1
|
de Jesus M, Settle AH, Vorselen D, Gaetjens TK, Galiano M, Romin Y, Lee E, Wong YY, Fu TM, Santosa E, Winer BY, Tamzalit F, Wang MS, Santella A, Bao Z, Sun JC, Shah P, Theriot JA, Abel SM, Huse M. Single-cell topographical profiling of the immune synapse reveals a biomechanical signature of cytotoxicity. Sci Immunol 2024; 9:eadj2898. [PMID: 38941478 DOI: 10.1126/sciimmunol.adj2898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 06/05/2024] [Indexed: 06/30/2024]
Abstract
Immune cells have intensely physical lifestyles characterized by structural plasticity and force exertion. To investigate whether specific immune functions require stereotyped mechanical outputs, we used super-resolution traction force microscopy to compare the immune synapses formed by cytotoxic T cells with contacts formed by other T cell subsets and by macrophages. T cell synapses were globally compressive, which was fundamentally different from the pulling and pinching associated with macrophage phagocytosis. Spectral decomposition of force exertion patterns from each cell type linked cytotoxicity to compressive strength, local protrusiveness, and the induction of complex, asymmetric topography. These features were validated as cytotoxic drivers by genetic disruption of cytoskeletal regulators, live imaging of synaptic secretion, and in silico analysis of interfacial distortion. Synapse architecture and force exertion were sensitive to target stiffness and size, suggesting that the mechanical potentiation of killing is biophysically adaptive. We conclude that cellular cytotoxicity and, by implication, other effector responses are supported by specialized patterns of efferent force.
Collapse
Affiliation(s)
- Miguel de Jesus
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexander H Settle
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daan Vorselen
- Cell Biology and Immunology Group, Wageningen University & Research, Wageningen, Netherlands
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Thomas K Gaetjens
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Michael Galiano
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yevgeniy Romin
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Esther Lee
- Immunology & Molecular Pathogenesis Program, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY, USA
| | - Yung Yu Wong
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Tian-Ming Fu
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, USA
| | - Endi Santosa
- Immunology & Molecular Pathogenesis Program, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY, USA
| | - Benjamin Y Winer
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Fella Tamzalit
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Mitchell S Wang
- Pharmacology Program, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY, USA
| | - Anthony Santella
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Zhirong Bao
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Joseph C Sun
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Pavak Shah
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, CA, USA
| | - Julie A Theriot
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Steven M Abel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | - Morgan Huse
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| |
Collapse
|
2
|
Dimitriou P, Li J, Jamieson WD, Schneider JJ, Castell OK, Barrow DA. Manipulation of encapsulated artificial phospholipid membranes using sub-micellar lysolipid concentrations. Commun Chem 2024; 7:120. [PMID: 38824266 PMCID: PMC11144220 DOI: 10.1038/s42004-024-01209-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 05/24/2024] [Indexed: 06/03/2024] Open
Abstract
Droplet Interface Bilayers (DIBs) constitute a commonly used model of artificial membranes for synthetic biology research applications. However, their practical use is often limited by their requirement to be surrounded by oil. Here we demonstrate in-situ bilayer manipulation of submillimeter, hydrogel-encapsulated droplet interface bilayers (eDIBs). Monolithic, Cyclic Olefin Copolymer/Nylon 3D-printed microfluidic devices facilitated the eDIB formation through high-order emulsification. By exposing the eDIB capsules to varying lysophosphatidylcholine (LPC) concentrations, we investigated the interaction of lysolipids with three-dimensional DIB networks. Micellar LPC concentrations triggered the bursting of encapsulated droplet networks, while at lower concentrations the droplet network endured structural changes, precisely affecting the membrane dimensions. This chemically-mediated manipulation of enclosed, 3D-orchestrated membrane mimics, facilitates the exploration of readily accessible compartmentalized artificial cellular machinery. Collectively, the droplet-based construct can pose as a chemically responsive soft material for studying membrane mechanics, and drug delivery, by controlling the cargo release from artificial cell chassis.
