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Yamamoto KK, Koklu A, Beskok A, Ajaev VS. Polarization of disk electrodes in high-conductivity electrolyte solutions. J Chem Phys 2024; 160:054702. [PMID: 38299629 DOI: 10.1063/5.0179083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/17/2023] [Indexed: 02/02/2024] Open
Abstract
We investigate the polarization of disk electrodes immersed in an electrolyte solution and subjected to a small external AC voltage over a wide range of frequencies. A mathematical model is developed based on the Debye-Falkenhagen approximation to the coupled Poisson-Nernst-Planck equations. Analytical techniques are used for predicting the spatial distribution of the electric potential and the complex impedance of the system. Scales for impedance and frequency are identified, which lead to a self-similar behavior for a range of frequencies. Experiments are conducted with gold electrodes of sizes in the range 100-350 μm immersed in a high-conductivity KCl solution over five orders of magnitude in frequency. A collapse of data on impedance magnitude and phase angle onto universal curves is observed with scalings motivated by the mathematical model. A direct comparison with the approximate analytical formula for impedance is made without any fitting parameters, and a good agreement is found for the range of frequencies where the analytical model is valid.
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Affiliation(s)
- Kenneth K Yamamoto
- Department of Mathematics, Southern Methodist University, Dallas, Texas 75275, USA
| | - Anil Koklu
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75275, USA
| | - Vladimir S Ajaev
- Department of Mathematics, Southern Methodist University, Dallas, Texas 75275, USA
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75275, USA
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2
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Panklang N, Vijitnukoonpradit K, Putaporntip C, Chotivanich K, Nakano M, Horprathum M, Techaumnat B. Study on the dielectrophoretic characteristics of malaria-infected red blood cells. Electrophoresis 2023; 44:1837-1846. [PMID: 37753817 DOI: 10.1002/elps.202300088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 08/21/2023] [Accepted: 09/14/2023] [Indexed: 09/28/2023]
Abstract
Malaria is a tropical disease caused by parasites in the genus Plasmodium, which still presents 241 million cases and nearly 627,000 deaths recently. In this work, we used the dielectrophoresis (DEP) to characterize red blood cells in a microchannel. The purpose of this work is to determine the difference between the normal and the malaria-infected cells based on the DEP characteristics. The samples were infected cells and normal red blood cells, which were either prepared in culture or obtained from volunteers. Diamond-shaped and curved micropillars were used to create different degrees of DEP in the gap between them. The DEP crossover frequencies were observed with the diamond-shaped micropillars. The cell velocity under negative dielectrophoresis (nDEP) at a low frequency was examined with the curved micropillars. The measured lower crossover frequencies were remarkably different between the malaria-infected cells and the normal cells, whereas the higher crossover frequencies were similar among the samples. The velocity under nDEP was lower for the infected cells than the normal cells. The results imply that the malaria infection significantly decreases the capacitance but increases the conductance of the cell membrane, whereas a change in cytoplasmic conductivity may occur in a later stage of infection.
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Affiliation(s)
- Nitipong Panklang
- Department of Electrical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Pathumthani, Thailand
| | - Kitipob Vijitnukoonpradit
- Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
| | - Chaturong Putaporntip
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Kesinee Chotivanich
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Michihiko Nakano
- Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan
| | - Mati Horprathum
- Spectroscopic and Sensing Devices Research Group, National Electronic and Computer Technology Center (NECTEC), National Science and Technology Development Agency, Pathumthani, Thailand
| | - Boonchai Techaumnat
- Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
- Micro/Nano Electromechanical Integrated Device Research Unit, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
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3
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Zhang Y, Murakami K, Borra VJ, Ozen MO, Demirci U, Nakamura T, Esfandiari L. A Label-Free Electrical Impedance Spectroscopy for Detection of Clusters of Extracellular Vesicles Based on Their Unique Dielectric Properties. BIOSENSORS 2022; 12:bios12020104. [PMID: 35200364 PMCID: PMC8869858 DOI: 10.3390/bios12020104] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 06/01/2023]
Abstract
Extracellular vesicles (EVs) have gained considerable attention as vital circulating biomarkers since their structure and composition resemble the originating cells. The investigation of EVs' biochemical and biophysical properties is of great importance to map them to their parental cells and to better understand their functionalities. In this study, a novel frequency-dependent impedance measurement system has been developed to characterize EVs based on their unique dielectric properties. The system is composed of an insulator-based dielectrophoretic (iDEP) device to entrap and immobilize a cluster of vesicles followed by utilizing electrical impedance spectroscopy (EIS) to measure their impedance at a wide frequency spectrum, aiming to analyze both their membrane and cytosolic charge-dependent contents. The EIS was initially utilized to detect nano-size vesicles with different biochemical compositions, including liposomes synthesized with different lipid compositions, as well as EVs and lipoproteins with similar biophysical properties but dissimilar biochemical properties. Moreover, EVs derived from the same parental cells but treated with different culture conditions were characterized to investigate the correlation of impedance changes with biochemical properties and functionality in terms of pro-inflammatory responses. The system also showed the ability to discriminate between EVs derived from different cellular origins as well as among size-sorted EVs harbored from the same cellular origin. This proof-of-concept approach is the first step towards utilizing EIS as a label-free, non-invasive, and rapid sensor for detection and characterization of pathogenic EVs and other nanovesicles in the future.
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Affiliation(s)
- Yuqian Zhang
- Department of Surgery, Division of Surgical Research, Mayo Clinic, Rochester, MN 55905, USA;
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Kazutoshi Murakami
- Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; (K.M.); (V.J.B.); (T.N.)
| | - Vishnupriya J. Borra
- Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; (K.M.); (V.J.B.); (T.N.)
| | - Mehmet Ozgun Ozen
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, Stanford School of Medicine, Stanford University, Palo Alto, CA 94305, USA; (M.O.O.); (U.D.)
- Bio-Acoustic MEMS in Medicine (BAMM) Laboratory, Department of Radiology, School of Medicine, Stanford University, Palo Alto, CA 94304, USA
| | - Utkan Demirci
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, Stanford School of Medicine, Stanford University, Palo Alto, CA 94305, USA; (M.O.O.); (U.D.)
- Bio-Acoustic MEMS in Medicine (BAMM) Laboratory, Department of Radiology, School of Medicine, Stanford University, Palo Alto, CA 94304, USA
| | - Takahisa Nakamura
- Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; (K.M.); (V.J.B.); (T.N.)
- Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA
- Department of Metabolic Bioregulation, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8577, Miyagi, Japan
| | - Leyla Esfandiari
- Department of Biomedical Engineering, College of Engineering and Applied Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
- Department of Electrical Engineering and Computer Science, College of Engineering and Applied Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
- Department of Environmental and Public Health Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
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4
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Dielectric Spectroscopy Based Detection of Specific and Nonspecific Cellular Mechanisms. SENSORS 2021; 21:s21093177. [PMID: 34063599 PMCID: PMC8124793 DOI: 10.3390/s21093177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022]
Abstract
Using radiofrequency dielectric spectroscopy, we have investigated the impact of the interaction between a G protein-coupled receptor (GPCR), the sterile2 α-factor receptor protein (Ste2), and its cognate agonist ligand, the α-factor pheromone, on the dielectric properties of the plasma membrane in living yeast cells (Saccharomyces cerevisiae). The dielectric properties of a cell suspension containing a saturating concentration of α-factor were measured over the frequency range 40Hz–110 MHz and compared to the behavior of a similarly prepared suspension of cells in the absence of α-factor. A spherical three-shell model was used to determine the electrical phase parameters for the yeast cells in both types of suspensions. The relative permittivity of the plasma membrane showed a significant increase after exposure to α-factor (by 0.06 ± 0.05). The equivalent experiment performed on yeast cells lacking the ability to express Ste2 showed no change in plasma membrane permittivity. Interestingly, a large change also occurred to the electrical properties of the cellular interior after the addition of α-factor to the cell suspending medium, whether or not the cells were expressing Ste2. We present a number of different complementary experiments performed on the yeast to support these dielectric data and interpret the results in terms of specific cellular reactions to the presence of α-factor.
