1
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Koh D, Sonker M, Arriaga EA, Ros A. Numerical modeling reveals improved organelle separation for dielectrophoretic ratchet migration. Electrophoresis 2023; 44:1826-1836. [PMID: 37622551 PMCID: PMC10905386 DOI: 10.1002/elps.202300091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 08/26/2023]
Abstract
Organelle size varies with normal and abnormal cell function. Thus, size-based particle separation techniques are key to assessing the properties of organelle subpopulations differing in size. Recently, insulator-based dielectrophoresis (iDEP) has gained significant interest as a technique to manipulate sub-micrometer-sized particles enabling the assessment of organelle subpopulations. Based on iDEP, we recently reported a ratchet device that successfully demonstrated size-based particle fractionation in combination with continuous flow sample injection. Here, we used a numerical model to optimize the performance with flow rates a factor of three higher than previously and increased the channel volume to improve throughput. We evaluated the amplitude and duration of applied low-frequency DC-biased AC potentials improving separation efficiency. A separation efficiency of nearly 0.99 was achieved with the optimization of key parameters-improved from 0.80 in previous studies (Ortiz et al. Electrophoresis, 2022;43;1283-1296)-demonstrating that fine-tuning the periodical driving forces initiating the ratchet migration under continuous flow conditions can significantly improve the fractionation of organelles of different sizes.
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Affiliation(s)
- Domin Koh
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Mukul Sonker
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Edgar A Arriaga
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
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2
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Zavatski S, Bandarenka H, Martin OJF. Protein Dielectrophoresis with Gradient Array of Conductive Electrodes Sheds New Light on Empirical Theory. Anal Chem 2023; 95:2958-2966. [PMID: 36692365 PMCID: PMC9909730 DOI: 10.1021/acs.analchem.2c04708] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Dielectrophoresis (DEP) is a versatile tool for the precise microscale manipulation of a broad range of substances. To unleash the full potential of DEP for the manipulation of complex molecular-sized particulates such as proteins requires the development of appropriate theoretical models and their comprehensive experimental verification. Here, we construct an original DEP platform and test the Hölzel-Pethig empirical model for protein DEP. Three different proteins are studied: lysozyme, BSA, and lactoferrin. Their molecular Clausius-Mossotti function is obtained by detecting their trapping event via the measurement of the fluorescence intensity to identify the minimum electric field gradient required to overcome dispersive forces. We observe a significant discrepancy with published theoretical data and, after a very careful analysis to rule out experimental errors, conclude that more sophisticated theoretical models are required for the response of molecular entities in DEP fields. The developed experimental platform, which includes arrays of sawtooth metal electrode pairs with varying gaps and produces variations of the electric field gradient, provides a versatile tool that can broaden the utilization of DEP for molecular entities.
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Affiliation(s)
- Siarhei Zavatski
- Nanophotonics
and Metrology Laboratory (NAM), Swiss Federal
Institute of Technology Lausanne (EPFL), Lausanne1015, Switzerland,,
| | - Hanna Bandarenka
- The
Polytechnic School, Arizona State University, Mesa, Arizona85212, United States
| | - Olivier J. F. Martin
- Nanophotonics
and Metrology Laboratory (NAM), Swiss Federal
Institute of Technology Lausanne (EPFL), Lausanne1015, Switzerland,
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3
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Tijunelyte I, Teillet J, Bruand P, Courson R, Lecestre A, Joseph P, Bancaud A. Hybridization-based DNA biosensing with a limit of detection of 4 fM in 30 s using an electrohydrodynamic concentration module fabricated by grayscale lithography. BIOMICROFLUIDICS 2022; 16:044111. [PMID: 35992636 PMCID: PMC9385222 DOI: 10.1063/5.0073542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Speeding up and enhancing the performances of nucleic acid biosensing technologies have remained drivers for innovation. Here, we optimize a fluorimetry-based technology for DNA detection based on the concentration of linear targets paired with probes. The concentration module consists of a microfluidic channel with the shape of a funnel in which we monitor a viscoelastic flow and a counter-electrophoretic force. We report that the technology performs better with a target longer than 100 nucleotides (nt) and a probe shorter than 30 nt. We also prove that the control of the funnel geometry in 2.5D using grayscale lithography enhances sensitivity by 100-fold in comparison to chips obtained by conventional photolithography. With these optimized settings, we demonstrate a limit of detection of 4 fM in 30 s and a detection range of more than five decades. This technology hence provides an excellent balance between sensitivity and time to result.
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Affiliation(s)
- Inga Tijunelyte
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
| | - Jeffrey Teillet
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
| | - Paul Bruand
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
| | - Rémi Courson
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
| | | | - Pierre Joseph
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
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4
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Ortiz R, Koh D, Kim DH, Rabbani MT, Anguaya Velasquez C, Sonker M, Arriaga EA, Ros A. Continuous organelle separation in an insulator-based dielectrophoretic device. Electrophoresis 2022; 43:1283-1296. [PMID: 34964147 PMCID: PMC10905415 DOI: 10.1002/elps.202100326] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/30/2021] [Accepted: 12/13/2021] [Indexed: 11/06/2022]
Abstract
Heterogeneity in organelle size has been associated with devastating human maladies such as neurodegenerative diseases or cancer. Therefore, assessing the size-based subpopulation of organelles is imperative to understand the biomolecular foundations of these diseases. Here, we demonstrated a ratchet migration mechanism using insulator-based dielectrophoresis in conjunction with a continuous flow component that allows the size-based separation of submicrometer particles. The ratchet mechanism was realized in a microfluidic device exhibiting an array of insulating posts, tailoring electrokinetic and dielectrophoretic transport. A numerical model was developed to elucidate the particle migration and the size-based separation in various conditions. Experimentally, the size-based separation of a mixture of polystyrene beads (0.28 and 0.87 μ $\umu $ m) was accomplished demonstrating good agreement with the numerical model. Furthermore, the size-based separation of mitochondria was investigated using a mitochondria mixture isolated from HepG2 cells and HepG2 cells carrying the gene Mfn-1 knocked out, indicating distinct size-related migration behavior. With the presented continuous flow separation device, larger amounts of fractionated organelles can be collected in the future allowing access to the biomolecular signature of mitochondria subpopulations differing in size.
