1
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Nannette C, Baudry J, Chen A, Song Y, Shglabow A, Bremond N, Démoulin D, Walters J, Weitz DA, Bibette J. Thin adhesive oil films lead to anomalously stable mixtures of water in oil. Science 2024; 384:209-213. [PMID: 38603504 DOI: 10.1126/science.adj6728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 03/06/2024] [Indexed: 04/13/2024]
Abstract
Oil and water can only be mixed by dispersing droplets of one fluid in the other. When two droplets approach one another, the thin film that separates them invariably becomes unstable, causing the droplets to coalesce. The only known way to avoid this instability is through addition of a third component, typically a surfactant, which stabilizes the thin film at its equilibrium thickness. We report the observation that a thin fluid film of oil separating two water droplets can lead to an adhesive interaction between the droplets. Moreover, this interaction prevents their coalescence over timescales of several weeks, without the use of any surfactant or solvent.
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Affiliation(s)
- Claire Nannette
- Laboratoire Colloïdes et Matériaux Divisés, CBI, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
- Calyxia, 94380 Bonneuil-sur-Marne, France
| | - Jean Baudry
- Laboratoire Colloïdes et Matériaux Divisés, CBI, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
| | - Anqi Chen
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Yiqiao Song
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Abdulwahed Shglabow
- Laboratoire Colloïdes et Matériaux Divisés, CBI, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
| | - Nicolas Bremond
- Laboratoire Colloïdes et Matériaux Divisés, CBI, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
| | | | | | - David A Weitz
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02215, USA
| | - Jérôme Bibette
- Laboratoire Colloïdes et Matériaux Divisés, CBI, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
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2
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Mashali F, Basham CM, Xu X, Servidio C, Silva PHJ, Stellacci F, Sarles SA. Simultaneous Electrophysiology and Imaging Reveal Changes in Lipid Membrane Thickness and Tension upon Uptake of Amphiphilic Gold Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15031-15045. [PMID: 37812767 DOI: 10.1021/acs.langmuir.3c01973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Amphiphilic gold core nanoparticles (AmNPs) striped with hydrophilic 11-mercapto-1-undecanesulfonate (MUS) and hydrophobic 1-octanethiol (OT) ligands are promising candidates for drug carriers that passively and nondisruptively enter cells. Yet, how they interact with cellular membranes is still only partially understood. Herein, we use electrophysiology and imaging to carefully assess changes in droplet interface bilayer lipid membranes (DIBs) incurred by striped AmNPs added via microinjection. We find that AmNPs spontaneously reduce the steady-state specific capacitance and contact angle of phosphatidylcholine DIBs by amounts dependent on the final NP concentration. These reductions, which are greater for NPs with a higher % OT ligands and membranes containing unsaturated lipids but negligible for MUS-only-coated NPs, reveal that AmNPs passively embed in the interior of the bilayer where they increase membrane thickness and lateral tension through disruption of lipid packing. These results demonstrate the enhanced evaluation of nano-bio interactions possible via electrophysiology and imaging of DIBs.
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Affiliation(s)
- Farzin Mashali
- Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Colin M Basham
- Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Xufeng Xu
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Camilla Servidio
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Paulo H Jacob Silva
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Francesco Stellacci
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Stephen A Sarles
- Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
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3
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Nolle F, Starke LJ, Griffo A, Lienemann M, Jacobs K, Seemann R, Fleury JB, Hub JS, Hähl H. Hydrophobin Bilayer as Water Impermeable Protein Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13790-13800. [PMID: 37726241 PMCID: PMC10552762 DOI: 10.1021/acs.langmuir.3c01006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/24/2023] [Indexed: 09/21/2023]
Abstract
One of the most important properties of membranes is their permeability to water and other small molecules. A targeted change in permeability allows the passage of molecules to be controlled. Vesicles made of membranes with low water permeability are preferable for drug delivery, for example, because they are more stable and maintain the drug concentration inside. This study reports on the very low water permeability of pure protein membranes composed of a bilayer of the amphiphilic protein hydrophobin HFBI. Using a droplet interface bilayer setup, we demonstrate that HFBI bilayers are essentially impermeable to water. HFBI bilayers withstand far larger osmotic pressures than lipid membranes. Only by disturbing the packing of the proteins in the HFBI bilayer is a measurable water permeability induced. To investigate possible molecular mechanisms causing the near-zero permeability, we used all-atom molecular dynamics simulations of various HFBI bilayer models. The simulations suggest that the experimental HFBI bilayer permeability is compatible neither with a lateral honeycomb structure, as found for HFBI monolayers, nor with a residual oil layer within the bilayer or with a disordered lateral packing similar to the packing in lipid bilayers. These results suggest that the low permeabilities of HFBI and lipid bilayers rely on different mechanisms. With their extremely low but adaptable permeability and high stability, HFBI membranes could be used as an osmotic pressure-insensitive barrier in situations where lipid membranes fail such as desalination membranes.
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Affiliation(s)
- Friederike Nolle
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Leonhard J. Starke
- Department
of Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Alessandra Griffo
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
- Max
Planck School, Matter to Life, Jahnstraße 29, 69120 Heidelberg, Germany
- Max
Planck Institute for Medical Research Heidelberg, 69120 Heidelberg, Germany
| | | | - Karin Jacobs
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
- Max
Planck School, Matter to Life, Jahnstraße 29, 69120 Heidelberg, Germany
| | - Ralf Seemann
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Jean-Baptiste Fleury
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Jochen S. Hub
- Department
of Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany
| | - Hendrik Hähl
- Department
of Experimental Physics, Saarland University, D-66123 Saarbrücken, Germany
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4
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Payne EM, Taraji M, Murray BE, Holland-Moritz DA, Moore JC, Haddad PR, Kennedy RT. Evaluation of Analyte Transfer between Microfluidic Droplets by Mass Spectrometry. Anal Chem 2023; 95:4662-4670. [PMID: 36862378 DOI: 10.1021/acs.analchem.2c04985] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Droplet microfluidics enables high-throughput experimentation and screening by encapsulating chemical and biochemical samples in aqueous droplets segmented by an immiscible fluid. In such experiments, it is critical that each droplet remains chemically distinct. A common approach is to use fluorinated oils with surfactants to stabilize droplets. However, some small molecules have been observed to transport between droplets under these conditions. Attempts to study and mitigate this effect have relied on evaluating crosstalk using fluorescent molecules, which inherently limits the analyte scope and conclusions drawn about the mechanism of the effect. In this work, transport of low molecular weight compounds between droplets was investigated using electrospray ionization mass spectrometry (ESI-MS) for measurement. The use of ESI-MS significantly expands the scope of analytes that can be tested. We tested 36 structurally diverse analytes that were found to exhibit crosstalk ranging from negligible to complete transfer using HFE 7500 as the carrier fluid and 008-fluorosurfactant as a surfactant. Using this data set, we developed a predictive tool showing that high log P and log D values correlate with high crosstalk, and high polar surface area and log S correlate with low crosstalk. We then investigated several carrier fluids, surfactants, and flow conditions. It was discovered that transport is strongly dependent on all of these factors and that experimental design and surfactant tailoring can reduce carryover. We present evidence for mixed crosstalk mechanisms including both micellar and oil partitioning transfer. By understanding the driving mechanisms, surfactant and oil compositions can be designed to better reduce chemical transport for screening workflows.
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Affiliation(s)
- Emory M Payne
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
| | - Maryam Taraji
- The Australian Wine Research Institute, Adelaide, South Australia 5064, Australia.,Metabolomics Australia, Adelaide, South Australia 5064, Australia.,School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7005, Australia
| | - Bridget E Murray
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
| | - Daniel A Holland-Moritz
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Jeffrey C Moore
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Paul R Haddad
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7005, Australia
| | - Robert T Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
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5
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Ruszczak A, Jankowski P, Vasantham SK, Scheler O, Garstecki P. Physicochemical Properties Predict Retention of Antibiotics in Water-in-Oil Droplets. Anal Chem 2023; 95:1574-1581. [PMID: 36598882 PMCID: PMC9850403 DOI: 10.1021/acs.analchem.2c04644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Water-in-oil droplet microfluidics promises capacity for high-throughput single-cell antimicrobial susceptibility assays and investigation of drug resistance mechanisms. Every droplet must serve as an isolated environment with a controlled antibiotic concentration in such assays. While technologies for generation, incubation, screening, and sorting droplets mature, predictable retention of active molecules inside droplets remains a major outstanding challenge. Here, we analyzed 36 descriptors of the antibiotic molecules against experimental results on the cross-talk of antibiotics in droplets. We show that partition coefficient and fractional polar surface area are the key physicochemical properties that predict antibiotic retention. We verified the prediction by monitoring growth inhibition by antibiotic-loaded neighboring droplets. Our experiments also demonstrate that transfer of antibiotics between droplets is concentration- and distance-dependent. Our findings immediately apply to designing droplet antibiotic assays and give deeper insight into the retention of small molecules in water-in-oil emulsions.
