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Lapizco-Encinas BH. Nonlinear Electrokinetic Methods of Particles and Cells. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2024; 17:243-264. [PMID: 38360552 DOI: 10.1146/annurev-anchem-061622-040810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Nonlinear electrokinetic phenomena offer label-free, portable, and robust approaches for particle and cell assessment, including selective enrichment, separation, sorting, and characterization. The field of electrokinetics has evolved substantially since the first separation reports by Arne Tiselius in the 1930s. The last century witnessed major advances in the understanding of the weak-field theory, which supported developments in the use of linear electrophoresis and its adoption as a routine analytical technique. More recently, an improved understanding of the strong-field theory enabled the development of nonlinear electrokinetic techniques such as electrorotation, dielectrophoresis, and nonlinear electrophoresis. This review discusses the operating principles and recent applications of these three nonlinear electrokinetic phenomena for the analysis and manipulation of particles and cells and provides an overview of some of the latest developments in the field of nonlinear electrokinetics.
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Affiliation(s)
- Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA;
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2
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Biquet-Bisquert A, Carrio B, Meyer N, Fernandes TFD, Abkarian M, Seduk F, Magalon A, Nord AL, Pedaci F. Spatiotemporal dynamics of the proton motive force on single bacterial cells. SCIENCE ADVANCES 2024; 10:eadl5849. [PMID: 38781330 PMCID: PMC11114223 DOI: 10.1126/sciadv.adl5849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/18/2024] [Indexed: 05/25/2024]
Abstract
Electrochemical gradients across biological membranes are vital for cellular bioenergetics. In bacteria, the proton motive force (PMF) drives essential processes like adenosine triphosphate production and motility. Traditionally viewed as temporally and spatially stable, recent research reveals a dynamic PMF behavior at both single-cell and community levels. Moreover, the observed lateral segregation of respiratory complexes could suggest a spatial heterogeneity of the PMF. Using a light-activated proton pump and detecting the activity of the bacterial flagellar motor, we perturb and probe the PMF of single cells. Spatially homogeneous PMF perturbations reveal millisecond-scale temporal dynamics and an asymmetrical capacitive response. Localized perturbations show a rapid lateral PMF homogenization, faster than proton diffusion, akin to the electrotonic potential spread observed in passive neurons, explained by cable theory. These observations imply a global coupling between PMF sources and consumers along the membrane, precluding sustained PMF spatial heterogeneity but allowing for rapid temporal changes.
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Affiliation(s)
- Anaïs Biquet-Bisquert
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Baptiste Carrio
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Nathan Meyer
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Thales F. D. Fernandes
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Manouk Abkarian
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Farida Seduk
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402 Marseille, France
| | - Axel Magalon
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402 Marseille, France
| | - Ashley L. Nord
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Francesco Pedaci
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
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Mansor MA, Ahmad MR, Petrů M, Rahimian Koloor SS. An impedance flow cytometry with integrated dual microneedle for electrical properties characterization of single cell. ARTIFICIAL CELLS, NANOMEDICINE, AND BIOTECHNOLOGY 2023; 51:371-383. [PMID: 37548425 DOI: 10.1080/21691401.2023.2239274] [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: 03/27/2023] [Revised: 07/10/2023] [Accepted: 07/12/2023] [Indexed: 08/08/2023]
Abstract
Electrical characteristics of living cells have been proven to reveal important details about their internal structure, charge distribution and composition changes in the cell membrane, as well as the extracellular context. An impedance flow cytometry is a common approach to determine the electrical properties of a cell, having the advantage of label-free and high throughput. However, the current techniques are complex and costly for the fabrication process. For that reason, we introduce an integrated dual microneedle-microchannel for single-cell detection and electrical properties extraction. The dual microneedles utilized a commercially available tungsten needle coated with parylene. When a single cell flows through the parallel-facing electrode configuration of the dual microneedle, the electrical impedance at multiple frequencies is measured. The impedance measurement demonstrated the differential of normal red blood cells (RBCs) with three different sizes of microbeads at low and high frequencies, 100 kHz and 2 MHz, respectively. An electrical equivalent circuit model (ECM) was used to determine the unique membrane capacitance of individual cells. The proposed technique demonstrated that the specific membrane capacitance of an RBC is 9.42 mF/m-2, with the regression coefficients, ρ at 0.9895. As a result, this device may potentially be used in developing countries for low-cost single-cell screening and detection.
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Affiliation(s)
- Muhammad Asraf Mansor
- Department of Control and Mechatronics Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai, Malaysia
| | - Mohd Ridzuan Ahmad
- Department of Control and Mechatronics Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai, Malaysia
| | - Michal Petrů
- Faculty of Mechanical Engineering, Technical University of Liberec, Liberec, Czech Republic
| | - Seyed Saeid Rahimian Koloor
- Institute for Nanomaterials, Advanced Technologies and Innovation, Technical University of Liberec, Liberec, Czech Republic
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Belleville P, Merlin G, Ramousse J, Deseure J. Characterization of spatiotemporal electroactive anodic biofilm activity distribution using 1D simulations. Sci Rep 2022; 12:5849. [PMID: 35393459 PMCID: PMC8990003 DOI: 10.1038/s41598-022-09596-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 03/14/2022] [Indexed: 11/17/2022] Open
Abstract
Activity distribution limitation in electroactive biofilm remains an unclear phenomenon. Some observations using confocal microscopy have shown notable difference between activity close to the anode and activity at the liquid interface. A numerical model is developed in this work to describe biofilm growth and local biomass segregation in electroactive biofilm. Under our model hypothesis, metabolic activity distribution in the biofilm results from the competition between two limiting factors: acetate diffusion and electronic conduction in the biofilm. Influence of inactive biomass fraction (i.e. non-growing biomass fraction) properties (such as conductivity and density) is simulated to show variation in local biomass distribution. Introducing a dependence of effective diffusion to local density leads to a drastic biomass fraction segregation. Increasing density of inactive fraction reduces significantly acetate diffusion in biofilm, enhances biomass activity on the outer layer (liquid/biofilm interface) and maintains inner core largely inactive. High inactive fraction conductivity enhances biomass activity in the outer layer and enhances current production. Hence, investment in extracellular polymer substance (EPS), anchoring redox components, is benefit for biofilm electroactivity. However, under our model hypothesis it means that conductivity should be two order lower than biofilm conductivity reported in order to observe inner core active biomass segregation.
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Affiliation(s)
- Pierre Belleville
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.,Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Gerard Merlin
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.,Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Julien Ramousse
- Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Jonathan Deseure
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.
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Péter B, Farkas E, Kurunczi S, Szittner Z, Bősze S, Ramsden JJ, Szekacs I, Horvath R. Review of Label-Free Monitoring of Bacteria: From Challenging Practical Applications to Basic Research Perspectives. BIOSENSORS 2022; 12:bios12040188. [PMID: 35448248 PMCID: PMC9026780 DOI: 10.3390/bios12040188] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/07/2022] [Accepted: 03/11/2022] [Indexed: 05/10/2023]
Abstract
Novel biosensors already provide a fast way to detect the adhesion of whole bacteria (or parts of them), biofilm formation, and the effect of antibiotics. Moreover, the detection sensitivities of recent sensor technologies are large enough to investigate molecular-scale biological processes. Usually, these measurements can be performed in real time without using labeling. Despite these excellent capabilities summarized in the present work, the application of novel, label-free sensor technologies in basic biological research is still rare; the literature is dominated by heuristic work, mostly monitoring the presence and amount of a given analyte. The aims of this review are (i) to give an overview of the present status of label-free biosensors in bacteria monitoring, and (ii) to summarize potential novel directions with biological relevancies to initiate future development. Optical, mechanical, and electrical sensing technologies are all discussed with their detailed capabilities in bacteria monitoring. In order to review potential future applications of the outlined techniques in bacteria research, we summarize the most important kinetic processes relevant to the adhesion and survival of bacterial cells. These processes are potential targets of kinetic investigations employing modern label-free technologies in order to reveal new fundamental aspects. Resistance to antibacterials and to other antimicrobial agents, the most important biological mechanisms in bacterial adhesion and strategies to control adhesion, as well as bacteria-mammalian host cell interactions are all discussed with key relevancies to the future development and applications of biosensors.