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Affiliation(s)
- Ricardo Ortiz
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Domin Koh
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Dai Hyun Kim
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Mohammad Towshif Rabbani
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Cesar Anguaya Velasquez
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Mukul Sonker
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Edgar A Arriaga
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
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5
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Protein Dielectrophoresis: A Tale of Two Clausius–Mossottis or Something Else? MICROMACHINES 2022; 13:mi13020261. [PMID: 35208384 PMCID: PMC8876334 DOI: 10.3390/mi13020261] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 01/31/2022] [Accepted: 02/03/2022] [Indexed: 11/17/2022]
Abstract
Standard DEP theory, based on the Clausius–Mossotti (CM) factor derived from solving the boundary-value problem of macroscopic electrostatics, fails to describe the dielectrophoresis (DEP) data obtained for 22 different globular proteins over the past three decades. The calculated DEP force appears far too small to overcome the dispersive forces associated with Brownian motion. An empirical theory, employing the equivalent of a molecular version of the macroscopic CM-factor, predicts a protein’s DEP response from the magnitude of the dielectric β-dispersion produced by its relaxing permanent dipole moment. A new theory, supported by molecular dynamics simulations, replaces the macroscopic boundary-value problem with calculation of the cross-correlation between the protein and water dipoles of its hydration shell. The empirical and formal theory predicts a positive DEP response for protein molecules up to MHz frequencies, a result consistently reported by electrode-based (eDEP) experiments. However, insulator-based (iDEP) experiments have reported negative DEP responses. This could result from crystallization or aggregation of the proteins (for which standard DEP theory predicts negative DEP) or the dominating influences of electrothermal and other electrokinetic (some non-linear) forces now being considered in iDEP theory.
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6
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Waskasi MM, Lazaric A, Heyden M. Solvent-mediated forces in protein dielectrophoresis. Electrophoresis 2021; 42:2060-2069. [PMID: 34302698 DOI: 10.1002/elps.202100087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 12/23/2022]
Abstract
DEP is an established method to manipulate micrometer-sized particles, but standard continuum theories predict only negligible effects for nanometer-sized proteins despite contrary experimental evidence. A theoretical description of protein DEP needs to consider details on the molecular scale. Previous work toward this goal addressed the role of orientational polarization of static protein dipole moments for dielectrophoretic effects, which successfully predicts the general magnitude of dielectrophoretic forces on proteins but does not readily explain negative DEP forces observed for proteins in some experiments. However, contributions to the protein chemical potential due to protein-water interactions have not yet been considered in this context. Here, we utilize atomistic molecular dynamics simulations to evaluate polarization-induced changes in the protein solvation free energy, which result in a solvent-mediated contribution to dielectrophoretic forces. We quantify solvent-mediated dielectrophoretic forces for two proteins and a small peptide in water, which follow expectations for protein-water dipole-dipole interactions. The magnitude of solvent-mediated dielectrophoretic forces exceeds predictions of nonmolecular continuum theories, but plays a minor role for the total dielectrophoretic force for the simulated proteins due to dominant contributions from the orientational polarization of their static protein dipoles. However, we extrapolate that solvent-mediated contributions to negative protein DEP forces will become increasingly relevant for multidomain proteins, complexes and aggregates with large protein-water interfaces, as well as for high electric field frequencies, which provides a potential mechanism for corresponding experimental observations of negative protein DEP.
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Affiliation(s)
- Morteza M Waskasi
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
| | | | - Matthias Heyden
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
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7
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Liu Y, Hayes MA. Orders-of-Magnitude Larger Force Demonstrated for Dielectrophoresis of Proteins Enabling High-Resolution Separations Based on New Mechanisms. Anal Chem 2020; 93:1352-1359. [DOI: 10.1021/acs.analchem.0c02763] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Yameng Liu
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Mark A. Hayes
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
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8
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Ho BD, Beech JP, Tegenfeldt JO. Charge-Based Separation of Micro- and Nanoparticles. MICROMACHINES 2020; 11:E1014. [PMID: 33218201 PMCID: PMC7702211 DOI: 10.3390/mi11111014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/11/2020] [Accepted: 11/14/2020] [Indexed: 12/13/2022]
Abstract
Deterministic Lateral Displacement (DLD) is a label-free particle sorting method that separates by size continuously and with high resolution. By combining DLD with electric fields (eDLD), we show separation of a variety of nano and micro-sized particles primarily by their zeta potential. Zeta potential is an indicator of electrokinetic charge-the charge corresponding to the electric field at the shear plane-an important property of micro- and nanoparticles in colloidal or separation science. We also demonstrate proof of principle of separation of nanoscale liposomes of different lipid compositions, with strong relevance for biomedicine. We perform careful characterization of relevant experimental conditions necessary to obtain adequate sorting of different particle types. By choosing a combination of frequency and amplitude, sorting can be made sensitive to the particle subgroup of interest. The enhanced displacement effect due to electrokinetics is found to be significant at low frequency and for particles with high zeta potential. The effect appears to scale with the square of the voltage, suggesting that it is associated with either non-linear electrokinetics or dielectrophoresis (DEP). However, since we observe large changes in separation behavior over the frequency range at which DEP forces are expected to remain constant, DEP can be ruled out.