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Sabuncu AC, Muldur S, Cetin B, Usta OB, Aubry N. β-Dispersion of blood during sedimentation. Sci Rep 2021; 11:2642. [PMID: 33514847 PMCID: PMC7846779 DOI: 10.1038/s41598-021-82171-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 01/08/2021] [Indexed: 01/30/2023] Open
Abstract
Aggregation of human red blood cells (RBC) is central to various pathological conditions from bacterial infections to cancer. When left at low shear conditions or at hemostasis, RBCs form aggregates, which resemble stacks of coins, known as 'rouleaux'. We experimentally examined the interfacial dielectric dispersion of aggregating RBCs. Hetastarch, an RBC aggregation agent, is used to mimic conditions leading to aggregation. Hetastrach concentration is incrementally increased in blood from healthy donors to measure the sensitivity of the technique. Time lapse electrical impedance measurements were conducted as red blood cells form rouleaux and sediment in a PDMS chamber. Theoretical modeling was used for obtaining complex permittivity of an effective single red blood cell aggregate at various concentrations of hetastarch. Time response of red blood cells' impedance was also studied to parametrize the time evolution of impedance data. Single aggregate permittivity at the onset of aggregation, evolution of interfacial dispersion parameters, and sedimentation kinetics allowed us to distinguish differential aggregation in blood.
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Affiliation(s)
- Ahmet C. Sabuncu
- grid.268323.e0000 0001 1957 0327Mechanical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609 USA
| | - Sinan Muldur
- grid.32224.350000 0004 0386 9924Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, MA 02114 USA
| | - Barbaros Cetin
- grid.18376.3b0000 0001 0723 2427Microfluidics & Lab-On-a-Chip Research Group, Department of Mechanical Engineering, I.D. Bilkent University, Ankara, Turkey
| | - O. Berk Usta
- grid.32224.350000 0004 0386 9924Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, MA 02114 USA
| | - Nadine Aubry
- grid.429997.80000 0004 1936 7531School of Engineering, Tufts University, Medford, MA 02155 USA
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6
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Jiang Y, Manz A, Wu W. Fully automatic integrated continuous-flow digital PCR device for absolute DNA quantification. Anal Chim Acta 2020; 1125:50-56. [DOI: 10.1016/j.aca.2020.05.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 04/27/2020] [Accepted: 05/02/2020] [Indexed: 01/09/2023]
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Liang H, Zhang Y, Chen D, Tan H, Zheng Y, Wang J, Chen J. Characterization of Single-Nucleus Electrical Properties by Microfluidic Constriction Channel. MICROMACHINES 2019; 10:mi10110740. [PMID: 31683555 PMCID: PMC6915630 DOI: 10.3390/mi10110740] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/26/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023]
Abstract
As key bioelectrical markers, equivalent capacitance (Cne, i.e., capacitance per unit area) and resistance (Rne, i.e., resistivity multiply thickness) of nuclear envelopes have emerged as promising electrical indicators, which cannot be effectively measured by conventional approaches. In this study, single nuclei were isolated from whole cells and trapped at the entrances of microfluidic constriction channels, and then corresponding impedance profiles were sampled and translated into single-nucleus Cne and Rne based on a home-developed equivalent electrical model. Cne and Rne of A549 nuclei were first quantified as 3.43 ± 1.81 μF/cm2 and 2.03 ± 1.40 Ω·cm2 (Nn = 35), which were shown not to be affected by variations of key parameters in nuclear isolation and measurement. The developed approach in this study was also used to measure a second type of nuclei, producing Cne and Rne of 3.75 ± 3.17 μF/cm2 and 1.01 ± 0.70 Ω·cm2 for SW620 (Nn = 17). This study may provide a new perspective in single-cell electrical characterization, enabling cell type classification and cell status evaluation based on bioelectrical markers of nuclei.
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Affiliation(s)
- Hongyan Liang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Yi Zhang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Deyong Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Huiwen Tan
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Yu Zheng
- Shandong University, Jinan 250100, China.
| | - Junbo Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Jian Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China.
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8
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Koklu A, Ajaev V, Beskok A. Self-Similar Response of Electrode Polarization for Binary Electrolytes in Parallel Plate Capacitor Systems. Anal Chem 2019; 91:11231-11239. [DOI: 10.1021/acs.analchem.9b02162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Anil Koklu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75205, United States
| | - Vladimir Ajaev
- Department of Mathematics, Southern Methodist University, Dallas, Texas 75275, United States
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75205, United States
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9
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Zhang H, Zhang W, Xiao L, Liu Y, Gilbertson TA, Zhou A. Use of Surface-Enhanced Raman Scattering (SERS) Probes to Detect Fatty Acid Receptor Activity in a Microfluidic Device. SENSORS 2019; 19:s19071663. [PMID: 30965560 PMCID: PMC6480160 DOI: 10.3390/s19071663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 11/16/2022]
Abstract
In this study, 4-mercaptobenzoic acid (MBA)-Au nanorods conjugated with a GPR120 antibody were developed as a highly sensitive surface-enhanced Raman spectroscopy (SERS) probe, and were applied to detect the interaction of fatty acids (FA) and their cognate receptor, GPR120, on the surface of human embryonic kidney cells (HEK293-GPRR120) cultured in a polydimethylsiloxane (PDMS) microfluidic device. Importantly, the two dominant characteristic SERS peaks of the Raman reporter molecule MBA, 1078 cm−1 and 1581 cm−1, do not overlap with the main Raman peaks from the PDMS substrate when the appropriate spectral scanning range is selected, which effectively avoided the interference from the PDMS background signals. The proposed microfluidic device consisted of two parts, that is, the concentration gradient generator (CGG) and the cell culture well array. The CGG part was fabricated to deliver five concentrations of FA simultaneously. A high aspect ratio well structure was designed to address the problem of HEK cells vulnerable to shear flow. The results showed a positive correlation between the SERS peak intensity and the FA concentrations. This work, for the first time, achieved the simultaneous monitoring of the Raman spectra of cells and the responses of the receptor in the cells upon the addition of fatty acid. The development of this method also provides a platform for the monitoring of cell membrane receptors on single-cell analysis using SERS in a PDMS-based microfluidic device.
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Affiliation(s)
- Han Zhang
- Department of Biological Engineering, Utah State University, Logan, UT 84322-4105, USA.
| | - Wei Zhang
- Department of Biological Engineering, Utah State University, Logan, UT 84322-4105, USA.
| | - Lifu Xiao
- Department of Biological Engineering, Utah State University, Logan, UT 84322-4105, USA.
| | - Yan Liu
- Department of Internal Medicine, University Central Florida, Orlando, FL 32827-7408, USA.
| | - Timothy A Gilbertson
- Department of Internal Medicine, University Central Florida, Orlando, FL 32827-7408, USA.
| | - Anhong Zhou
- Department of Biological Engineering, Utah State University, Logan, UT 84322-4105, USA.
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10
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Selective Detection of Human Lung Adenocarcinoma Cells Based on the Aptamer-Conjugated Self-Assembled Monolayer of Gold Nanoparticles. MICROMACHINES 2019; 10:mi10030195. [PMID: 30893795 PMCID: PMC6470481 DOI: 10.3390/mi10030195] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/09/2019] [Accepted: 03/17/2019] [Indexed: 12/24/2022]
Abstract
This study established a microfluidic chip for the capture of A549 human lung circulating tumor cells via the aptamer-conjugated self-assembled monolayer (SAM) of gold nanoparticles (AuNPs) in the channel. AuNPs are among the most attractive nanomaterials for the signal enhancement of biosensors owing to their unique chemical, physical, and mechanical properties. The microchip was fabricated using soft photolithography and casting and molding techniques. A self-assembly method was designed to attach AuNPs, cell-specific aptamers, and target cells onto the desired area (i.e., SAM area). In this study, the gold microelectrode configuration was characterized by fluorescence microscopy and impedance measurements to confirm the important modification steps. Subsequently, several investigations with the proposed assay were conducted with different cell samples to determine the specific binding ability of the device for A549 adenocarcinoma cancer cells. This work has ensured a simple, convenient, selective, and sensitive approach for the development of biosensors for lung cancer detection during the early stages.