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Affiliation(s)
- Beatrix Péter
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
- Correspondence: (B.P.); (R.H.)
| | - Eniko Farkas
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
| | - Sandor Kurunczi
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
| | - Zoltán Szittner
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
| | - Szilvia Bősze
- MTA-ELTE Research Group of Peptide Chemistry, Eötvös Loránd Research Network (ELKH), Institute of Chemistry, Eötvös Loránd University, 1120 Budapest, Hungary;
- National Public Health Center, 1097 Budapest, Hungary
| | - Jeremy J. Ramsden
- Clore Laboratory, Department of Biomedical Research, University of Buckingham, Buckingham MK18 1AD, UK;
| | - Inna Szekacs
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
| | - Robert Horvath
- Nanobiosensorics Laboratory, Centre for Energy Research, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (S.K.); (Z.S.); (I.S.)
- Correspondence: (B.P.); (R.H.)
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Zhang F, Wang S, Yang Y, Jiang J, Tao N. Imaging Single Bacterial Cells with Electro-optical Impedance Microscopy. ACS Sens 2021; 6:348-354. [PMID: 32456424 DOI: 10.1021/acssensors.0c00751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Impedance measurements have been an important tool for biosensor applications, including protein detection, DNA quantification, and cell study. We present here an electro-optical impedance microscopy (EIM) based on the dependence of surface optical transmission on local surface charge density for single bacteria impedance imaging. We applied a potential modulation to bacteria placed on an indium tin oxide-coated slide and simultaneously recorded a sequence of transmitted microscopy images. By performing fast Fourier transform analysis on the image sequences, we obtained the DC component (signal at 0 Hz) for cell morphology imaging and the AC component (signal at the modulation frequency) for the mapping of cell impedance responses with subcellular resolution for the first time. Using this method, we have monitored the viability of Escherichia coli bacterial cells under treatment with two different classes of antibiotics with low-frequency potential modulation. The results showed that the impedance response is sensitive to the antibiotic that targets the bacterial cell membrane as the membrane capacitance dominated at low-frequency modulation. Heterogeneous responses to the antibiotic treatment were observed at a single bacteria level. In addition to the high spatial resolution, EIM is label-free and simple and can be potentially used for the continuous mapping of single bacteria impedance changes under different conditions.
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Affiliation(s)
- Fenni Zhang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287-5801, United States
| | - Shaopeng Wang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287-5801, United States
| | - Yunze Yang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287-5801, United States
| | - Jiapei Jiang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287-5801, United States
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, United States
| | - Nongjian Tao
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287-5801, United States
- School of Electrical Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, United States
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7
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Yamaguchi Y, Yamamoto T. One-Dimensional Flow of Bacteria on an Electrode Rail by Dielectrophoresis: Toward Single-Cell-Based Analysis. MICROMACHINES 2021; 12:mi12020123. [PMID: 33498919 PMCID: PMC7911595 DOI: 10.3390/mi12020123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/17/2021] [Accepted: 01/21/2021] [Indexed: 12/15/2022]
Abstract
Many applications in biotechnology and medicine, among other disciplines, require the rapid enumeration of bacteria, preferably using miniaturized portable devices. Microfluidic technology is expected to solve this miniaturization issue. In the enumeration of bacteria in microfluidic devices, the technique of aligning bacteria in a single line prior to counting is the key to an accurate count at single-bacterium resolution. Here, we describe the numerical and experimental evaluation of a device utilizing a dielectrophoretic force to array bacteria in a single line, allowing their facile numeration. The device comprises a channel to flow bacteria, two counter electrodes, and a capture electrode several microns or less in width for arranging bacteria in a single line. When the capture electrode is narrower than the diameter of a bacterium, the entrapment efficiency of the one-dimensional array is 80% or more within 2 s. Furthermore, since some cell-sorting applications require bacteria to move against the liquid flow, we demonstrated that bacteria can move in a single line in the off-axial direction tilted 30° from the flow direction. Our findings provide the basis for designing miniature, portable devices for evaluating bacteria with single-cell accuracy.
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Çağlayan Z, Demircan Yalçın Y, Külah H. A Prominent Cell Manipulation Technique in BioMEMS: Dielectrophoresis. MICROMACHINES 2020; 11:E990. [PMID: 33153069 PMCID: PMC7693018 DOI: 10.3390/mi11110990] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/22/2020] [Accepted: 10/28/2020] [Indexed: 12/17/2022]
Abstract
BioMEMS, the biological and biomedical applications of micro-electro-mechanical systems (MEMS), has attracted considerable attention in recent years and has found widespread applications in disease detection, advanced diagnosis, therapy, drug delivery, implantable devices, and tissue engineering. One of the most essential and leading goals of the BioMEMS and biosensor technologies is to develop point-of-care (POC) testing systems to perform rapid prognostic or diagnostic tests at a patient site with high accuracy. Manipulation of particles in the analyte of interest is a vital task for POC and biosensor platforms. Dielectrophoresis (DEP), the induced movement of particles in a non-uniform electrical field due to polarization effects, is an accurate, fast, low-cost, and marker-free manipulation technique. It has been indicated as a promising method to characterize, isolate, transport, and trap various particles. The aim of this review is to provide fundamental theory and principles of DEP technique, to explain its importance for the BioMEMS and biosensor fields with detailed references to readers, and to identify and exemplify the application areas in biosensors and POC devices. Finally, the challenges faced in DEP-based systems and the future prospects are discussed.
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Affiliation(s)
- Zeynep Çağlayan
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06800, Turkey; (Z.Ç.); (Y.D.Y.)
- METU MEMS Research and Application Center, Ankara 06800, Turkey
| | - Yağmur Demircan Yalçın
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06800, Turkey; (Z.Ç.); (Y.D.Y.)
- Mikro Biyosistemler Electronics Inc., Ankara 06530, Turkey
| | - Haluk Külah
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06800, Turkey; (Z.Ç.); (Y.D.Y.)