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Affiliation(s)
| | | | - Jonas O. Tegenfeldt
- Division of Solid State Physics and NanoLund, Physics Department, Lund University, P.O. Box 118, 22100 Lund, Sweden; (B.D.H.); (J.P.B.)
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9
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Quevedo DF, Lentz CJ, Coll de Peña A, Hernandez Y, Habibi N, Miki R, Lahann J, Lapizco-Encinas BH. Electrokinetic characterization of synthetic protein nanoparticles. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1556-1567. [PMID: 33134000 PMCID: PMC7590587 DOI: 10.3762/bjnano.11.138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/29/2020] [Indexed: 05/11/2023]
Abstract
The application of nanoparticle in medicine is promising for the treatment of a wide variety of diseases. However, the slow progress in the field has resulted in relatively few therapies being translated into the clinic. Anisotropic synthetic protein nanoparticles (ASPNPs) show potential as a next-generation drug-delivery technology, due to their biocompatibility, biodegradability, and functionality. Even though ASPNPs have the potential to be used in a variety of applications, such as in the treatment of glioblastoma, there is currently no high-throughput technology for the processing of these particles. Insulator-based electrokinetics employ microfluidics devices that rely on electrokinetic principles to manipulate micro- and nanoparticles. These miniaturized devices can selectively trap and enrich nanoparticles based on their material characteristics, and subsequently release them, which allows for particle sorting and processing. In this study, we use insulator-based electrokinetic (EK) microdevices to characterize ASPNPs. We found that anisotropy strongly influences electrokinetic particle behavior by comparing compositionally identical anisotropic and non-anisotropic SPNPs. Additionally, we were able to estimate the empirical electrokinetic equilibrium parameter (eE EEC) for all SPNPs. This particle-dependent parameter can allow for the design of various separation and purification processes. These results show how promising the insulator-based EK microdevices are for the analysis and purification of clinically relevant SPNPs.
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Affiliation(s)
- Daniel F Quevedo
- Biointerfaces Institute, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Biomedical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
| | - Cody J Lentz
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, Rochester NY, USA
| | - Adriana Coll de Peña
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, Rochester NY, USA
| | - Yazmin Hernandez
- Biointerfaces Institute, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Biomedical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
| | - Nahal Habibi
- Biointerfaces Institute, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Chemical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
| | - Rikako Miki
- Biointerfaces Institute, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Biomedical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
| | - Joerg Lahann
- Biointerfaces Institute, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Biomedical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
- Chemical Engineering, University of Michigan - Ann Arbor, Ann Arbor MI, USA
| | - Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, Rochester NY, USA
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10
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Benhal P, Quashie D, Kim Y, Ali J. Insulator Based Dielectrophoresis: Micro, Nano, and Molecular Scale Biological Applications. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5095. [PMID: 32906803 PMCID: PMC7570478 DOI: 10.3390/s20185095] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/16/2020] [Accepted: 09/04/2020] [Indexed: 12/31/2022]
Abstract
Insulator based dielectrophoresis (iDEP) is becoming increasingly important in emerging biomolecular applications, including particle purification, fractionation, and separation. Compared to conventional electrode-based dielectrophoresis (eDEP) techniques, iDEP has been demonstrated to have a higher degree of selectivity of biological samples while also being less biologically intrusive. Over the past two decades, substantial technological advances have been made, enabling iDEP to be applied from micro, to nano and molecular scales. Soft particles, including cell organelles, viruses, proteins, and nucleic acids, have been manipulated using iDEP, enabling the exploration of subnanometer biological interactions. Recent investigations using this technique have demonstrated a wide range of applications, including biomarker screening, protein folding analysis, and molecular sensing. Here, we review current state-of-art research on iDEP systems and highlight potential future work.
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Affiliation(s)
- Prateek Benhal
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, USA;
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - David Quashie
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, USA;
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Yoontae Kim
- American Dental Association Science & Research Institute, Gaithersburg, MD 20899, USA;
| | - Jamel Ali
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, USA;
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
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11
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Rabbani MT, Schmidt CF, Ros A. Length-Selective Dielectrophoretic Manipulation of Single-Walled Carbon Nanotubes. Anal Chem 2020; 92:8901-8908. [PMID: 32447955 DOI: 10.1021/acs.analchem.0c00794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-walled carbon nanotubes (SWNTs) possess unique physical, optical, and electrical properties with great potential for future nanoscale device applications. Common synthesis procedures yield SWNTs with large length polydispersity and varying chirality. Electrical and optical applications of SWNTs often require specific lengths, but the preparation of SWNTs with the desired length is still challenging. Insulator-based dielectrophoresis (iDEP) integrated into a microfluidic device has the potential to separate SWNTs by length. Semiconducting SWNTs of varying length suspended with sodium deoxycholate (NaDOC) show unique dielectrophoretic properties at low frequencies (<1 kHz) that were exploited here using an iDEP-based microfluidic constriction sorter device for length-based sorting. Specific migration directions in the constriction sorter were induced for long SWNTs (≥1000 nm) with negative dielectrophoretic properties compared to short (≤300 nm) SWNTs with positive dielectrophoretic properties. We report continuous fractionation conditions for length-based iDEP migration of SWNTs, and we characterize the dynamics of migration of SWNTs in the microdevice using a finite element model. Based on the length and dielectrophoretic characteristics, sorting efficiencies for long and short SWNTs recovered from separate channels of the constriction sorter amounted to >90% and were in excellent agreement with a numerical model for the sorting process.