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11
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Stelson AC, Liu M, Little CAE, Long CJ, Orloff ND, Stephanopoulos N, Booth JC. Label-free detection of conformational changes in switchable DNA nanostructures with microwave microfluidics. Nat Commun 2019; 10:1174. [PMID: 30862776 PMCID: PMC6414672 DOI: 10.1038/s41467-019-09017-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 02/11/2019] [Indexed: 01/23/2023] Open
Abstract
Detection of conformational changes in biomolecular assemblies provides critical information into biological and self-assembly processes. State-of-the-art in situ biomolecular conformation detection techniques rely on fluorescent labels or protein-specific binding agents to signal conformational changes. Here, we present an on-chip, label-free technique to detect conformational changes in a DNA nanomechanical tweezer structure with microwave microfluidics. We measure the electromagnetic properties of suspended DNA tweezer solutions from 50 kHz to 110 GHz and directly detect two distinct conformations of the structures. We develop a physical model to describe the electrical properties of the tweezers, and correlate model parameters to conformational changes. The strongest indicator for conformational changes in DNA tweezers are the ionic conductivity, while shifts in the magnitude of the cooperative water relaxation indicate the addition of fuel strands used to open the tweezer. Microwave microfluidic detection of conformational changes is a generalizable, non-destructive technique, making it attractive for high-throughput measurements. Methods to study conformational changes in biomolecules are limited in resolution and require labelling or other modifications of target analytes. Here the authors present a label-free, microwave microfluidic approach to detect conformational changes of DNA nanostructures based on ionic conductivity.
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Affiliation(s)
- Angela C Stelson
- National Institute of Standards and Technology, Radio Frequency Electronics Group, Boulder CO 325 Broadway St, Boulder, CO, 80305, USA
| | - Minghui Liu
- School of Molecular Sciences, Arizona State University, 551 E University Dr, Tempe, AZ, 85281, USA.,Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, 727 E. Tyler St., Tempe, AZ, 85281, USA
| | - Charles A E Little
- National Institute of Standards and Technology, Radio Frequency Electronics Group, Boulder CO 325 Broadway St, Boulder, CO, 80305, USA
| | - Christian J Long
- National Institute of Standards and Technology, Radio Frequency Electronics Group, Boulder CO 325 Broadway St, Boulder, CO, 80305, USA
| | - Nathan D Orloff
- National Institute of Standards and Technology, Radio Frequency Electronics Group, Boulder CO 325 Broadway St, Boulder, CO, 80305, USA
| | - Nicholas Stephanopoulos
- School of Molecular Sciences, Arizona State University, 551 E University Dr, Tempe, AZ, 85281, USA. .,Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, 727 E. Tyler St., Tempe, AZ, 85281, USA.
| | - James C Booth
- National Institute of Standards and Technology, Radio Frequency Electronics Group, Boulder CO 325 Broadway St, Boulder, CO, 80305, USA.
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12
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Mansoorifar A, Koklu A, Beskok A. Quantification of Cell Death Using an Impedance-Based Microfluidic Device. Anal Chem 2019; 91:4140-4148. [PMID: 30793881 DOI: 10.1021/acs.analchem.8b05890] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Dielectric spectroscopy is a nondestructive method to characterize dielectric properties by measuring impedance data over a frequency spectrum. This method has been widely used for various applications such as counting, sizing, and monitoring biological cells and particles. Recently, utilization of this method has been suggested in various stages of the drug discovery process due to low sample consumption and fast analysis time. In this study, we used a previously developed microfluidic system to confine single PC-3 cells in microwells using dielectrophoretic forces and perform the impedance measurements. PC-3 cells are treated with 100 μM Enzalutamide drug, and their impedance response is recorded until the cells are totally dead as predicted with viability tests. Four different approaches are used to analyze the impedance spectrum. Equivalent circuit modeling is used to extract the cell electrical properties as a function of time. Principal component analysis (PCA) is used to quantify cellular response to drug as a function of time. Single frequency measurements are conducted to observe how the cells respond over time. Finally, opacity ratio is defined as an additional quantification method. This device is capable of quantitatively measuring drug effects on biological cells and detecting cell death. The results show that the proposed microfluidic system has the potential to be used in early stages of the drug discovery process.
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Affiliation(s)
- Amin Mansoorifar
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
| | - Anil Koklu
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
| | - Ali Beskok
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
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13
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Koklu A, Mansoorifar A, Giuliani J, Monton C, Beskok A. Self-Similar Interfacial Impedance of Electrodes in High Conductivity Media: II. Disk Electrodes. Anal Chem 2018; 91:2455-2463. [DOI: 10.1021/acs.analchem.8b05275] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Anil Koklu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75205, United States
| | - Amin Mansoorifar
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75205, United States
| | - Jason Giuliani
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Carlos Monton
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75205, United States
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14
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An Aptamer-Based Capacitive Sensing Platform for Specific Detection of Lung Carcinoma Cells in the Microfluidic Chip. BIOSENSORS-BASEL 2018; 8:bios8040098. [PMID: 30347814 PMCID: PMC6316635 DOI: 10.3390/bios8040098] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/16/2018] [Accepted: 10/18/2018] [Indexed: 12/14/2022]
Abstract
Improvement of methods for reliable and early diagnosis of the cellular diseases is necessary. A biological selectivity probe, such as an aptamer, is one of the candidate recognition layers that can be used to detect important biomolecules. Lung cancer is currently a typical cause of cancer-related deaths. In this work, an electrical sensing platform is built based on amine-terminated aptamer modified-gold electrodes for the specific, label-free detection of a human lung carcinoma cell line (A549). The microdevice, that includes a coplanar electrodes configuration and a simple microfluidic channel on a glass substrate, is fabricated using standard photolithography and cast molding techniques. A procedure of self-assembly onto the gold surface is proposed. Optical microscope observations and electrical impedance spectroscopy measurements confirm that the fabricated microchip can specifically and effectively identify A549 cells. In the experiments, the capacitance element that is dominant in the change of the impedance is calculated at the appropriate frequency for evaluation of the sensitivity of the biosensor. Therefore, a simple, inexpensive, biocompatible, and selective biosensor that has the potential to detect early-stage lung cancer would be developed.
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15
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Koklu A, Mansoorifar A, Beskok A. Effects of electrode size and surface morphology on electrode polarization in physiological buffers. Electrophoresis 2018. [DOI: 10.1002/elps.201800303] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Anil Koklu
- Department of Mechanical Engineering; Southern Methodist University; Dallas TX USA
| | - Amin Mansoorifar
- Department of Mechanical Engineering; Southern Methodist University; Dallas TX USA
| | - Ali Beskok
- Department of Mechanical Engineering; Southern Methodist University; Dallas TX USA
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Mansoorifar A, Koklu A, Ma S, Raj GV, Beskok A. Electrical Impedance Measurements of Biological Cells in Response to External Stimuli. Anal Chem 2018; 90:4320-4327. [PMID: 29402081 DOI: 10.1021/acs.analchem.7b05392] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Dielectric spectroscopy (DS) is a noninvasive technique for real-time measurements of the impedance spectra of biological cells. DS enables characterization of cellular dielectric properties such as membrane capacitance and cytoplasmic conductivity. We have developed a lab-on-a-chip device that uses an electro-activated microwells array for capturing, DS measurements, and unloading of biological cells. Impedance measurements were conducted at 0.2 V in the 10 kHz to 40 MHz range with 6 s time resolution. An equivalent circuit model was developed to extract the cell membrane capacitance and cell cytoplasmic conductivity from the impedance spectra. A human prostate cancer cell line, PC-3, was used to evaluate the device performance. Suspension of PC-3 cells in low conductivity buffers (LCB) enhanced their dielectrophoretic trapping and impedance response. We report the time course of the variations in dielectric properties of PC-3 cells suspended in LCB and their response to sudden pH change from a pH of 7.3 to a pH of 5.8. Importantly, we demonstrated that our device enabled real-time measurements of dielectric properties of live cancer cells and allowed the assessment of the cellular response to variations in buffer conductivity and pH. These data support further development of this device toward single cell measurements.