Collapse
Affiliation(s)
- Pantelitsa Dimitriou
- School of Engineering, Cardiff University, Queen's Buildings, Cardiff, CF24 3AA, UK.
| | - Jin Li
- School of Engineering, Cardiff University, Queen's Buildings, Cardiff, CF24 3AA, UK.
| | - William David Jamieson
- School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, Redwood Building, Kind Edward VII Avenue, Cardiff, CF10 3NB, UK
| | - Johannes Josef Schneider
- Institute of Applied Mathematics and Physics, School of Engineering, Zurich University of Applied Sciences, Technikumstr. 9, 8401, Winterthur, Switzerland
| | - Oliver Kieran Castell
- School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, Redwood Building, Kind Edward VII Avenue, Cardiff, CF10 3NB, UK
| | - David Anthony Barrow
- School of Engineering, Cardiff University, Queen's Buildings, Cardiff, CF24 3AA, UK
| |
Collapse
|
3
|
Segars B, Makhoul-Mansour M, Beyrouthy J, Freeman EC. Measuring the Transmembrane Registration of Lipid Domains in Droplet Interface Bilayers through Tensiometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:11228-11238. [PMID: 38753461 PMCID: PMC11140749 DOI: 10.1021/acs.langmuir.4c00958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/18/2024]
Abstract
Diverse collections of lipids self-assemble into domains within biological membranes, and these domains are typically organized in both the transverse and lateral directions of the membrane. The ability of the membrane to link these domains across the membrane's interior grants cells control over features on the external cellular surface. Numerous hypothesized factors drive the cross-membrane (or transverse) coupling of lipid domains. In this work we seek to isolate these transverse lipid-lipid influences in a simple model system using droplet interface bilayers (DIBs) to better understand the associated mechanics. DIBs enable symmetric and asymmetric combinations of domain-forming lipid mixtures within a model bilayer, and the evolving energetics of the membrane may be tracked using drop-shape analysis. We find that symmetric distributions of domain-forming lipids produce long-lasting, gradual shifts in the DIB membrane energetics that are not observed in asymmetric distributions of the lipids where the domain-forming lipids are only within one leaflet. The approach selected for this work provides experimental measurement of the mismatch penalty associated with antiregistered lipid domains as well as measurements of the influence of rafts on DIB behaviors with suggestions for their future use as a model platform.
Collapse
Affiliation(s)
- Braydon
G. Segars
- School
of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, 110 Riverbend Road, Athens, Georgia 30605, United States
| | - Michelle Makhoul-Mansour
- School
of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, 110 Riverbend Road, Athens, Georgia 30605, United States
- Mechanical,
Agricultural, Biomedical, and Environmental Engineering Department,
Tickle College of Engineering, University
of Tennessee Knoxville, 1512 Middle Dr., Knoxville, Tennessee 37916, United States
| | - Joyce Beyrouthy
- School
of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, 110 Riverbend Road, Athens, Georgia 30605, United States
| | - Eric C. Freeman
- School
of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, 110 Riverbend Road, Athens, Georgia 30605, United States
| |
Collapse
|
4
|
Huang Y, Chandran Suja V, Yang M, Malkovskiy AV, Tandon A, Colom A, Qin J, Fuller GG. Interfacial stresses on droplet interface bilayers using two photon fluorescence lifetime imaging microscopy. J Colloid Interface Sci 2024; 653:1196-1204. [PMID: 37793246 DOI: 10.1016/j.jcis.2023.09.092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 09/06/2023] [Accepted: 09/14/2023] [Indexed: 10/06/2023]
Abstract
HYPOTHESIS Response of lipid bilayers to external mechanical stimuli is an active area of research with implications for fundamental and synthetic cell biology. Developing novel tools for systematically imposing mechanical strains and non-invasively mapping out interfacial (membrane) stress distributions on lipid bilayers can accelerate research in this field. EXPERIMENTS We report a miniature platform to manipulate model cell membranes in the form of droplet interface bilayers (DIBs), and non-invasively measure spatio-temporally resolved interfacial stresses using two photon fluorescence lifetime imaging of an interfacially active molecular flipper (Flipper-TR). We established the effectiveness of the developed framework by investigating interfacial stresses accompanying three key processes associated with DIBs: thin film drainage between lipid monolayer coated droplets, bilayer formation, and bilayer separation. FINDINGS The measurements revealed fundamental aspects of DIBs including the existence of a radially decaying interfacial stress distribution post bilayer formation, and the simultaneous build up and decay of stress respectively at the bilayer corner and center during bilayer separation. Finally, utilizing interfacial rheology measurements and MD simulations, we also reveal that the tested molecular flipper is sensitive to membrane fluidity that changes with interfacial stress - expanding the scientific understanding of how molecular flippers sense stress.