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Affiliation(s)
- Mohammad T Rabbani
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States.,Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States.,Third Institute of Physics - Biophysics, Department of Physics, University of Göttingen, Göttingen, Germany
| | - Christoph F Schmidt
- Third Institute of Physics - Biophysics, Department of Physics, University of Göttingen, Göttingen, Germany.,Department of Physics and Soft Matter Center, Duke University, Durham, North Carolina 27708, United States
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States.,Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
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12
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Detection of cell-free DNA nanoparticles in insulator based dielectrophoresis systems. J Chromatogr A 2020; 1626:461262. [PMID: 32797810 DOI: 10.1016/j.chroma.2020.461262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/07/2020] [Accepted: 05/18/2020] [Indexed: 01/22/2023]
Abstract
In this paper, a semi-analytical investigation was performed to study the effect of the geometrical parameters of insulator-based dielectrophoresis (iDEP) systems for cell free DNA (cfDNA) trapping. For this purpose, first electrical potential and fluid flow fields were calculated by solving the governing equations including Poisson and Navier-stokes equations with appropriate boundary conditions (BCs) and then a Lagrangian approach was utilized to analyze the motion of cfDNA under the most important forces affected on it including Brownian, Drag, electrophoresis and dielectrophoresis (DEP) forces. The effect of the different parameters such as the electrical conductivity of the medium, shape and geometrical parameters of the insulators on the dielectrophoretic behavior of cfDNA was studied and the optimal value of these parameters was presented. Finally, in order to predict the minimum voltage required for cfDNA trapping, artificial neural network (ANN) was utilized and a relation between input and output parameters was introduced.
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13
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Hayes MA. Dielectrophoresis of proteins: experimental data and evolving theory. Anal Bioanal Chem 2020; 412:3801-3811. [PMID: 32314000 PMCID: PMC7250158 DOI: 10.1007/s00216-020-02623-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/28/2020] [Accepted: 03/27/2020] [Indexed: 02/07/2023]
Abstract
The ability to selectively move and trap proteins is core to their effective use as building blocks and for their characterization. Analytical and preparative strategies for proteins have been pursued and modeled for nearly a hundred years, with great advances and success. Core to all of these studies is the separation, isolation, purification, and concentration of pure homogeneous fractions of a specific protein in solution. Processes to accomplish this useful solution include biphasic equilibrium (chromatographies, extractions), mechanical, bulk property, chemical equilibria, and molecular recognition. Ultimately, the goal of all of these is to physically remove all non-like protein molecules-to the finest detail: all atoms in the full three-dimensional structure being identical down the chemical bond and bulk structure chirality. One strategy which has not been effectively pursued is exploiting the higher order subtle electrical properties of the protein-solvent system. The advent of microfluidic systems has enabled the use of very high electric fields and well-defined gradients such that extremely high resolution separations of protein mixtures are possible. These advances and recognition of these capabilities have caused a re-evaluation of the underlying theoretical models and they were found to be inadequate. New theoretical descriptions are being considered which align more closely to the total forces present and the subtlety of differences between similar proteins. These are focused on the interfacial area between the protein and hydrating solvent molecules, as opposed to the macroscale assumptions of homogeneous solutions and particles. This critical review examines all data which has been published that place proteins in electric field gradients which induce collection of those proteins, demonstrating a force greater than dispersive effects or countering forces. Evolving theoretical constructs are presented and discussed, and a general estimate of future capabilities using the higher order effects and the high fields and precise gradients of microfluidic systems is discussed. Graphical abstract.
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Affiliation(s)
- Mark A Hayes
- School of Molecular Sciences, Arizona State University, Mail Stop 1604, Tempe, AZ, 85287, USA.
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14
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Hölzel R, Pethig R. Protein Dielectrophoresis: I. Status of Experiments and an Empirical Theory. MICROMACHINES 2020; 11:E533. [PMID: 32456059 PMCID: PMC7281080 DOI: 10.3390/mi11050533] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/20/2020] [Accepted: 05/20/2020] [Indexed: 12/04/2022]
Abstract
The dielectrophoresis (DEP) data reported in the literature since 1994 for 22 different globular proteins is examined in detail. Apart from three cases, all of the reported protein DEP experiments employed a gradient field factor ∇Em2 that is much smaller (in some instances by many orders of magnitude) than the ~4 1021 V2/m3 required, according to current DEP theory, to overcome the dispersive forces associated with Brownian motion. This failing results from the macroscopic Clausius-Mossotti (CM) factor being restricted to the range 1.0 > CM > -0.5. Current DEP theory precludes the protein's permanent dipole moment (rather than the induced moment) from contributing to the DEP force. Based on the magnitude of the β-dispersion exhibited by globular proteins in the frequency range 1 kHz-50 MHz, an empirically derived molecular version of CM is obtained. This factor varies greatly in magnitude from protein to protein (e.g., ~37,000 for carboxypeptidase; ~190 for phospholipase) and when incorporated into the basic expression for the DEP force brings most of the reported protein DEP above the minimum required to overcome dispersive Brownian thermal effects. We believe this empirically-derived finding validates the theories currently being advanced by Matyushov and co-workers.