- METU MEMS Research and Application Center, Ankara 06800, Turkey
- Mikro Biyosistemler Electronics Inc., Ankara 06530, Turkey
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Novickij V, Stanevičienė R, Staigvila G, Gruškienė R, Sereikaitė J, Girkontaitė I, Novickij J, Servienė E. Effects of pulsed electric fields and mild thermal treatment on antimicrobial efficacy of nisin-loaded pectin nanoparticles for food preservation. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2019.108915] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Checa M, Millan-Solsona R, Blanco N, Torrents E, Fabregas R, Gomila G. Mapping the dielectric constant of a single bacterial cell at the nanoscale with scanning dielectric force volume microscopy. NANOSCALE 2019; 11:20809-20819. [PMID: 31657419 DOI: 10.1039/c9nr07659j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mapping the dielectric constant at the nanoscale of samples showing a complex topography, such as non-planar nanocomposite materials or single cells, poses formidable challenges to existing nanoscale dielectric microscopy techniques. Here we overcome these limitations by introducing Scanning Dielectric Force Volume Microscopy. This scanning probe microscopy technique is based on the acquisition of electrostatic force approach curves at every point of a sample and its post-processing and quantification by using a computational model that incorporates the actual measured sample topography. The technique provides quantitative nanoscale images of the local dielectric constant of the sample with unparalleled accuracy, spatial resolution and statistical significance, irrespectively of the complexity of its topography. We illustrate the potential of the technique by presenting a nanoscale dielectric constant map of a single bacterial cell, including its small-scale appendages. The bacterial cell shows three characteristic equivalent dielectric constant values, namely, εr,bac1 = 2.6 ± 0.2, εr,bac2 = 3.6 ± 0.4 and εr,bac3 = 4.9 ± 0.5, which enable identifying different dielectric properties of the cell wall and of the cytoplasmatic region, as well as, the existence of variations in the dielectric constant along the bacterial cell wall itself. Scanning Dielectric Force Volume Microscopy is expected to have an important impact in Materials and Life Sciences where the mapping of the dielectric properties of samples showing complex nanoscale topographies is often needed.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Nuria Blanco
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Eduard Torrents
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Rene Fabregas
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
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11
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Conteduca D, Brunetti G, Dell'Olio F, Armenise MN, Krauss TF, Ciminelli C. Monitoring of individual bacteria using electro-photonic traps. BIOMEDICAL OPTICS EXPRESS 2019; 10:3463-3471. [PMID: 31467790 PMCID: PMC6706028 DOI: 10.1364/boe.10.003463] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 05/07/2023]
Abstract
Antimicrobial resistance (AMR) describes the ability of bacteria to become immune to antimicrobial treatments. Current testing for AMR is based on culturing methods that are very slow because they assess the average response of billions of bacteria. In principle, if tests were available that could assess the response of individual bacteria, they could be much faster. Here, we propose an electro-photonic approach for the analysis and the monitoring of susceptibility at the single-bacterium level. Our method employs optical tweezers based on photonic crystal cavities for the trapping of individual bacteria. While the bacteria are trapped, antibiotics can be added to the medium and the corresponding changes in the optical properties and motility of the bacteria be monitored via changes of the resonance wavelength and transmission. Furthermore, the proposed assay is able to monitor the impedance of the medium surrounding the bacterium, which allows us to record changes in metabolic rate in response to the antibiotic challenge. For example, our simulations predict a variation in measurable electrical current of up to 40% between dead and live bacteria. The proposed platform is the first, to our knowledge, that allows the parallel study of both the optical and the electrical response of individual bacteria to antibiotic challenge. Our platform opens up new lines of enquiry for monitoring the response of bacteria and it could lead the way towards the dissemination of a new generation of antibiogram study, which is relevant for the development of a point-of-care AMR diagnostics.
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Affiliation(s)
- Donato Conteduca
- Optoelectronics Laboratory, Politecnico di Bari, Via Orabona, 4, 70125, Bari, Italy
- Photonics Group, Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Giuseppe Brunetti
- Optoelectronics Laboratory, Politecnico di Bari, Via Orabona, 4, 70125, Bari, Italy
| | - Francesco Dell'Olio
- Optoelectronics Laboratory, Politecnico di Bari, Via Orabona, 4, 70125, Bari, Italy
| | - Mario N Armenise
- Optoelectronics Laboratory, Politecnico di Bari, Via Orabona, 4, 70125, Bari, Italy
| | - Thomas F Krauss
- Photonics Group, Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Caterina Ciminelli
- Optoelectronics Laboratory, Politecnico di Bari, Via Orabona, 4, 70125, Bari, Italy
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12
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Duarte LC, Figueredo F, Ribeiro LEB, Cortón E, Coltro WKT. Label-free counting of Escherichia coli cells in nanoliter droplets using 3D printed microfluidic devices with integrated contactless conductivity detection. Anal Chim Acta 2019; 1071:36-43. [PMID: 31128753 DOI: 10.1016/j.aca.2019.04.045] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/27/2019] [Accepted: 04/17/2019] [Indexed: 01/21/2023]
Abstract
This study describes for the first time the development of 3D printed microfluidic devices with integrated electrodes for label-free counting of E. coli cells incorporated inside droplets based on capacitively coupled contactless conductivity detection (C4D). Microfluidic devices were fully fabricated by 3D printing in the T-junction shape containing two channels for disperse and continuous phases and two sensing electrodes for C4D measurements. The disperse phase containing E. coli K12 cells and the continuous phase containing oil and 1% Span® 80 were pumped through flow rates fixed at 5 and 60 μL min-1, respectively. The droplets with incorporated cells were monitored in the C4D system applying a 500-kHz sinusoidal wave with 1 Vpp amplitude. The generated droplets exhibited a spherical shape with average diameter of 321 ± 9 μm and presented volume of 17.3 ± 0.5 nL. The proposed approach demonstrated ability to detect E. coli cells in the concentration range between 86.5 and 8650 CFU droplet-1. The number of cells per droplet was quantified through the plate counting method and revealed a good agreement with the Poisson distribution. The limit of detection achieved for counting E. coli cells was 63.66 CFU droplet-1. The label-free counting method has offered instrumental simplicity, low cost, high sensitivity and compatibility to be integrated on single microfluidic platforms entirely fabricated by 3D printing, thus opening new possibilities of applications in microbiology.
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Affiliation(s)
- Lucas C Duarte
- Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, 74690-900, Goiânia, GO, Brazil
| | - Federico Figueredo
- Laboratorio de Biosensores y Bioanalisis (LABB), Departamento de Química Biológica e IQUIBICEN-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina
| | - Luiz E B Ribeiro
- Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, 74690-900, Goiânia, GO, Brazil; Instituto Federal de Goiás - Campus Senador Canedo, 75250-000, Senador Canedo, GO, Brazil
| | - Eduardo Cortón
- Laboratorio de Biosensores y Bioanalisis (LABB), Departamento de Química Biológica e IQUIBICEN-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina
| | - Wendell K T Coltro
- Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, 74690-900, Goiânia, GO, Brazil; Instituto Nacional de Ciência e Tecnologia de Bioanalítica, 13084-971, Campinas, SP, Brazil.
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13
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Hilton SH, Hayes MA. A mathematical model of dielectrophoretic data to connect measurements with cell properties. Anal Bioanal Chem 2019; 411:2223-2237. [PMID: 30879117 PMCID: PMC6459731 DOI: 10.1007/s00216-019-01757-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/10/2019] [Accepted: 02/01/2019] [Indexed: 10/27/2022]
Abstract
Dielectrophoresis (DEP) brings about the high-resolution separations of cells and other bioparticles arising from very subtle differences in their properties. However, an unanticipated limitation has arisen: difficulty in assignment of specific biological features which vary between two cell populations. This hampers the ability to interpret the significance of the variations. To realize the opportunities made possible by dielectrophoresis, the data and the diversity of structures found in cells and bioparticles must be linked. While the crossover frequency in DEP has been studied in-depth and exploited in applications using AC fields, less attention has been given when a DC field is present. Here, a new mathematical model of dielectrophoretic data is introduced which connects the physical properties of cells to specific elements of the data from potential- or time-varied DEP experiments. The slope of the data in either analysis is related to the electrokinetic mobility, while the potential at which capture initiates in potential-based analysis is related to both the electrokinetic and dielectrophoretic mobilities. These mobilities can be assigned to cellular properties for which values appear in the literature. Representative examples of high and low values of properties such as conductivity, zeta potential, and surface charge density for bacteria including Streptococcus mutans, Rhodococcus erythropolis, Pasteurella multocida, Escherichia coli, and Staphylococcus aureus are considered. While the many properties of a cell collapse into one or two features of data, for a well-vetted system the model can indicate the extent of dissimilarity. The influence of individual properties on the features of dielectrophoretic data is summarized, allowing for further interpretation of data. Graphical abstract.