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Affiliation(s)
- Artur Ruszczak
- Institute
of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Paweł Jankowski
- Institute
of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Shreyas K. Vasantham
- Institute
of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Ott Scheler
- Department
of Chemistry and Biotechnology, Tallinn
University of Technology (TalTech), Akadeemia tee 15, Tallinn 12618, Estonia,
| | - Piotr Garstecki
- Institute
of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland,
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6
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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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7
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Faugeras V, Duclos O, Bazile D, Thiam AR. Impact of Cyclization and Methylation on Peptide Penetration through Droplet Interface Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5682-5691. [PMID: 35452243 DOI: 10.1021/acs.langmuir.2c00269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cell-penetrating peptides enter cells via diverse mechanisms, such as endocytosis, active transport, or direct translocation. For the design of orally delivered cell-penetrating peptides, it is crucial to know the contribution of these different mechanisms. In particular, the ability of a peptide to translocate through a lipid bilayer remains a key parameter for the delivery of cargos. However, existing approaches used to assess translocation often provide discrepant results probably because they have different sensitivities to the distinct translocation mechanisms. Here, we focus on the passive permeation of a range of hydrophobic cyclic peptides inspired by somatostatin, a somatotropin release-inhibiting factor. Using droplet interface bilayers (DIB), we assess the passive membrane permeability of these peptides and study the impact of the peptide cyclization and backbone methylation on translocation rates. Cyclization systematically improved the permeability of the tested peptides while methylation did not. By studying the interaction of the peptides with the DIB interfaces, we found membrane insertion and peptide intrinsic diffusion to be two independent factors of permeability. Compared to the industrial gold standard Caco-2 and parallel artificial membrane permeability assay (PAMPA) models, DIBs provide intermediate membrane permeability values, closer to Caco-2. Even for conditions where Caco-2 and PAMPA are discrepant, the DIB approach also gives results closer to Caco-2. Thereupon, DIBs represent a robust alternative to the PAMPA approach for predicting the permeability of peptides, even if the latter present extremely small structural differences.
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Affiliation(s)
- Vincent Faugeras
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris Cité, F-75005 Paris, France
- Pharmaceutics Development Platform, Sanofi R&D, 94250 Gentilly, France
| | - Olivier Duclos
- Integrated Drug Discovery Platform, Sanofi R&D, 91380 Chilly-Mazarin, France
| | - Didier Bazile
- Pharmaceutics Development Platform, Sanofi R&D, 94250 Gentilly, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris Cité, F-75005 Paris, France
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8
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Guzowski J, Buda RJ, Costantini M, Ćwiklińska M, Garstecki P, Stone HA. From dynamic self-organization to avalanching instabilities in soft-granular threads. SOFT MATTER 2022; 18:1801-1818. [PMID: 35166293 PMCID: PMC8889560 DOI: 10.1039/d1sm01350e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/20/2021] [Indexed: 06/14/2023]
Abstract
We study the dynamics of threads of monodisperse droplets, including droplet chains and multi-chains, in which the droplets are interconnected by capillary bridges of another immiscible liquid phase. This system represents wet soft-granular matter - a class of granular materials in which the grains are soft and wetted by thin fluid films-with other examples including wet granular hydrogels or foams. In contrast to wet granular matter with rigid grains (e.g., wet sand), studied previously, the deformability of the grains raises the number of available metastable states and facilitates rearrangements which allow for reorganization and self-assembly of the system under external drive, e.g., applied via viscous forces. We use a co-flow configuration to generate a variety of unique low-dimensional regular granular patterns, intermediate between 1D and 2D, ranging from linear chains and chains with periodically occurring folds to multi-chains and segmented structures including chains of finite length. In particular, we observe that the partially folded chains self-organize via limit cycle of displacements and rearrangements occurring at a frequency self-adapted to the rate of build-up of compressive strain in the chain induced by the viscous forces. Upon weakening of the capillary arrest of the droplets, we observe spontaneous fluidization of the quasi-solid structures and avalanches of rearrangements. We identify two types of fluidization-induced instabilities and rationalize them in terms of a competition between advection and propagation. While we use aqueous droplets as the grains we demonstrate that the reported mechanisms of adaptive self-assembly apply to other types of soft granular systems including foams and microgels. We discuss possible application of the reported quasi-1D compartmentalized structures in tissue engineering, bioprinting and materials science.
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Affiliation(s)
- J Guzowski
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - R J Buda
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - M Costantini
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - M Ćwiklińska
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - P Garstecki
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - H A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, 08544 NJ, USA
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9
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Schmidt BVKJ. Multicompartment Hydrogels. Macromol Rapid Commun 2022; 43:e2100895. [PMID: 35092101 DOI: 10.1002/marc.202100895] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/27/2022] [Indexed: 11/11/2022]
Abstract
Hydrogels belong to the most promising materials in polymer and materials science at the moment. As they feature soft and tissue-like character as well as high water-content, a broad range of applications are addressed with hydrogels, e.g. tissue engineering and wound dressings but also soft robotics, drug delivery, actuators and catalysis. Ways to tailor hydrogel properties are crosslinking mechanism, hydrogel shape and reinforcement, but new features can be introduced by variation of hydrogel composition as well, e.g. via monomer choice, functionalization or compartmentalization. Especially, multicompartment hydrogels drive progress towards complex and highly functional soft materials. In the present review the latest developments in multicompartment hydrogels are highlighted with a focus on three types of compartments, i.e. micellar/vesicular, droplets or multi-layers including various sub-categories. Furthermore, several morphologies of compartmentalized hydrogels and applications of multicompartment hydrogels will be discussed as well. Finally, an outlook towards future developments of the field will be given. The further development of multicompartment hydrogels is highly relevant for a broad range of applications and will have a significant impact on biomedicine and organic devices. This article is protected by copyright. All rights reserved.
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10
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Makhoul-Mansour MM, Challita EJ, Chaurasia A, Leo DJ, Sukharev S, Freeman EC. A skin-inspired soft material with directional mechanosensation. BIOINSPIRATION & BIOMIMETICS 2021; 16:046014. [PMID: 33848998 DOI: 10.1088/1748-3190/abf746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Lessons about artificial sensor design may be taken from evolutionarily perfected physiological systems. Mechanosensory cells in human skin are exquisitely sensitive to gentle touch and enable us to distinguish objects of different stiffnesses and textures. These cells are embedded in soft epidermal layers of gel-like consistency. Reproducing these mechanosensing capabilities in new soft materials may lead to the development of adaptive mechanosensors which will further enhance the abilities of engineered membrane-based structures with bioinspired sensing strategies. This strategy is explored here using droplet interface bilayers embedded within a thermoreversible organogel. The interface between two lipid-coated aqueous inclusions contained within a soft polymeric matrix forms a lipid bilayer resembling the lipid matrix of cell membranes. These interfaces are functionalized with bacterial mechanosensitive channels (V23T MscL) which convert membrane tension into changes in membrane conductance, mimicking mechanosensitive channel activation in mammalian mechanosensory cells. The distortion of encapsulated adhered droplets by cyclical external forces are first explored using a finite element composite model illustrating the directional propagation of mechanical disturbances imposed by a piston. The model predicts that the orientation of the droplet pair forming the membrane relative to the direction of the compression plays a role in the membrane response. The directional dependence of mechanosensitive channel activation in response to gel compression is confirmed experimentally and shows that purely compressive perturbations normal to the interface invoke different channel activities as compared to shearing displacement along a plane of the membrane. The developed system containing specially positioned pairs of droplets functionalized with bacterial mechanosensitive channels and embedded in a gel creates a skin-inspired soft material with a directional response to mechanical perturbation.
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Affiliation(s)
| | - Elio J Challita
- College of Engineering, University of Georgia, Athens, GA, United States of America
- George W. Woodruff School of Mechanical Engineering, Georgia Tech, Atlanta, GA, United States of America
- School of Chemical & Biomolecular Engineering, Georgia Tech, Atlanta, GA, United States of America
| | | | - Donald J Leo
- College of Engineering, University of Georgia, Athens, GA, United States of America
| | - Sergei Sukharev
- Department of Biology, University of Maryland, College Park, MD, United States of America
| | - Eric C Freeman
- College of Engineering, University of Georgia, Athens, GA, United States of America
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11
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Wood M, Morales M, Miller E, Braziel S, Giancaspro J, Scollan P, Rosario J, Gayapa A, Krmic M, Lee S. Ibuprofen and the Phosphatidylcholine Bilayer: Membrane Water Permeability in the Presence and Absence of Cholesterol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:4468-4480. [PMID: 33826350 DOI: 10.1021/acs.langmuir.0c03638] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The interactions between drugs and cell membranes can modulate the structural and physical properties of membranes. The resultant perturbations of the membrane integrity may affect the conformation of the proteins inserted within the membrane, disturbing the membrane-hosted biological functions. In this study, the droplet interface bilayer (DIB), a model cell membrane, is used to examine the effects of ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), on transbilayer water permeability, which is a fundamental membrane biophysical property. Our results indicate that the presence of neutral ibuprofen (pH 3) increases the water permeability of the lipid membranes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). When cholesterol is present with the DOPC, however, the water permeability is not influenced by addition of ibuprofen, regardless of the cholesterol content in DOPC. Given the fact that cholesterol is generally considered to impact packing in the hydrocarbon chain regions, our findings suggest that a potential competition between opposing effects of ibuprofen molecules and cholesterol on the hydrocarbon core environment of the phospholipid assembly may influence the overall water transport phenomena. Results from confocal Raman microspectroscopy and interfacial tensiometry show that ibuprofen molecules induce substantial structural and dynamic changes in the DOPC lipid bilayer. These results, demonstrating that the presence of ibuprofen increases the water permeability of pure DOPC but not that of DOPC-cholesterol mixtures, provide insight into the differential effect of a representative NSAID on heterogeneous biological membranes, depending upon the local composition and structure, results which will signal increased understanding of the gastrointestinal damage and toxicity induced by these molecules.