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Affiliation(s)
- Ralph Hölzel
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam-Golm, Germany;
| | - Ronald Pethig
- School of Engineering, Institute for Integrated Micro and Nanosystems, University of Edinburgh, The King’s Buildings, Edinburgh EH9 3JF, UK
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15
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Lentz CJ, Hidalgo-Caballero S, Lapizco-Encinas BH. Low frequency cyclical potentials for fine tuning insulator-based dielectrophoretic separations. BIOMICROFLUIDICS 2019; 13:044114. [PMID: 31489061 PMCID: PMC6715440 DOI: 10.1063/1.5115153] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/13/2019] [Indexed: 05/25/2023]
Abstract
In this study, we demonstrate the use of cyclical low frequency signals with insulator-based dielectrophoresis (iDEP) devices for the separation of particles of similar characteristics and an experimental method for estimating particle DEP mobilities. A custom signal designer program was created using Matlab® and COMSOL Multiphysics® for the identification of specific low frequency signals aimed at separating particle mixtures by exploiting slight differences in surface charge (particle zeta potential) or particle size. For the separation by surface charge, a mixture of two types of 10 μm particles was analyzed and effectively separated employing both a custom step signal and a sawtooth left signal. Notably, these particles had the same shape, size, and surface functionalization as well as were made from the same substrate material. For the separation by size, a sample containing 2 μm and 5 μm particles was successfully separated using a custom step signal; these particles had the same shape, surface functionalization, were made from the same substrate materials, and had only a small difference in zeta potential (10 mV). Additionally, an experimental technique was developed to estimate the dielectrophoretic mobility of each particle type; this information was then utilized by the signal designer program. The technique developed in this study is readily applicable for designing signals capable of separating micron-sized particles of similar characteristics, such as microorganisms, where slight differences in cell size and the shape of surface charge could be effectively exploited. These findings open the possibility for applications in microbial screening using iDEP devices.
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Affiliation(s)
- Cody J. Lentz
- Microscale Bioseparations Laboratory, Rochester Institute of Technology, Rochester, New York 14623, USA
| | | | - Blanca H. Lapizco-Encinas
- Microscale Bioseparations Laboratory, Rochester Institute of Technology, Rochester, New York 14623, USA
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16
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Sonker M, Kim D, Egatz-Gomez A, Ros A. Separation Phenomena in Tailored Micro- and Nanofluidic Environments. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2019; 12:475-500. [PMID: 30699038 DOI: 10.1146/annurev-anchem-061417-125758] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Separations of bioanalytes require robust, effective, and selective migration phenomena. However, due to the complexity of biological matrices such as body fluids or tissue, these requirements are difficult to achieve. The separations field is thus constantly evolving to develop suitable methods to separate biomarkers and fractionate biospecimens for further interrogation of biomolecular content. Advances in the field of microfabrication allow the tailored generation of micro- and nanofluidic environments. These can be exploited to induce interactions and dynamics of biological species with the corresponding geometrical features, which in turn can be capitalized for novel separation approaches. This review provides an overview of several unique separation applications demonstrated in recent years in tailored micro- and nanofluidic environments. These include electrokinetic methods such as dielectrophoresis and electrophoresis, but also rather nonintuitive ratchet separation mechanisms, continuous flow separations, and fractionations such as deterministic lateral displacement, as well as methods employing entropic forces for separation.
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Affiliation(s)
- Mukul Sonker
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA;
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
| | - Daihyun Kim
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA;
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
| | - Ana Egatz-Gomez
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA;
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA;
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
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17
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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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18
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Natu R, Islam M, Martinez-Duarte R. Nondimensional Streaming Dielectrophoresis Number for a System of Continuous Particle Separation. Anal Chem 2019; 91:4357-4367. [PMID: 30827100 DOI: 10.1021/acs.analchem.8b04599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cell sorting methods are required in numerous healthcare assays. Although flow cytometry and magnetically actuated sorting are widespread techniques for cell sorting, there is intense research on label-free techniques to reduce the cost and complexity of the process. Among label-free techniques, dielectrophoresis (DEP) offers the capability to separate cells not only on the basis of size but also on their membrane capacitance. This is important because it enables cell discrimination on the basis of specific traits such as viability, identity, fate, and age. StreamingDEP refers to the continuous sorting of cells thanks to the generation of streams of targeted particles by equilibrating the drag and DEP forces acting on targeted particles. In this work, we provide an analytical expression for a streamingDEP number toward enabling the a priori design of DEP devices to agglomerate targeted particles into streams. The nondimensional streamingDEP number (SDN) obtained in this analysis is applied to experiments with 1 μm polystyrene particles and Candida cells. On the basis of these experiments, three characteristic zones are mapped to different values of the SDN: (1) physical capture thanks to DEP for 0 < SDN < 0.6; (2) streaming due to DEP for 0.6 < SDN < 1; (3) elution without experiencing DEP for SDN > 1.