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Affiliation(s)
- Shannon Huey Hilton
- School of Molecular Sciences, Arizona State University, Mail Stop 1604, Tempe, AZ, 85281, USA
| | - Mark A Hayes
- School of Molecular Sciences, Arizona State University, Mail Stop 1604, Tempe, AZ, 85281, USA.
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14
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Zhao W, Cui W, Xu S, Cheong LZ, Wang D, Shen C. Direct study of the electrical properties of PC12 cells and hippocampal neurons by EFM and KPFM. NANOSCALE ADVANCES 2019; 1:537-545. [PMID: 36132273 PMCID: PMC9473159 DOI: 10.1039/c8na00202a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/19/2018] [Indexed: 05/30/2023]
Abstract
Electrical related properties play important roles in biological structures and functions. Herein, the capacitance gradient and local contact potential difference (CPD) of cell bodies and processes of PC12 cells (representative cells of the sympathetic nervous system), hippocampal neurons (representative cells of the central nervous system) and spines were investigated by Electrostatic Force Microscopy (EFM) and Kelvin Probe Force Microscopy (KPFM) at high lateral spatial resolution directly. The results demonstrate that the capacitance gradients of cell bodies, processes and spines of PC12 cells and hippocampal neurons are very close (in the range of 19-23 zF nm-1) and fit well with the theoretical calculation results (21.7 zF nm-1). This indicates that the differences of nerve signal activities and functions of the sympathetic and central nervous systems are not related to the electric polarization properties. The CPD of cell bodies and processes of PC12 cells is smaller than that of hippocampal neurons. The CPD of spines is much more negative than that of the cell bodies and processes. These results reveal that the surface potential is closely related to the neural signal transduction functions, and spines play vital roles in neural signal transmission. This work indicates the similarity (capacitance gradient) and differences (surface potential) of the electrical properties between the sympathetic and central nervous systems for the first time. The methods and results of this work are useful in the further study of the electrical properties in cellular activities and physiological processes.
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Affiliation(s)
- Weidong Zhao
- Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences 1219 Zhongguan Road Ningbo Zhejiang China
| | - Wei Cui
- Ningbo Key Laboratory of Behavioral Neuroscience, Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University Ningbo Zhejiang China
| | - Shujun Xu
- Ningbo Key Laboratory of Behavioral Neuroscience, Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University Ningbo Zhejiang China
| | - Ling-Zhi Cheong
- School of Marine Science, Ningbo University Ningbo 315211 China
| | - Deyu Wang
- Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences 1219 Zhongguan Road Ningbo Zhejiang China
| | - Cai Shen
- Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences 1219 Zhongguan Road Ningbo Zhejiang China
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15
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Rohani A, Moore JH, Su YH, Stagnaro V, Warren C, Swami NS. Single-cell electro-phenotyping for rapid assessment of Clostridium difficile heterogeneity under vancomycin treatment at sub-MIC (minimum inhibitory concentration) levels. SENSORS AND ACTUATORS. B, CHEMICAL 2018; 276:472-480. [PMID: 30369719 PMCID: PMC6201234 DOI: 10.1016/j.snb.2018.08.137] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Current methods for measurement of antibiotic susceptibility of pathogenic bacteria are highly reliant on microbial culture, which is time consuming (requires > 16 hours), especially at near minimum inhibitory concentration (MIC) levels of the antibiotic. We present the use of single-cell electrophysiology-based microbiological analysis for rapid phenotypic identification of antibiotic susceptibility at near-MIC levels, without the need for microbial culture. Clostridium difficile (C. difficile) is the single most common cause of antibiotic-induced enteric infection and disease recurrence is common after antibiotic treatments to suppress the pathogen. Herein, we show that de-activation of C. difficile after MIC-level vancomycin treatment, as validated by microbiological growth assays, can be ascertained rapidly by measuring alterations to the microbial cytoplasmic conductivity that is gauged by the level of positive dielectrophoresis (pDEP) and the frequency spectra for co-field electro-rotation (ROT). Furthermore, this single-cell electrophysiology technique can rapidly identify and quantify the live C. difficile subpopulation after vancomycin treatment at sub-MIC levels, whereas methods based on measurement of the secreted metabolite toxin or the microbiological growth rate can identify this persistent C. difficile subpopulation only after 24 hours of microbial culture, without any ability to quantify the subpopulation. The application of multiplexed versions of this technique is envisioned for antibiotic susceptibility screening.
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Affiliation(s)
- Ali Rohani
- Electrical & Computer Engineering, University of Virginia
| | - John H. Moore
- Electrical & Computer Engineering, University of Virginia
| | - Yi-Hsuan Su
- Electrical & Computer Engineering, University of Virginia
| | | | - Cirle Warren
- Infectious Diseases, School of Medicine, University of Virginia
| | - Nathan S. Swami
- Electrical & Computer Engineering, University of Virginia
- Corresponding author: 351 McCormick Road, Charlottesville, VA 22904-1000;
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16
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Chow YT, Man T, Acosta‐Vélez GF, Zhu X, Wen X, Chung P, Liu T“L, Wu BM, Chiou P. Liquid Metal-Based Multifunctional Micropipette for 4D Single Cell Manipulation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1700711. [PMID: 30027027 PMCID: PMC6051373 DOI: 10.1002/advs.201700711] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/12/2018] [Indexed: 05/30/2023]
Abstract
A novel manufacturing approach to fabricate liquid metal-based, multifunctional microcapillary pipettes able to provide electrodes with high electrical conductivity for high-frequency electrical stimulation and measurement is proposed. 4D single cell manipulation is realized by applying multifrequency, multiamplitude, and multiphase electrical signals to the microelectrodes near the pipette tip to create 3D dielectrophoretic trap and 1D electrorotation, simultaneously. Functions such as single cell trapping, patterning, transfer, and rotation are accomplished. Cell viability and multiday proliferation characterization has confirmed the biocompatibility of this approach. This is a simple, low-cost, and fast fabrication process that requires no cleanroom and photolithography step to manufacture 3D microelectrodes and microchannels for easy access to a wide user base for broad applications.
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Affiliation(s)
- Yu Ting Chow
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | - Tianxing Man
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | | | - Xiongfeng Zhu
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | - Ximiao Wen
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | - Pei‐Shan Chung
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | - Tingyi “Leo” Liu
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
| | - Benjamin M. Wu
- Bioengineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
- School of DentistryUniversity of CaliforniaLos AngelesCA90095USA
| | - Pei‐Yu Chiou
- Mechanical and Aerospace Engineering DepartmentUniversity of CaliforniaLos AngelesCA90095USA
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17
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Lyu C, Wang J, Powell-Palm M, Rubinsky B. Simultaneous electroporation and dielectrophoresis in non-electrolytic micro/nano-electroporation. Sci Rep 2018; 8:2481. [PMID: 29410434 PMCID: PMC5802840 DOI: 10.1038/s41598-018-20535-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/19/2018] [Indexed: 12/15/2022] Open
Abstract
It was recently shown that electrolysis may play a substantial detrimental role in microfluidic electroporation. To overcome this problem, we have developed a non-electrolytic micro/nano electroporation (NEME) electrode surface, in which the metal electrodes are coated with a dielectric. A COMSOL based numerical scheme was used to simultaneously calculate the excitation frequency and dielectric material properties dependent electric field delivered across the dielectric, fluid flow, electroporation field and Clausius-Mossotti factor for yeast and E. coli cells flowing in a channel flow across a NEME surface. A two-layer model for yeast and a three-layer model for E. coli was used. The numerical analysis shows that in NEME electroporation, the electric fields could induce electroporation and dielectrophoresis simultaneously. The simultaneous occurrence of electroporation and dielectrophoresis gives rise to several interesting phenomena. For example, we found that a certain frequency exists for which an intact yeast cell is drawn to the NEME electrode, and once electroporated, the yeast cell is pushed back in the bulk fluid. The results suggest that developing electroporation technologies that combine, simultaneously, electroporation and dielectrophoresis could lead to new applications. Obviously, this is an early stage numerical study and much more theoretical and experimental research is needed.