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Affiliation(s)
- Megan Wood
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Michael Morales
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Elizabeth Miller
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Samuel Braziel
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Joseph Giancaspro
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Patrick Scollan
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Juan Rosario
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Alyssa Gayapa
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Michael Krmic
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
| | - Sunghee Lee
- Department of Chemistry, Iona College, 715 North Avenue, New Rochelle, New York 10801, United States
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12
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Zhao J, Pan Z, Snyder D, Stone HA, Emrick T. Chemically Triggered Coalescence and Reactivity of Droplet Fibers. J Am Chem Soc 2021; 143:5558-5564. [PMID: 33793226 PMCID: PMC8631051 DOI: 10.1021/jacs.1c02576] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe the role of functional polymer surfactants in the construction and triggered collapse of droplet-based fibers and the use of these macroscopic supracolloidal structures for reagent compartmentalization. Copolymer surfactants containing both zwitterionic and tertiary amine pendent groups were synthesized for stabilization of oil-in-water droplets, in which the self-adherent properties of the selected zwitterions impart interdroplet adherence, while the amine groups provide access to pH-triggered coalescence. Macroscopic fibers, obtained by droplet extrusion, were prepared with reagents embedded in spatially distinct components of the fibers. Upon acidification of the continuous aqueous phase, protonation of the polymer surfactants increases their hydrophilicity and causes rapid fiber disruption and collapse. Cross-linked versions of these supracolloidal fibers were stable upon acidification and appeared to direct interdroplet passage of encapsulants along the fiber length. Overall, these functional, responsive emulsions provide a strategy to impart on-demand chemical reactivity to soft materials structures that benefits from the interfacial chemistry of the system.
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Affiliation(s)
- Jing Zhao
- Polymer Science & Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Zehao Pan
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Deborah Snyder
- Polymer Science & Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Todd Emrick
- Polymer Science & Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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13
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Makhoul-Mansour MM, Freeman EC. Droplet-Based Membranous Soft Materials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3231-3247. [PMID: 33686860 DOI: 10.1021/acs.langmuir.0c03289] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Inspired by the structure and functionality of natural cellular tissues, droplet interface bilayer (DIB)-based materials strategically combine model membrane assembly techniques and droplet microfluidics. These structures have shown promising results in applications ranging from biological computing to chemical microrobots. This Feature Article briefly explores recent advances in the areas of construction, manipulation, and functionalization of DIB networks; discusses their unique mechanics; and focuses on the contributions of our lab in the advancement of this platform. We also reflect on some of the limitations facing DIB-based materials and how they might be addressed, highlighting promising applications made possible through the refinement of the material concept.
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Affiliation(s)
- Michelle M Makhoul-Mansour
- School of Environmental, Civil, Agricultural and Mechanical Engineering, University of Georgia, Athens, Georgia 30602, United States
| | - Eric C Freeman
- School of Environmental, Civil, Agricultural and Mechanical Engineering, University of Georgia, Athens, Georgia 30602, United States
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14
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Huang Y, Chandran Suja V, Tajuelo J, Fuller GG. Surface energy and separation mechanics of droplet interface phospholipid bilayers. J R Soc Interface 2021; 18:20200860. [PMID: 33530859 PMCID: PMC8086854 DOI: 10.1098/rsif.2020.0860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 01/12/2021] [Indexed: 01/06/2023] Open
Abstract
Droplet interface bilayers are a convenient model system to study the physio-chemical properties of phospholipid bilayers, the major component of the cell membrane. The mechanical response of these bilayers to various external mechanical stimuli is an active area of research because of its implications for cellular viability and the development of artificial cells. In this article, we characterize the separation mechanics of droplet interface bilayers under step strain using a combination of experiments and numerical modelling. Initially, we show that the bilayer surface energy can be obtained using principles of energy conservation. Subsequently, we subject the system to a step strain by separating the drops in a step-wise manner, and track the evolution of the bilayer contact angle and radius. The relaxation time of the bilayer contact angle and radius along with the decay magnitude of the bilayer radius were observed to increase with each separation step. By analysing the forces acting on the bilayer and the rate of separation, we show that the bilayer separates primarily through the peeling process with the dominant resistance to separation coming from viscous dissipation associated with corner flows. Finally, we explain the intrinsic features of the observed bilayer separation by means of a mathematical model comprising the Young-Laplace equation and an evolution equation. We believe that the reported experimental and numerical results extend the scientific understanding of lipid bilayer mechanics, and that the developed experimental and numerical tools offer a convenient platform to study the mechanics of other types of bilayers.
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Affiliation(s)
- Y. Huang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - V. Chandran Suja
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - J. Tajuelo
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Departamento de Física Interdisciplinar, Universidad Nacional de Eduación a Distancia UNED, Madrid 28040, Spain
| | - G. G. Fuller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
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15
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Wu Q, van der Gucht J, Kodger TE. Syneresis of Colloidal Gels: Endogenous Stress and Interfacial Mobility Drive Compaction. PHYSICAL REVIEW LETTERS 2020; 125:208004. [PMID: 33258652 DOI: 10.1103/physrevlett.125.208004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/21/2020] [Indexed: 06/12/2023]
Abstract
Colloidal gels may experience syneresis, an increase in volume fraction through expulsion of the continuous phase. This poroelastic process occurs when adhesion to the container is weak compared to endogenous stresses which develop during gelation. In this work, we measure the magnitude of syneresis, ΔV/V_{0}, for gels composed of solid, rubber, and liquid particles. Surprisingly, despite a constant thermoresponsive interparticle potential, gels composed of liquid and elastic particles synerese to a far greater extent. We conclude that this magnitude difference arises from contrasting modes of stress relaxation within the colloidal gel during syneresis either by bending or stretching of interparticle bonds.
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Affiliation(s)
- Q Wu
- Physical Chemistry and Soft Matter, Wageningen University & Research, Wageningen, Gelderland, 6708 WE, The Netherlands
| | - J van der Gucht
- Physical Chemistry and Soft Matter, Wageningen University & Research, Wageningen, Gelderland, 6708 WE, The Netherlands
| | - T E Kodger
- Physical Chemistry and Soft Matter, Wageningen University & Research, Wageningen, Gelderland, 6708 WE, The Netherlands
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16
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Gehan P, Kulifaj S, Soule P, Bodin J, Amoura M, Walrant A, Sagan S, Thiam A, Ngo K, Vivier V, Cribier S, Rodriguez N. Penetratin translocation mechanism through asymmetric droplet interface bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183415. [DOI: 10.1016/j.bbamem.2020.183415] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/06/2020] [Accepted: 07/11/2020] [Indexed: 01/15/2023]
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17
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Tawfik H, Puza S, Seemann R, Fleury JB. Transport Properties of Gramicidin A Ion Channel in a Free-Standing Lipid Bilayer Filled With Oil Inclusions. Front Cell Dev Biol 2020; 8:531229. [PMID: 33015051 PMCID: PMC7498540 DOI: 10.3389/fcell.2020.531229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 08/14/2020] [Indexed: 11/13/2022] Open
Abstract
Ion channels are key proteins in mammalian cell membranes. They have a central role in the physiology of excitable cells such as neurons, muscle, and heart cells. They also play a crucial role in kidney physiology. The gramicidin ion channel is one of the most studied ion channels, in particular it was intensively employed to investigate the lipid–protein interactions in model cell membranes. For example, even though the sequence of gramicidin is extremely hydrophobic, its motion is impaired in membrane bilayer, i.e., it does not rapidly flip to the other membrane leaflet, and low channel activity were observed when gramicidin is added asymmetrically to only one leaflet of a model cell membrane. In this article, we study the transport properties of gramicidin channel in a heterogeneous model membrane. Using microfluidics, we are forming freestanding bilayers as model cell membranes including heterogeneous domains that are created by oil inclusions. The presence of oil inclusions is then demonstrated by measuring the bilayer capacity via a patch-clamp amplifier and fluorescent confocal inspection. Based on electrophysiological and optical measurements Gramicidin A (gA) ion channels are dispersed into the buffer phases on both side of the formed lipid bilayer and insert spontaneously into the bilayer upon formation. The presence of functional Gramicidin A is then demonstrated by measuring conductivity signals. Based on electrophysiological and optical measurements, we explore the consequence of the presence of these oil inclusions on the functionality of incorporated gA ion channels. For low oil concentration, we measure a decrease of gA transport properties due to the reduction of the bilayer tension. For large oil concentration, we measure a saturation of gA transport properties due to an increase of the bilayer thickness.