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Affiliation(s)
- Rucha Natu
- Multiscale Manufacturing Laboratory, Department of Mechanical Engineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - Monsur Islam
- Multiscale Manufacturing Laboratory, Department of Mechanical Engineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - Rodrigo Martinez-Duarte
- Multiscale Manufacturing Laboratory, Department of Mechanical Engineering , Clemson University , Clemson , South Carolina 29634 , United States
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19
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Affiliation(s)
- Daihyun Kim
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Mukul Sonker
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
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20
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Lapizco-Encinas BH. On the recent developments of insulator-based dielectrophoresis: A review. Electrophoresis 2018; 40:358-375. [PMID: 30112789 DOI: 10.1002/elps.201800285] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/06/2018] [Accepted: 08/08/2018] [Indexed: 01/26/2023]
Abstract
Insulator-based dielectrophoresis (iDEP), also known as electrodeless DEP, has become a well-known dielectrophoretic technique, no longer viewed as a new methodology. Significant advances on iDEP have been reported during the last 15 years. This review article aims to summarize some of the most important findings on iDEP organized by the type of dielectrophoretic mode: streaming and trapping iDEP. The former is primarily used for particle sorting, while the latter has great capability for particle enrichment. The characteristics of a wide array of devices are discussed for each type of dielectrophoretic mode in order to present an overview of the distinct designs and applications developed with iDEP. A short section on Joule heating effects and electrothermal flow is also included to highlight some of the challenges in the utilization of iDEP systems. The significant progress on iDEP illustrates its potential for a large number of applications, ranging from bioanalysis to clinical and biomedical assessments. The present article discusses the work on iDEP by numerous research groups around the world, with the aim of proving the reader with an overview of the state-of-the-art in iDEP microfluidic systems.
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21
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Cao Z, Zhu Y, Liu Y, Dong S, Chen X, Bai F, Song S, Fu J. Dielectrophoresis-Based Protein Enrichment for a Highly Sensitive Immunoassay Using Ag/SiO 2 Nanorod Arrays. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703265. [PMID: 29377602 DOI: 10.1002/smll.201703265] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/06/2017] [Indexed: 06/07/2023]
Abstract
A nanoscale insulator-based dielectrophoresis (iDEP) technique is developed for rapid enrichment of proteins and highly sensitive immunoassays. Dense arrays of nanorods (NDs) by oblique angle deposition create a super high electric field gradient of 2.6 × 1024 V2 m-3 and the concomitant strong dielectrophoresis force successfully traps small proteins at a bias as low as 5 V. 1800-fold enrichment of bovine serum albumin protein at a remarkable rate of up to 180-fold s-1 is achieved using oxide coated Ag nanorod arrays with pre-patterned sawtooth electrodes. Based on this system, an ultrasensitive immunoassay of mouse immunoglobulin G is demonstrated with a reduction in the limit of detection from 5.8 ng mL-1 (37.6 pM) down to 275.3 fg mL-1 (1.8 f M), compared with identical assays performed on glass plates. This methodology is also applied to detect a cancer biomarker prostate-specific antigen spiked in human serum with a detection limit of 2.6 ng mL-1 . This high sensitivity results from rapid biomarker enrichment and metal enhanced fluorescence through the integration of nanostructures. The concentrated proteins also accelerate binding kinetics and enable signal saturation within 1 min. Given the easy fabrication process, this nanoscale iDEP system provides a highly sensitive detection platform for point-of-care diagnostics.
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Affiliation(s)
- Zhen Cao
- College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Yu Zhu
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Yang Liu
- College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Shurong Dong
- College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Xin Chen
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Fan Bai
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Shengxin Song
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Junxue Fu
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong
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22
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Viefhues M, Eichhorn R. DNA dielectrophoresis: Theory and applications a review. Electrophoresis 2017; 38:1483-1506. [PMID: 28306161 DOI: 10.1002/elps.201600482] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/07/2017] [Accepted: 03/08/2017] [Indexed: 01/24/2023]
Abstract
Dielectrophoresis is the migration of an electrically polarizable particle in an inhomogeneous electric field. This migration can be exploited for several applications with (bio)molecules or cells. Dielectrophoresis is a noninvasive technique; therefore, it is very convenient for (selective) manipulation of (bio)molecules or cells. In this review, we will focus on DNA dielectrophoresis as this technique offers several advantages in trapping and immobilization, separation and purification, and analysis of DNA molecules. We present and discuss the underlying theory of the most important forces that have to be considered for applications with dielectrophoresis. Moreover, a review of DNA dielectrophoresis applications is provided to present the state-of-the-art and to offer the reader a perspective of the advances and current limitations of DNA dielectrophoresis.