Collapse
Affiliation(s)
- Yaoqi Huang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Vineeth Chandran Suja
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; School of Engineering and Applied Sciences, Harvard University, MA - 02138, USA.
| | - Menghao Yang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Andrey V Malkovskiy
- Carnegie Institute for Science, Department of Plant Biology, Stanford CA 94305, USA
| | - Arnuv Tandon
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Adai Colom
- Biofisika Institute (CSIC, UPV/EHU), 48940 Leioa, Spain; Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Campus Universitario, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | - Jian Qin
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Gerald G Fuller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
El-Beyrouthy J, Makhoul-Mansour M, Gulle J, Freeman E. Morphogenesis-inspired two-dimensional electrowetting in droplet networks. BIOINSPIRATION & BIOMIMETICS 2023; 18. [PMID: 37074106 DOI: 10.1088/1748-3190/acc779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/24/2023] [Indexed: 05/03/2023]
Abstract
Living tissues dynamically reshape their internal cellular structures through carefully regulated cell-to-cell interactions during morphogenesis. These cellular rearrangement events, such as cell sorting and mutual tissue spreading, have been explained using the differential adhesion hypothesis, which describes the sorting of cells through their adhesive interactions with their neighbors. In this manuscript we explore a simplified form of differential adhesion within a bioinspired lipid-stabilized emulsion approximating cellular tissues. The artificial cellular tissues are created as a collection of aqueous droplets adhered together in a network of lipid membranes. Since this abstraction of the tissue does not retain the ability to locally vary the adhesion of the interfaces through biological mechanisms, instead we employ electrowetting with offsets generated by spatial variations in lipid compositions to capture a simple form of bioelectric control over the tissue characteristics. This is accomplished by first conducting experiments on electrowetting in droplet networks, next creating a model for describing electrowetting in collections of adhered droplets, then validating the model against the experimental measurements. This work demonstrates how the distribution of voltage within a droplet network may be tuned through lipid composition then used to shape directional contraction of the adhered structure using two-dimensional electrowetting events. Predictions from this model were used to explore the governing mechanics for complex electrowetting events in networks, including directional contraction and the formation of new interfaces.
Collapse
Affiliation(s)
- Joyce El-Beyrouthy
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, GA, United States of America
| | - Michelle Makhoul-Mansour
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, GA, United States of America
- College of Engineering, University of Tennessee Knoxville, Knoxville, TN, United States of America
| | - Jesse Gulle
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, GA, United States of America
| | - Eric Freeman
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, GA, United States of America
| |
Collapse
|
7
|
de Jesus M, Settle AH, Vorselen D, Gaetjens TK, Galiano M, Wong YY, Fu TM, Santosa E, Winer BY, Tamzalit F, Wang MS, Bao Z, Sun JC, Shah P, Theriot JA, Abel SM, Huse M. Topographical analysis of immune cell interactions reveals a biomechanical signature for immune cytolysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.16.537078. [PMID: 37131635 PMCID: PMC10153123 DOI: 10.1101/2023.04.16.537078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Immune cells live intensely physical lifestyles characterized by structural plasticity, mechanosensitivity, and force exertion. Whether specific immune functions require stereotyped patterns of mechanical output, however, is largely unknown. To address this question, we used super-resolution traction force microscopy to compare cytotoxic T cell immune synapses with contacts formed by other T cell subsets and macrophages. T cell synapses were globally and locally protrusive, which was fundamentally different from the coupled pinching and pulling of macrophage phagocytosis. By spectrally decomposing the force exertion patterns of each cell type, we associated cytotoxicity with compressive strength, local protrusiveness, and the induction of complex, asymmetric interfacial topographies. These features were further validated as cytotoxic drivers by genetic disruption of cytoskeletal regulators, direct imaging of synaptic secretory events, and in silico analysis of interfacial distortion. We conclude that T cell-mediated killing and, by implication, other effector responses are supported by specialized patterns of efferent force.
