51
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Tamaddoni N, Sarles SA. Toward cell-inspired materials that feel: measurements and modeling of mechanotransduction in droplet-based, multi-membrane arrays. BIOINSPIRATION & BIOMIMETICS 2016; 11:036008. [PMID: 27127199 DOI: 10.1088/1748-3190/11/3/036008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The droplet interface bilayer (DIB) was recently used to show that a 5 nm thick lipid membrane placed near a vibrating synthetic hair could transduce hair motion into electrical current. Herein, we study for the first time mechanoelectrical transduction of hair motion using multi-membrane DIB arrays formed with more than 2 droplets connected in series, and we introduce a transduction model to investigate how airflow across the hair generates current in a membrane-based hair cell. Measurements of sensing currents across every membrane in serial chains of up to 5 connected droplets demonstrate that perturbation of a single hair creates vibrations that propagate across several droplets, allowing for membranes that are not directly attached to the hair to still transduce its motion. Membranes positioned closest to the hair generate the largest currents, while those farther away produce less current due to energy loss from fluid damping. Inserting multiple hairs of different lengths into different droplets in the array yields sensing currents that exhibit multiple characteristic frequencies in addition to location specific current intensities, features that can be used to spatially localize mechanical perturbations. We also develop a transduction model that provides an order-of-magnitude approximation of the sensing current generated by a membrane in response to airflow across the hair. This model provides physical insights into how membrane-based materials can be used for sensing mechanical stimuli--just like nature does.
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Affiliation(s)
- Nima Tamaddoni
- Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, 1512 Middle Dr, 414 Dougherty Engr. Bldg., Knoxville, TN, 37996, USA
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52
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Chemical polyglycosylation and nanolitre detection enables single-molecule recapitulation of bacterial sugar export. Nat Chem 2016; 8:461-9. [DOI: 10.1038/nchem.2487] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/24/2016] [Indexed: 01/17/2023]
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53
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Booth MJ, Schild VR, Graham AD, Olof SN, Bayley H. Light-activated communication in synthetic tissues. SCIENCE ADVANCES 2016; 2:e1600056. [PMID: 27051884 PMCID: PMC4820383 DOI: 10.1126/sciadv.1600056] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/25/2016] [Indexed: 05/17/2023]
Abstract
We have previously used three-dimensional (3D) printing to prepare tissue-like materials in which picoliter aqueous compartments are separated by lipid bilayers. These printed droplets are elaborated into synthetic cells by using a tightly regulated in vitro transcription/translation system. A light-activated DNA promoter has been developed that can be used to turn on the expression of any gene within the synthetic cells. We used light activation to express protein pores in 3D-printed patterns within synthetic tissues. The pores are incorporated into specific bilayer interfaces and thereby mediate rapid, directional electrical communication between subsets of cells. Accordingly, we have developed a functional mimic of neuronal transmission that can be controlled in a precise way.
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54
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Schmidt J. Membrane platforms for biological nanopore sensing and sequencing. Curr Opin Biotechnol 2016; 39:17-27. [PMID: 26773300 DOI: 10.1016/j.copbio.2015.12.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 12/12/2022]
Abstract
In the past two decades, biological nanopores have been developed and explored for use in sensing applications as a result of their exquisite sensitivity and easily engineered, reproducible, and economically manufactured structures. Nanopore sensing has been shown to differentiate between highly similar analytes, measure polymer size, detect the presence of specific genes, and rapidly sequence nucleic acids translocating through the pore. Devices featuring protein nanopores have been limited in part by the membrane support containing the nanopore, the shortcomings of which have been addressed in recent work developing new materials, approaches, and apparatus resulting in membrane platforms featuring automatability and increased robustness, lifetime, and measurement throughput.
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Affiliation(s)
- Jacob Schmidt
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA.
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55
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Elani Y, Solvas XCI, Edel JB, Law RV, Ces O. Microfluidic generation of encapsulated droplet interface bilayer networks (multisomes) and their use as cell-like reactors. Chem Commun (Camb) 2016; 52:5961-4. [DOI: 10.1039/c6cc01434h] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a microfluidic device to incorporate bilayer networks inside droplets, we generate compartmentalised cell-like microreactors based on lipid membranes.
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Affiliation(s)
- Yuval Elani
- Department of Chemistry
- Imperial College London
- London SW7 2AZ
- UK
- Institute of Chemical Biology
| | | | - Joshua B. Edel
- Department of Chemistry
- Imperial College London
- London SW7 2AZ
- UK
- Institute of Chemical Biology
| | - Robert V. Law
- Department of Chemistry
- Imperial College London
- London SW7 2AZ
- UK
- Institute of Chemical Biology
| | - Oscar Ces
- Department of Chemistry
- Imperial College London
- London SW7 2AZ
- UK
- Institute of Chemical Biology
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56
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Carreras P, Elani Y, Law RV, Brooks NJ, Seddon JM, Ces O. A microfluidic platform for size-dependent generation of droplet interface bilayer networks on rails. BIOMICROFLUIDICS 2015; 9:064121. [PMID: 26759638 PMCID: PMC4698115 DOI: 10.1063/1.4938731] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/14/2015] [Indexed: 05/30/2023]
Abstract
Droplet interface bilayer (DIB) networks are emerging as a cornerstone technology for the bottom up construction of cell-like and tissue-like structures and bio-devices. They are an exciting and versatile model-membrane platform, seeing increasing use in the disciplines of synthetic biology, chemical biology, and membrane biophysics. DIBs are formed when lipid-coated water-in-oil droplets are brought together-oil is excluded from the interface, resulting in a bilayer. Perhaps the greatest feature of the DIB platform is the ability to generate bilayer networks by connecting multiple droplets together, which can in turn be used in applications ranging from tissue mimics, multicellular models, and bio-devices. For such applications, the construction and release of DIB networks of defined size and composition on-demand is crucial. We have developed a droplet-based microfluidic method for the generation of different sized DIB networks (300-1500 pl droplets) on-chip. We do this by employing a droplet-on-rails strategy where droplets are guided down designated paths of a chip with the aid of microfabricated grooves or "rails," and droplets of set sizes are selectively directed to specific rails using auxiliary flows. In this way we can uniquely produce parallel bilayer networks of defined sizes. By trapping several droplets in a rail, extended DIB networks containing up to 20 sequential bilayers could be constructed. The trapped DIB arrays can be composed of different lipid types and can be released on-demand and regenerated within seconds. We show that chemical signals can be propagated across the bio-network by transplanting enzymatic reaction cascades for inter-droplet communication.