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Affiliation(s)
- Amin Mansoorifar
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
| | - Anil Koklu
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
| | - Shihong Ma
- Departments of Urology and Pharmacology , University of Texas Southwestern Medical Center , Dallas , Texas 75390 , United States
| | - Ganesh V Raj
- Departments of Urology and Pharmacology , University of Texas Southwestern Medical Center , Dallas , Texas 75390 , United States
| | - Ali Beskok
- Department of Mechanical Engineering , Southern Methodist University , Dallas , Texas 75205 , United States
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17
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Dielectric properties of isolated adrenal chromaffin cells determined by microfluidic impedance spectroscopy. Bioelectrochemistry 2017; 119:84-91. [PMID: 28918192 DOI: 10.1016/j.bioelechem.2017.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/01/2017] [Accepted: 09/04/2017] [Indexed: 01/07/2023]
Abstract
Knowledge of the dielectric properties of biological cells plays an important role in numerical models aimed at understanding how high intensity ultrashort nanosecond electric pulses affect the plasma membrane and the membranes of intracellular organelles. To this end, using electrical impedance spectroscopy, the dielectric properties of isolated, neuroendocrine adrenal chromaffin cells were obtained. Measured impedance data of the cell suspension, acquired between 1kHz and 20MHz, were fit into a combination of constant phase element and Cole-Cole models from which the effect of electrode polarization was extracted. The dielectric spectrum of each cell suspension was fit into a Maxwell-Wagner mixture model and the Clausius-Mossotti factor was obtained. Lastly, to extract the cellular dielectric parameters, the cell dielectric data were fit into a granular cell model representative of a chromaffin cell, which was based on the inclusion of secretory granules in the cytoplasm. Chromaffin cell parameters determined from this study were the cell and secretory granule membrane specific capacitance (1.22 and 7.10μF/cm2, respectively), the cytoplasmic conductivity, which excludes and includes the effect of intracellular membranous structures (1.14 and 0.49S/m, respectively), and the secretory granule milieu conductivity (0.35S/m). These measurements will be crucial for incorporating into numerical models aimed at understanding the differential poration effect of nanosecond electric pulses on chromaffin cell membranes.
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18
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Santelices IB, Friesen DE, Bell C, Hough CM, Xiao J, Kalra A, Kar P, Freedman H, Rezania V, Lewis JD, Shankar K, Tuszynski JA. Response to Alternating Electric Fields of Tubulin Dimers and Microtubule Ensembles in Electrolytic Solutions. Sci Rep 2017; 7:9594. [PMID: 28851923 PMCID: PMC5574899 DOI: 10.1038/s41598-017-09323-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 07/20/2017] [Indexed: 12/17/2022] Open
Abstract
Microtubules (MTs), which are cylindrical protein filaments that play crucial roles in eukaryotic cell functions, have been implicated in electrical signalling as biological nanowires. We report on the small-signal AC (“alternating current”) conductance of electrolytic solutions containing MTs and tubulin dimers, using a microelectrode system. We find that MTs (212 nM tubulin) in a 20-fold diluted BRB80 electrolyte increase solution conductance by 23% at 100 kHz, and this effect is directly proportional to the concentration of MTs in solution. The frequency response of MT-containing electrolytes exhibits a concentration-independent peak in the conductance spectrum at 111 kHz (503 kHz FWHM that decreases linearly with MT concentration), which appears to be an intrinsic property of MT ensembles in aqueous environments. Conversely, tubulin dimers (42 nM) decrease solution conductance by 5% at 100 kHz under similar conditions. We attribute these effects primarily to changes in the mobility of ionic species due to counter-ion condensation effects, and changes in the solvent structure and solvation dynamics. These results provide insight into MTs’ ability to modulate the conductance of aqueous electrolytes, which in turn, has significant implications for biological information processing, especially in neurons, and for intracellular electrical communication in general.
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Affiliation(s)
- Iara B Santelices
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.,Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Douglas E Friesen
- Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Clayton Bell
- Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Cameron M Hough
- Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
| | - Jack Xiao
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.,Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Aarat Kalra
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.,Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada.,Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Piyush Kar
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada
| | - Holly Freedman
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Vahid Rezania
- Department of Physical Sciences, MacEwan University, Edmonton, Alberta, T5J 4S2, Canada
| | - John D Lewis
- Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada
| | - Karthik Shankar
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada. .,NRC National Institute for Nanotechnology, Edmonton, Alberta, T6G 2M9, Canada.
| | - Jack A Tuszynski
- Department of Oncology, University of Alberta, Edmonton, Alberta, T6G 1Z2, Canada. .,Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada.
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19
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Adrenal Chromaffin Cells Exposed to 5-ns Pulses Require Higher Electric Fields to Porate Intracellular Membranes than the Plasma Membrane: An Experimental and Modeling Study. J Membr Biol 2017; 250:535-552. [PMID: 28840286 DOI: 10.1007/s00232-017-9983-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 08/19/2017] [Indexed: 12/17/2022]
Abstract
Nanosecond-duration electric pulses (NEPs) can permeabilize the endoplasmic reticulum (ER), causing release of Ca2+ into the cytoplasm. This study used experimentation coupled with numerical modeling to understand the lack of Ca2+ mobilization from Ca2+-storing organelles in catecholamine-secreting adrenal chromaffin cells exposed to 5-ns pulses. Fluorescence imaging determined a threshold electric (E) field of 8 MV/m for mobilizing intracellular Ca2+ whereas whole-cell recordings of membrane conductance determined a threshold E-field of 3 MV/m for causing plasma membrane permeabilization. In contrast, a 2D numerical model of a chromaffin cell, which was constructed with internal structures representing a nucleus, mitochondrion, ER, and secretory granule, predicted that exposing the cell to the same 5-ns pulse electroporated the plasma and ER membranes at the same E-field amplitude, 3-4 MV/m. Agreement of the numerical simulations with the experimental results was obtained only when the ER interior conductivity was 30-fold lower than that of the cytoplasm and the ER membrane permittivity was twice that of the plasma membrane. A more realistic intracellular geometry for chromaffin cells in which structures representing multiple secretory granules and an ER showed slight differences in the thresholds necessary to porate the membranes of the secretory granules. We conclude that more sophisticated cell models together with knowledge of accurate dielectric properties are needed to understand the effects of NEPs on intracellular membranes in chromaffin cells, information that will be important for elucidating how NEPs porate organelle membranes in other cell types having a similarly complex cytoplasmic ultrastructure.