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Affiliation(s)
- Chenang Lyu
- Zhejiang University, College of Biosystems Engineering and Food Science, Hangzhou, 310058, China.
- University of California Berkeley, Department of Mechanical Engineering, Berkeley, CA, 94720, USA.
| | - Jianping Wang
- Zhejiang University, College of Biosystems Engineering and Food Science, Hangzhou, 310058, China
| | - Matthew Powell-Palm
- University of California Berkeley, Department of Mechanical Engineering, Berkeley, CA, 94720, USA
| | - Boris Rubinsky
- University of California Berkeley, Department of Mechanical Engineering, Berkeley, CA, 94720, USA
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18
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Benhal P, Chase G, Gaynor P, Oback B, Wang W. Multiple-Cylindrical Electrode System for Rotational Electric Field Generation in Particle Rotation Applications. INT J ADV ROBOT SYST 2015. [DOI: 10.5772/60456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Lab-on-a-chip micro-devices utilizing electric field-mediated particle movement provide advantages over current cell rotation techniques due to the flexibility in configuring micro-electrodes. Recent technological advances in micro-milling, three-dimensional (3D) printing and photolithography have facilitated fabrication of complex micro-electrode shapes. Using the finite-element method to simulate and optimize electric field induced particle movement systems can save time and cost by simplifying the analysis of electric fields within complex 3D structures. Here we investigated different 3D electrode structures to obtain and analyse rotational electric field vectors. Finite-element analysis was conducted by an electric current stationary solver based on charge relaxation theory. High-resolution data were obtained for three-, four-, six- and eight-cylindrical electrode arrangements to characterize the rotational fields. The results show that increasing the number of electrodes within a fixed circular boundary provides larger regions of constant amplitude rotational electric field. This is a very important finding in practice, as larger rotational regions with constant electric field amplitude make placement of cells into these regions, where cell rotation occurs, a simple task – enhancing flexibility in cell manipulation. Rotation of biological particles over the extended region would be useful for biotechnology applications which require guiding cells to a desired location, such as automation of nuclear transfer cloning.
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Affiliation(s)
- Prateek Benhal
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - Paul Gaynor
- Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand
| | - Björn Oback
- AgResearch Ruakura Research Centre, Hamilton, New Zealand
| | - Wenhui Wang
- State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing, China
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19
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Single Cell Electrical Characterization Techniques. Int J Mol Sci 2015; 16:12686-712. [PMID: 26053399 PMCID: PMC4490468 DOI: 10.3390/ijms160612686] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/13/2015] [Indexed: 01/09/2023] Open
Abstract
Electrical properties of living cells have been proven to play significant roles in understanding of various biological activities including disease progression both at the cellular and molecular levels. Since two decades ago, many researchers have developed tools to analyze the cell’s electrical states especially in single cell analysis (SCA). In depth analysis and more fully described activities of cell differentiation and cancer can only be accomplished with single cell analysis. This growing interest was supported by the emergence of various microfluidic techniques to fulfill high precisions screening, reduced equipment cost and low analysis time for characterization of the single cell’s electrical properties, as compared to classical bulky technique. This paper presents a historical review of single cell electrical properties analysis development from classical techniques to recent advances in microfluidic techniques. Technical details of the different microfluidic techniques are highlighted, and the advantages and limitations of various microfluidic devices are discussed.
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20
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Trainito CI, Français O, Le Pioufle B. Monitoring the permeabilization of a single cell in a microfluidic device, through the estimation of its dielectric properties based on combined dielectrophoresis and electrorotation in situ experiments. Electrophoresis 2015; 36:1115-22. [PMID: 25641658 DOI: 10.1002/elps.201400482] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/01/2015] [Accepted: 01/19/2015] [Indexed: 11/08/2022]
Abstract
The electric field is commonly used in microdevices to handle, treat, or monitor living cells for various biological or biomedical applications (cells electrofusion, gene electrotransfer, drugs injection, cell sorting, …). Dielectrophoresis (DEP) forces, using stationary waves (conventional DEP) or traveling waves, are widely used for the cell handling or sorting. Electrorotation, which is induced by a rotating electrical field, is used for the determination of cell dielectric parameters. The application of pulsed electric field (PEF) results in the cell membrane permeabilization that might allow the transfer of various molecules in the cytoplasm. In this paper, we propose a method to monitor in situ the level of electropermeabilization induced by PEF application on a single cell, by combining the dielectrophoresis force and the electrorotation torque within a microfluidic device. The method was experimented on two different cell lines (human leukemic T-cell lymphoblast and murine melanoma cell): a single cell is captured by dielectrophoresis while its dielectric properties (both permittivity and conductivity of cytoplasm and membrane) are estimated thanks to a rotating electric field, which is applied simultaneously. The permeabilization effect of PEF, applied to the single cell trapped in such conditions in the biodevice, could be monitored by the estimation of its dielectric properties before and after pulse application.
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21
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Esteban-Ferrer D, Edwards MA, Fumagalli L, Juárez A, Gomila G. Electric polarization properties of single bacteria measured with electrostatic force microscopy. ACS NANO 2014; 8:9843-9. [PMID: 25184827 DOI: 10.1021/nn5041476] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We quantified the electrical polarization properties of single bacterial cells using electrostatic force microscopy. We found that the effective dielectric constant, ε(r,eff), for the four bacterial types investigated (Salmonella typhimurium, Escherchia coli, Lactobacilus sakei, and Listeria innocua) is around 3-5 under dry air conditions. Under ambient humidity, it increases to ε(r,eff) ∼ 6-7 for the Gram-negative bacterial types (S. typhimurium and E. coli) and to ε(r,eff) ∼ 15-20 for the Gram-positive ones (L. sakei and L. innocua). We show that the measured effective dielectric constants can be consistently interpreted in terms of the electric polarization properties of the biochemical components of the bacterial cell compartments and of their hydration state. These results demonstrate the potential of electrical studies of single bacterial cells.
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Affiliation(s)
- Daniel Esteban-Ferrer
- Institut de Bioenginyeria de Catalunya (IBEC) , C/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
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22
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Bahrieh G, Erdem M, Özgür E, Gündüz U, Külah H. Assessment of effects of multi drug resistance on dielectric properties of K562 leukemic cells using electrorotation. RSC Adv 2014. [DOI: 10.1039/c4ra04873c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this study, dielectric characterization of multidrug resistant (MDR) K562 human leukemia cells was carried out using a MEMS based electrorotation (ER) device with 3D electrodes.