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Affiliation(s)
- P Carreras
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Y Elani
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - R V Law
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - N J Brooks
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - J M Seddon
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - O Ces
- Department of Chemistry and Institute of Chemical Biology , Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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57
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Lagny TJ, Bassereau P. Bioinspired membrane-based systems for a physical approach of cell organization and dynamics: usefulness and limitations. Interface Focus 2015; 5:20150038. [PMID: 26464792 PMCID: PMC4590427 DOI: 10.1098/rsfs.2015.0038] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Being at the periphery of each cell compartment and enclosing the entire cell while interacting with a large part of cell components, cell membranes participate in most of the cell's vital functions. Biologists have worked for a long time on deciphering how membranes are organized, how they contribute to trafficking, motility, cytokinesis, cell-cell communication, information transport, etc., using top-down approaches and always more advanced techniques. In contrast, physicists have developed bottom-up approaches and minimal model membrane systems of growing complexity in order to build up general models that explain how cell membranes work and how they interact with proteins, e.g. the cytoskeleton. We review the different model membrane systems that are currently available, and how they can help deciphering cell functioning, but also list their limitations. Model membrane systems are also used in synthetic biology and can have potential applications beyond basic research. We discuss the possible synergy between the development of complex in vitro membrane systems in a biological context and for technological applications. Questions that could also be discussed are: what can we still do with synthetic systems, where do we stop building up and which are the alternative solutions?
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Affiliation(s)
- Thibaut J Lagny
- Institut Curie, PSL Research University , Laboratory PhysicoChimie Curie , 75248 Paris, Cedex 05 , France ; CNRS , UMR168, 75248 Paris, Cedex 05 , France ; Université Pierre et Marie Curie , 75252 Paris, Cedex 05 , France
| | - Patricia Bassereau
- Institut Curie, PSL Research University , Laboratory PhysicoChimie Curie , 75248 Paris, Cedex 05 , France ; CNRS , UMR168, 75248 Paris, Cedex 05 , France ; Université Pierre et Marie Curie , 75252 Paris, Cedex 05 , France
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58
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Syeda R, Xu J, Dubin AE, Coste B, Mathur J, Huynh T, Matzen J, Lao J, Tully DC, Engels IH, Petrassi HM, Schumacher AM, Montal M, Bandell M, Patapoutian A. Chemical activation of the mechanotransduction channel Piezo1. eLife 2015; 4. [PMID: 26001275 PMCID: PMC4456433 DOI: 10.7554/elife.07369] [Citation(s) in RCA: 395] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 05/08/2015] [Indexed: 12/24/2022] Open
Abstract
Piezo ion channels are activated by various types of mechanical stimuli and function as biological pressure sensors in both vertebrates and invertebrates. To date, mechanical stimuli are the only means to activate Piezo ion channels and whether other modes of activation exist is not known. In this study, we screened ∼3.25 million compounds using a cell-based fluorescence assay and identified a synthetic small molecule we termed Yoda1 that acts as an agonist for both human and mouse Piezo1. Functional studies in cells revealed that Yoda1 affects the sensitivity and the inactivation kinetics of mechanically induced responses. Characterization of Yoda1 in artificial droplet lipid bilayers showed that Yoda1 activates purified Piezo1 channels in the absence of other cellular components. Our studies demonstrate that Piezo1 is amenable to chemical activation and raise the possibility that endogenous Piezo1 agonists might exist. Yoda1 will serve as a key tool compound to study Piezo1 regulation and function. DOI:http://dx.doi.org/10.7554/eLife.07369.001 Within our bodies, cells and tissues are constantly being pushed and pulled by their surrounding environment. These mechanical forces are then transformed into electrical or chemical signals by cells. This process is crucial for many biological structures, such as blood vessels, to develop correctly, and is also a key part of our senses of touch and hearing. In 2010, researchers discovered a group of ion channels—proteins embedded in the membrane that surrounds a cell—that open up when a force is applied and allow ions such as calcium, potassium, and sodium to flow. This movement of ions generates the electrical response of the cell to the applied force. However, not much is known about how these ‘Piezo’ ion channels work. To investigate this, it is important to be able to precisely control how and when the Piezo channels open. Many other ion channels are studied by using small chemical compounds to activate them, but there were none that were known to act on Piezo proteins. Syeda et al.—including some of the researchers involved in the 2010 work—screened over three million compounds for their ability to cause calcium ions to flow into human cells to try to identify chemicals that activate the Piezo channels. This revealed one promising candidate named Yoda1, which specifically activated Piezo1: a Piezo protein that had previously been linked to a role in blood vessel development in embryos. To investigate how Yoda1 activates Piezo1, Syeda et al. placed Piezo1 in an artificial cell membrane that did not contain any other cellular components. When Yoda1 was added to this set up, the Piezo1 channels opened up. This suggests that Piezo1 and Yoda1 interact in a manner that does not require additional cellular components other than a cell membrane. Separate work by Cahalan, Lukacs et al. uses Yoda1 to reveal that Piezo1 helps to control the volume of red blood cells, showing that in the future, Yoda1 could be valuable in research that investigates the roles of Piezo1. DOI:http://dx.doi.org/10.7554/eLife.07369.002
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Affiliation(s)
- Ruhma Syeda
- Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Jie Xu
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Adrienne E Dubin
- Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Bertrand Coste
- Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
| | - Jayanti Mathur
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Truc Huynh
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Jason Matzen
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Jianmin Lao
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - David C Tully
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Ingo H Engels
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - H Michael Petrassi
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Andrew M Schumacher
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Mauricio Montal
- University of California, San Diego, La Jolla, United States
| | - Michael Bandell
- Genomics Institute of the Novartis Research Foundation, San Diego, United States
| | - Ardem Patapoutian
- Department of Molecular and Cellular Neuroscience, Howard Hughes Medical Institute, The Scripps Research Institute, La Jolla, United States
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59
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Hirano-Iwata A, Ishinari Y, Yamamoto H, Niwano M. Micro- and Nano-Technologies for Lipid Bilayer-Based Ion-Channel Functional Assays. Chem Asian J 2015; 10:1266-74. [DOI: 10.1002/asia.201403391] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Ayumi Hirano-Iwata
- CREST (Japan) Science and Technology Agency (JST); 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
| | - Yutaka Ishinari
- CREST (Japan) Science and Technology Agency (JST); 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
| | - Hideaki Yamamoto
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
- Frontier Research Institute for Interdisciplinary Sciences; Tohoku University; 6-3 Aoba Aramaki, Aoba-ku Sendai 980-8578 Japan
| | - Michio Niwano
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
- Laboratory for Nanoelectronics and Spintronics; Research Institute of Electrical Communication; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
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60
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Czekalska MA, Kaminski TS, Jakiela S, Tanuj Sapra K, Bayley H, Garstecki P. A droplet microfluidic system for sequential generation of lipid bilayers and transmembrane electrical recordings. LAB ON A CHIP 2015; 15:541-8. [PMID: 25412368 DOI: 10.1039/c4lc00985a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This paper demonstrates a microfluidic system that automates i) formation of a lipid bilayer at the interface between a pair of nanoliter-sized aqueous droplets in oil, ii) exchange of one droplet of the pair to form a new bilayer, and iii) current measurements on single proteins. A new microfluidic architecture is introduced - a set of traps designed to localize the droplets with respect to each other and with respect to the recording electrodes. The system allows for automated execution of experimental protocols by active control of the flow on chip with the use of simple external valves. Formation of stable artificial lipid bilayers, incorporation of α-hemolysin into the bilayers and electrical measurements of ionic transport through the protein pore are demonstrated.