Collapse
Affiliation(s)
- Miguel de Jesus
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Alexander H. Settle
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Daan Vorselen
- Cell Biology and Immunology Group, Wageningen University & Research, Wageningen, Netherlands
- Department of Biology, University of Washington, Seattle, WA USA
| | - Thomas K. Gaetjens
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN USA
| | - Michael Galiano
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Yung Yu Wong
- Louis V. Gerstner, Jr., Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Tian-Ming Fu
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ USA
| | - Endi Santosa
- Immunology & Molecular Pathogenesis Program, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY USA
| | - Benjamin Y. Winer
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Fella Tamzalit
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Mitchell S. Wang
- Pharmacology Program, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY USA
| | - Zhirong Bao
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Joseph C. Sun
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| | - Pavak Shah
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, CA USA
| | - Julie A. Theriot
- Department of Biology, University of Washington, Seattle, WA USA
| | - Steven M. Abel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN USA
| | - Morgan Huse
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY USA
| |
Collapse
|
8
|
Abdel-Gawad WM, Abdelmohsen M, Gaber MH, Khalil WMA, Abu-Elmagd MSM. Molecular dynamics simulation of phosphatidylcholine membrane in low ionic strengths of sodium chloride. J Biomol Struct Dyn 2023; 41:13891-13901. [PMID: 36812302 DOI: 10.1080/07391102.2023.2183040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 02/14/2023] [Indexed: 02/24/2023]
Abstract
The one-microsecond molecular dynamics simulations of a membrane-protein complex investigate the influence of the aqueous sodium chloride solutions on the structure and dynamics of a palmitoyl-oleoyl-phosphatidylcholine bilayer membrane. The simulations were performed on five different concentrations (40, 150, 200, 300, and 400 mM) in addition to a salt-free system by using the charmm36 force field for all atoms. Four biophysical parameters, (membrane thicknesses of annular and bulk lipids, and the area per lipid of both leaflets), were computed separately. Nevertheless, the area per lipid was expressed by using the Voronoi algorithm. All time-independent analyses were carried out for the last 400 ns trajectories. Different concentrations revealed dissimilar membrane dynamics before equilibration. The biophysical properties of the membrane (thickness, area-per-lipid, and order parameter) have non-significant changes with increasing ionic strength, however, the 150 mM system had exceptional behavior. Sodium cations were dynamically penetrating the membrane forming weak coordinate bonds with single or multiple lipids. Nevertheless, the binding constant was unaffected by the cation concentration. The electrostatic and Van der Waals energies of lipid-lipid interactions were influenced by the ionic strength. On the other hand, the Fast Fourier Transform was performed to figure out the dynamics at the membrane-protein interface. The nonbonding energies of membrane-protein interactions and order parameters explained the differences in the synchronization pattern. All results were consensus with experimental and theoretical works.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
| | - Mahmoud Abdelmohsen
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
- Mathematics and Engineering Physics Department, The Higher Institute of Engineering, Shorouk Academy, El-Shorouk City, Cairo, Egypt
| | | | | | | |
Collapse
|
9
|
Smirnova EY, Anosov AA. Bilayer Lipid Membrane as Memcapacitance: Capacitance-Voltage Pinched Hysteresis and Negative Insertion Conductance. MEMBRANES 2023; 13:97. [PMID: 36676904 PMCID: PMC9861822 DOI: 10.3390/membranes13010097] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Inelastic (dissipative) effects of different natures in lipid bilayer membranes can lead to hysteresis phenomena. Early, it was shown that lipid bilayer membranes, under the action of a periodic sinusoidal voltage, demonstrate pinched-hysteresis loops in the experimental capacitance-voltage dependences and are almost the only example of the physical implementation of memcapacitance. Here, we propose an equivalent circuit and mathematical framework for analyzing the dynamic nonlinear current response of a lipid bilayer membrane as an externally controlled memcapacitance. Solving a nonlinear differential equation for the equivalent circuit of a membrane in the form of a parallel connection of a nonlinear viscoelastic capacitor and an active resistance using the small parameter method, we obtain explicit analytical dependences for the current response of the membrane and pinched-hysteresis loops. The explicit solutions and their comparison with experimental data allow us to identify the lumped equivalent circuit parameters that govern the memcapacitor behavior of the membrane and hence the magnitude of the hysteresis. We quantify the memcapacitance hysteresis in terms of negative work done by the control signal. An analysis of the formulas leads to the conclusion that the determining factor for the appearance of pinched hysteresis is the type of nonlinear dependence of the device capacitance on voltage.