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20
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Mansoorifar A, Ghosh A, Sabuncu AC, Beskok A. Accuracy of the Maxwell–Wagner and the Bruggeman–Hanai mixture models for single cell dielectric spectroscopy. IET Nanobiotechnol 2017. [DOI: 10.1049/iet-nbt.2017.0064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Amin Mansoorifar
- Mechanical Engineering DepartmentSouthern Methodist UniversityDallasTX 75205USA
| | - Arindam Ghosh
- Mechanical Engineering DepartmentVirginia Tech UniversityBlacksburgVA 24061USA
| | - Ahmet C. Sabuncu
- Mechanical Engineering DepartmentSouthern Methodist UniversityDallasTX 75205USA
| | - Ali Beskok
- Mechanical Engineering DepartmentSouthern Methodist UniversityDallasTX 75205USA
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21
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Mansoorifar A, Koklu A, Sabuncu AC, Beskok A. Dielectrophoresis assisted loading and unloading of microwells for impedance spectroscopy. Electrophoresis 2017; 38:1466-1474. [PMID: 28256738 PMCID: PMC5547746 DOI: 10.1002/elps.201700020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 12/19/2022]
Abstract
Dielectric spectroscopy (DS) is a noninvasive, label-free, fast, and promising technique for measuring dielectric properties of biological cells in real time. We demonstrate a microchip that consists of electro-activated microwell arrays for positive dielectrophoresis assisted cell capture, DS measurements, and negative dielectrophoresis driven cell unloading; thus, providing a high-throughput cell analysis platform. To the best of our knowledge, this is the first microfluidic chip that combines electro-activated microwells and DS to analyze biological cells. Device performance is tested using Saccharomyces cerevisiae (yeast) cells. DEP response of yeast cells is determined by measuring their Clausius-Mossotti factor using biophysical models in parallel plate microelectrode geometry. This information is used to determine the excitation frequency to load and unload wells. Effect of yeast cells on the measured impedance spectrum was examined both experimentally and numerically. Good match between the numerical and experimental results establishes the potential use of the microchip device for extracting subcellular properties of biological cells in a rapid and nonexpensive manner.
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Affiliation(s)
- Amin Mansoorifar
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX 75205, USA
| | - Anil Koklu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX 75205, USA
| | - Ahmet Can Sabuncu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX 75205, USA
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX 75205, USA
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22
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Koklu A, Sabuncu AC, Beskok A. Enhancement of dielectrophoresis using fractal gold nanostructured electrodes. Electrophoresis 2017; 38:1458-1465. [PMID: 28130914 DOI: 10.1002/elps.201600456] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 12/30/2016] [Accepted: 01/22/2017] [Indexed: 11/07/2022]
Abstract
Dielectrophoretic motions of Saccharomyces cerevisiae (yeast) cells and colloidal gold are investigated using electrochemically modified electrodes exhibiting fractal topology. Electrodeposition of gold on electrodes generated repeated patterns with a fern-leaf type self-similarity. A particle tracking algorithm is used to extract dielectrophoretic particle velocities using fractal and planar electrodes in two different medium conductivities. The results show increased dielectrophoretic force when using fractal electrodes. Strong negative dielectrophoresis of yeast cells in high-conductivity media (1.5 S/m) is observed using fractal electrodes, while no significant motion is present using planar electrodes. Electrical impedance at the electrode/electrolyte interface is measured using impedance spectroscopy technique. Stronger electrode polarization (EP) effects are reported for planar electrodes. Decreased EP in fractal electrodes is considered as a reason for enhanced dielectrophoretic response.
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Affiliation(s)
- Anil Koklu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX, USA
| | - Ahmet C Sabuncu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX, USA
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, TX, USA
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23
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24
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Tsikritsis D, Shi H, Wang Y, Velugotla S, Sršeň V, Elfick A, Downes A. Label-free biomarkers of human embryonic stem cell differentiation to hepatocytes. Cytometry A 2016; 89:575-84. [PMID: 27214589 DOI: 10.1002/cyto.a.22875] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/15/2016] [Accepted: 04/26/2016] [Indexed: 01/09/2023]
Abstract
Four different label-free, minimally invasive, live single cell analysis techniques were applied in a quantitative comparison, to characterize embryonic stem cells and the hepatocytes into which they were differentiated. Atomic force microscopy measures the cell's mechanical properties, Raman spectroscopy measures its chemical properties, and dielectrophoresis measures the membrane's capacitance. They were able to assign cell type of individual cells with accuracies of 91% (atomic force microscopy), 95.5% (Raman spectroscopy), and 72% (dielectrophoresis). In addition, stimulated Raman scattering (SRS) microscopy was able to easily identify hepatocytes in images by the presence of lipid droplets. These techniques, used either independently or in combination, offer label-free methods to study individual living cells. Although these minimally invasive biomarkers can be applied to sense phenotypical or environmental changes to cells, these techniques have most potential in human stem cell therapies where the use of traditional biomarkers is best avoided. Destructive assays consume valuable stem cells and do not characterize the cells which go on to be used in therapies; whereas immunolabeling risks altering cell behavior. It was suggested how these four minimally invasive methods could be applied to cell culture, and how they could in future be combined into one microfluidic chip for cell sorting. © 2016 International Society for Advancement of Cytometry.
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Affiliation(s)
- Dimitrios Tsikritsis
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Hu Shi
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Yuan Wang
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Srinivas Velugotla
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - Vlastimil Sršeň
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Alistair Elfick
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew Downes
- Institute for BioEngineering, University of Edinburgh, Edinburgh, United Kingdom
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25
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Li Q, Yuan YJ. Application of Vertical Electrodes in Microfluidic Channels for Impedance Analysis. MICROMACHINES 2016; 7:E96. [PMID: 30404271 PMCID: PMC6190462 DOI: 10.3390/mi7060096] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 12/28/2022]
Abstract
This paper presents a microfluidic device with electroplated vertical electrodes in the side walls for impedance measurement. Based on the proposed device, the impedance of NaCl solutions with different concentrations and polystyrene microspheres with different sizes was measured and analyzed. The electroplating and SU-8-PDMS (SU-8-poly(dimethylsiloxane)) bonding technologies were firstly integrated for the fabrication of the proposed microfluidic device, resulting in a tightly three-dimensional structure for practical application. The magnitude of impedance of the tested solutions in the frequency range of 1 Hz to 100 kHz was analyzed by the Zennium electrochemical workstation. The results show that the newly designed microfluidic device has potential for impedance analysis with the advantages of ease of fabrication and the integration of 3D electrodes in the side walls. The newly designed impedance sensor can distinguish different concentrations of polystyrene microspheres and may have potential for cell counting in biological areas. By integrating with other techniques such as dielectrophoresis (DEP) and biological recognition technology, the proposed device may have potential for the assay to identify foodborne pathogen bacteria.
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Affiliation(s)
- Qiang Li
- Laboratory of Biosensing and MicroMechatronics, School of Materials Science and Engineering, Southwest Jiaotong University, 610031 Chengdu, China.
| | - Yong J Yuan
- Laboratory of Biosensing and MicroMechatronics, School of Materials Science and Engineering, Southwest Jiaotong University, 610031 Chengdu, China.
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26
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Fernandez RE, Koklu A, Mansoorifar A, Beskok A. Platinum black electrodeposited thread based electrodes for dielectrophoretic assembly of microparticles. BIOMICROFLUIDICS 2016; 10:033101. [PMID: 27158295 PMCID: PMC4833733 DOI: 10.1063/1.4946015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/13/2016] [Indexed: 05/12/2023]
Abstract
We report dielectrophoretic (DEP) assembly of biological cells and microparticles using platinum-black electrodeposited conductive textile fiber. The three-dimensional conductive structures with high aspect ratios were found to facilitate high electric field regions, as revealed by scanning electron microscope characterization. The effective conducting area (Aeff) and its stability of thread electrodes were estimated using electrochemical methods. Potential of platinum black electrodeposited thread as 3-D electrodes for creating high gradient electrical field for dielectrophoretic assembly of microspheres and Saccharomyces cerevisiae (yeast cells) into 1D and two-dimensional structures over long ranges under the application of low voltages (4-10 Vpp) has been demonstrated. The formation of highly ordered pearl chains of microparticles using thread electrodes when subjected to dielectrophoresis (DEP) has been discussed in detail.