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Affiliation(s)
- Garsha Bahrieh
- Department of Electrical and Electronics Engineering
- METU
- Ankara, Turkey
- METU-MEMS Research and Applications Center
- Ankara, Turkey
| | | | - Ebru Özgür
- METU-MEMS Research and Applications Center
- Ankara, Turkey
| | | | - Haluk Külah
- Department of Electrical and Electronics Engineering
- METU
- Ankara, Turkey
- METU-MEMS Research and Applications Center
- Ankara, Turkey
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23
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Zheng Y, Nguyen J, Wei Y, Sun Y. Recent advances in microfluidic techniques for single-cell biophysical characterization. LAB ON A CHIP 2013; 13:2464-83. [PMID: 23681312 DOI: 10.1039/c3lc50355k] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Biophysical (mechanical and electrical) properties of living cells have been proven to play important roles in the regulation of various biological activities at the molecular and cellular level, and can serve as promising label-free markers of cells' physiological states. In the past two decades, a number of research tools have been developed for understanding the association between the biophysical property changes of biological cells and human diseases; however, technical challenges of realizing high-throughput, robust and easy-to-perform measurements on single-cell biophysical properties have yet to be solved. In this paper, we review emerging tools enabled by microfluidic technologies for single-cell biophysical characterization. Different techniques are compared. The technical details, advantages, and limitations of various microfluidic devices are discussed.
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Affiliation(s)
- Yi Zheng
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
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24
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Frey W, Gusbeth C, Schwartz T. Inactivation of Pseudomonas putida by pulsed electric field treatment: a study on the correlation of treatment parameters and inactivation efficiency in the short-pulse range. J Membr Biol 2013; 246:769-81. [PMID: 23660812 DOI: 10.1007/s00232-013-9547-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/17/2013] [Indexed: 01/19/2023]
Abstract
An important issue for an economic application of the pulsed electric field treatment for bacterial decontamination of wastewater is the specific treatment energy needed for effective reduction of bacterial populations. The present experimental study performed in a field amplitude range of 40 > E > 200 kV/cm and for a suspension conductivity of 0.01 = κ(e) > 0.2 S/m focusses on the application of short pulses, 25 ns > T > 10 μs, of rectangular, bipolar and exponential shape and was made on Pseudomonas putida, which is a typical and widespread wastewater microorganism. The comparison of inactivation results with calculations of the temporal and azimuthal membrane charging dynamics using the model of Pauly and Schwan revealed that for efficient inactivation, membrane segments at the cell equator have to be charged quickly and to a sufficiently high value, on the order of 0.5 V. After fulfilling this basic condition by an appropriate choice of pulse field strength and duration, the log rate of inactivation for a given suspension conductivity of 0.2 S/m was found to be independent of the duration of individual pulses for constant treatment energy expenditure. Moreover, experimental results suggest that even pulse shape plays a minor role in inactivation efficiency. The variation of the suspension conductivity resulted in comparable inactivation performance of identical pulse parameters if the product of pulse duration and number of pulses was the same, i.e., required treatment energy can be linearly downscaled for lower conductivities, provided that pulse amplitude and duration are selected for entire membrane surface permeabilization.
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Affiliation(s)
- Wolfgang Frey
- Institute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany,
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25
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David F, Hebeisen M, Schade G, Franco-Lara E, Di Berardino M. Viability and membrane potential analysis of Bacillus megaterium cells by impedance flow cytometry. Biotechnol Bioeng 2011; 109:483-92. [PMID: 21956238 DOI: 10.1002/bit.23345] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 08/18/2011] [Accepted: 09/12/2011] [Indexed: 11/10/2022]
Abstract
Single cell analysis is an important tool to gain deeper insights into microbial physiology for the characterization and optimization of bioprocesses. In this study a novel single cell analysis technique was applied for estimating viability and membrane potential (MP) of Bacillus megaterium cells cultured in minimal medium. Its measurement principle is based on the analysis of the electrical cell properties and is called impedance flow cytometry (IFC). Comparatively, state-of-the-art fluorescence-based flow cytometry (FCM) was used to verify the results obtained by IFC. Viability and MP analyses were performed with cells at different well-defined growth stages, focusing mainly on exponential and stationary phase cells, as well as on dead cells. This was done by PI and DiOC(2)(3) staining assays in FCM and by impedance measurements at 0.5 and 10 MHz in IFC. In addition, transition growth stages of long-term cultures and agar plate colonies were characterized with both methods. FCM and IFC analyses of all experiments gave comparable results, quantitatively and qualitatively, indicating that IFC is an equivalent technique to FCM for the study of physiological cell states of bacteria.
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Affiliation(s)
- F David
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, Germany
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26
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Chen J, Zheng Y, Tan Q, Shojaei-Baghini E, Zhang YL, Li J, Prasad P, You L, Wu XY, Sun Y. Classification of cell types using a microfluidic device for mechanical and electrical measurement on single cells. LAB ON A CHIP 2011; 11:3174-81. [PMID: 21826361 DOI: 10.1039/c1lc20473d] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This paper presents a microfluidic system for cell type classification using mechanical and electrical measurements on single cells. Cells are aspirated continuously through a constriction channel with cell elongations and impedance profiles measured simultaneously. The cell transit time through the constriction channel and the impedance amplitude ratio are quantified as cell's mechanical and electrical property indicators. The microfluidic device and measurement system were used to characterize osteoblasts (n=206) and osteocytes (n=217), revealing that osteoblasts, compared with osteocytes, have a larger cell elongation length (64.51 ± 14.98 μm vs. 39.78 ± 7.16 μm), a longer transit time (1.84 ± 1.48 s vs. 0.94 ± 1.07 s), and a higher impedance amplitude ratio (1.198 ± 0.071 vs. 1.099 ± 0.038). Pattern recognition using the neural network was applied to cell type classification, resulting in classification success rates of 69.8% (transit time alone), 85.3% (impedance amplitude ratio alone), and 93.7% (both transit time and impedance amplitude ratio as input to neural network) for osteoblasts and osteocytes. The system was also applied to test EMT6 (n=747) and EMT6/AR1.0 cells (n=770, EMT6 treated by doxorubicin) that have a comparable size distribution (cell elongation length: 51.47 ± 11.33 μm vs. 50.09 ± 9.70 μm). The effects of cell size on transit time and impedance amplitude ratio were investigated. Cell classification success rates were 51.3% (cell elongation alone), 57.5% (transit time alone), 59.6% (impedance amplitude ratio alone), and 70.2% (both transit time and impedance amplitude ratio). These preliminary results suggest that biomechanical and bioelectrical parameters, when used in combination, could provide a higher cell classification success rate than using electrical or mechanical parameter alone.