Collapse
Affiliation(s)
- Elena Yu. Smirnova
- The Department of Medical and Biological Physics, Sechenov First Moscow State Medical University (Sechenov University), 119991 Moscow, Russia
| | - Andrey A. Anosov
- The Department of Medical and Biological Physics, Sechenov First Moscow State Medical University (Sechenov University), 119991 Moscow, Russia
- Kotelnikov Institute of Radioengineering and Electronics of RAS, 125009 Moscow, Russia
| |
Collapse
|
10
|
Basham CM, Spittle S, Sangoro J, El-Beyrouthy J, Freeman E, Sarles SA. Entrapment and Voltage-Driven Reorganization of Hydrophobic Nanoparticles in Planar Phospholipid Bilayers. ACS APPLIED MATERIALS & INTERFACES 2022; 14:54558-54571. [PMID: 36459500 DOI: 10.1021/acsami.2c16677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Engineered nanoparticles (NPs) possess diverse physical and chemical properties, which make them attractive agents for targeted cellular interactions within the human body. Once affiliated with the plasma membrane, NPs can become embedded within its hydrophobic core, which can limit the intended therapeutic functionality and affect the associated toxicity. As such, understanding the physical effects of embedded NPs on a plasma membrane is critical to understanding their design and clinical use. Here, we demonstrate that functionalized, hydrophobic gold NPs dissolved in oil can be directly trapped within the hydrophobic interior of a phospholipid membrane assembled using the droplet interface bilayer technique. This approach to model membrane formation preserves lateral lipid diffusion found in cell membranes and permits simultaneous imaging and electrophysiology to study the effects of embedded NPs on the electromechanical properties of the bilayer. We show that trapped NPs enhance ion conductance and lateral membrane tension in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers while lowering the adhesive energy of the joined droplets. Embedded NPs also cause changes in bilayer capacitance and area in response to applied voltage, which are nonmonotonic for DOPC bilayers. This electrophysical characterization can reveal NP entrapment without relying on changes in membrane thickness. By evaluating the energetic components of membrane tension under an applied potential, we demonstrate that these nonmonotonic, voltage-dependent responses are caused by reversible clustering of NPs within the unsaturated DOPC membrane core; aggregates form spontaneously at low voltages and are dispersed by higher transmembrane potentials of magnitude similar to those found in the cellular environment. These findings allow for a better understanding of lipid-dependent NP interactions, while providing a platform to study relationships between other hydrophobic nanomaterials and organic membranes.
Collapse
Affiliation(s)
- Colin M Basham
- Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Stephanie Spittle
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Joshua Sangoro
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Joyce El-Beyrouthy
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, Georgia30602, United States
| | - Eric Freeman
- School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, Georgia30602, United States
| | - Stephen A Sarles
- Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| |
Collapse
|
11
|
Koner S, Tawfik J, Mashali F, Kennison KB, McClintic WT, Heberle FA, Tu YM, Kumar M, Sarles SA. Homogeneous hybrid droplet interface bilayers assembled from binary mixtures of DPhPC phospholipids and PB-b-PEO diblock copolymers. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183997. [PMID: 35718208 DOI: 10.1016/j.bbamem.2022.183997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 06/09/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Hybrid membranes built from phospholipids and amphiphilic block copolymers seek to capitalize on the benefits of both constituents for constructing biomimetic interfaces with improved performance. However, hybrid membranes have not been formed or studied using the droplet interface bilayer (DIB) method, an approach that offers advantages for revealing nanoscale changes in membrane structure and mechanics and offers a path toward assembling higher-order tissues. We report on hybrid droplet interface bilayers (hDIBs) formed in hexadecane from binary mixtures of synthetic diphytanoyl phosphatidylcholine (DPhPC) lipids and low molecular weight 1,2 polybutadiene-b-polyethylene oxide (PBPEO) amphiphilic block copolymers and use electrophysiology measurements and imaging to assess the effects of PBPEO in the membrane. This work reveals that hDIBs containing up to 15 mol% PBPEO plus DPhPC are homogeneously mixtures of lipids and polymers, remain highly resistive to ion transport, and are stable-including under applied voltage. Moreover, they exhibit hydrophobic thicknesses similar to DPhPC-only bilayers, but also have significantly lower values of membrane tension. These characteristics coincide with reduced energy of adhesion between droplets and the formation of alamethicin ion channels at significantly lower threshold voltages, demonstrating that even moderate amounts of amphiphilic block copolymers in a lipid bilayer provide a route for tuning the physical properties of a biomimetic membrane.
Collapse
Affiliation(s)
- Subhadeep Koner
- Department of Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Joseph Tawfik
- Department of Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Farzin Mashali
- Department of Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Kristen B Kennison
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA
| | | | | | - Yu-Ming Tu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Manish Kumar
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712, USA; Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Stephen A Sarles
- Department of Mechanical Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA.
