - Aviad Levin
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
| | - Wilhelm T S Huck
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, United Kingdom
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, CB2 0HE Cambridge, United Kingdom
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4
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Allen-Benton M, Findlay HE, Booth PJ. Probing membrane protein properties using droplet interface bilayers. Exp Biol Med (Maywood) 2019; 244:709-720. [PMID: 31053046 PMCID: PMC6552395 DOI: 10.1177/1535370219847939] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
IMPACT STATEMENT The paper presents a comprehensive review of integral membrane protein studies utilizing droplet interface bilayers. Droplet interface bilayers are a novel method of constructing artificial lipid bilayers with enhanced stability and physicochemical complexity compared to existing methods. Their unique morphology also suggests applications in the construction of synthetic biological systems and protocells. As well as serving as a guide to in vitro membrane protein functional studies using droplet interface bilayers in the literature to date, a novel in vitro study of a flippase protein in a droplet interface bilayer is presented.
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Affiliation(s)
| | | | - Paula J Booth
- Department of Chemistry, King’s College London,
London SE1 1DB, UK
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5
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Barlow NE, Kusumaatmaja H, Salehi-Reyhani A, Brooks N, Barter LMC, Flemming AJ, Ces O. Measuring bilayer surface energy and curvature in asymmetric droplet interface bilayers. J R Soc Interface 2018; 15:rsif.2018.0610. [PMID: 30464059 PMCID: PMC6283991 DOI: 10.1098/rsif.2018.0610] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/23/2018] [Indexed: 11/12/2022] Open
Abstract
For the past decade, droplet interface bilayers (DIBs) have had an increased prevalence in biomolecular and biophysical literature. However, much of the underlying physics of these platforms is poorly characterized. To further our understanding of these structures, lipid membrane tension on DIB membranes is measured by analysing the equilibrium shape of asymmetric DIBs. To this end, the morphology of DIBs is explored for the first time using confocal laser scanning fluorescence microscopy. The experimental results confirm that, in accordance with theory, the bilayer interface of a volume-asymmetric DIB is curved towards the smaller droplet and a lipid-asymmetric DIB is curved towards the droplet with the higher monolayer surface tension. Moreover, the DIB shape can be exploited to measure complex bilayer surface energies. In this study, the bilayer surface energy of DIBs composed of lipid mixtures of phosphatidylgylcerol (PG) and phosphatidylcholine are shown to increase linearly with PG concentrations up to 25%. The assumption that DIB bilayer area can be geometrically approximated as a spherical cap base is also tested, and it is discovered that the bilayer curvature is negligible for most practical symmetric or asymmetric DIB systems with respect to bilayer area.
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Affiliation(s)
- Nathan E Barlow
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Halim Kusumaatmaja
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK.,FABRICELL, Imperial College London, London SW7 2AZ, UK
| | - Nick Brooks
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Laura M C Barter
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Anthony J Flemming
- Syngenta, Jealott's Hill International Research Centre, Bracknell RG42 6EY, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK .,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK.,FABRICELL, Imperial College London, London SW7 2AZ, UK
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6
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Guiselin B, Law JO, Chakrabarti B, Kusumaatmaja H. Dynamic Morphologies and Stability of Droplet Interface Bilayers. PHYSICAL REVIEW LETTERS 2018; 120:238001. [PMID: 29932701 DOI: 10.1103/physrevlett.120.238001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 01/24/2018] [Indexed: 06/08/2023]
Abstract
We develop a theoretical framework for understanding dynamic morphologies and stability of droplet interface bilayers (DIBs), accounting for lipid kinetics in the monolayers and bilayer, and droplet evaporation due to imbalance between osmotic and Laplace pressures. Our theory quantitatively describes distinct pathways observed in experiments when DIBs become unstable. We find that when the timescale for lipid desorption is slow compared to droplet evaporation, the lipid bilayer will grow and the droplets approach a hemispherical shape. In contrast, when lipid desorption is fast, the bilayer area will shrink and the droplets eventually detach. Our model also suggests there is a critical size below which DIBs can become unstable, which may explain experimental difficulties in miniaturizing the DIB platform.