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Affiliation(s)
- Magdalena A Czekalska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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61
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Weatherill EE, Wallace MI. Combining Single-Molecule Imaging and Single-Channel Electrophysiology. J Mol Biol 2015; 427:146-57. [DOI: 10.1016/j.jmb.2014.07.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/07/2014] [Accepted: 07/07/2014] [Indexed: 12/29/2022]
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62
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63
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Beales PA, Ciani B, Cleasby AJ. Nature's lessons in design: nanomachines to scaffold, remodel and shape membrane compartments. Phys Chem Chem Phys 2015; 17:15489-507. [DOI: 10.1039/c5cp00480b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our understanding of the membrane sculpting capabilities of proteins from experimental model systems could be used to construct functional compartmentalised architectures for the engineering of synthetic cells.
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Affiliation(s)
- Paul A. Beales
- School of Chemistry and Astbury Centre for Structural Molecular Biology
- University of Leeds
- Leeds LS2 9JT
- UK
| | - Barbara Ciani
- Centre for Membrane Interaction and Dynamics
- Department of Chemistry
- University of Sheffield
- Sheffield S3 7HF
- UK
| | - Alexa J. Cleasby
- Centre for Membrane Interaction and Dynamics
- Department of Chemistry
- University of Sheffield
- Sheffield S3 7HF
- UK
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64
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Taylor GJ, Sarles SA. Heating-enabled formation of droplet interface bilayers using Escherichia coli total lipid extract. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:325-37. [PMID: 25514167 DOI: 10.1021/la503471m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Droplet interface bilayers (DIBs) serve as a convenient platform to study interactions between synthetic lipid membranes and proteins. However, a majority of DIBs have been assembled using a single lipid type, diphytanoylphosphatidylcholine (DPhPC). The work described herein establishes a new method to assemble DIBs using total lipid extract from Escherichia coli (eTLE); it is found that incubating oil-submerged aqueous droplets containing eTLE liposomes at a temperature above the gel-fluid phase transition temperature (Tg) promotes monolayer self-assembly that does not occur below Tg. Once monolayers are properly assembled via heating, droplets can be directly connected or cooled below Tg and then connected to initiate bilayer formation. This outcome contrasts immediate droplet coalescence observed upon contact between nonheated eTLE-infused droplets. Specific capacitance measurements confirm that the interface between droplets containing eTLE lipids is a lipid bilayer with thickness of 29.6 Å at 25 °C in hexadecane. We observe that bilayers formed from eTLE or DPhPC survive cooling and heating between 25 and 50 °C and demonstrate gigaohm (GΩ) membrane resistances at all temperatures tested. Additionally, we study the insertion of alamethicin peptides into both eTLE and DPhPC membranes to understand how lipid composition, temperature, and membrane phase influence ion channel formation. Like in DPhPC bilayers, alamethicin peptides in eTLE exhibit discrete, voltage-dependent gating characterized by multiple open channel conductance levels, though at significantly lower applied voltages. Cyclic voltammetry measurements of macroscopic channel currents confirm that the voltage-dependent conductance of alamethicin channels in eTLE bilayers occurs at lower voltages than in DPhPC bilayers at equivalent peptide concentrations. This result suggests that eTLE membranes, via composition, fluidity, or the presence of subdomains, offer an environment that enhances alamethicin insertion. For both membrane compositions, increasing temperature reduces the lifetimes of single channel gating events and increases the voltage required to cause an exponential increase in channel current. However, the fact that alamethicin insertion in eTLE exhibits significantly greater sensitivity to temperature changes through its Tg suggests that membrane phase plays an important role in channel formation. These effects are much less severe in DPhPC, where heating from 25 to 50 °C does not induce a phase change. The described technique for heating-assisted monolayer formation permits the use of other high transition temperature lipids in aqueous droplets for DIB formation, thereby increasing the types of lipids that can be considered for assembling model membranes.
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Affiliation(s)
- Graham J Taylor
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States
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65
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High-throughput formation of lipid bilayer membrane arrays with an asymmetric lipid composition. Sci Rep 2014; 4:7076. [PMID: 25399694 PMCID: PMC4233334 DOI: 10.1038/srep07076] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 10/30/2014] [Indexed: 12/02/2022] Open
Abstract
We present a micro-device in which more than 10,000 asymmetric lipid bilayer membranes are formed at a time on micro-chamber arrays. The arrayed asymmetric lipid bilayers, where lipid compositions are different between the inner and outer leaflets, are formed with high efficiency of over 97% by injecting several types of liquids into a micro-device that has hydrophilic-in-hydrophobic surfaces. The lipid compositional asymmetry is an intrinsic property of bio-membranes, and therefore, this micro-device extends the versatility of artificial lipid-bilayer systems, which were previously limited to symmetric bilayer formation, and could contribute to the understanding of the role of lipid compositional asymmetry in cell physiology and also to further analytical and pharmacological applications.
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66
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Vesicle-based artificial cells as chemical microreactors with spatially segregated reaction pathways. Nat Commun 2014; 5:5305. [DOI: 10.1038/ncomms6305] [Citation(s) in RCA: 299] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/17/2014] [Indexed: 11/08/2022] Open
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67
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Yanez Arteta M, Ainalem ML, Porcar L, Martel A, Coker H, Lundberg D, Chang DP, Soltwedel O, Barker R, Nylander T. Interactions of PAMAM Dendrimers with Negatively Charged Model Biomembranes. J Phys Chem B 2014; 118:12892-906. [DOI: 10.1021/jp506510s] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Marianna Yanez Arteta
- Physical
Chemistry, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden
| | | | - Lionel Porcar
- Institut Laue-Langevin, 71 avenue
des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Anne Martel
- Institut Laue-Langevin, 71 avenue
des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Helena Coker
- Institut Laue-Langevin, 71 avenue
des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Dan Lundberg
- Physical
Chemistry, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden
- CR
Competence AB, Center for Chemistry and Chemical Engineering, SE-221
00 Lund, Sweden
| | - Debby P. Chang
- Physical
Chemistry, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden
| | - Olaf Soltwedel
- Max-Planck-Institute
for Solid State Research, Outstation at MLZ, Lichtenbergstr.