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Affiliation(s)
- Harvey Tawfik
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Sevde Puza
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Ralf Seemann
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
| | - Jean-Baptiste Fleury
- Experimental Physics and Center for Biophysics, Universität des Saarlandes, Saarbrücken, Germany
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18
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Foley S, Miller E, Braziel S, Lee S. Molecular organization in mixed SOPC and SDPC model membranes: Water permeability studies of polyunsaturated lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183365. [DOI: 10.1016/j.bbamem.2020.183365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 05/18/2020] [Accepted: 05/20/2020] [Indexed: 12/16/2022]
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19
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Triacylglycerols sequester monotopic membrane proteins to lipid droplets. Nat Commun 2020; 11:3944. [PMID: 32769983 PMCID: PMC7414839 DOI: 10.1038/s41467-020-17585-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/08/2020] [Indexed: 01/05/2023] Open
Abstract
Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into organelles called lipid droplets (LDs). LDs are covered by a single phospholipid monolayer contiguous with the ER bilayer. This connection is used by several monotopic integral membrane proteins, with hydrophobic membrane association domains (HDs), to diffuse between the organelles. However, how proteins partition between ER and LDs is not understood. Here, we employed synthetic model systems and found that HD-containing proteins strongly prefer monolayers and returning to the bilayer is unfavorable. This preference for monolayers is due to a higher affinity of HDs for TG over membrane phospholipids. Protein distribution is regulated by PC/PE ratio via alterations in monolayer packing and HD-TG interaction. Thus, HD-containing proteins appear to non-specifically accumulate to the LD surface. In cells, protein editing mechanisms at the ER membrane would be necessary to prevent unspecific relocation of HD-containing proteins to LDs. Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into monolayer lipid droplets (LDs), but how proteins partition between ER and LDs is poorly understood. Here authors use synthetic model systems and find that proteins containing hydrophobic membrane association domains strongly prefer monolayers and that returning to the bilayer is unfavorable.
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20
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Faugeras V, Duclos O, Bazile D, Thiam AR. Membrane determinants for the passive translocation of analytes through droplet interface bilayers. SOFT MATTER 2020; 16:5970-5980. [PMID: 32543614 DOI: 10.1039/d0sm00667j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding how small molecules cross cell membranes is crucial to pharmaceutics. Several methods have been developed to evaluate such a process, but they need improvement since many false-positive candidates are often selected. Robust tools enabling rapid and reproducible screening can increase confidence on hits, and artificial membranes based on droplet interface bilayers (DIBs) offer this possibility. DIBs consist in the adhesion of two phospholipid-covered water-in-oil droplets which reproduce a bilayer. By having donor and acceptor droplets, the permeability of an analyte can be studied. However, the relevance of this system relies on the comprehension of how well the physical chemistry of the produced bilayer recapitulates the behavior of cell membranes. This information is missing, and we address it here. Taking small fluorophores as model analytes, we studied their permeation through DIBs made of a wide range of phospholipids. We found that both the phospholipid acyl chain and polar head affect permeability. Overall, these parameters impact the phospholipid shape and thereupon the membrane lateral pressure, which is a major factor modulating with permeability in our system. These results depend on the nature of the chosen oil. We thereupon identified relevant physical chemistry conditions that best mimic the compactness and subsequent permeability of biological membranes.
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Affiliation(s)
- Vincent Faugeras
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Paris, France.
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21
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Fleury JB. Enhanced water permeability across a physiological droplet interface bilayer doped with fullerenes. RSC Adv 2020; 10:19686-19692. [PMID: 35515425 PMCID: PMC9054109 DOI: 10.1039/d0ra01413c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/23/2020] [Indexed: 11/21/2022] Open
Abstract
We measure the water permeability across a physiological lipid bilayer produced by the droplet interface bilayer (DiB) technique. This lipid bilayer can be considered as physiologically relevant because it presents a lipidic composition close to human cell membranes. The measured water permeability coefficients across this lipid bilayer are reported as a function of the cholesterol concentration. It is found that the water permeability coefficients decreased with increasing cholesterol concentration, in agreement with the existing literature. And, consistently, the extracted corresponding activation energies increase with increasing cholesterol concentration in the lipid bilayer. Hence having demonstrated the robustness of the experimental system, we extend this study by exploring the influence of fullerenes on the water permeability of a physiological lipid bilayer. Interestingly, we observe a significant increase of the measured water permeability coefficients across this lipid bilayer for large fullerenes concentration. This enhanced permeability might be related to the conductive properties of fullerenes. We measure the water permeability across a physiological lipid bilayer produced by the droplet interface bilayer technique.![]()
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Affiliation(s)
- Jean-Baptiste Fleury
- Experimental Physics and Center for Biophysics, Saarland University D-66123 Saarbruecken Germany +49 681 302 70121
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22
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Alcinesio A, Meacock OJ, Allan RG, Monico C, Restrepo Schild V, Cazimoglu I, Cornall MT, Krishna Kumar R, Bayley H. Controlled packing and single-droplet resolution of 3D-printed functional synthetic tissues. Nat Commun 2020; 11:2105. [PMID: 32355158 PMCID: PMC7192927 DOI: 10.1038/s41467-020-15953-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 04/02/2020] [Indexed: 11/25/2022] Open
Abstract
3D-printing networks of droplets connected by interface bilayers are a powerful platform to build synthetic tissues in which functionality relies on precisely ordered structures. However, the structural precision and consistency in assembling these structures is currently limited, which restricts intricate designs and the complexity of functions performed by synthetic tissues. Here, we report that the equilibrium contact angle (θDIB) between a pair of droplets is a key parameter that dictates the tessellation and precise positioning of hundreds of picolitre-sized droplets within 3D-printed, multi-layer networks. When θDIB approximates the geometrically-derived critical angle (θc) of 35.3°, the resulting networks of droplets arrange in regular hexagonal close-packed (hcp) lattices with the least fraction of defects. With this improved control over droplet packing, we can 3D-print functional synthetic tissues with single-droplet-wide conductive pathways. Our new insights into 3D droplet packing permit the fabrication of complex synthetic tissues, where precisely positioned compartments perform coordinated tasks.
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Affiliation(s)
- Alessandro Alcinesio
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Oliver J Meacock
- Department of Zoology, University of Oxford, Zoology Research & Administration Building, 11a Mansfield Road, Oxford, OX1 3SZ, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK
| | - Rebecca G Allan
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
- Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada
| | - Carina Monico
- Micron Advanced Bioimaging Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Vanessa Restrepo Schild
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Idil Cazimoglu
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Matthew T Cornall
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Ravinash Krishna Kumar
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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23
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Dendronized fluorosurfactant for highly stable water-in-fluorinated oil emulsions with minimal inter-droplet transfer of small molecules. Nat Commun 2019; 10:4546. [PMID: 31586046 PMCID: PMC6778136 DOI: 10.1038/s41467-019-12462-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 08/28/2019] [Indexed: 02/03/2023] Open
Abstract
Fluorosurfactant-stabilized microfluidic droplets are widely used as pico- to nanoliter volume reactors in chemistry and biology. However, current surfactants cannot completely prevent inter-droplet transfer of small organic molecules encapsulated or produced inside the droplets. In addition, the microdroplets typically coalesce at temperatures higher than 80 °C. Therefore, the use of droplet-based platforms for ultrahigh-throughput combination drug screening and polymerase chain reaction (PCR)-based rare mutation detection has been limited. Here, we provide insights into designing surfactants that form robust microdroplets with improved stability and resistance to inter-droplet transfer. We used a panel of dendritic oligo-glycerol-based surfactants to demonstrate that a high degree of inter- and intramolecular hydrogen bonding, as well as the dendritic architecture, contribute to high droplet stability in PCR thermal cycling and minimize inter-droplet transfer of the water-soluble fluorescent dye sodium fluorescein salt and the drug doxycycline. Microdroplets are used as chemical and biological reactors; however, stability and inter-droplet transfer are major issues. Here, the authors report on the development of dendritic glycerol-based surfactants for the creation of stable microdroplets and demonstrate application for PCR, minimal emulsion, and cell encapsulation.
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24
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Chen J, Vestergaard M, Shen J, Solem C, Dufva M, Jensen PR. Droplet-based microfluidics as a future tool for strain improvement in lactic acid bacteria. FEMS Microbiol Lett 2019. [DOI: 10.1093/femsle/fny258s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
ABSTRACTStrain development is frequently used to improve the performance and functionality of industrially important microbes. As traditional mutagenesis screen is especially utilized by the food industry to improve strains used in food fermentation, high-throughput and cost-effective screening tools are important in mutant selection. The emerging droplet-based microfluidics technology miniaturizes the volume for cell cultivation and phenotype interrogation down to the picoliter scales, which facilitates screening of microbes for improved phenotypical properties tremendously. In this mini review, we present recent application of the droplet-based microfluidics in microbial strain improvement with a focus on its potential use in the screening of lactic acid bacteria.