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Affiliation(s)
- Benjamin Guiselin
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Jack O Law
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Buddhapriya Chakrabarti
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
| | - Halim Kusumaatmaja
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
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7
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Booth MJ, Restrepo Schild V, Downs FG, Bayley H. Functional aqueous droplet networks. MOLECULAR BIOSYSTEMS 2018; 13:1658-1691. [PMID: 28766622 DOI: 10.1039/c7mb00192d] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Droplet interface bilayers (DIBs), comprising individual lipid bilayers between pairs of aqueous droplets in an oil, are proving to be a useful tool for studying membrane proteins. Recently, attention has turned to the elaboration of networks of aqueous droplets, connected through functionalized interface bilayers, with collective properties unachievable in droplet pairs. Small 2D collections of droplets have been formed into soft biodevices, which can act as electronic components, light-sensors and batteries. A substantial breakthrough has been the development of a droplet printer, which can create patterned 3D droplet networks of hundreds to thousands of connected droplets. The 3D networks can change shape, or carry electrical signals through defined pathways, or express proteins in response to patterned illumination. We envisage using functional 3D droplet networks as autonomous synthetic tissues or coupling them with cells to repair or enhance the properties of living tissues.
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Affiliation(s)
- Michael J Booth
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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8
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Venkatesan GA, Taylor GJ, Basham CM, Brady NG, Collier CP, Sarles SA. Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids. BIOMICROFLUIDICS 2018; 12:024101. [PMID: 29576833 PMCID: PMC5832467 DOI: 10.1063/1.5016523] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/13/2018] [Indexed: 05/25/2023]
Abstract
In this article, we report on a new experimental methodology to enable reliable formation of droplet interface bilayer (DIB) model membranes with two types of unsaturated lipids that have proven difficult for creating stable DIBs. Through the implementation of a simple evaporation technique to condition the spontaneously assembled lipid monolayer around each droplet, we increased the success rates of DIB formation for two distinct unsaturated lipids, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), from less than 10% to near 100%. Separately, using a pendant drop tensiometer, we learned that: (a) DOPC and POPC monolayers do not spontaneously assemble into their tightest possible configurations at an oil-water interface, and (b) reducing the surface area of a water droplet coated with a partially packed monolayer leads to a more tightly packed monolayer with an interfacial tension lower than that achieved by spontaneous assembly alone. We also estimated from Langmuir compression isotherms obtained for both lipids that the brief droplet evaporation procedure prior to DIB formation resulted in a 6%-16% reduction in area per lipid for DOPC and POPC, respectively. Finally, the increased success rates of formation for DOPC and POPC DIBs enabled quantitative characterization of unsaturated lipid membrane properties including electrical resistance, rupture potential, and specific capacitance.
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Affiliation(s)
- Guru A Venkatesan
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | | | - Colin M Basham
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Nathan G Brady
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, USA
| | | | - Stephen A Sarles
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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9
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Barlow NE, Bolognesi G, Flemming AJ, Brooks NJ, Barter LMC, Ces O. Multiplexed droplet Interface bilayer formation. LAB ON A CHIP 2016; 16:4653-4657. [PMID: 27831583 DOI: 10.1039/c6lc01011c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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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10
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Nguyen MA, Srijanto B, Collier CP, Retterer ST, Sarles SA. Hydrodynamic trapping for rapid assembly and in situ electrical characterization of droplet interface bilayer arrays. LAB ON A CHIP 2016; 16:3576-3588. [PMID: 27513561 DOI: 10.1039/c6lc00810k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The droplet interface bilayer (DIB) is a modular technique for assembling planar lipid membranes between water droplets in oil. The DIB method thus provides a unique capability for developing digital, droplet-based membrane platforms for rapid membrane characterization, drug screening and ion channel recordings. This paper demonstrates a new, low-volume microfluidic system that automates droplet generation, sorting, and sequential trapping in designated locations to enable the rapid assembly of arrays of DIBs. The channel layout of the device is guided by an equivalent circuit model, which predicts that a serial arrangement of hydrodynamic DIB traps enables sequential droplet placement and minimizes the hydrodynamic pressure developed across filled traps to prevent squeeze-through of trapped droplets. Furthermore, the incorporation of thin-film electrodes fabricated via evaporation metal deposition onto the glass substrate beneath the channels allows for the first time in situ, simultaneous electrical interrogation of multiple DIBs within a sealed device. Combining electrical measurements with imaging enables measurements of membrane capacitance and resistance and bilayer area, and our data show that DIBs formed in different trap locations within the device exhibit similar sizes and transport properties. Simultaneous, single channel recordings of ion channel gating in multiple membranes are obtained when alamethicin peptides are incorporated into the captured droplets, qualifying the thin-film electrodes as a means for measuring stimuli-responsive functions of membrane-bound biomolecules. This novel microfluidic-electrophysiology platform provides a reproducible, high throughput method for performing electrical measurements to study transmembrane proteins and biomembranes in low-volume, droplet-based membranes.
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Affiliation(s)
- Mary-Anne Nguyen
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, USA.