1, 85747 Garching, Germany
| | - Robert Barker
- Institut Laue-Langevin, 71 avenue
des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Tommy Nylander
- Physical
Chemistry, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden
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68
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Braun CJ, Baer T, Moroni A, Thiel G. Pseudo painting/air bubble technique for planar lipid bilayers. J Neurosci Methods 2014; 233:13-7. [DOI: 10.1016/j.jneumeth.2014.05.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 05/21/2014] [Accepted: 05/24/2014] [Indexed: 10/25/2022]
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69
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Mruetusatorn P, Boreyko JB, Venkatesan GA, Sarles SA, Hayes DG, Collier CP. Dynamic morphologies of microscale droplet interface bilayers. SOFT MATTER 2014; 10:2530-2538. [PMID: 24647872 DOI: 10.1039/c3sm53032a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Droplet interface bilayers (DIBs) are a powerful platform for studying the dynamics of synthetic cellular membranes; however, very little has been done to exploit the unique dynamical features of DIBs. Here, we generate microscale droplet interface bilayers (μDIBs) by bringing together femtoliter-volume water droplets in a microfluidic oil channel, and characterize morphological changes of the μDIBs as the droplets shrink due to evaporation. By varying the initial conditions of the system, we identify three distinct classes of dynamic morphology. (1) Buckling and fission: when forming μDIBs using the lipid-out method (lipids in oil phase), lipids in the shrinking monolayers continually pair together and slide into the bilayer to conserve their mass. As the bilayer continues to grow, it becomes confined, buckles, and eventually fissions one or more vesicles. (2) Uniform shrinking: when using the lipid-in method (lipids in water phase) to form μDIBs, lipids uniformly transfer from the monolayers and bilayer into vesicles contained inside the water droplets. (3) Stretching and unzipping: finally, when the droplets are pinned to the wall(s) of the microfluidic channel, the droplets become stretched during evaporation, culminating in the unzipping of the bilayer and droplet separation. These findings offer a better understanding of the dynamics of coupled lipid interfaces.
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Affiliation(s)
- Prachya Mruetusatorn
- Department of Biosystems Engineering & Soil Science, The University of Tennessee, Knoxville, Tennessee 37996, USA
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70
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King PH, Jones G, Morgan H, de Planque MRR, Zauner KP. Interdroplet bilayer arrays in millifluidic droplet traps from 3D-printed moulds. LAB ON A CHIP 2014; 14:722-9. [PMID: 24336841 DOI: 10.1039/c3lc51072g] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In droplet microfluidics, aqueous droplets are typically separated by an oil phase to ensure containment of molecules in individual droplets of nano-to-picoliter volume. An interesting variation of this method involves bringing two phospholipid-coated droplets into contact to form a lipid bilayer in-between the droplets. These interdroplet bilayers, created by manual pipetting of microliter droplets, have proved advantageous for the study of membrane transport phenomena, including ion channel electrophysiology. In this study, we adapted the droplet microfluidics methodology to achieve automated formation of interdroplet lipid bilayer arrays. We developed a 'millifluidic' chip for microliter droplet generation and droplet packing, which is cast from a 3D-printed mould. Droplets of 0.7-6.0 μL volume were packed as homogeneous or heterogeneous linear arrays of 2-9 droplets that were stable for at least six hours. The interdroplet bilayers had an area of up to 0.56 mm(2), or an equivalent diameter of up to 850 μm, as determined from capacitance measurements. We observed osmotic water transfer over the bilayers as well as sequential bilayer lysis by the pore-forming toxin melittin. These millifluidic interdroplet bilayer arrays combine the ease of electrical and optical access of manually pipetted microdroplets with the automation and reproducibility of microfluidic technologies. Moreover, the 3D-printing based fabrication strategy enables the rapid implementation of alternative channel geometries, e.g. branched arrays, with a design-to-device time of just 24-48 hours.
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Affiliation(s)
- Philip H King
- Electronics and Computer Science & Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
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71
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Wauer T, Gerlach H, Mantri S, Hill J, Bayley H, Sapra KT. Construction and manipulation of functional three-dimensional droplet networks. ACS NANO 2014; 8:771-9. [PMID: 24341760 DOI: 10.1021/nn405433y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Previously, we reported the manual assembly of lipid-coated aqueous droplets in oil to form two-dimensional (2D) networks in which the droplets are connected through single lipid bilayers. Here we assemble lipid-coated droplets in robust, freestanding 3D geometries: for example, a 14-droplet pyramidal assembly. The networks are designed, and each droplet is placed in a designated position. When protein pores are inserted in the bilayers between specific constituent droplets, electrical and chemical communication pathways are generated. We further describe an improved means to construct 3D droplet networks with defined organizations by the manipulation of aqueous droplets containing encapsulated magnetic beads. The droplets are maneuvered in a magnetic field to form simple construction modules, which are then used to form larger 2D and 3D structures including a 10-droplet pyramid. A methodology to construct freestanding, functional 3D droplet networks is an important step toward the programmed and automated manufacture of synthetic minimal tissues.
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Affiliation(s)
- Tobias Wauer
- Department of Chemistry, University of Oxford , Oxford OX1 3TA, United Kingdom
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72
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Tsuji Y, Kawano R, Osaki T, Kamiya K, Miki N, Takeuchi S. Droplet Split-and-Contact Method for High-Throughput Transmembrane Electrical Recording. Anal Chem 2013; 85:10913-9. [DOI: 10.1021/ac402299z] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Yutaro Tsuji
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
- Department
of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi,
Kohoku-ku, Yokohama 223-8522, Japan
| | - Ryuji Kawano
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
| | - Toshihisa Osaki
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
| | - Koki Kamiya
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
| | - Norihisa Miki
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
- Department
of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi,
Kohoku-ku, Yokohama 223-8522, Japan
| | - Shoji Takeuchi
- Artificial
Cell
Membrane System Group, Kanagawa Academy of Science and Technology (KAST), 3-2-1
Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
- CIRMM-IIS, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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73
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Hydrogel-stabilized droplet bilayers for high speed solution exchange. Sci Rep 2013; 3:3139. [PMID: 24190577 PMCID: PMC3817439 DOI: 10.1038/srep03139] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 10/18/2013] [Indexed: 11/18/2022] Open
Abstract
Many applications utilizing artificial lipid bilayers require the ability to exchange the bilayer's solution environment. However, because of the instability of the bilayer, the rate of solution exchange is limited, which significantly hinders the measurement rate and throughput. We have developed an artificial bilayer system that can withstand high flow speeds, up to 2.1 m/s, by supporting the bilayer with a hydrogel. We demonstrated the ability to measure during flow by measuring the conductance of gramicidin-A channels while switching between solutions of two different compositions, recording a time to measure 90% change in current of approximately 2.7 seconds at a flow rate of 0.1 m/s. We also demonstrated a potential application of this system by measuring the conductance modulation of the rat TRPM8 ion channel by an agonist and antagonist at varying concentrations, obtaining 7-point IC50 and EC50 values in approximately 7 minutes and 4-point values within 4 minutes.