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Affiliation(s)
- Jun Chen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Mike Vestergaard
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Jing Shen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Christian Solem
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Martin Dufva
- Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Peter Ruhdal Jensen
- National Food Institute, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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25
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Lee Y, Choi SQ. Quantitative analysis for lipophilic drug transport through a model lipid membrane with membrane retention. Eur J Pharm Sci 2019; 134:176-184. [DOI: 10.1016/j.ejps.2019.04.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/17/2019] [Accepted: 04/17/2019] [Indexed: 12/27/2022]
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26
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Arriaga LR, Huang Y, Kim SH, Aragones JL, Ziblat R, Koehler SA, Weitz DA. Single-step assembly of asymmetric vesicles. LAB ON A CHIP 2019; 19:749-756. [PMID: 30672918 DOI: 10.1039/c8lc00882e] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Asymmetric vesicles are membranes in which amphiphiles are asymmetrically distributed between each membrane leaflet. This asymmetry dictates chemical and physical properties of these vesicles, enabling their use as more realistic models of biological cell membranes, which also are asymmetric, and improves their potential for drug delivery and cosmetic applications. However, their fabrication is difficult as the self-assembly of amphiphiles always leads to symmetric vesicles. Here, we report the use of water-in-oil-in-oil-in-water triple emulsion drops to direct the assembly of the two leaflets to form asymmetric vesicles. Different compositions of amphiphiles are dissolved in each of the two oil shells of the triple emulsion; the amphiphiles diffuse to the interfaces and adsorb differentially at each of the two oil/water interfaces of the triple emulsion. These middle oil phases dewet from the innermost water cores of the triple emulsion drops, leading to the formation of membranes with degrees of asymmetry up to 70%. The triple emulsion drops are fabricated using capillary microfluidics, enabling production of highly monodisperse drops at rates as high as 300 Hz. Vesicles produced by this method can very efficiently encapsulate many different ingredients; this further enhances the utility of asymmetric vesicles as artificial cells, bioreactors and delivery vehicles.
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Affiliation(s)
- Laura R Arriaga
- School of Engineering and Applied Science and Department of Physics, Harvard University, 02138 Cambridge, MA, USA.
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27
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Pinon L, Montel L, Mesdjian O, Bernard M, Michel A, Ménager C, Fattaccioli J. Kinetically Enhanced Fabrication of Homogeneous Biomimetic and Functional Emulsion Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15319-15326. [PMID: 30507132 DOI: 10.1021/acs.langmuir.8b02721] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Characterized by a fluid and deformable interface, ligand-functionalized emulsion droplets are used as model probes to address biophysical, biological, and developmental questions. Functionalization protocols usually rely on the use of headgroup-modified phospholipids that are dissolved in the oil phase prior to emulsification, leading to a broad range of surface densities within a given droplet population. With the aim to coat particles homogeneously with biologically relevant lipids and proteins (streptavidin, immunoglobulins, etc.), we developed a reliable surface decoration protocol based on the use of polar cosolvents to dissolve the lipids in the aqueous phase after the droplet production. We show that the surface density of the lipids at the interface has a narrow normal distribution for droplets having the same size. We performed titration isotherms for lipids and biologically relevant proteins on these drops. Then, we studied the influence of the presence of surfactants in the medium on lipid insertion and compared the results for a range of polar cosolvents of increasing polarity. To assess both the generality and the biocompatibility of the method, we show that we can produce more sophisticated, monodisperse functional magnetic emulsions with a very high surface homogeneity. Using an oil denser than the surrounding culture medium, we show that IgG-coated droplets can be used as probes for phagocytosis experiments.
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Affiliation(s)
- L Pinon
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS , 75005 Paris , France
- Institut Curie, PSL University, INSERM U932 , 26 rue d'Ulm , 75248 Paris Cedex 05 , France
| | - L Montel
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS , 75005 Paris , France
| | - O Mesdjian
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS , 75005 Paris , France
| | - M Bernard
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS , 75005 Paris , France
- UMR 144, Institut Curie , 12 rue Lhomond , 75005 Paris , France
| | - A Michel
- Sorbonne Université, CNRS, Laboratoire Physicochimie des Électrolytes et Nanosystèmes Interfaciaux PHENIX , 4 place Jussieu , F-75005 Paris , France
| | - C Ménager
- Sorbonne Université, CNRS, Laboratoire Physicochimie des Électrolytes et Nanosystèmes Interfaciaux PHENIX , 4 place Jussieu , F-75005 Paris , France
| | - J Fattaccioli
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS , 75005 Paris , France
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28
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Dupin A, Simmel FC. Signalling and differentiation in emulsion-based multi-compartmentalized in vitro gene circuits. Nat Chem 2018; 11:32-39. [PMID: 30478365 PMCID: PMC6298583 DOI: 10.1038/s41557-018-0174-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 10/19/2018] [Indexed: 01/18/2023]
Abstract
Multicellularity enables the growth of complex life forms as it allows for specialization of cell types, differentiation, and large scale spatial organization. In a similar way, modular construction of synthetic multicellular systems will lead to dynamic biomimetic materials that can respond to their environment in complex ways. In order to achieve this goal, artificial cellular communication and developmental programs still have to be established. Here, we create geometrically controlled spatial arrangements of emulsion-based artificial cellular compartments containing synthetic in vitro gene circuitry, separated by lipid bilayer membranes. We quantitatively determine the membrane pore-dependent response of the circuits to artificial morphogen gradients, which are established via diffusion from dedicated organizer cells. Utilizing different types of feed-forward and feedback in vitro gene circuits, we then implement artificial signaling and differentiation processes, demonstrating the potential for the realization of complex spatiotemporal dynamics in artificial multicellular systems.
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Affiliation(s)
- Aurore Dupin
- Physics Department E14 and ZNN, Technical University Munich, Garching, Germany
| | - Friedrich C Simmel
- Physics Department E14 and ZNN, Technical University Munich, Garching, Germany.
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29
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Lee S. Good to the Last Drop: Interfacial Droplet Chemistry, from Crystals to Biological Membranes. Acc Chem Res 2018; 51:2524-2534. [PMID: 30247878 DOI: 10.1021/acs.accounts.8b00277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The study of the liquid-liquid interface has a long and storied history yet still holds important implications for science and technology. Although deep examination of this buried interface poses challenges, recent progress in experimental and theoretical methodology has allowed for advanced understanding of the molecular bases of such interfaces. This Account will focus on the behavior of surfaces of aqueous microdroplets immersed in an immiscible phase, exhibiting physicochemical behavior dependent on the presence of interfacial self-assembled structures. Amphiphiles spontaneously form self-assembled nanostructures at the liquid interface, creating a soft liquid surface for the aqueous microdroplet that can modulate its behavior. A prominent characteristic of a micron-sized droplet is its elevated surface area/volume ratio, a feature that presents opportunities for investigating the role of the interface in aspects of droplet chemistry. In two notable examples, a surfactant self-assembly can act as a template for crystal nucleation of droplet solutes at the monolayer level, while at the level of a bilayer, formed when two monolayer-covered droplets are made to adhere, the apposition of monolayers bears remarkable similarities to cell membranes. Each type of system provides arbitrary control of important factors, both for studying crystallization nucleation and for modeling semipermeable lipid membranes at an interdroplet contact zone, the droplet interface bilayer (DIB). The droplet bilayer allows for direct observation of species transport across an unsupported bilayer and versatile parameter control to expore the effects of membrane lipid structure on bilayer transport. It is demonstrated that molecular shape for monoglycerides and phospholipids influences the surface characteristics of monolayers and bilayers. Additionally, subtle interfacial interactions between aqueous contents (ions, solutes) and the monolayer/bilayer are shown to have a marked influence on lipid packing and permeability. It is anticipated that this successful demonstration of surface engineering at the micron scale will deliver cogent insights into many biologically relevant phenomena, such as membrane transport and biomineralization.
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Affiliation(s)
- Sunghee Lee
- Department of Chemistry, Iona College, New Rochelle, New York 10801, United States
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30
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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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31
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Demulsifier assisted film thinning and coalescence in crude oil emulsions under DC electric fields. Chem Eng Res Des 2018. [DOI: 10.1016/j.cherd.2018.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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32
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Challita EJ, Makhoul-Mansour MM, Freeman EC. Reconfiguring droplet interface bilayer networks through sacrificial membranes. BIOMICROFLUIDICS 2018; 12:034112. [PMID: 30867859 PMCID: PMC6404924 DOI: 10.1063/1.5023386] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/22/2018] [Indexed: 05/19/2023]
Abstract
The droplet interface bilayer platform allows for the fabrication of stimuli-responsive microfluidic materials, using phospholipids as an organic surfactant in water-in-oil mixtures. In this approach, lipid-coated droplets are adhered together in arranged networks, forming lipid bilayer membranes with embedded transporters and establishing selective exchange pathways between neighboring aqueous subcompartments. The resulting material is a biologically inspired droplet-based material that exhibits emergent properties wherein different droplets accomplish different functions, similar to multicellular organisms. These networks have been successfully applied towards biomolecular sensing and energy harvesting applications. However, unlike their source of inspiration, these droplet structures are often static. This limitation not only renders the networks unable to adapt or modify their structure and function after formation but also limits their long term use as passive ionic exchange between neighboring droplet pairs may initiate immediately after the membranes are established. This work addresses this shortcoming by rupturing selected sacrificial membranes within the collections of droplets to rearrange the remaining droplets into new configurations, redirecting the droplet-droplet exchange pathways. This is accomplished through electrical shocks applied between selected droplets. Experimental outcomes are compared to predictions provided by a coupled mechanical-electrical model for the droplet networks, and then advanced configurations are proposed using this model.