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11
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Venkatesan GA, Sarles SA. Droplet immobilization within a polymeric organogel improves lipid bilayer durability and portability. LAB ON A CHIP 2016; 16:2116-2125. [PMID: 27164314 DOI: 10.1039/c6lc00391e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The droplet interface bilayer (DIB) is a promising technique for assembling lipid membrane-based materials and devices using water droplets in oil, but it has largely been limited to laboratory environments due to its liquid construction. With a vision to transform this lab-based technique into a more-durable embodiment, we investigate the use of a polymer-based organogel to encapsulate DIBs within a more-solid material matrix to improve their handling and portability. Specifically, a temperature-sensitive organogel formed from hexadecane and poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) triblock copolymer is used to replace the liquid solvent that surrounds the lipid-coated droplets to establish a novel liquid-in-gel DIB system. Through specific capacitance measurements and single-channel recordings of the pore forming peptide alamethicin, we verify that the structural and functional membrane properties are retained when DIBs are assembled within SEBS organogel. In addition, we demonstrate that organogel encapsulation offers improved handling of droplets and yields DIBs with a near 3× higher bilayer durability, as quantified by the lateral acceleration required to rupture the membrane, compared to liquid-in-liquid DIBs in oil. This encapsulated DIB system provides a barrier against contamination from the environment and offers a new material platform for supporting multilayered DIB-based devices as well as other digital microfluidic systems that feature water droplets in oil.
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Affiliation(s)
- Guru A Venkatesan
- Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, 1512 Middle Drive, 414 Dougherty Engineering Building, Knoxville, TN 37996, USA.
| | - Stephen A Sarles
- Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, 1512 Middle Drive, 414 Dougherty Engineering Building, Knoxville, TN 37996, USA.
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12
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Venkatesan GA, Lee J, Farimani AB, Heiranian M, Collier CP, Aluru NR, Sarles SA. Adsorption Kinetics Dictate Monolayer Self-Assembly for Both Lipid-In and Lipid-Out Approaches to Droplet Interface Bilayer Formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12883-12893. [PMID: 26556227 DOI: 10.1021/acs.langmuir.5b02293] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The droplet interface bilayer (DIB)--a method to assemble planar lipid bilayer membranes between lipid-coated aqueous droplets--has gained popularity among researchers in many fields. Well-packed lipid monolayer on aqueous droplet-oil interfaces is a prerequisite for successfully assembling DIBs. Such monolayers can be achieved by two different techniques: "lipid-in", in which phospholipids in the form of liposomes are placed in water, and "lipid-out", in which phospholipids are placed in oil as inverse micelles. While both approaches are capable of monolayer assembly needed for bilayer formation, droplet pairs assembled with these two techniques require significantly different incubation periods and exhibit different success rates for bilayer formation. In this study, we combine experimental interfacial tension measurements with molecular dynamics simulations of phospholipids (DPhPC and DOPC) assembled from water and oil origins to understand the differences in kinetics of monolayer formation. With the results from simulations and by using a simplified model to analyze dynamic interfacial tensions, we conclude that, at high lipid concentrations common to DIBs, monolayer formation is simple adsorption controlled for lipid-in technique, whereas it is predominantly adsorption-barrier controlled for the lipid-out technique due to the interaction of interface-bound lipids with lipid structures in the subsurface. The adsorption barrier established in lipid-out technique leads to a prolonged incubation time and lower bilayer formation success rate, proving a good correlation between interfacial tension measurements and bilayer formation. We also clarify that advective flow expedites monolayer formation and improves bilayer formation success rate by disrupting lipid structures, rather than enhancing diffusion, in the subsurface and at the interface for lipid-out technique. Additionally, electrical properties of DIBs formed with varying lipid placement and type are characterized.
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Affiliation(s)
- Guru A Venkatesan
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
| | - Joonho Lee
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Amir Barati Farimani
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Mohammad Heiranian
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Narayana R Aluru
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Stephen A Sarles
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
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13
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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: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [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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14
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Bilayer membrane interactions with nanofabricated scaffolds. Chem Phys Lipids 2015; 192:75-86. [DOI: 10.1016/j.chemphyslip.2015.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/16/2015] [Accepted: 07/25/2015] [Indexed: 01/17/2023]
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15
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Richens JL, Lane JS, Mather ML, O'Shea P. The interactions of squalene, alkanes and other mineral oils with model membranes; effects on membrane heterogeneity and function. J Colloid Interface Sci 2015; 457:225-31. [PMID: 26188729 DOI: 10.1016/j.jcis.2015.06.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/18/2015] [Accepted: 06/18/2015] [Indexed: 10/23/2022]
Abstract
Droplet interface bilayers (DIBs) offer many favourable facets as an artificial membrane system but the influence of any residual oil that remains in the bilayer following preparation is ill-defined. In this study the fluorescent membrane probes di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (Di-8-ANEPPS) and Fluoresceinphosphatidylethanolamine (FPE) were used to help understand the nature of the phospholipid-oil interaction and to examine any structural and functional consequences of such interactions on membrane bilayer properties. Concentration-dependent modifications of the membrane dipole potential were found to occur in phospholipid vesicles exposed to a variety of different oils. Incorporation of oil into the lipid bilayer was shown to have no significant effect on the movement of fatty acids across the lipid bilayer. Changes in membrane heterogeneity were, however, demonstrated with increased microdomain formation being visible in the bilayer following exposure to mineral oil, pentadecane and squalene. As it is important that artificial systems provide an accurate representation of the membrane environment, careful consideration should be taken prior to the application of DIBs in studies of membrane structure and organisation.