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74
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Stochastic detection of Pim protein kinases reveals electrostatically enhanced association of a peptide substrate. Proc Natl Acad Sci U S A 2013; 110:E4417-26. [PMID: 24194548 DOI: 10.1073/pnas.1312739110] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In stochastic sensing, the association and dissociation of analyte molecules is observed as the modulation of an ionic current flowing through a single engineered protein pore, enabling the label-free determination of rate and equilibrium constants with respect to a specific binding site. We engineered sensors based on the staphylococcal α-hemolysin pore to allow the single-molecule detection and characterization of protein kinase-peptide interactions. We enhanced this approach by using site-specific proteolysis to generate pores bearing a single peptide sensor element attached by an N-terminal peptide bond to the trans mouth of the pore. Kinetics and affinities for the Pim protein kinases (Pim-1, Pim-2, and Pim-3) and cAMP-dependent protein kinase were measured and found to be independent of membrane potential and in good agreement with previously reported data. Kinase binding exhibited a distinct current noise behavior that forms a basis for analyte discrimination. Finally, we observed unusually high association rate constants for the interaction of Pim kinases with their consensus substrate Pimtide (~10(7) to 10(8) M(-1) · s(-1)), the result of electrostatic enhancement, and propose a cellular role for this phenomenon.
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75
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Kawano R, Tsuji Y, Sato K, Osaki T, Kamiya K, Hirano M, Ide T, Miki N, Takeuchi S. Automated parallel recordings of topologically identified single ion channels. Sci Rep 2013; 3:1995. [PMID: 23771282 PMCID: PMC3683667 DOI: 10.1038/srep01995] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 05/30/2013] [Indexed: 02/07/2023] Open
Abstract
Although ion channels are attractive targets for drug discovery, the systematic screening of ion channel-targeted drugs remains challenging. To facilitate automated single ion-channel recordings for the analysis of drug interactions with the intra- and extracellular domain, we have developed a parallel recording methodology using artificial cell membranes. The use of stable lipid bilayer formation in droplet chamber arrays facilitated automated, parallel, single-channel recording from reconstituted native and mutated ion channels. Using this system, several types of ion channels, including mutated forms, were characterised by determining the protein orientation. In addition, we provide evidence that both intra- and extracellular amyloid-beta fragments directly inhibit the channel open probability of the hBK channel. This automated methodology provides a high-throughput drug screening system for the targeting of ion channels and a data-intensive analysis technique for studying ion channel gating mechanisms.
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Affiliation(s)
- Ryuji Kawano
- BioMicrosystems Project, Kanagawa Academy of Science and Technology (KAST), Kawasaki, Japan
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76
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Abstract
Realization of a functional artificial cell, the so-called protocell, is a major challenge posed by synthetic biology. A subsequent goal is to use the protocellular units for the bottom-up assembly of prototissues. There is, however, a looming chasm in our knowledge between protocells and prototissues. In the present paper, we give a brief overview of the work on protocells to date, followed by a discussion on the rational design of key structural elements specific to linking two protocellular bilayers. We propose that designing synthetic parts capable of simultaneous insertion into two bilayers may be crucial in the hierarchical assembly of protocells into a functional prototissue.
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77
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Leptihn S, Castell OK, Cronin B, Lee EH, Gross LCM, Marshall DP, Thompson JR, Holden M, Wallace MI. Constructing droplet interface bilayers from the contact of aqueous droplets in oil. Nat Protoc 2013; 8:1048-57. [DOI: 10.1038/nprot.2013.061] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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78
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Tsuji Y, Kawano R, Osaki T, Kamiya K, Miki N, Takeuchi S. Droplet-based lipid bilayer system integrated with microfluidic channels for solution exchange. LAB ON A CHIP 2013; 13:1476-81. [PMID: 23450304 DOI: 10.1039/c3lc41359d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This paper proposes a solution exchange of a droplet-based lipid bilayer system, in which the inner solution of a droplet is replaced for the purpose of efficient ion channel analyses. In our previous report, we successfully recorded the channel conductance of alpha-hemolysin in a bilayer lipid membrane using a droplet contact method that can create a spontaneous lipid bilayer at the interface of contacting droplets; this method is widely used as highly efficient method for preparing planar lipid membranes. When only pipetting droplets of the solution, this method is highly efficient for preparing lipid membranes. However, the drawback of droplet-based systems is their inability to exchange the solution within the droplets. To study the effect of inhibitors and promoters of ion channels in drug discovery, it would be beneficial to conduct a solution exchange of droplets to introduce membrane proteins and to apply or wash-out the chemicals. In this study, we propose a droplet contact method that allows for the solution exchange of droplets via microfluidic channels. We experimentally and numerically investigated the bilayer stability with respect to exchanging flow rates, and then demonstrated a binding assay of an alpha-hemolysin using one of its blockers. The solution exchange in this system was conducted in less than 20 s without rupturing the membrane. We believe that the proposed system will enhance the efficiency of ion channel analyses.
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Affiliation(s)
- Yutaro Tsuji
- Kanagawa Academy of Science and Technology (KAST), KSP EAST 303, 3-2-1, Sakado, Kawasaki, Kanagawa, Japan
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79
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Oshima A, Hirano-Iwata A, Mozumi H, Ishinari Y, Kimura Y, Niwano M. Reconstitution of Human Ether-a-go-go-Related Gene Channels in Microfabricated Silicon Chips. Anal Chem 2013; 85:4363-9. [DOI: 10.1021/ac303484k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Azusa Oshima
- Graduate School of Biomedical
Engineering, Tohoku University, 6-6 Aoba,
Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Ayumi Hirano-Iwata
- Graduate School of Biomedical
Engineering, Tohoku University, 6-6 Aoba,
Aramaki, Aoba-ku, Sendai 980-8579, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi,
Saitama 332-0012, Japan
| | - Hideki Mozumi
- Graduate School of Biomedical
Engineering, Tohoku University, 6-6 Aoba,
Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Yutaka Ishinari
- Graduate School of Biomedical
Engineering, Tohoku University, 6-6 Aoba,
Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Yasuo Kimura
- Laboratory
for Nanoelectronics
and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai,
Miyagi 980-8577, Japan
| | - Michio Niwano
- Graduate School of Biomedical
Engineering, Tohoku University, 6-6 Aoba,
Aramaki, Aoba-ku, Sendai 980-8579, Japan
- Laboratory
for Nanoelectronics
and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai,
Miyagi 980-8577, Japan
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80
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Boreyko JB, Mruetusatorn P, Sarles SA, Retterer ST, Collier CP. Evaporation-Induced Buckling and Fission of Microscale Droplet Interface Bilayers. J Am Chem Soc 2013; 135:5545-8. [DOI: 10.1021/ja4019435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jonathan B. Boreyko
- Center for
Nanophase Materials Sciences and ‡Biological and Nanoscale Systems Group, Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, United States
- Department of Biosystems Engineering & Soil Science and ⊥Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Prachya Mruetusatorn
- Center for
Nanophase Materials Sciences and ‡Biological and Nanoscale Systems Group, Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, United States
- Department of Biosystems Engineering & Soil Science and ⊥Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Stephen A. Sarles
- Center for