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Affiliation(s)
- Martina Viefhues
- Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld, Germany
| | - Ralf Eichhorn
- Nordita, Royal Institute of Technology and Stockholm University, Stockholm, Sweden
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23
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Jones PV, Salmon GL, Ros A. Continuous Separation of DNA Molecules by Size Using Insulator-Based Dielectrophoresis. Anal Chem 2017; 89:1531-1539. [DOI: 10.1021/acs.analchem.6b03369] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul V. Jones
- School of Molecular
Sciences, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287, United States
- Center
for Applied Structural
Discovery, The Biodesign Institute, Tempe, Arizona 85281, United States
| | - Gabriel L. Salmon
- School of Molecular
Sciences, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287, United States
- Center
for Applied Structural
Discovery, The Biodesign Institute, Tempe, Arizona 85281, United States
| | - Alexandra Ros
- School of Molecular
Sciences, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287, United States
- Center
for Applied Structural
Discovery, The Biodesign Institute, Tempe, Arizona 85281, United States
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24
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Luo J, Muratore KA, Arriaga EA, Ros A. Deterministic Absolute Negative Mobility for Micro- and Submicrometer Particles Induced in a Microfluidic Device. Anal Chem 2016; 88:5920-7. [PMID: 27149097 PMCID: PMC5316477 DOI: 10.1021/acs.analchem.6b00837] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Efficient separations of particles with micron and submicron dimensions are extremely useful in preparation and analysis of materials for nanotechnological and biological applications. Here, we demonstrate a nonintuitive, yet efficient, separation mechanism for μm and subμm colloidal particles and organelles, taking advantage of particle transport in a nonlinear post array in a microfluidic device under the periodic action of electrokinetic and dielectrophoretic forces. We reveal regimes in which deterministic particle migration opposite to the average applied force occurs for a larger particle, a typical signature of deterministic absolute negative mobility (dANM), whereas normal response is obtained for smaller particles. The coexistence of dANM and normal migration was characterized and optimized in numerical modeling and subsequently implemented in a microfluidic device demonstrating at least 2 orders of magnitude higher migration speeds as compared to previous ANM systems. We also induce dANM for mouse liver mitochondria and envision that the separation mechanisms described here provide size selectivity required in future separations of organelles, nanoparticles, and protein nanocrystals.
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Affiliation(s)
- Jinghui Luo
- School of Molecular Sciences, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Katherine A. Muratore
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Edgar A. Arriaga
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alexandra Ros
- School of Molecular Sciences, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
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25
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Saucedo-Espinosa MA, Rauch MM, LaLonde A, Lapizco-Encinas BH. Polarization behavior of polystyrene particles under direct current and low-frequency (<1 kHz) electric fields in dielectrophoretic systems. Electrophoresis 2015; 37:635-44. [PMID: 26531799 DOI: 10.1002/elps.201500338] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/26/2015] [Accepted: 10/22/2015] [Indexed: 11/11/2022]
Abstract
The relative polarization behavior of micron and submicron polystyrene particles was investigated under direct current and very low frequency (<1 kHz) alternating current electric fields. Relative polarization of particles with respect to the suspending medium is expressed in terms of the Clausius-Mossotti factor, a parameter of crucial importance in dielectrophoretic-based operations. Particle relative polarization was studied by employing insulator-based dielectrophoretic (iDEP) devices. The effects of particle size, medium conductivity, and frequency (10-1000 Hz) of the applied electric potential on particle response were assessed through experiments and mathematical modeling with COMSOL Multiphysics(®). Particles of different sizes (100-1000 nm diameters) were introduced into iDEP devices fabricated from polydimethylsiloxane (PDMS) and their dielectrophoretic responses under direct and alternating current electric fields were recorded and analyzed in the form of images and videos. The results illustrated that particle polarizability and dielectrophoretic response depend greatly on particle size and the frequency of the electric field. Small particles tend to exhibit positive DEP at higher frequencies (200-1000 Hz), while large particles exhibit negative DEP at lower frequencies (20-200 Hz). These differences in relative polarization can be used for the design of iDEP-based separations and analysis of particle mixtures.
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Affiliation(s)
| | - Mallory M Rauch
- Microscale Bioseparations Laboratory, Rochester Institute of Technology, Rochester, NY, USA
| | - Alexandra LaLonde
- Microscale Bioseparations Laboratory, Rochester Institute of Technology, Rochester, NY, USA
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26
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Saucedo-Espinosa MA, LaLonde A, Gencoglu A, Romero-Creel MF, Dolas JR, Lapizco-Encinas BH. Dielectrophoretic manipulation of particle mixtures employing asymmetric insulating posts. Electrophoresis 2015; 37:282-90. [DOI: 10.1002/elps.201500195] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 09/12/2015] [Accepted: 10/09/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Mario A. Saucedo-Espinosa
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
| | - Alexandra LaLonde
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
| | - Aytug Gencoglu
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
| | - Maria F. Romero-Creel
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
| | - Jay R. Dolas
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
| | - Blanca H. Lapizco-Encinas
- Biomedical Engineering Department; Microscale Bioseparations Laboratory, Rochester Institute of Technology; Rochester NY USA
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27
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Pesch GR, Kiewidt L, Du F, Baune M, Thöming J. Electrodeless dielectrophoresis: Impact of geometry and material on obstacle polarization. Electrophoresis 2015; 37:291-301. [DOI: 10.1002/elps.201500313] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/24/2015] [Accepted: 09/27/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Georg R. Pesch
- Chemical Engineering, Recovery and Recycling, Department of Production Engineering and Center for Environmental Research and Sustainable Technology; University of Bremen; Bremen Germany
| | - Lars Kiewidt
- Chemical Engineering, Recovery and Recycling, Department of Production Engineering and Center for Environmental Research and Sustainable Technology; University of Bremen; Bremen Germany
| | - Fei Du
- Chemical Engineering, Recovery and Recycling, Department of Production Engineering and Center for Environmental Research and Sustainable Technology; University of Bremen; Bremen Germany