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Affiliation(s)
- Elio J Challita
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering, University of Georgia, Athens, Georgia 30602, USA
| | - Michelle M Makhoul-Mansour
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering, University of Georgia, Athens, Georgia 30602, USA
| | - Eric C Freeman
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, College of Engineering, University of Georgia, Athens, Georgia 30602, USA
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33
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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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34
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Lee Y, Lee HR, Kim K, Choi SQ. Static and Dynamic Permeability Assay for Hydrophilic Small Molecules Using a Planar Droplet Interface Bilayer. Anal Chem 2018; 90:1660-1667. [PMID: 29308648 DOI: 10.1021/acs.analchem.7b03004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Because numerous drugs are administered through an oral route and primarily absorbed at the intestine, the prediction of drug permeability across an intestinal epithelial cell membrane has been a crucial issue in drug discovery. Thus, various in vitro permeability assays have been developed such as the Caco-2 assay, the parallel artificial membrane permeability assay (PAMPA), the phospholipid vesicle-based permeation assays (PVPA) and Permeapad. However, because of the time-consuming and quite expensive process for culturing cells in the Caco-2 assay and the unknown microscopic membrane structures of the other assays, a simpler yet more accurate and versatile technique is still required. Accordingly, we developed a new platform to measure the permeability of small molecules across a planar freestanding lipid bilayer with a well-defined area and structure. The lipid bilayer was constructed within a conventional UV spectrometer cell, and the transport of drug molecules across the bilayer was recorded by UV absorbance over time. We then computed the permeability from the time-dependent diffusion equation. We tested this assay for five exemplary hydrophilic drugs and compared their values with previously reported ones. We found that our assay has a much higher permeability compared to the other techniques, and this higher permeability is related to the thickness of the lipid bilayer. Also we were able to measure the dynamic permeability upon the addition of a membrane-disrupting surfactant demonstrating that our assay has the capability to detect real-time changes in permeability across the lipid bilayer.
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Affiliation(s)
- Yohan Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Hyun-Ro Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - KyuHan Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Siyoung Q Choi
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
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35
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Braziel S, Sullivan K, Lee S. Quantitative Raman microspectroscopy for water permeability parameters at a droplet interface bilayer. Analyst 2018; 143:747-755. [DOI: 10.1039/c7an01349c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Using confocal Raman microspectroscopy, we derive parameters for bilayer water transport across an isolated nanoliter aqueous droplet pair.
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Affiliation(s)
- S. Braziel
- Department of Chemistry
- Iona College
- New Rochelle
- USA
| | - K. Sullivan
- Department of Chemistry
- Iona College
- New Rochelle
- USA
| | - S. Lee
- Department of Chemistry
- Iona College
- New Rochelle
- USA
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36
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Makhoul-Mansour M, Zhao W, Gay N, O'Connor C, Najem JS, Mao L, Freeman EC. Ferrofluid-Based Droplet Interface Bilayer Networks. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13000-13007. [PMID: 29043824 DOI: 10.1021/acs.langmuir.7b03055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Droplet interface bilayer (DIB) networks allow for the construction of stimuli-responsive, membrane-based materials. Traditionally used for studying cellular transport phenomena, the DIB technique has proven its practicality when creating structured droplet networks. These structures consist of aqueous compartments capable of exchanging their contents across membranous barriers in a regulated fashion via embedded biomolecules, thus approximating the activity of natural cellular systems. However, lipid bilayer networks are often static and incapable of any reconfiguration in their architecture. In this study, we investigate the incorporation of a magnetic fluid or ferrofluid within the droplet phases for the creation of magnetically responsive DIB arrays. The impact of adding ferrofluid to the aqueous phases of the DIB networks is assessed by examining the bilayers' interfacial tensions, thickness, and channel activity. Once compatibility is established, potential applications of the ferrofluid-enabled DIBs are showcased by remotely modifying membrane qualities through magnetic fields. Ferrofluids do not significantly alter the bilayers' properties or functionality and can therefore be safely embedded within the DIB platform, allowing for remote manipulation of the interfacial bilayer properties.
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Affiliation(s)
| | | | - Nicole Gay
- Department of Genetics, Stanford University , Stanford, California 94305, United States
| | - Colleen O'Connor
- College of Engineering and UW Medicine, University of Washington , Seattle, Washington 98195, United States
| | - Joseph S Najem
- Joint Institute for Biological Sciences, Oak Ridge National Laboratory, and Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
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37
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Kim H, Kim K, Lee HR, Jo H, Jeong DW, Ryu J, Gweon DG, Choi SQ. Formation of stable adhesive water-in-oil emulsions using a phospholipid and cosurfactants. J IND ENG CHEM 2017. [DOI: 10.1016/j.jiec.2017.06.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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38
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Letteri RA, Santa Chalarca CF, Bai Y, Hayward RC, Emrick T. Forming Sticky Droplets from Slippery Polymer Zwitterions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1702921. [PMID: 28833762 DOI: 10.1002/adma.201702921] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Indexed: 06/07/2023]
Abstract
Polymer zwitterions are generally regarded as hydrophilic and repellant or "slippery" materials. Here, a case is described in which the polymer zwitterion structure is tailored to decrease water solubility, stabilize emulsion droplets, and promote interdroplet adhesion. Harnessing the upper critical solution temperature of sulfonium- and ammonium-based polymer zwitterions in water, adhesive droplets are prepared by adding organic solvent to an aqueous polymer solution at elevated temperature, followed by agitation to induce emulsification. Droplet aggregation is observed as the mixture cools. Variation of salt concentration, temperature, polymer concentration, and polymer structure modulates these interdroplet interactions, resulting in distinct changes in emulsion stability and fluidity. Under attractive conditions, emulsions encapsulating 50-75% oil undergo gelation. By contrast, emulsions prepared under conditions where droplets are nonadhesive remain fluid and, for oil fractions exceeding 0.6, coalescence is observed. The uniquely reactive nature of the selected zwitterions allows their in situ modification and affords a route to chemically trigger deaggregation and droplet dispersion. Finally, experiments performed in a microfluidic device, in which droplets are formed under conditions that either promote or suppress adhesion, confirm the salt-responsive character of these emulsions and the persistence of adhesive interdroplet interactions under flow.
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Affiliation(s)
- Rachel A Letteri
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Cristiam F Santa Chalarca
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Ying Bai
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Ryan C Hayward
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA, 01003, USA
| | - Todd Emrick
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA, 01003, USA
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39
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Ben M'barek K, Ajjaji D, Chorlay A, Vanni S, Forêt L, Thiam AR. ER Membrane Phospholipids and Surface Tension Control Cellular Lipid Droplet Formation. Dev Cell 2017; 41:591-604.e7. [PMID: 28579322 DOI: 10.1016/j.devcel.2017.05.012] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/08/2017] [Accepted: 05/10/2017] [Indexed: 10/19/2022]
Abstract
Cells convert excess energy into neutral lipids that are made in the endoplasmic reticulum (ER) bilayer. The lipids are then packaged into spherical or budded lipid droplets (LDs) covered by a phospholipid monolayer containing proteins. LDs play a key role in cellular energy metabolism and homeostasis. A key unanswered question in the life of LDs is how they bud off from the ER. Here, we tackle this question by studying the budding of artificial LDs from model membranes. We find that the bilayer phospholipid composition and surface tension are key parameters of LD budding. Phospholipids have differential LD budding aptitudes, and those inducing budding decrease the bilayer tension. We observe that decreasing tension favors the egress of neutral lipids from the bilayer and LD budding. In cells, budding conditions favor the formation of small LDs. Our discovery reveals the importance of altering ER physical chemistry for controlled cellular LD formation.
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Affiliation(s)
- Kalthoum Ben M'barek
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Dalila Ajjaji
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Stefano Vanni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Lionel Forêt
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Département de Physique de l'ENS, École Normale Supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Université Paris 06, CNRS, 75005 Paris, France.