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Affiliation(s)
- Joanna L Richens
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, School of Life Sciences, University of Nottingham, University Park, Nottingham, United Kingdom.
| | - Jordan S Lane
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, School of Life Sciences, University of Nottingham, University Park, Nottingham, United Kingdom.
| | - Melissa L Mather
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, School of Life Sciences, University of Nottingham, University Park, Nottingham, United Kingdom.
| | - Paul O'Shea
- Cell Biophysics Group, Institute of Biophysics, Imaging and Optical Science, School of Life Sciences, University of Nottingham, University Park, Nottingham, United Kingdom.
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16
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Mruetusatorn P, Polizos G, Datskos PG, Taylor G, Sarles SA, Boreyko JB, Hayes DG, Collier CP. Control of membrane permeability in air-stable droplet interface bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:4224-4231. [PMID: 25790280 DOI: 10.1021/la504712g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Air-stable droplet interface bilayers (airDIBs) on oil-infused surfaces are versatile model membranes for synthetic biology applications, including biosensing of airborne species. However, airDIBs are subject to evaporation, which can, over time, destabilize them and reduce their useful lifetime compared to traditional DIBs that are fully submerged in oil. Here, we show that the lifetimes of airDIBs can be extended by as much as an order of magnitude by maintaining the temperature just above the dew point. We find that raising the temperature from near the dew point (which was 7 °C at 38.5% relative humidity and 22 °C air temperature) to 20 °C results in the loss of hydrated water molecules from the polar headgroups of the lipid bilayer membrane due to evaporation, resulting in a phase transition with increased disorder. This dehydration transition primarily affects the bilayer electrical resistance by increasing the permeability through an increasingly disordered polar headgroup region of the bilayer. Temperature and relative humidity are conveniently tunable parameters for controlling the stability and composition of airDIB membranes while still allowing for operation in ambient environments.
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Affiliation(s)
| | | | | | | | | | - Jonathan B Boreyko
- #Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
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17
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Damle VG, Tummala A, Chandrashekar S, Kido C, Roopesh A, Sun X, Doudrick K, Chinn J, Lee JR, Burgin TP, Rykaczewski K. "Insensitive" to touch: fabric-supported lubricant-swollen polymeric films for omniphobic personal protective gear. ACS APPLIED MATERIALS & INTERFACES 2015; 7:4224-4232. [PMID: 25633081 DOI: 10.1021/am5085226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The use of personal protective gear made from omniphobic materials that easily shed drops of all sizes could provide enhanced protection from direct exposure to most liquid-phase biological and chemical hazards and facilitate the postexposure decontamination of the gear. In recent literature, lubricated nanostructured fabrics are seen as attractive candidates for personal protective gear due to their omniphobic and self-healing characteristics. However, the ability of these lubricated fabrics to shed low surface tension liquids after physical contact with other objects in the surrounding, which is critical in demanding healthcare and military field operations, has not been investigated. In this work, we investigate the depletion of oil from lubricated fabrics in contact with highly absorbing porous media and the resulting changes in the wetting characteristics of the fabrics by representative low and high surface tension liquids. In particular, we quantify the loss of the lubricant and the dynamic contact angles of water and ethanol on lubricated fabrics upon repeated pressurized contact with highly absorbent cellulose-fiber wipes at different time intervals. We demonstrate that, in contrast to hydrophobic nanoparticle coated microfibers, fabrics encapsulated within a polymer that swells with the lubricant retain the majority of the oil and are capable of repelling high as well as low surface tension liquids even upon multiple contacts with the highly absorbing wipes. The fabric supported lubricant-swollen polymeric films introduced here, therefore, could provide durable and easy to decontaminate protection against hazardous biological and chemical liquids.
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Affiliation(s)
- Viraj G Damle
- School for Engineering of Matter, Transport and Energy, Arizona State University , Tempe, Arizona 85287, United States
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