Nanophase Materials Sciences and ‡Biological and Nanoscale Systems Group, Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, United States
- Department of Biosystems Engineering & Soil Science and ⊥Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Scott T. Retterer
- Center for
Nanophase Materials Sciences and ‡Biological and Nanoscale Systems Group, Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, United States
- Department of Biosystems Engineering & Soil Science and ⊥Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - C. Patrick Collier
- Center for
Nanophase Materials Sciences and ‡Biological and Nanoscale Systems Group, Oak Ridge National Laboratory, Oak Ridge,
Tennessee 37831, United States
- Department of Biosystems Engineering & Soil Science and ⊥Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
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81
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Friddin MS, Morgan H, de Planque MRR. Cell-free protein expression systems in microdroplets: Stabilization of interdroplet bilayers. BIOMICROFLUIDICS 2013; 7:14108. [PMID: 24404000 PMCID: PMC3579860 DOI: 10.1063/1.4791651] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/29/2013] [Indexed: 05/29/2023]
Abstract
Cell-free protein expression with bacterial lysates has been demonstrated to produce soluble proteins in microdroplets. However, droplet assays with expressed membrane proteins require the presence of a lipid bilayer. A bilayer can be formed in between lipid-coated aqueous droplets by bringing these into contact by electrokinetic manipulation in a continuous oil phase, but it is not known whether such interdroplet bilayers are compatible with high concentrations of biomolecules. In this study, we have characterized the lifetime and the structural integrity of interdroplet bilayers by measuring the bilayer current in the presence of three different commercial cell-free expression mixtures and their individual components. Samples of pure proteins and of a polymer were included for comparison. It is shown that complete expression mixtures reduce the bilayer lifetime to several minutes or less, and that this is mainly due to the lysate fraction itself. The fraction that contains the molecules for metabolic energy generation does not reduce the bilayer lifetime but does give rise to current steps that are indicative of lipid packing defects. Gel electrophoresis confirmed that proteins are only present at significant amounts in the lysate fractions and, when supplied separately, in the T7 enzyme mixture. Interestingly, it was also found that pure-protein and pure-polymer solutions perturb the interdroplet bilayer at higher concentrations; 10% (w/v) polyethylene glycol 8000 (PEG 8000) and 3 mM lysozyme induce large bilayer currents without a reduction in bilayer lifetime, whereas 3 mM albumin causes rapid bilayer failure. It can, therefore, be concluded that the high protein content of the lysates and the presence of PEG polymer, a typical lysate supplement, compromise the structural integrity of interdroplet bilayers. However, we established that the addition of lipid vesicles to the cell-free expression mixture stabilizes the interdroplet bilayer, allowing the exposure of interdroplet bilayers to cell-free expression solutions. Given that cell-free expressed membrane proteins can insert in lipid bilayers, we envisage that microdroplet technology may be extended to the study of in situ expressed membrane receptors and ion channels.
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Affiliation(s)
- Mark S Friddin
- Electronics and Computer Science and Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Hywel Morgan
- Electronics and Computer Science and Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Maurits R R de Planque
- Electronics and Computer Science and Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
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82
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Friddin MS, Smithers NP, Beaugrand M, Marcotte I, Williamson PTF, Morgan H, de Planque MRR. Single-channel electrophysiology of cell-free expressed ion channels by direct incorporation in lipid bilayers. Analyst 2013; 138:7294-8. [DOI: 10.1039/c3an01540h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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83
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Kendall EL, Shao C, DeVoe DL. Visualizing the growth and dynamics of liquid-ordered domains during lipid bilayer folding in a microfluidic chip. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3613-3619. [PMID: 22888063 DOI: 10.1002/smll.201200831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/29/2012] [Indexed: 06/01/2023]
Abstract
A microfluidic platform enabling optical monitoring of bilayer lipid membrane formation by a new monolayer folding process is described. The thermoplastic chips integrate dried lipid films that are rehydrated by microfluidic perfusion, which enables delivery of lipid-laden air bubbles across a membrane-supporting aperture. As in traditional Montal-Mueller bilayer formation, lipid monolayers are delivered independently to each side of the aperture, thereby allowing asymmetric lipid composition in the resulting bilayer to be achieved. Confocal microscopy is used to image the monolayer folding process, and reveals the growth and dynamics of asymmetric liquid-ordered domains during bilayer stabilization.
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Affiliation(s)
- Eric L Kendall
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
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84
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Sapra KT, Bayley H. Lipid-coated hydrogel shapes as components of electrical circuits and mechanical devices. Sci Rep 2012; 2:848. [PMID: 23152939 PMCID: PMC3497031 DOI: 10.1038/srep00848] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 10/30/2012] [Indexed: 11/20/2022] Open
Abstract
Recently, two-dimensional networks of aqueous droplets separated by lipid bilayers, with engineered protein pores as functional elements, were used to construct millimeter-sized devices such as a light sensor, a battery, and half- and full-wave rectifiers. Here, for the first time, we show that hydrogel shapes, coated with lipid monolayers, can be used as building blocks for such networks, yielding scalable electrical circuits and mechanical devices. Examples include a mechanical switch, a rotor driven by a magnetic field and painted circuits, analogous to printed circuit boards, made with centimeter-length agarose wires. Bottom-up fabrication with lipid-coated hydrogel shapes is therefore a useful step towards the synthetic biology of functional devices including minimal tissues.
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Affiliation(s)
- K Tanuj Sapra
- Department of Chemistry, University of Oxford, Oxford, UK.
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85
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Boersma AJ, Bayley H. Continuous stochastic detection of amino acid enantiomers with a protein nanopore. Angew Chem Int Ed Engl 2012; 51:9606-9. [PMID: 22930401 DOI: 10.1002/anie.201205687] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Indexed: 11/07/2022]
Affiliation(s)
- Arnold J Boersma
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
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86
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Boersma AJ, Bayley H. Continuous Stochastic Detection of Amino Acid Enantiomers with a Protein Nanopore. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205687] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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87
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Proteopolymersomes: in vitro production of a membrane protein in polymersome membranes. Biointerphases 2012; 6:153-7. [PMID: 22239807 DOI: 10.1116/1.3644384] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Polymersomes are stable self-assembled architectures which mimic cell membranes. For characterization, membrane proteins can be incorporated into such bio-mimetic membranes by reconstitution methods, leading to so-called proteopolymersomes. In this work, we demonstrate the direct incorporation of a membrane protein into polymersome membranes by a cell-free expression system. Firstly, we demonstrate pore formation in the preformed polymersome membrane using α-hemolysin. Secondly, we use claudin-2, a protein involved in cell-cell interactions, to demonstrate the in vitro expression of a membrane protein into these polymersomes. Surface plasmon resonance (Biacore) binding studies with the claudin-2 proteopolymersomes and claudin-2 specific antibodies are performed to show the presence of the in vitro expressed protein in polymersome membranes.