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40
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Shi C, Zhang L, Xie L, Lu X, Liu Q, He J, Mantilla CA, Van den Berg FGA, Zeng H. Surface Interaction of Water-in-Oil Emulsion Droplets with Interfacially Active Asphaltenes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:1265-1274. [PMID: 28081605 DOI: 10.1021/acs.langmuir.6b04265] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Adsorption of interfacially active components at the water/oil interface plays critical roles in determining the properties and behaviors of emulsion droplets. In this study, the droplet probe atomic force microscopy (AFM) technique was applied, for the first time, to quantitatively study the interaction mechanism between water-in-oil (W/O) emulsion droplets with interfacially adsorbed asphaltenes. The behaviors and stability of W/O emulsion droplets were demonstrated to be significantly influenced by the asphaltene concentration of organic solution where the emulsions were aged, aging time, force load, contact time, and solvent type. Bare water droplets could readily coalesce with each other in oil (i.e., toluene), while interfacially adsorbed asphaltenes could sterically inhibit droplet coalescence and induce interfacial adhesion during separation of the water droplets. For low asphaltene concentration cases, the adhesion increased with increasing asphaltene concentration (≤100 mg/L), but it significantly decreased at relatively high asphaltene concentration (e.g., 500 mg/L). Experiments in Heptol (i.e., mixture of toluene and heptane) showed that the addition of a poor solvent for asphaltenes (e.g., heptane) could enhance the interfacial adhesion between emulsion droplets at relatively low asphaltene concentration but could weaken the adhesion at relatively high asphaltene concentration. This work has quantified the interactions between W/O emulsion droplets with interfacially adsorbed asphaltenes, and the results provide useful implications into the stabilization mechanisms of W/O emulsions in oil production. The methodology in this work can be readily extended to other W/O emulsion systems with interfacially active components.
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Affiliation(s)
- Chen Shi
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
| | - Ling Zhang
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
| | - Lei Xie
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
| | - Xi Lu
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
| | - Qingxia Liu
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
| | - Jiajun He
- Shell International Exploration and Production Inc., Houston, Texas 77079, United States
| | - Cesar A Mantilla
- Shell International Exploration and Production Inc., Houston, Texas 77079, United States
| | | | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, AB T6G 1H9, Canada
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41
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Lopez M, Evangelista SE, Morales M, Lee S. Enthalpic Effects of Chain Length and Unsaturation on Water Permeability across Droplet Bilayers of Homologous Monoglycerides. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:900-912. [PMID: 28073244 DOI: 10.1021/acs.langmuir.6b03932] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A deeper understanding of unassisted passive transport processes can better delineate basic lipid dynamics in biological membranes. A droplet interface bilayer (DIB) is made by contacting two aqueous droplets covered with a lipid monolayer, and has increasingly been employed as a model artificial biological membrane. In this study, we have investigated the effect of acyl chain structure of amphiphilic monoglycerides on the osmotic permeability of water across DIB membranes composed of these monoglycerides, where the acyl chain length (C14-C24), number of double bonds (1-4), and the position of double bond are varied systematically along the acyl chains. Both permeability values and activation energies have been extracted for water transport across a lipid bilayer formed of a homologous series of lipids, allowing us to make ready comparisons between the different lipids and potentially better elucidate the contributions that molecular motifs make to the permeation process.
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Affiliation(s)
- Maria Lopez
- Department of Chemistry, Iona College , 715 North Avenue, New Rochelle, New York 10801, United States
| | - Sue Ellen Evangelista
- Department of Chemistry, Iona College , 715 North Avenue, New Rochelle, New York 10801, United States
| | - Melissa Morales
- Department of Chemistry, Iona College , 715 North Avenue, New Rochelle, New York 10801, United States
| | - Sunghee Lee
- Department of Chemistry, Iona College , 715 North Avenue, New Rochelle, New York 10801, United States
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42
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Thul PJ, Tschapalda K, Kolkhof P, Thiam AR, Oberer M, Beller M. Lipid droplet subset targeting of the Drosophila protein CG2254/dmLdsdh1. J Cell Sci 2017; 130:3141-3157. [DOI: 10.1242/jcs.199661] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 07/26/2017] [Indexed: 01/02/2023] Open
Abstract
Lipid droplets (LDs) are the principal organelles of lipid storage. They consist of a hydrophobic core of storage lipids, surrounded by a phospholipid monolayer with proteins attached. While some of these proteins are essential to regulate cellular and organismic lipid metabolism, key questions concerning LD protein function, such as their targeting to LDs, are still unanswered. Intriguingly, some proteins are restricted to LD subsets by an as yet unknown mechanism. This finding makes LD targeting even more complex.
Here, we characterize the Drosophila protein CG2254 which targets LD subsets in cultured cells and different larval Drosophila tissues, where the prevalence of LD subsets appears highly dynamic. We find that an amphipathic amino acid stretch mediates CG2254 LD localization. Additionally, we identified a juxtaposed sequence stretch limiting CG2254 localization to LD subsets. This sequence is sufficient to restrict a chimeric protein - consisting of the subset targeting sequence introduced to an otherwise pan LD localized protein sequence - to LD subsets. Based on its subcellular localization and annotated function, we suggest to rename CG2254 to Lipid droplet subset dehydrogenase 1 (Ldsdh1).
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Affiliation(s)
- Peter J. Thul
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Department of Molecular Developmental Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Kirsten Tschapalda
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Department of Molecular Developmental Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Department of Chemical Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Petra Kolkhof
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Ecole Normale Superieure, PSL Research University, Universite de Paris Diderot Sorbonne Paris-Cite, Paris, France
| | - Monika Oberer
- Institute of Molecular Biosciences, BioTechMed Graz, University of Graz, Austria
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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43
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Jeong DW, Jang H, Choi SQ, Choi MC. Enhanced stability of freestanding lipid bilayer and its stability criteria. Sci Rep 2016; 6:38158. [PMID: 27982049 PMCID: PMC5159868 DOI: 10.1038/srep38158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/04/2016] [Indexed: 11/08/2022] Open
Abstract
We present a new strategy to dramatically enhance the stability of freestanding lipid bilayers. We found that an addition of a water in oil emulsion stabilizer, SPAN 80 to a solvent phase guarantees nearly millimeter-scale stable freestanding lipid bilayers. The water permeability, bilayer area, contact angle, and interfacial tension were measured as a function of time and SPAN 80-to-lipid weight ratio (ΦSPAN 80) with several different solvents. Surprisingly, the SPAN 80, instead of remaining in the bilayer, was moved out of the bilayer during the bilayer formation. Also we studied the effect of solvent on freestanding bilayer formation, and found that squalene was the only solvent that was not incorporated into the bilayer. The regime of stable bilayer formation was experimentally determined to be 3/1 < ΦSPAN 80 < 15/1, and we suggest general stability criteria for bilayer formation. This technique and the suggested stability criteria can be potentially helpful to many model membrane-based researches in life sciences, physical sciences and biomedical engineering fields.
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Affiliation(s)
- Dae-Woong Jeong
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
| | - Hyunwoo Jang
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
| | - Siyoung Q. Choi
- KAIST, Department of Chemical and Biomolecular Engineering, Daejeon, 34141, Korea
| | - Myung Chul Choi
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
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44
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Walsh E, Feuerborn A, Cook PR. Formation of droplet interface bilayers in a Teflon tube. Sci Rep 2016; 6:34355. [PMID: 27681313 PMCID: PMC5041184 DOI: 10.1038/srep34355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/09/2016] [Indexed: 02/08/2023] Open
Abstract
Droplet-interface bilayers (DIBs) have applications in disciplines ranging from biology to computing. We present a method for forming them manually using a Teflon tube attached to a syringe pump; this method is simple enough it should be accessible to those without expertise in microfluidics. It exploits the properties of interfaces between three immiscible liquids, and uses fluid flow through the tube to pack together drops coated with lipid monolayers to create bilayers at points of contact. It is used to create functional nanopores in DIBs composed of phosphocholine using the protein α-hemolysin (αHL), to demonstrate osmotically-driven mass transfer of fluid across surfactant-based DIBs, and to create arrays of DIBs. The approach is scalable, and thousands of DIBs can be prepared using a robot in one hour; therefore, it is feasible to use it for high throughput applications.
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Affiliation(s)
- Edmond Walsh
- Osney Thermo-Fluids Laboratory, Department of Engineering Science, University of Oxford, Southwell Building, Osney Mead, Oxford OX2 0ES, UK
| | - Alexander Feuerborn
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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45
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Wang H, Becuwe M, Housden BE, Chitraju C, Porras AJ, Graham MM, Liu XN, Thiam AR, Savage DB, Agarwal AK, Garg A, Olarte MJ, Lin Q, Fröhlich F, Hannibal-Bach HK, Upadhyayula S, Perrimon N, Kirchhausen T, Ejsing CS, Walther TC, Farese RV. Seipin is required for converting nascent to mature lipid droplets. eLife 2016; 5. [PMID: 27564575 PMCID: PMC5035145 DOI: 10.7554/elife.16582] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/25/2016] [Indexed: 12/16/2022] Open
Abstract
How proteins control the biogenesis of cellular lipid droplets (LDs) is poorly understood. Using Drosophila and human cells, we show here that seipin, an ER protein implicated in LD biology, mediates a discrete step in LD formation-the conversion of small, nascent LDs to larger, mature LDs. Seipin forms discrete and dynamic foci in the ER that interact with nascent LDs to enable their growth. In the absence of seipin, numerous small, nascent LDs accumulate near the ER and most often fail to grow. Those that do grow prematurely acquire lipid synthesis enzymes and undergo expansion, eventually leading to the giant LDs characteristic of seipin deficiency. Our studies identify a discrete step of LD formation, namely the conversion of nascent LDs to mature LDs, and define a molecular role for seipin in this process, most likely by acting at ER-LD contact sites to enable lipid transfer to nascent LDs.