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Affiliation(s)
- Renny Edwin Fernandez
- Department of Mechanical Engineering, Southern Methodist University , Dallas, Texas 75205, USA
| | - Anil Koklu
- Department of Mechanical Engineering, Southern Methodist University , Dallas, Texas 75205, USA
| | - Amin Mansoorifar
- Department of Mechanical Engineering, Southern Methodist University , Dallas, Texas 75205, USA
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University , Dallas, Texas 75205, USA
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27
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Fernandez RE, Lebiga E, Koklu A, Sabuncu AC, Beskok A. Flexible Bioimpedance Sensor for Label-Free Detection of Cell Viability and Biomass. IEEE Trans Nanobioscience 2015; 14:700-6. [PMID: 26415205 DOI: 10.1109/tnb.2015.2451594] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We introduce a flexible microfluidic bioimpedance sensor that is capable of detecting biomass and cell viability variations in a cell suspension. The sensor is developed on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrate and is devoid of gold, silicon, PDMS, or glass. In conjugation with a custom built PCB read-out module, the impedance characteristics of a cell suspension can be measured within one minute of sample introduction using liquid volumes less than 5 μL. The portable sensor system occupies very little bench space and has the potential to be developed as a disposable electrical bioimpedance probe for rapid detection of dielectric variations in a biological suspension. The sensor is designed to generate a differential impedance spectra exclusive to a cell suspension with a dual-electrode-pair system. The potential of the sensor to discriminate between live and heat treated Saccharomyces cerevisiae is demonstrated in this study. The disposable sensor along with the distance variation technique is touted to be an inexpensive alternative to some of the existing online disposable biomass detection probes and electrochemical sensors.
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28
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Heileman K, Daoud J, Hasilo C, Gasparrini M, Paraskevas S, Tabrizian M. Microfluidic platform for assessing pancreatic islet functionality through dielectric spectroscopy. BIOMICROFLUIDICS 2015; 9:044125. [PMID: 26339324 PMCID: PMC4552695 DOI: 10.1063/1.4929652] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/14/2015] [Indexed: 05/07/2023]
Abstract
Human pancreatic islets are seldom assessed for dynamic responses to external stimuli. Thus, the elucidation of human islet functionality would provide insights into the progression of diabetes mellitus, evaluation of preparations for clinical transplantation, as well as for the development of novel therapeutics. The objective of this study was to develop a microfluidic platform for in vitro islet culture, allowing the multi-parametric investigation of islet response to chemical and biochemical stimuli. This was accomplished through the fabrication and implementation of a microfluidic platform that allowed the perifusion of islet culture while integrating real-time monitoring using impedance spectroscopy, through microfabricated, interdigitated electrodes located along the microchamber arrays. Real-time impedance measurements provide important dielectric parameters, such as cell membrane capacitance and cytoplasmic conductivity, representing proliferation, differentiation, viability, and functionality. The perifusion of varying glucose concentrations and monitoring of the resulting impedance of pancreatic islets were performed as proof-of-concept validation of the lab-on-chip platform. This novel technique to elucidate the underlying mechanisms that dictate islet functionality is presented, providing new information regarding islet function that could improve the evaluation of islet preparations for transplantation. In addition, it will lead to a better understanding of fundamental diabetes-related islet dysfunction and the development of therapeutics through evaluation of potential drug effects.
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Affiliation(s)
- K Heileman
- Biomedical Engineering Department, McGill University , Montreal, Quebec H3A 2B4, Canada
| | - J Daoud
- Biomedical Engineering Department, McGill University , Montreal, Quebec H3A 2B4, Canada
| | - C Hasilo
- Department of Surgery, McGill University , Montreal, Quebec H3A 0G4, Canada
| | - M Gasparrini
- Department of Surgery, McGill University , Montreal, Quebec H3A 0G4, Canada
| | - S Paraskevas
- Department of Surgery, McGill University , Montreal, Quebec H3A 0G4, Canada
| | - M Tabrizian
- Biomedical Engineering Department, McGill University , Montreal, Quebec H3A 2B4, Canada
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29
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Sabuncu AC, Asmar AJ, Stacey MW, Beskok A. Differential dielectric responses of chondrocyte and Jurkat cells in electromanipulation buffers. Electrophoresis 2015; 36:1499-506. [PMID: 25958778 PMCID: PMC4555997 DOI: 10.1002/elps.201500119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 04/10/2015] [Accepted: 04/14/2015] [Indexed: 12/17/2022]
Abstract
Electromanipulation of cells as a label-free cell manipulation and characterization tool has gained particular interest recently. However, the applicability of electromanipulation, particularly dielectrophoresis (DEP), to biological cells is limited to cells suspended in buffers containing lower amounts of salts relative to the physiological buffers. One might question the use of low conductivity buffers (LCBs) for DEP separation, as cells are stressed in buffers lacking physiological levels of salt. In LCB, cells leak ions and undergo volume regulation. Therefore, cells exhibit time-dependent DEP response in LCB. In this work, cellular changes in LCB are assessed by dielectric spectroscopy, cell viability assay, and gene expression of chondrocytes and Jurkats. Results indicate leakage of ions from cells, increases in cytoplasmic conductivity, membrane capacitance, and conductance. Separability factor, which defines optimum conditions for DEP cell separation, for the two cell types is calculated using the cellular dielectric data. Optimum DEP separation conditions change as cellular dielectric properties evolve in LCB. Genetic analyses indicate no changes in expression of ionic channel proteins for chondrocytes suspended in LCB. Retaining cellular viability might be important during dielectrophoretic separation, especially when cells are to be biologically tested at a downstream microfluidic component.
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Affiliation(s)
- Ahmet C. Sabuncu
- Department of Mechanical Engineering, Southern Methodist University, Dallas, VA, 75275, USA
| | - Anthony J. Asmar
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23529, USA
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Michael W. Stacey
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23529, USA
| | - Ali Beskok
- Department of Mechanical Engineering, Southern Methodist University, Dallas, VA, 75275, USA
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30
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Microfluidic impedance flow cytometry enabling high-throughput single-cell electrical property characterization. Int J Mol Sci 2015; 16:9804-30. [PMID: 25938973 PMCID: PMC4463619 DOI: 10.3390/ijms16059804] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 04/10/2015] [Accepted: 04/20/2015] [Indexed: 01/09/2023] Open
Abstract
This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications.
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Abstract
There is a growing interest in protein dielectrophoresis (DEP) for biotechnological and pharmaceutical applications. However, the DEP behavior of proteins is still not well understood which is important for successful protein manipulation. In this paper, we elucidate the information gained in dielectric spectroscopy (DS) and electrochemical impedance spectroscopy (EIS) and how these techniques may be of importance for future protein DEP manipulation. EIS and DS can be used to determine the dielectric properties of proteins predicting their DEP behavior. Basic principles of EIS and DS are discussed and related to protein DEP through examples from previous studies. Challenges of performing DS measurements as well as potential designs to incorporate EIS and DS measurements in DEP experiments are also discussed.
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Affiliation(s)
| | - Alexandra Ros
- Department of Chemistry & Biochemistry, Arizona State University, Tempe, AZ, USA
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32
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Spencer D, Hollis V, Morgan H. Microfluidic impedance cytometry of tumour cells in blood. BIOMICROFLUIDICS 2014; 8:064124. [PMID: 25553198 PMCID: PMC4265026 DOI: 10.1063/1.4904405] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/05/2014] [Indexed: 05/12/2023]
Abstract
The dielectric properties of tumour cells are known to differ from normal blood cells, and this difference can be exploited for label-free separation of cells. Conventional measurement techniques are slow and cannot identify rare circulating tumour cells (CTCs) in a realistic timeframe. We use high throughput single cell microfluidic impedance cytometry to measure the dielectric properties of the MCF7 tumour cell line (representative of CTCs), both as pure populations and mixed with whole blood. The data show that the MCF7 cells have a large membrane capacitance and size, enabling clear discrimination from all other leukocytes. Impedance analysis is used to follow changes in cell viability when cells are kept in suspension, a process which can be understood from modelling time-dependent changes in the dielectric properties (predominantly membrane conductivity) of the cells. Impedance cytometry is used to enumerate low numbers of MCF7 cells spiked into whole blood. Chemical lysis is commonly used to remove the abundant erythrocytes, and it is shown that this process does not alter the MCF7 cell count or change their dielectric properties. Combining impedance cytometry with magnetic bead based antibody enrichment enables MCF7 cells to be detected down to 100 MCF7 cells in 1 ml whole blood, a log 3.5 enrichment and a mean recovery of 92%. Microfluidic impedance cytometry could be easily integrated within complex cell separation systems for identification and enumeration of specific cell types, providing a fast in-line single cell characterisation method.