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Affiliation(s)
- Jian Chen
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
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27
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Cossins BP, Jacobson MP, Guallar V. A new view of the bacterial cytosol environment. PLoS Comput Biol 2011; 7:e1002066. [PMID: 21695225 PMCID: PMC3111478 DOI: 10.1371/journal.pcbi.1002066] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 04/09/2011] [Indexed: 11/19/2022] Open
Abstract
The cytosol is the major environment in all bacterial cells. The true physical and dynamical nature of the cytosol solution is not fully understood and here a modeling approach is applied. Using recent and detailed data on metabolite concentrations, we have created a molecular mechanical model of the prokaryotic cytosol environment of Escherichia coli, containing proteins, metabolites and monatomic ions. We use 200 ns molecular dynamics simulations to compute diffusion rates, the extent of contact between molecules and dielectric constants. Large metabolites spend ∼80% of their time in contact with other molecules while small metabolites vary with some only spending 20% of time in contact. Large non-covalently interacting metabolite structures mediated by hydrogen-bonds, ionic and π stacking interactions are common and often associate with proteins. Mg2+ ions were prominent in NIMS and almost absent free in solution. Κ+ is generally not involved in NIMSs and populates the solvent fairly uniformly, hence its important role as an osmolyte. In simulations containing ubiquitin, to represent a protein component, metabolite diffusion was reduced owing to long lasting protein-metabolite interactions. Hence, it is likely that with larger proteins metabolites would diffuse even more slowly. The dielectric constant of these simulations was found to differ from that of pure water only through a large contribution from ubiquitin as metabolite and monatomic ion effects cancel. These findings suggest regions of influence specific to particular proteins affecting metabolite diffusion and electrostatics. Also some proteins may have a higher propensity for associations with metabolites owing to their larger electrostatic fields. We hope that future studies may be able to accurately predict how binding interactions differ in the cytosol relative to dilute aqueous solution. The cytosol is the major cellular environment housing the majority of cellular activity. Although the cytosol is an aqueous environment, it contains high concentrations of ions, metabolites, and proteins, making it very different from dilute aqueous solution, which is frequently used for in vitro biochemistry. Recent advances in metabolomics have provided detailed concentration data for metabolites in E.coli. We used this information to construct accurate atomistic models of the cytosol solution. We find that, unlike the situation in dilute solutions, most metabolites spend the majority of their time in contact with other metabolites, or in contact with proteins. Furthermore, we find large non-covalently interacting metabolite structures are common and often associated with proteins. The presence of proteins reduced metabolite diffusion owing to long lasting correlations of motion. The dielectric constant of these simulations was found to differ from that of pure water only through a large contribution from proteins as metabolite and monatomic ion effects largely cancel. These findings suggest specific protein spheres of influence affecting metabolite diffusion and the electrostatic environment.
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Affiliation(s)
- Benjamin P. Cossins
- Department of Life Science, Barcelona Supercomputer Center, Barcelona, Spain
| | - Matthew P. Jacobson
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Victor Guallar
- Department of Life Science, Barcelona Supercomputer Center, Barcelona, Spain
- * E-mail:
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Chen J, Zheng Y, Tan Q, Zhang YL, Li J, Geddie WR, Jewett MAS, Sun Y. A microfluidic device for simultaneous electrical and mechanical measurements on single cells. BIOMICROFLUIDICS 2011; 5:14113. [PMID: 21523251 PMCID: PMC3082353 DOI: 10.1063/1.3571530] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 03/08/2011] [Indexed: 05/06/2023]
Abstract
This paper presents a microfluidic device for simultaneous mechanical and electrical characterization of single cells. The device performs two types of cellular characterization (impedance spectroscopy and micropipette aspiration) on a single chip to enable cell electrical and mechanical characterization. To investigate the performance of the device design, electrical and mechanical properties of MC-3T3 osteoblast cells were measured. Based on electrical models, membrane capacitance of MC-3T3 cells was determined to be 3.39±1.23 and 2.99±0.82 pF at the aspiration pressure of 50 and 100 Pa, respectively. Cytoplasm resistance values were 110.1±37.7 kΩ (50 Pa) and 145.2±44.3 kΩ (100 Pa). Aspiration length of cells was found to be 0.813±0.351 μm at 50 Pa and 1.771±0.623 μm at 100 Pa. Quantified Young's modulus values were 377±189 Pa at 50 Pa and 344±156 Pa at 100 Pa. Experimental results demonstrate the device's capability for characterizing both electrical and mechanical properties of single cells.
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30
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Henning A, Henkel J, Bier FF, Hölzel R. Label-free electrical quantification of the dielectrophoretic response of DNA. PMC BIOPHYSICS 2008; 1:4. [PMID: 19351426 PMCID: PMC2666632 DOI: 10.1186/1757-5036-1-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 11/05/2008] [Indexed: 12/11/2022]
Abstract
A purely electrical sensing scheme is presented that determines the concentration of macromolecules in solution by measuring the capacitance between planar microelectrodes. Concentrations of DNA in the ng/mL range have been used in samples of 1 μL volume. The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications. The influence of electrical parameters like duty cycle, voltage and frequency has been investigated. The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA. Extension of the method down to the single molecule level appears feasible. PACS: 87.50.ch, 87.80.Fe, 87.85.fK
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Affiliation(s)
- Anja Henning
- Fraunhofer Institute for Biomedical Engineering, Am Mühlenberg 13, 14476 Potsdam-Golm, Germany.
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31
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Impedimetric approach for monitoring the formation of biofilms on metallic surfaces and the subsequent application to the detection of bacteriophages. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.03.050] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Abstract
Weak electric currents generated using conductive electrodes have been shown to increase the efficacy of antibiotics against bacterial biofilms, a phenomenon termed "the bioelectric effect." The purposes of the present study were (i) to find out whether insulated electrodes that generate electric fields without "ohmic" electric currents, and thus are not associated with the formation of metal ions and free radicals, can inhibit the growth of planktonic bacteria and (ii) to define the parameters that are most effective against bacterial growth. The results obtained indicate that electric fields generated using insulated electrodes can inhibit the growth of planktonic Staphylococcus aureus and Pseudomonas aeruginosa and that the effect is amplitude and frequency dependent, with a maximum at 10 MHz. The combined effect of the electric field and chloramphenicol was found to be additive. Several possible mechanisms underlying the observed effect, as well as its potential clinical uses, are discussed.
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33
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Impedimetric approach for quantifying low bacteria concentrations based on the changes produced in the electrode–solution interface during the pre-attachment stage. Biosens Bioelectron 2008; 23:1540-6. [DOI: 10.1016/j.bios.2008.01.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 01/07/2008] [Accepted: 01/09/2008] [Indexed: 11/24/2022]
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34
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Bai W, Zhao K, Asami K. Effects of copper on dielectric properties of E. coli cells. Colloids Surf B Biointerfaces 2007; 58:105-15. [PMID: 17433633 DOI: 10.1016/j.colsurfb.2007.02.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 02/06/2007] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
Dielectric properties of E. coli cells before and after Cu(2+) incubation were investigated by using the dielectric spectroscopic technique. The dielectric spectra are analyzed theoretically by means of the extended three-shell ellipsoidal model, which can reflect the complicated morphological structure of E. coli cell including the outer membrane, the periplasmic space, the inner membrane and the cytoplasm. The results showed that dielectric properties of these cellular components were changed with Cu(2+) treatment in a time- and concentration-dependent way. The permttivity of the outer membrane increased with the incubation time and concentration of Cu(2+), possibly because polarizability of the outer leaflet of lipopolysaccharides was affected by Cu(2+). The conductivity of the periplasmic space decreased with the incubation time and concentration of Cu(2+), possibly due to the damage of peptidoglycan. The decreased permittivity of the inner membrane may be caused by disturbance of the lipid bilayer structure produced by Cu(2+) incubation. The decreased cytoplasmic conductivity may be the consequence of the leakage of K(+) from it. The cytoplasmic permittivity decreased with Cu(2+) treatment probably because of the leakage of its some components.