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Affiliation(s)
- Huajin Wang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, United States.,Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Michel Becuwe
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | | | - Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Ashley J Porras
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Morven M Graham
- Center for Cellular and Molecular Imaging, Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Xinran N Liu
- Center for Cellular and Molecular Imaging, Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University, Université Paris Diderot Sorbonne Paris-Cité, Sorbonne Universités UPMC Univ Paris 06, CNRS UMR 8550, Paris, France
| | - David B Savage
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
| | - Anil K Agarwal
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Maria-Jesus Olarte
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Qingqing Lin
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Florian Fröhlich
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Molecular Membrane Biology Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Hans Kristian Hannibal-Bach
- VILLUM Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Srigokul Upadhyayula
- Department of Cell Biology, Harvard Medical School, Boston, United States.,Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States
| | - Tomas Kirchhausen
- Department of Cell Biology, Harvard Medical School, Boston, United States.,Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
| | - Christer S Ejsing
- VILLUM Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States.,Broad Institute of Harvard and MIT, Cambridge, United States
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T H Chan School of Public Health, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States.,Broad Institute of Harvard and MIT, Cambridge, United States
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46
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Tamaddoni N, Taylor G, Hepburn T, Michael Kilbey S, Sarles SA. Reversible, voltage-activated formation of biomimetic membranes between triblock copolymer-coated aqueous droplets in good solvents. SOFT MATTER 2016; 12:5096-5109. [PMID: 27174295 DOI: 10.1039/c6sm00400h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Biomimetic membranes assembled from block copolymers attract considerable interest because they exhibit greater stability and longetivity compared to lipid bilayers, and some enable the reconstitution of functional transmembrane biomolecules. Yet to-date, block copolymer membranes have not been achieved using the droplet interface bilayer (DIB) method, which uniquely allows assembling single- and multi-membrane networks between water droplets in oil. Herein, we investigate the formation of poly(ethylene oxide)-b-poly(dimethyl siloxane)-b-poly(ethylene oxide) triblock copolymer-stabilized interfaces (CSIs) between polymer-coated aqueous droplets in solutions comprising combinations of decane, hexadecane and AR20 silicone oil. We demonstrate that triblock-coated droplets do not spontaneously adhere in these oils because all are thermodynamically good solvents for the hydrophobic PDMS middle block. However, thinned planar membranes are reversibly formed at the interface between droplets upon the application of a sufficient transmembrane voltage, which removes excess solvent from between droplets through electrocompression. At applied voltages above the threshold required to initiate membrane thinning, electrowetting causes the area of the CSI between droplets to increase while thickness remains constant; the CSI electrowetting response is similar to that encountered with lipid-based DIBs. In combination, these results reveal that stable membranes can be assembled in a manner that is completely reversible when an external pressure is used to overcome a barrier to adhesion caused by solvent-chain interactions, and they demonstrate new capability for connecting and disconnecting aqueous droplets via polymer-stabilized membranes.
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Affiliation(s)
- Nima Tamaddoni
- Dept. of Mech., Aero. and Biomed. Engr., 1512 Middle Dr. 414 Dougherty Hall, University of Tennessee, Knoxville, TN 37996, USA.
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47
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Guzowski J, Gizynski K, Gorecki J, Garstecki P. Microfluidic platform for reproducible self-assembly of chemically communicating droplet networks with predesigned number and type of the communicating compartments. LAB ON A CHIP 2016; 16:764-772. [PMID: 26785761 DOI: 10.1039/c5lc01526j] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a microfluidic system for individually tailored generation and incubation of core-shell liquid structures with multiple cores that chemically communicate with each other via lipid membranes. We encapsulate an oscillating reaction-diffusion Belousov-Zhabotinsky (BZ) medium inside the aqueous droplets and study the propagation of chemical wave-fronts through the membranes. We further encapsulate the sets of interconnected BZ-droplets inside oil-lipid shells in order to i) chemically isolate the structures and ii) confine them via tunable capillary forces which leads to self-assembly of predesigned topologies. We observe that doublets (pairs) of droplets encapsulated in the shell exhibit oscillation patterns that evolve in time. We collect statistical data from tens of doublets all created under precisely controlled, almost identical conditions from which we conclude that the different types of transitions between the patterns depend on the relative volumes of the droplets within a chemically coupled pair. With this we show that the volume of the compartment is an important control parameter in designing chemical networks, a feature previously appreciated only by theory. Our system not only allows for new insights into the dynamics of geometrically complex and interacting chemical systems but is also suitable for generating autonomous chemically interconnected microstructures with possible future use, e.g., as smart biosensors or drug-release capsules.
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Affiliation(s)
- Jan Guzowski
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 03-982 Warsaw, Poland.
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48
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Controlling molecular transport in minimal emulsions. Nat Commun 2016; 7:10392. [PMID: 26797564 PMCID: PMC4735829 DOI: 10.1038/ncomms10392] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 12/08/2015] [Indexed: 12/24/2022] Open
Abstract
Emulsions are metastable dispersions in which molecular transport is a major mechanism driving the system towards its state of minimal energy. Determining the underlying mechanisms of molecular transport between droplets is challenging due to the complexity of a typical emulsion system. Here we introduce the concept of ‘minimal emulsions', which are controlled emulsions produced using microfluidic tools, simplifying an emulsion down to its minimal set of relevant parameters. We use these minimal emulsions to unravel the fundamentals of transport of small organic molecules in water-in-fluorinated-oil emulsions, a system of great interest for biotechnological applications. Our results are of practical relevance to guarantee a sustainable compartmentalization of compounds in droplet microreactors and to design new strategies for the dynamic control of droplet compositions. Emulsion droplets have many biotechnological applications, such as parallelized single cell analysis. Here, Gruner et al. introduce the concept of the minimal emulsions in a microfluidic device that allows full control of molecular transport between emulsion droplets.
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49
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Schwarz-Schilling M, Aufinger L, Mückl A, Simmel FC. Chemical communication between bacteria and cell-free gene expression systems within linear chains of emulsion droplets. Integr Biol (Camb) 2016; 8:564-70. [PMID: 26778746 DOI: 10.1039/c5ib00301f] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Position-dependent gene expression in gradients of morphogens is one of the key processes involved in cellular differentiation during development. Here, we study a simple artificial differentiation process, which is based on the diffusion of genetic inducers within one-dimensional arrangements of 50 μm large water-in-oil droplets. The droplets are filled with either bacteria or cell-free gene expression systems, both equipped with genetic constructs that produce inducers or respond to them via expression of a fluorescent protein. We quantitatively study the coupled diffusion-gene expression process and demonstrate that gene expression can be made position-dependent both within bacteria-containing and cell-free droplets. By generating diffusing quorum sensing signals in situ, we also establish communication between artificial cell-free sender cells and bacterial receivers, and vice versa.
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Affiliation(s)
- M Schwarz-Schilling
- Technical University of Munich, Physics Department E14 and ZNN/WSI, Am Coulombwall 4a, 85748 Garching, Germany.
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50
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Taylor GJ, Venkatesan GA, Collier CP, Sarles SA. Direct in situ measurement of specific capacitance, monolayer tension, and bilayer tension in a droplet interface bilayer. SOFT MATTER 2015; 11:7592-605. [PMID: 26289743 DOI: 10.1039/c5sm01005e] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Thickness and tension are important physical parameters of model cell membranes. However, traditional methods to measure these quantities require multiple experiments using separate equipment. This work introduces a new multi-step procedure for directly accessing in situ multiple physical properties of droplet interface bilayers (DIB), including specific capacitance (related to thickness), lipid monolayer tension in the Plateau-Gibbs border, and bilayer tension. The procedure employs a combination of mechanical manipulation of bilayer area followed by electrowetting of the capacitive interface to examine the sensitivities of bilayer capacitance to area and contact angle to voltage, respectively. These data allow for determining the specific capacitance of the membrane and surface tension of the lipid monolayer, which are then used to compute bilayer thickness and tension, respectively. The use of DIBs affords accurate optical imaging of the connected droplets in addition to electrical measurements of bilayer capacitance, and it allows for reversibly varying bilayer area. After validating the accuracy of the technique with diphytanoyl phosphatidylcholine (DPhPC) DIBs in hexadecane, the method is applied herein to quantify separately the effects on membrane thickness and tension caused by varying the solvent in which the DIB is formed and introducing cholesterol into the bilayer. Because the technique relies only on capacitance measurements and optical images to determine both thickness and tension, this approach is specifically well-suited for studying the effects of peptides, biomolecules, natural and synthetic nanoparticles, and other species that accumulate within membranes without altering bilayer conductance.
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Affiliation(s)
- Graham J Taylor
- Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, 1512 Middle Drive, 414 Dougherty Engineering Building, Knoxville, TN 37996, USA.
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