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88
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Tan Q, Ritzo B, Tian K, Gu LQ. Tuning the tetraethylammonium sensitivity of potassium channel Kcv by subunit combination. ACTA ACUST UNITED AC 2012; 139:295-304. [PMID: 22450486 PMCID: PMC3315146 DOI: 10.1085/jgp.201110725] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tetraethylammonium (TEA) is a potassium (K+) channel inhibitor that has been extensively used as a molecular probe to explore the structure of channels’ ion pathway. In this study, we identified that Leu70 of the virus-encoded potassium channel Kcv is a key amino acid that plays an important role in regulating the channel’s TEA sensitivity. Site-directed mutagenesis of Leu70 can change the TEA sensitivity by 1,000-fold from ∼100 µM to ∼100 mM. Because no compelling trends exist to explain this amino acid’s specific interaction with TEA, the role of Leu70 at the binding site is likely to ensure an optimal conformation of the extracellular mouth that confers high TEA affinity. We further assembled the subunits of mutant and wt-Kcv into a series of heterotetramers. The differences in these heterochannels suggest that all of the four subunits in a Kcv channel additively participate in the TEA binding, and each of the four residues at the binding site independently contributes an equal binding energy. We therefore can present a series of mutant/wild-type tetramer combinations that can probe TEA over three orders of magnitude in concentration. This study may give insight into the mechanism for the interaction between the potassium channel and its inhibitor.
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Affiliation(s)
- Qiulin Tan
- Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA
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89
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El-Arabi AM, Salazar CS, Schmidt JJ. Ion channel drug potency assay with an artificial bilayer chip. LAB ON A CHIP 2012; 12:2409-2413. [PMID: 22549308 DOI: 10.1039/c2lc40087a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The potency of pharmaceutical compounds acting on ion channels can be determined through measurements of ion channel conductance as a function of compound concentration. We have developed an artificial lipid bilayer chip for simple, fast, and high-yield measurement of ion channel conductance with simultaneous solution perfusion. Here we show the application of this chip to the measurement of the mammalian cold and menthol receptor TRPM8. Ensemble measurements of TRPM8 as a function of concentration of menthol and 2-aminoethoxydiphenyl borate (2-APB) enabled efficient determination of menthol's EC(50) (111.8 μM ± 2.4 μM) and 2-APB's IC(50) (4.9 μM ± 0.2 μM) in agreement with published values. This validation, coupled with the compatibility of this platform with automation and parallelization, indicates significant potential for large-scale pharmaceutical ion channel screening.
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Affiliation(s)
- Ahmad M El-Arabi
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
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90
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Zagnoni M. Miniaturised technologies for the development of artificial lipid bilayer systems. LAB ON A CHIP 2012; 12:1026-1039. [PMID: 22301684 DOI: 10.1039/c2lc20991h] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Artificially reproducing cellular environments is a key aim of synthetic biology, which has the potential to greatly enhance our understanding of cellular mechanisms. Microfluidic and lab-on-a-chip (LOC) techniques, which enable the controlled handling of sub-microlitre volumes of fluids in an automated and high-throughput manner, can play a major role in achieving this by offering alternative and powerful methodologies in an on-chip format. Such techniques have been successfully employed over the last twenty years to provide innovative solutions for chemical analysis and cell-, molecular- and synthetic- biology. In the context of the latter, the formation of artificial cell membranes (or artificial lipid bilayers) that incorporate membrane proteins within miniaturised LOC architectures offers huge potential for the development of highly sensitive molecular sensors and drug screening applications. The aim of this review is to give a comprehensive and critical overview of the field of microsystems for creating and exploiting artificial lipid bilayers. Advantages and limitations of three of the most popular approaches, namely suspended, supported and droplet-based lipid bilayers, are discussed. Examples are reported that show how artificial cell membrane microsystems, by combining together biological procedures and engineering techniques, can provide novel methodologies for basic biological and biophysical research and for the development of biotechnology tools.
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Affiliation(s)
- Michele Zagnoni
- Centre for Microsystems and Photonics, University of Strathclyde, Glasgow, UK.
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91
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Martel A, Cross B. Handling of artificial membranes using electrowetting-actuated droplets on a microfluidic device combined with integrated pA-measurements. BIOMICROFLUIDICS 2012; 6:12813-128137. [PMID: 22662080 PMCID: PMC3365332 DOI: 10.1063/1.3665719] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 11/14/2011] [Indexed: 06/01/2023]
Abstract
Artificial membranes, as a controllable environment, are an essential tool to study membrane proteins. Electrophysiology provides information about the ion transport mechanism across a membrane at the single-protein level. Unfortunately, high-throughput studies and screening are not accessible to electrophysiology because it is a set of not automated and technically delicate methods. Therefore, it is necessary to automate and parallelize electrophysiology measurement in artificial membranes. Here, we present a first step toward this goal: the fabrication and characterization of a microfluidic device integrating electrophysiology measurements and the handling of an artificial membrane which includes its formation, its displacement and the separation of its leaflets using electrowetting actuation of sub-μL droplets. To validate this device, we recorded the insertion of a model porin, α-hemolysin.
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92
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Castell OK, Berridge J, Wallace MI. Quantification of Membrane Protein Inhibition by Optical Ion Flux in a Droplet Interface Bilayer Array. Angew Chem Int Ed Engl 2012; 51:3134-8. [DOI: 10.1002/anie.201107343] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 01/24/2012] [Indexed: 01/01/2023]
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93
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Castell OK, Berridge J, Wallace MI. Quantification of Membrane Protein Inhibition by Optical Ion Flux in a Droplet Interface Bilayer Array. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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94
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Rotem D, Jayasinghe L, Salichou M, Bayley H. Protein detection by nanopores equipped with aptamers. J Am Chem Soc 2012; 134:2781-7. [PMID: 22229655 PMCID: PMC3278221 DOI: 10.1021/ja2105653] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
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Protein nanopores have been used as stochastic sensors
for the
detection of analytes that range from small molecules to proteins.
In this approach, individual analyte molecules modulate the ionic
current flowing through a single nanopore. Here, a new type of stochastic
sensor based on an αHL pore modified with an aptamer is described.
The aptamer is bound to the pore by hybridization to an oligonucleotide
that is attached covalently through a disulfide bond to a single cysteine
residue near a mouth of the pore. We show that the binding of thrombin
to a 15-mer DNA aptamer, which forms a cation-stabilized quadruplex,
alters the ionic current through the pore. The approach allows the
quantification of nanomolar concentrations of thrombin, and provides
association and dissociation rate constants and equilibrium dissociation
constants for thrombin·aptamer interactions. Aptamer-based nanopores
have the potential to be integrated into arrays for the parallel detection
of multiple analytes.