| |
Collapse
|
12
|
Abbas M, Law JO, Grellscheid SN, Huck WTS, Spruijt E. Peptide-Based Coacervate-Core Vesicles with Semipermeable Membranes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202913. [PMID: 35796384 DOI: 10.1002/adma.202202913] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Coacervates droplets have long been considered as potential protocells to mimic living cells. However, these droplets lack a membrane and are prone to coalescence, limiting their ability to survive, interact, and organize into higher-order assemblies. This work shows that tyrosine-rich peptide conjugates can undergo liquid-liquid phase separation in a well-defined pH window and transform into stable membrane-enclosed protocells by enzymatic oxidation and cross-linking at the liquid-liquid interface. The oxidation of the tyrosine-rich peptides into dityrosine creates a semipermeable, flexible membrane around the coacervates with tunable thickness, which displays strong intrinsic fluorescence, and stabilizes the coacervate protocells against coalescence. The membranes have an effective molecular weight cut-off of 2.5 kDa, as determined from the partitioning of small dyes and labeled peptides, RNA, and polymers into the membrane-enclosed coacervate protocells. Flicker spectroscopy reveals a membrane bending rigidity of only 0.1kB T, which is substantially lower than phospholipid bilayers despite a larger membrane thickness. Finally, it is shown that enzymes can be stably encapsulated inside the protocells and be supplied with substrates from outside, which opens the way for these membrane-bound compartments to be used as molecularly crowded artificial cells capable of communication or as a vehicle for drug delivery.
Collapse
Affiliation(s)
- Manzar Abbas
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen, 6525 AJ, The Netherlands
| | - Jack O Law
- Computational Biology Unit, University of Bergen, Bergen, 5020, Norway
| | - Sushma N Grellscheid
- Computational Biology Unit, University of Bergen, Bergen, 5020, Norway
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
| | - Wilhelm T S Huck
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen, 6525 AJ, The Netherlands
| | - Evan Spruijt
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen, 6525 AJ, The Netherlands
| |
Collapse
|
13
|
Challenges and opportunities in achieving the full potential of droplet interface bilayers. Nat Chem 2022; 14:862-870. [PMID: 35879442 DOI: 10.1038/s41557-022-00989-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/27/2022] [Indexed: 12/27/2022]
Abstract
Model membranes can be used to elucidate the intricacies of the chemical processes that occur in cell membranes, but the perfectly biomimetic, yet bespoke, model membrane has yet to be built. Droplet interface bilayers are a new type of model membrane able to mimic some features of real cell membranes better than traditional models, such as liposomes and black lipid membranes. In this Perspective, we discuss recent work in the field that is starting to showcase the potential of these model membranes to enable the quantification of membrane processes, such as the behaviour of protein transporters and the prediction of in vivo drug movement, and their use as scaffolds for electrophysiological measurements. We also highlight the challenges that remain to enable droplet interface bilayers to achieve their full potential as artificial cells, and as biological analytical platforms to quantify molecular transport.
Collapse
|
14
|
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.
Collapse
|
15
|
El-Beyrouthy J, Makhoul-Mansour MM, Freeman EC. Studying the Mechanics of Membrane Permeabilization through Mechanoelectricity. ACS APPLIED MATERIALS & INTERFACES 2022; 14:6120-6130. [PMID: 35073482 DOI: 10.1021/acsami.1c19880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this research, real-time monitoring of lipid membrane disruption is made possible by exploiting the dynamic properties of model lipid bilayers formed at oil-water interfaces. This involves tracking an electrical signal generated through rhythmic membrane perturbation translated into the adsorption and penetration of charged species within the membrane. Importantly, this allows for the detection of membrane surface interactions that occur prior to pore formation that may be otherwise undetected. The requisite dynamic membranes for this approach are made possible through the droplet interface bilayer (DIB) technique. Membranes are formed at the interface of lipid monolayer-coated aqueous droplets submerged in oil. We present how cyclically alternating the membrane area leads to the generation of mechanoelectric current. This current is negligible without a transmembrane voltage until a composition mismatch between the membrane monolayers is produced, such as a one-sided accumulation of disruptive agents. The generated mechanoelectric current is then eliminated when an applied electric field compensates for this asymmetry, enabling measurement of the transmembrane potential offset. Tracking the compensating voltage with respect to time then reveals the gradual accumulation of disruptive agents prior to membrane permeabilization. The innovation of this work is emphasized in its ability to continuously track membrane surface activity, highlighting the initial interaction steps of membrane disruption. In this paper, we begin by validating our proposed approach against measurements taken for fixed composition membranes using standard electrophysiological techniques. Next, we investigate surfactant adsorption, including hexadecyltrimethylammonium bromide (CTAB, cationic) and sodium decyl sulfate (SDS, anionic), demonstrating the ability to track adsorption prior to disruption. Finally, we investigate the penetration of lipid membranes by melittin, confirming that the peptide insertion and disruption mechanics are, in part, modulated by membrane composition.