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Affiliation(s)
- Daniel Spencer
- Faculty of Physical Sciences and Engineering, Institute for Life Sciences, University of Southampton SO17 1BJ, United Kingdom
| | - Veronica Hollis
- Faculty of Physical Sciences and Engineering, Institute for Life Sciences, University of Southampton SO17 1BJ, United Kingdom
| | - Hywel Morgan
- Faculty of Physical Sciences and Engineering, Institute for Life Sciences, University of Southampton SO17 1BJ, United Kingdom
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Chrimes AF, Khoshmanesh K, Stoddart PR, Mitchell A, Kalantar-Zadeh K. Microfluidics and Raman microscopy: current applications and future challenges. Chem Soc Rev 2014; 42:5880-906. [PMID: 23624774 DOI: 10.1039/c3cs35515b] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Raman microscopy systems are becoming increasingly widespread and accessible for characterising chemical species. Microfluidic systems are also progressively finding their way into real world applications. Therefore, it is anticipated that the integration of Raman systems with microfluidics will become increasingly attractive and practical. This review aims to provide an overview of Raman microscopy-microfluidics integrated systems for researchers who are actively interested in utilising these tools. The fundamental principles and application strengths of Raman microscopy are discussed in the context of microfluidics. Various configurations of microfluidics that incorporate Raman microscopy methods are presented, with applications highlighted. Data analysis methods are discussed, with a focus on assisting the interpretation of Raman-microfluidics data from complex samples. Finally, possible future directions of Raman-microfluidic systems are presented.
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Affiliation(s)
- Adam F Chrimes
- School of Electrical and Computer Engineering, RMIT University, 124 LaTrobe St, Melbourne, Australia.
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Stacey MW, Sabuncu AC, Beskok A. Dielectric characterization of costal cartilage chondrocytes. Biochim Biophys Acta Gen Subj 2013; 1840:146-52. [PMID: 24016606 DOI: 10.1016/j.bbagen.2013.08.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 07/24/2013] [Accepted: 08/29/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND Chondrocytes respond to biomechanical and bioelectrochemical stimuli by secreting appropriate extracellular matrix proteins that enable the tissue to withstand the large forces it experiences. Although biomechanical aspects of cartilage are well described, little is known of the bioelectrochemical responses. The focus of this study is to identify bioelectrical characteristics of human costal cartilage cells using dielectric spectroscopy. METHODS Dielectric spectroscopy allows non-invasive probing of biological cells. An in house computer program is developed to extract dielectric properties of human costal cartilage cells from raw cell suspension impedance data measured by a microfluidic device. The dielectric properties of chondrocytes are compared with other cell types in order to comparatively assess the electrical nature of chondrocytes. RESULTS The results suggest that electrical cell membrane characteristics of chondrocyte cells are close to cardiomyoblast cells, cells known to possess an array of active ion channels. The blocking effect of the non-specific ion channel blocker gadolinium is tested on chondrocytes with a significant reduction in both membrane capacitance and conductance. CONCLUSIONS We have utilized a microfluidic chamber to mimic biomechanical events through changes in bioelectrochemistry and described the dielectric properties of chondrocytes to be closer to cells derived from electrically excitably tissues. GENERAL SIGNIFICANCE The study describes dielectric characterization of human costal chondrocyte cells using physical tools, where results and methodology can be used to identify potential anomalies in bioelectrochemical responses that may lead to cartilage disorders.
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Affiliation(s)
- Michael W Stacey
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
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Kang G, Kim YJ, Moon HS, Lee JW, Yoo TK, Park K, Lee JH. Discrimination between the human prostate normal cell and cancer cell by using a novel electrical impedance spectroscopy controlling the cross-sectional area of a microfluidic channel. BIOMICROFLUIDICS 2013; 7:44126. [PMID: 24404059 PMCID: PMC3772938 DOI: 10.1063/1.4818838] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 08/06/2013] [Indexed: 05/12/2023]
Abstract
The prostate biopsy method shows a high false negative result because the suspicious tissue considered as cancer is not confirmed during tissue sampling. Thus, repeated biopsy procedures and diagnostic errors in relation to prostate cancer frequently occur. The purpose of this research is to enhance the prostate cancer detection rate by using microfluidic electrical impedance spectroscopy (μEIS), which allows real-time measurement of the electrical impedance of a single human prostate normal cell and cancer cell. The μEIS was equipped with a movable flexible membrane, which is operated by pneumatic pressure to capture the single cell on the surface of sensing electrodes. The forced tight contact between the cell and electrodes makes it possible to measure the electrical characteristics of the cell with a high sensitivity. The μEIS discriminates well between normal human prostate cells (RWPE-1) and cancer cells (PC-3) at 8.7 kHz based on the electrical signal responses of the cells. The average difference rates of admittance magnitude and susceptance are 54.55% and 54.59%, respectively. The developed μEIS also shows high repeatability, which was verified by a deionized water test conducted before and after each cell assay; the maximum variance of both the impedance and admittance at 8.7 kHz was as small as 9.48%.
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Affiliation(s)
- Giseok Kang
- Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea
| | - Young-Jae Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 151-744, South Korea
| | - Hong-Sang Moon
- Department of Urology, College of Medicine, Hanyang University, Guri 471-701, South Korea
| | - Jeong-Woo Lee
- Department of Urology, College of Medicine, Hanyang University, Guri 471-701, South Korea
| | - Tag-Keun Yoo
- Department of Urology, Eulji Medical Center, Eulji University School of Medicine, Seoul 139-872, South Korea
| | - Kwangsung Park
- Department of Urology, Chonnam National University Medical School, Gwangju 501-757, South Korea
| | - Jong-Hyun Lee
- Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea ; Department of Mechatronics, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea
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Sabuncu AC, Beskok A. A separability parameter for dielectrophoretic cell separation. Electrophoresis 2013; 34:1051-8. [PMID: 23348751 DOI: 10.1002/elps.201200411] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 11/23/2012] [Accepted: 11/23/2012] [Indexed: 11/08/2022]
Abstract
In this study, a separability parameter is introduced to determine the selection of optimum operating parameters for DEP separation of a cell pair. The separability parameter is defined as a function of cells' Clausius-Mossotti (CM) factors. T-cell leukemia Jurkat and mouse melanoma B16 cells are tested to validate the separability parameter. CM factors of cells are measured using a recently developed microfluidic impedance spectroscopy device. Separability maps are generated for varying values of field frequency and buffer conductivity. Cell separation is tested using a planar interdigitated electrode array at different buffer conductivities. Impedance measurements of the DEP device are performed at various buffer conductivities. Electrode polarization effects and energy allocation for dielectrophoretic manipulation of cells are computed from the impedance data utilizing an equivalent circuit model. Cell separation results are explained in the light of the impedance measurements.
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Affiliation(s)
- Ahmet C Sabuncu
- Department of Mechanical Engineering, Istanbul Technical University, Istanbul, Turkey
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Cima I, Wen Yee C, Iliescu FS, Phyo WM, Lim KH, Iliescu C, Tan MH. Label-free isolation of circulating tumor cells in microfluidic devices: Current research and perspectives. BIOMICROFLUIDICS 2013; 7:11810. [PMID: 24403992 PMCID: PMC3568085 DOI: 10.1063/1.4780062] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/17/2012] [Indexed: 05/04/2023]
Abstract
This review will cover the recent advances in label-free approaches to isolate and manipulate circulating tumor cells (CTCs). In essence, label-free approaches do not rely on antibodies or biological markers for labeling the cells of interest, but enrich them using the differential physical properties intrinsic to cancer and blood cells. We will discuss technologies that isolate cells based on their biomechanical and electrical properties. Label-free approaches to analyze CTCs have been recently invoked as a valid alternative to "marker-based" techniques, because classical epithelial and tumor markers are lost on some CTC populations and there is no comprehensive phenotypic definition for CTCs. We will highlight the advantages and drawbacks of these technologies and the status on their implementation in the clinics.