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Affiliation(s)
- Wei Bai
- College of Chemistry, Beijing Normal University, 100875 Beijing, China
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35
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Huang C, Yu J, Zhu J, Wang L, Guo M. Design and Fabrication of an Automated Microchip‐Based Cell Separation Device. ANAL LETT 2007. [DOI: 10.1080/00032710601017896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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36
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New Technologies for Imaging and Analysis of Individual Microbial Cells. IMAGING CELLULAR AND MOLECULAR BIOLOGICAL FUNCTIONS 2007. [DOI: 10.1007/978-3-540-71331-9_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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37
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Oh SH, Lee SH, Kenrick SA, Daugherty PS, Soh HT. Microfluidic Protein Detection through Genetically Engineered Bacterial Cells. J Proteome Res 2006; 5:3433-7. [PMID: 17137345 DOI: 10.1021/pr060193a] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein microarray technology, in which a large number of capture ligands are spatially arrayed at a high density, presents an attractive method for high-throughput proteomic analysis. Toward this end, we demonstrate the first cell-based protein detection in a microsystem, wherein Escherichia coli cells are genetically engineered to express the desired capture proteins on the membrane surface and are spatially arrayed as sensing elements in a microfluidic device. An E. coli clone expressing peptide ligands with high affinity and high specificity for target molecules was isolated a priori. Then these cells were electrokinetically immobilized on gold electrodes using dielectrophoresis, thus allowing each sensor element to be electrically addressable. Flow cytometry and subsequent fluorescence analysis verified the highly specific capture and detection of target molecules by the bacteria. Finally, through the coexpression of peptide-based capture ligands on the cell surface and fluorescent protein in the cytoplasm, we demonstrate an effective means of directly linking the fluorescence intensity to the density of capture ligands.
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Affiliation(s)
- Sang-Hyun Oh
- California Nanosystems Institute and Biomolecular Science and Engineering Program, University of California-Santa Barbara, California 93106, USA
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38
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Guyot S, Ferret E, Boehm JB, Gervais P. Yeast cell inactivation related to local heating induced by low-intensity electric fields with long-duration pulses. Int J Food Microbiol 2006; 113:180-8. [PMID: 17028031 DOI: 10.1016/j.ijfoodmicro.2006.06.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 02/08/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
The effects of electric field (EF) treatments on Saccharomyces cerevisiae viability were investigated using a PG200 electroporator (Hoefer Scientific Instrument, San Fransisco, CA, USA) with specific attention to induced thermal effects on cell death. Lethal electric fields (1.5 kV cm(-1) for 5 s) were shown to cause heat variations in the cell suspension medium (water+glycerol), while corresponding classical thermal treatments at equivalent temperatures had no effect on the cells viability. Variations of the electrical conductivity of the intra- and extracellular matrix caused by ions and solutes transfer across the membrane were shown to be involved in the observed heating. The results permitted to build a theoretical model for the temperature variations induced by electric fields. Using this model and the electrical conductivity of the different media, a plausible explanation of the cell death induced by low-intensity electric fields with long-duration pulses has been proposed. Indeed, cell mortality could in part be caused by direct and indirect effects of electric fields. Direct effects are related to well known electromechanical phenomena, whereas indirect effects are related to secondary thermal stress caused by plasma membrane thermoporation. This thermoporation was attributed to electrical conductivity variations and the corresponding intracellular heating.
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Affiliation(s)
- Stéphane Guyot
- GPAB Laboratory, ENSBANA, 1 Esplanade Erasme, F-21000 Dijon, France
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39
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Bai W, Zhao KS, Asami K. Dielectric properties of E. coli cell as simulated by the three-shell spheroidal model. Biophys Chem 2006; 122:136-42. [PMID: 16603309 DOI: 10.1016/j.bpc.2006.03.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2005] [Revised: 03/12/2006] [Accepted: 03/12/2006] [Indexed: 11/30/2022]
Abstract
Dielectric properties of E. coli cell have been re-studied by means of the three-shell spheroidal model, where the three shells correspond to the outer membrane, the periplasmic space and the inner membrane, respectively. With the model, a curve-fitting procedure has been developed to analyze the dielectric spectra. Although E. coli cell has been studied before, its special morphological structure was taken into account more comprehensively than any previous model in the present work. Dielectric properties of various cell components have been estimated from the observed dielectric spectra, especially the permittivity of the outer membrane, which was evaluated quantitatively for the first time. The values of epsilon(om) were 12 for kappa(om) of 0 to 10(-4) S/m and 34 for kappa(om) of 10(-3) S/m. The specific capacitance of the inner membrane was 0.6-0.70 microF/cm(2). The relative permittivity and the conductivity of the cytoplasm were about 100 and 0.22 S/m, respectively, and the conductivity of the periplasmic space was 2.2-3.2 S/m.
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Affiliation(s)
- Wei Bai
- Department of Chemistry, Beijing Normal University, 100875 Beijing, China
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40
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Zhao K, Bai W, Mi H. Dielectric spectroscopy of Anabaena 7120 protoplast suspensions. Bioelectrochemistry 2006; 69:49-57. [PMID: 16431165 DOI: 10.1016/j.bioelechem.2005.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 10/19/2005] [Accepted: 10/31/2005] [Indexed: 11/19/2022]
Abstract
The dielectric spectroscopy of Anabaena 7120 protoplast suspensions has been investigated over the frequency range of 40 Hz-110 MHz. The protoplast suspensions showed a complicated dielectric dispersion consisting of at least four distinct sub-dispersions with the increasing frequencies due to the Maxwell-Wagner interfacial polarization. The double-shell model, in which an equivalent shell of thylakoid was assumed inside the cytoplasm, was adopted to describe the special morphology of the protoplast. Under the assumption that the conductivity of plasmalemma was negligible and the conductivity of the equivalent shell was 0.1 microS/cm, we attempted to estimate the dielectric properties of various protoplast components by fitting theoretical curve to experimental data. The relative permittivity of the plasmalemma epsilon(mem) was estimated to be 6.5+/-0.5, and the permittivity of the equivalent shell of thylakoid epsilon(thy) was estimated to be about 3.2+/-0.2. The permittivity epsilon(cyt) and conductivity kappa(cyt) of the cytoplasm were estimated to be 60 and 0.88+/-0.11 mS/cm, respectively. The permittivity epsilon(nuc) and conductivity kappa(nuc) of the nucleoplasmic region were determined to be 100 and 0.13+/-0.02 mS/cm, respectively.
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Affiliation(s)
- Kongshuang Zhao
- Department of Chemistry, Beijing Normal University, 100875, Beijing, China.
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41
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Brehm-Stecher BF, Johnson EA. Single-cell microbiology: tools, technologies, and applications. Microbiol Mol Biol Rev 2004; 68:538-59, table of contents. [PMID: 15353569 PMCID: PMC515252 DOI: 10.1128/mmbr.68.3.538-559.2004] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The field of microbiology has traditionally been concerned with and focused on studies at the population level. Information on how cells respond to their environment, interact with each other, or undergo complex processes such as cellular differentiation or gene expression has been obtained mostly by inference from population-level data. Individual microorganisms, even those in supposedly "clonal" populations, may differ widely from each other in terms of their genetic composition, physiology, biochemistry, or behavior. This genetic and phenotypic heterogeneity has important practical consequences for a number of human interests, including antibiotic or biocide resistance, the productivity and stability of industrial fermentations, the efficacy of food preservatives, and the potential of pathogens to cause disease. New appreciation of the importance of cellular heterogeneity, coupled with recent advances in technology, has driven the development of new tools and techniques for the study of individual microbial cells. Because observations made at the single-cell level are not subject to the "averaging" effects characteristic of bulk-phase, population-level methods, they offer the unique capacity to observe discrete microbiological phenomena unavailable using traditional approaches. As a result, scientists have been able to characterize microorganisms, their activities, and their interactions at unprecedented levels of detail.
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Affiliation(s)
- Byron F Brehm-Stecher
- Department of Food Microbiology and Toxicology, University of Wisconsin-Madison Food Research Institute, 1925 Willow Drive, Madison, WI 53706, USA
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