Collapse
Affiliation(s)
- Joyce El-Beyrouthy
- Biomembranes Engineering Laboratory, School of Environment, Civil, Agriculture and Mechanical Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Michelle M Makhoul-Mansour
- Biomembranes Engineering Laboratory, School of Environment, Civil, Agriculture and Mechanical Engineering, The University of Georgia, Athens, Georgia 30602, United States
| | - Eric C Freeman
- Biomembranes Engineering Laboratory, School of Environment, Civil, Agriculture and Mechanical Engineering, The University of Georgia, Athens, Georgia 30602, United States
| |
Collapse
|
16
|
Shmelev ME, Titov SI, Belousov AS, Farniev VM, Zhmenia VM, Lanskikh DV, Penkova AO, Kumeiko VV. Cell and Tissue Nanomechanics: From Early Development to Carcinogenesis. Biomedicines 2022; 10:biomedicines10020345. [PMID: 35203554 PMCID: PMC8961777 DOI: 10.3390/biomedicines10020345] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/22/2022] [Accepted: 01/27/2022] [Indexed: 02/04/2023] Open
Abstract
Cell and tissue nanomechanics, being inspired by progress in high-resolution physical mapping, has recently burst into biomedical research, discovering not only new characteristics of normal and diseased tissues, but also unveiling previously unknown mechanisms of pathological processes. Some parallels can be drawn between early development and carcinogenesis. Early embryogenesis, up to the blastocyst stage, requires a soft microenvironment and internal mechanical signals induced by the contractility of the cortical actomyosin cytoskeleton, stimulating quick cell divisions. During further development from the blastocyst implantation to placenta formation, decidua stiffness is increased ten-fold when compared to non-pregnant endometrium. Organogenesis is mediated by mechanosignaling inspired by intercellular junction formation with the involvement of mechanotransduction from the extracellular matrix (ECM). Carcinogenesis dramatically changes the mechanical properties of cells and their microenvironment, generally reproducing the structural properties and molecular organization of embryonic tissues, but with a higher stiffness of the ECM and higher cellular softness and fluidity. These changes are associated with the complete rearrangement of the entire tissue skeleton involving the ECM, cytoskeleton, and the nuclear scaffold, all integrated with each other in a joint network. The important changes occur in the cancer stem-cell niche responsible for tumor promotion and metastatic growth. We expect that the promising concept based on the natural selection of cancer cells fixing the most invasive phenotypes and genotypes by reciprocal regulation through ECM-mediated nanomechanical feedback loop can be exploited to create new therapeutic strategies for cancer treatment.
Collapse
Affiliation(s)
- Mikhail E. Shmelev
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Sergei I. Titov
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Andrei S. Belousov
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Vladislav M. Farniev
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Valeriia M. Zhmenia
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Daria V. Lanskikh
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Alina O. Penkova
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
| | - Vadim V. Kumeiko
- Institute of Life Sciences and Biomedicine, Far Eastern Federal University, 690922 Vladivostok, Russia; (M.E.S.); (S.I.T.); (A.S.B.); (V.M.F.); (V.M.Z.); (D.V.L.); (A.O.P.)
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, Russia
- Correspondence: ; Tel.: +7-9-02-555-1821
| |
Collapse
|
17
|
Enhancing membrane-based soft materials with magnetic reconfiguration events. Sci Rep 2022; 12:1703. [PMID: 35105905 PMCID: PMC8807651 DOI: 10.1038/s41598-022-05501-7] [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] [Received: 09/17/2021] [Accepted: 01/12/2022] [Indexed: 11/08/2022] Open
Abstract
Adaptive and bioinspired droplet-based materials are built using the droplet interface bilayer (DIB) technique, assembling networks of lipid membranes through adhered microdroplets. The properties of these lipid membranes are linked to the properties of the droplets forming the interface. Consequently, rearranging the relative positions of the droplets within the network will also alter the properties of the lipid membranes formed between them, modifying the transmembrane exchanges between neighboring compartments. In this work, we achieved this through the use of magnetic fluids or ferrofluids selectively dispersed within the droplet-phase of DIB structures. First, the ferrofluid DIB properties are optimized for reconfiguration using a coupled experimental-computational approach, exploring the ideal parameters for droplet manipulation through magnetic fields. Next, these findings are applied towards larger, magnetically-heterogeneous collections of DIBs to investigate magnetically-driven reconfiguration events. Activating electromagnets bordering the DIB networks generates rearrangement events by separating and reforming the interfacial membranes bordering the dispersed magnetic compartments. These findings enable the production of dynamic droplet networks capable of modifying their underlying membranous architecture through magnetic forces.