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Affiliation(s)
- Igor Cima
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos #04-01, Singapore 138669
| | - Chay Wen Yee
- National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610
| | | | - Wai Min Phyo
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos #04-01, Singapore 138669
| | - Kiat Hon Lim
- Department of Pathology, Singapore General Hospital, Outram Road, Singapore 169608
| | - Ciprian Iliescu
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos #04-01, Singapore 138669
| | - Min Han Tan
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos #04-01, Singapore 138669 ; National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610
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Luongo K, Holton A, Kaushik A, Spence P, Ng B, Deschenes R, Sundaram S, Bhansali S. Microfluidic device for trapping and monitoring three dimensional multicell spheroids using electrical impedance spectroscopy. BIOMICROFLUIDICS 2013; 7:34108. [PMID: 24404028 PMCID: PMC3689825 DOI: 10.1063/1.4809590] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 05/22/2013] [Indexed: 05/11/2023]
Abstract
In this paper, we report the design, fabrication, and testing of a lab-on-a-chip based microfluidic device for application of trapping and measuring the dielectric properties of microtumors over time using electrical impedance spectroscopy (EIS). Microelectromechanical system (MEMS) techniques were used to embed opposing electrodes onto the top and bottom surfaces of a microfluidic channel fabricated using Pyrex substrate, chrome gold, SU-8, and polydimethylsiloxane. Differing concentrations of cell culture medium, differing sized polystyrene beads, and MCF-7 microtumor spheroids were used to validate the designs ability to detect background conductivity changes and dielectric particle diameter changes between electrodes. The observed changes in cell medium concentrations demonstrated a linear relation to extracted solution resistance (Rs), while polystyrene beads and multicell spheroids induced changes in magnitude consistent with diameter increase. This design permits optical correlation between electrical measurements and EIS spectra.
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Affiliation(s)
- Kevin Luongo
- BioMEMs and Microfabrication system Laboratory, Department of Electrical and Computer Engineering, Florida International University, Miami, Florida 33172, USA ; Bioengineering Center, Draper Laboratory, Tampa, Florida 33612, USA ; Electrical Engineering, University of South Florida, Tampa, Florida 33620, USA
| | - Angela Holton
- Bioengineering Center, Draper Laboratory, Tampa, Florida 33612, USA
| | - Ajeet Kaushik
- BioMEMs and Microfabrication system Laboratory, Department of Electrical and Computer Engineering, Florida International University, Miami, Florida 33172, USA
| | - Paige Spence
- Bioengineering Center, Draper Laboratory, Tampa, Florida 33612, USA
| | - Beng Ng
- Department of Molecular Medicine, University of South Florida, Tampa, Florida 33620, USA
| | - Robert Deschenes
- Department of Molecular Medicine, University of South Florida, Tampa, Florida 33620, USA
| | - Shankar Sundaram
- Bioengineering Center, Draper Laboratory, Tampa, Florida 33612, USA
| | - Shekhar Bhansali
- BioMEMs and Microfabrication system Laboratory, Department of Electrical and Computer Engineering, Florida International University, Miami, Florida 33172, USA
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Sabuncu AC, Zhuang J, Kolb JF, Beskok A. Microfluidic impedance spectroscopy as a tool for quantitative biology and biotechnology. BIOMICROFLUIDICS 2012; 6:34103. [PMID: 23853680 PMCID: PMC3407121 DOI: 10.1063/1.4737121] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 06/29/2012] [Indexed: 05/12/2023]
Abstract
A microfluidic device that is able to perform dielectric spectroscopy is developed. The device consists of a measurement chamber that is 250 μm thick and 750 μm in radius. Around 1000 cells fit inside the chamber assuming average quantities for cell radius and volume fraction. This number is about 1000 folds lower than the capacity of conventional fixtures. A T-cell leukemia cell line Jurkat is tested using the microfluidic device. Measurements of deionized water and salt solutions are utilized to determine parasitic effects and geometric capacitance of the device. Physical models, including Maxwell-Wagner mixture and double shell models, are used to derive quantities for sub-cellular units. Clausius-Mossotti factor of Jurkat cells is extracted from the impedance spectrum. Effects of cellular heterogeneity are discussed and parameterized. Jurkat cells are also tested with a time domain reflectometry system for verification of the microfluidic device. Results indicate good agreement of values obtained with both techniques. The device can be used as a unique cell diagnostic tool to yield information on sub-cellular units.
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Affiliation(s)
- Ahmet C Sabuncu
- Institute of Micro & Nanotechnology, Old Dominion University, Norfolk, Virginia 23529, USA
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Velugotla S, Pells S, Mjoseng HK, Duffy CRE, Smith S, De Sousa P, Pethig R. Dielectrophoresis based discrimination of human embryonic stem cells from differentiating derivatives. BIOMICROFLUIDICS 2012; 6:44113. [PMID: 24339846 PMCID: PMC3555604 DOI: 10.1063/1.4771316] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 11/27/2012] [Indexed: 05/04/2023]
Abstract
Assessment of the dielectrophoresis (DEP) cross-over frequency (f xo), cell diameter, and derivative membrane capacitance (C m) values for a group of undifferentiated human embryonic stem cell (hESC) lines (H1, H9, RCM1, RH1), and for a transgenic subclone of H1 (T8) revealed that hESC lines could not be discriminated on their mean f xo and C m values, the latter of which ranged from 14 to 20 mF/m(2). Differentiation of H1 and H9 to a mesenchymal stem cell-like phenotype resulted in similar significant increases in mean C m values to 41-49 mF/m(2) in both lines (p < 0.0001). BMP4-induced differentiation of RCM1 to a trophoblast cell-like phenotype also resulted in a distinct and significant increase in mean C m value to 28 mF/m(2) (p < 0.0001). The progressive transition to a higher membrane capacitance was also evident after each passage of cell culture as H9 cells transitioned to a mesenchymal stem cell-like state induced by growth on a substrate of hyaluronan. These findings confirm the existence of distinctive parameters between undifferentiated and differentiating cells on which future application of dielectrophoresis in the context of hESC manufacturing can be based.
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Affiliation(s)
- Srinivas Velugotla
- Institute for Integrated Micro and Nano Systems, School of Engineering, The University of Edinburgh, Edinburgh EH9 3JF, United Kingdom
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Bathany C, Beahm DL, Besch S, Sachs F, Hua SZ. A microfluidic platform for measuring electrical activity across cells. BIOMICROFLUIDICS 2012; 6:34121. [PMID: 24062863 PMCID: PMC3470600 DOI: 10.1063/1.4754599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 09/10/2012] [Indexed: 05/18/2023]
Abstract
In this paper, we present a microfluidic chip that is capable of measuring electrical conductance through gap junction channels in a 2-dimensional cell sheet. The chip utilizes a tri-stream laminar flow to create a non-conductive sucrose gap between the two conducting solutions so that electrical current can pass across the sucrose gap only through the cells. Using the chip, we tested the effect of a gap junction inhibitor, 2-APB, on the electrical coupling of connexin 43 (Cx43) gap junction channels in NRK-49F cells. We found that 2-APB reversibly blocks the conductivity in a dose-dependent manner. The tri-stream chip further allows us to simultaneously follow the conductance changes and dye diffusion in real time. We show that 2-APB affects both conductance and diffusion, supporting the interpretation that both sets of data reflect the same gap junction activity. The chip provides a generic platform to investigate gap junction properties and to screen drugs that may inhibit or potentiate gap junction transmission.
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Affiliation(s)
- Cédric Bathany
- Department of Mechanical and Aerospace Engineering, SUNY-Buffalo, Buffalo, New York 14260, USA
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