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Affiliation(s)
- Dvir Rotem
- Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom
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95
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Chuah K, Lai LMH, Goon IY, Parker SG, Amal R, Justin Gooding J. Ultrasensitive electrochemical detection of prostate-specific antigen (PSA) using gold-coated magnetic nanoparticles as ‘dispersible electrodes’. Chem Commun (Camb) 2012; 48:3503-5. [DOI: 10.1039/c2cc30512g] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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96
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Steller L, Kreir M, Salzer R. Natural and artificial ion channels for biosensing platforms. Anal Bioanal Chem 2011; 402:209-30. [PMID: 22080413 DOI: 10.1007/s00216-011-5517-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 10/14/2011] [Accepted: 10/18/2011] [Indexed: 10/15/2022]
Abstract
The single-molecule selectivity and specificity of the binding process together with the expected intrinsic gain factor obtained when utilizing flow through a channel have attracted the attention of analytical chemists for two decades. Sensitive and selective ion channel biosensors for high-throughput screening are having an increasing impact on modern medical care, drug screening, environmental monitoring, food safety, and biowarefare control. Even virus antigens can be detected by ion channel biosensors. The study of ion channels and other transmembrane proteins is expected to lead to the development of new medications and therapies for a wide range of illnesses. From the first attempts to use membrane proteins as the receptive part of a sensor, ion channels have been engineered as chemical sensors. Several other types of peptidic or nonpeptidic channels have been investigated. Various gating mechanisms have been implemented in their pores. Three technical problems had to be solved to achieve practical biosensors based on ion channels: the fabrication of stable lipid bilayer membranes, the incorporation of a receptor into such a structure, and the marriage of the modified membrane to a transducer. The current status of these three areas of research, together with typical applications of ion-channel biosensors, are discussed in this review.
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Affiliation(s)
- L Steller
- Department of Magnetic and Acoustic Resonances, Leibniz Institute for Solid State and Materials Research, Dresden, Germany.
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97
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Harms ZD, Mogensen KB, Nunes PS, Zhou K, Hildenbrand BW, Mitra I, Tan Z, Zlotnick A, Kutter JP, Jacobson SC. Nanofluidic devices with two pores in series for resistive-pulse sensing of single virus capsids. Anal Chem 2011; 83:9573-8. [PMID: 22029283 DOI: 10.1021/ac202358t] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report fabrication and characterization of nanochannel devices with two nanopores in series for resistive-pulse sensing of hepatitis B virus (HBV) capsids. The nanochannel and two pores are patterned by electron beam lithography between two microchannels and etched by reactive ion etching. The two nanopores are 50-nm wide, 50-nm deep, and 40-nm long and are spaced 2.0-μm apart. The nanochannel that brackets the two pores is 20× wider (1 μm) to reduce the electrical resistance adjacent to the two pores and to ensure the current returns to its baseline value between resistive-pulse events. Average pulse amplitudes differ by <2% between the two pores and demonstrate that the fabrication technique is able to produce pores with nearly identical geometries. Because the two nanopores in series sense single particles at two discrete locations, particle properties, e.g., electrophoretic mobility, are determined from the pore-to-pore transit time.
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Affiliation(s)
- Zachary D Harms
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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98
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Villar G, Heron AJ, Bayley H. Formation of droplet networks that function in aqueous environments. NATURE NANOTECHNOLOGY 2011; 6:803-8. [PMID: 22056724 PMCID: PMC3390173 DOI: 10.1038/nnano.2011.183] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/27/2011] [Indexed: 05/02/2023]
Abstract
Aqueous droplets in oil that are coated with lipid monolayers and joined through interface bilayers are useful for biophysical measurements on membrane proteins. Functional networks of droplets that can act as light sensors, batteries and electrical components can also be made by incorporating pumps, channels and pores into the bilayers. These networks of droplets mimic simple tissues, but so far have not been used in physiological environments because they have been constrained to a bulk oil phase. Here, we form structures called multisomes in which networks of aqueous droplets with defined compositions are encapsulated within small drops of oil in water. The encapsulated droplets adhere to one another and to the surface of the oil drop to form interface bilayers that allow them to communicate with each other and with the surrounding aqueous environment through membrane pores. The contents in the droplets can be released by changing the pH or temperature of the surrounding solution. The multicompartment framework of multisomes mimics a tissue and has potential applications in synthetic biology and medicine.
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Affiliation(s)
- Gabriel Villar
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Andrew J. Heron
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
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99
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Heitz BA, Xu J, Jones IW, Keogh JP, Comi TJ, Hall HK, Aspinwall CA, Saavedra SS. Polymerized planar suspended lipid bilayers for single ion channel recordings: comparison of several dienoyl lipids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1882-90. [PMID: 21226498 PMCID: PMC3043114 DOI: 10.1021/la1025944] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The stabilization of suspended planar lipid membranes, or black lipid membranes (BLMs), through polymerization of mono- and bis-functionalized dienoyl lipids was investigated. Electrical properties, including capacitance, conductance, and dielectric breakdown voltage, were determined for BLMs composed of mono-DenPC, bis-DenPC, mono-SorbPC, and bis-SorbPC both prior to and following photopolymerization, with diphytanoyl phosphocholine (DPhPC) serving as a control. Poly(lipid) BLMs exhibited significantly longer lifetimes and increased the stability of air-water transfers. BLM stability followed the order bis-DenPC > mono-DenPC ≈ mono-SorbPC > bis-SorbPC. The conductance of bis-SorbPC BLMs was significantly higher than that of the other lipids, which is attributed to a high density of hydrophilic pores, resulting in relatively unstable membranes. The use of poly(lipid) BLMs as matrices for supporting the activity of an ion channel protein (IC) was explored using α-hemolysin (α-HL), a model IC. Characteristic i-V plots of α-HL were maintained following photopolymerization of bis-DenPC, mono-DenPC, and mono-SorbPC, demonstrating the utility of these materials for preparing more durable BLMs for single-channel recordings of reconstituted ICs.
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Affiliation(s)
- Benjamin A. Heitz
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - Juhua Xu
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - Ian W. Jones
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - John P. Keogh
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - Troy J. Comi
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - Henry K. Hall
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
| | - S. Scott Saavedra
- Department of Chemistry and Biochemistry and BIO5 Institute, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721
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100
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Demarche S, Sugihara K, Zambelli T, Tiefenauer L, Vörös J. Techniques for recording reconstituted ion channels. Analyst 2011; 136:1077-89. [PMID: 21267480 DOI: 10.1039/c0an00828a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review describes and discusses techniques useful for monitoring the activity of protein ion channels in vitro. In the first section the biological importance and the classification of ion channels are outlined in order to justify the strong motivation for dealing with this important class of membrane proteins. The expression, reconstitution and integration of recombinant proteins into lipid bilayers are crucial steps to obtain consistent data when working with ion channels. In the second section recording techniques used in research are presented. Since this review focuses on analytical systems bearing reconstituted ion channels the industrial most important patch-clamp techniques of cells are only briefly mentioned. In section three, artificial systems developed in the last decades are described while the emerging technologies using nanostructured supports or microfluidic systems are presented in section four. Finally, the remaining challenges of membrane protein analysis and its potential applications are briefly outlined.
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Affiliation(s)
- Sophie Demarche
- Biomolecular Research, Paul Scherrer Institut (PSI), CH-5232 Villigen, Switzerland
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