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
El-Beyrouthy J, Freeman E. Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology. MEMBRANES 2021; 11:319. [PMID: 33925756 PMCID: PMC8145864 DOI: 10.3390/membranes11050319] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/22/2021] [Accepted: 04/25/2021] [Indexed: 11/16/2022]
Abstract
The cell membrane is a protective barrier whose configuration determines the exchange both between intracellular and extracellular regions and within the cell itself. Consequently, characterizing membrane properties and interactions is essential for advancements in topics such as limiting nanoparticle cytotoxicity. Characterization is often accomplished by recreating model membranes that approximate the structure of cellular membranes in a controlled environment, formed using self-assembly principles. The selected method for membrane creation influences the properties of the membrane assembly, including their response to electric fields used for characterizing transmembrane exchanges. When these self-assembled model membranes are combined with electrophysiology, it is possible to exploit their non-physiological mechanics to enable additional measurements of membrane interactions and phenomena. This review describes several common model membranes including liposomes, pore-spanning membranes, solid supported membranes, and emulsion-based membranes, emphasizing their varying structure due to the selected mode of production. Next, electrophysiology techniques that exploit these structures are discussed, including conductance measurements, electrowetting and electrocompression analysis, and electroimpedance spectroscopy. The focus of this review is linking each membrane assembly technique to the properties of the resulting membrane, discussing how these properties enable alternative electrophysiological approaches to measuring membrane characteristics and interactions.
Collapse
Affiliation(s)
| | - Eric Freeman
- School of Environmental, Civil, Agricultural and Mechanical Engineering, College of Engineering, University of Georgia, Athens, GA 30602, USA;
| |
Collapse
|
20
|
Iwamoto M, Oiki S. Hysteresis of a Tension-Sensitive K + Channel Revealed by Time-Lapse Tension Measurements. JACS AU 2021; 1:467-474. [PMID: 34467309 PMCID: PMC8395652 DOI: 10.1021/jacsau.0c00098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Indexed: 05/05/2023]
Abstract
Various types of channels vary their function by membrane tension changes upon cellular activities, and lipid bilayer methods allow elucidation of direct interaction between channels and the lipid bilayer. However, the dynamic responsiveness of the channel to the membrane tension remains elusive. Here, we established a time-lapse tension measurement system. A bilayer is formed by docking two monolayer-lined water bubbles, and tension is evaluated via measuring intrabubble pressure as low as <100 Pa (Young-Laplace principle). The prototypical KcsA potassium channel is tension-sensitive, and single-channel current recordings showed that the activation gate exhibited distinct tension sensitivity upon stretching and relaxing. The mechanism underlying the hysteresis is discussed in the mode shift regime, in which the channel protein bears short "memory" in their conformational changes.
Collapse
Affiliation(s)
- Masayuki Iwamoto
- Department
of Molecular Neuroscience, University of
Fukui Faculty of Medical Science, 910-1193 Fukui, Japan
| | - Shigetoshi Oiki
- Biomedical
Imaging Research Center, University of Fukui, 910-1193 Fukui, Japan
| |
Collapse
|
21
|
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.
Collapse
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
| |
Collapse
|
22
|
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]
|
23
|
Rofeh J, Theogarajan L. Instantaneous tension measurements in droplet interface bilayers using an inexpensive, integrated pendant drop camera. SOFT MATTER 2020; 16:4484-4493. [PMID: 32337523 DOI: 10.1039/d0sm00418a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, droplet interface bilayers (DIBs) have been used to determine bilayer tension and thickness in situ by automated image analysis using a microscope and an applied voltage. In this paper, we demonstrate improvements to these measurements by integrating an inexpensive pendant drop setup onto the microscope stage, which allows for simultaneous imaging of DIBs from both the bottom and side. By using pendant drop shape analysis in situ to determine the monolayer tension of the droplets, we avoid the reliance on applied voltages to determine tension. The integrated system also allows for direct measurement of both the major and minor diameter of the elliptical contact region, which produces a more direct measurement of the bilayer specific capacitance. Additionally, we demonstrate a technique for measuring the instantaneous monolayer tension of DIBs using shape analysis despite the assumed requirement for axial symmetry in pendant drop tensiometry. Compared to previous DIB measurements, the integrated pendant drop-microscope system provides improved accuracy accompanied by a fivefold to twentyfold improvement in precision while considerably decreasing the experiment time.
Collapse
Affiliation(s)
- Justin Rofeh
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Luke Theogarajan
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA.
| |
Collapse
|