| | - Michael Baune
- Chemical Engineering, Recovery and Recycling, Department of Production Engineering and Center for Environmental Research and Sustainable Technology; University of Bremen; Bremen Germany
| | - Jorg Thöming
- Chemical Engineering, Recovery and Recycling, Department of Production Engineering and Center for Environmental Research and Sustainable Technology; University of Bremen; Bremen Germany
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28
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Saucedo-Espinosa MA, Lapizco-Encinas BH. Experimental and theoretical study of dielectrophoretic particle trapping in arrays of insulating structures: Effect of particle size and shape. Electrophoresis 2015; 36:1086-97. [DOI: 10.1002/elps.201400408] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 10/27/2014] [Accepted: 11/28/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Mario A. Saucedo-Espinosa
- Microscale Bioseparations Laboratory, Department of Biomedical Engineering; Rochester Institute of Technology; Rochester NY USA
| | - Blanca H. Lapizco-Encinas
- Microscale Bioseparations Laboratory, Department of Biomedical Engineering; Rochester Institute of Technology; Rochester NY USA
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29
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Nakano A, Camacho-Alanis F, Ros A. Insulator-based dielectrophoresis with β-galactosidase in nanostructured devices. Analyst 2015; 140:860-8. [PMID: 25479537 PMCID: PMC4386925 DOI: 10.1039/c4an01503g] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Insulator-based dielectrophoresis (iDEP) has been explored as a powerful analytical technique in recent years. Unlike with larger entities such as cells, bacteria or organelles, the mechanism of iDEP transport of proteins remains little explored. In this work, we extended the pool of proteins investigated with iDEP in nanostructured devices with β-galactosidase. Our work indicates that β-galactosidase shows concentration due to negative DEP which we compare to DEP response of immunoglobulin G (IgG) encapsulated in micelles also showing negative DEP. Experimental observations are further compared with numerical simulations to elucidate the influence of electrokinetic transport and the magnitude of DEP mobility. Numerical simulations suggest that the DEP mobility calculated using the classical model underestimates the actual contribution of DEP on the experimentally monitored concentration effect of proteins. Moreover, we observed a unique voltage dependent β-galactosidase concentration which we attribute to an additional factor influencing the protein concentration at the nanoconstrictions, namely ion concentration polarization. Our work aids in understanding factors influencing protein iDEP transport which is required for the future development of protein preconcentration or separation methods based on iDEP.
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Affiliation(s)
- Asuka Nakano
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
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30
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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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31
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Zhou Y, Sheng H, Harrison DJ. Mechanism of DNA trapping in nanoporous structures during asymmetric pulsed-field electrophoresis. Analyst 2014; 139:6044-51. [PMID: 25271806 DOI: 10.1039/c4an01364f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the trapping mechanism of individual DNA molecules in ordered nanoporous structures generated by crystalline particle arrays. Two requisites for trapping are revealed by the dynamics of single trapped DNA, fully-stretched U/J shapes and hernia formation. The experimental results show there is a stronger possibility for hernias to lead the reorientation upon switching directions of the voltage at high field strengths, where trapping occurs. Fully stretched DNA has longer unhooking times than expected by a classic rope-on-pulley model. We propose a dielectrophoretic (DEP) force reduces the mobility of segments at the apex of the U or J, where field gradients are highest, based on simulations and observations of the trapping force dependence on field strength. A modified model for unhooking time is obtained after the DEP force is introduced. The new model explains the unhooking time data by predicting an infinite trapping time when the ratio of arm length differences (of the U or J) to molecule length Δx/L < β, where β is a DEP parameter that is found to strongly increase with electric field. The DNA polarizability calculated with the DEP model and experimental value of β is of the same magnitude of reported value. The results indicate the tension at the apex of U/J shape DNA is the primary reason for DNA trapping during pulsed field separation, instead of hernias.
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Affiliation(s)
- Ya Zhou
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada.
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32
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Dash S, Mohanty S. Dielectrophoretic separation of micron and submicron particles: a review. Electrophoresis 2014; 35:2656-72. [PMID: 24930837 DOI: 10.1002/elps.201400084] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 06/03/2014] [Accepted: 06/05/2014] [Indexed: 11/06/2022]
Abstract
This paper provides an overview on separation of micron and submicron sized biological (cells, yeast, virus, bacteria, etc.) and nonbiological particles (latex, polystyrene, CNTs, metals, etc.) by dielectrophoresis (DEP), which finds wide applications in the field of medical and environmental science. Mathematical models to predict the electric field, flow profile, and concentration profiles of the particles under the influence of DEP force have also been covered in this review. In addition, advancements made primarily in the last decade, in the area of electrode design (shape and arrangement), new materials for electrode (carbon, silicon, polymers), and geometry of the microdevice, for efficient DEP separation of particles have been highlighted.
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Affiliation(s)
- Swagatika Dash
- CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, India
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Nakano A, Luo J, Ros A. Temporal and spatial temperature measurement in insulator-based dielectrophoretic devices. Anal Chem 2014; 86:6516-24. [PMID: 24889741 PMCID: PMC4082381 DOI: 10.1021/ac501083h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 06/03/2014] [Indexed: 01/31/2023]
Abstract
Insulator-based dielectrophoresis is a relatively new analytical technique with a large potential for a number of applications, such as sorting, separation, purification, fractionation, and preconcentration. The application of insulator-based dielectrophoresis (iDEP) for biological samples, however, requires the precise control of the microenvironment with temporal and spatial resolution. Temperature variations during an iDEP experiment are a critical aspect in iDEP since Joule heating could lead to various detrimental effects hampering reproducibility. Additionally, Joule heating can potentially induce thermal flow and more importantly can degrade biomolecules and other biological species. Here, we investigate temperature variations in iDEP devices experimentally employing the thermosensitive dye Rhodamin B (RhB) and compare the measured results with numerical simulations. We performed the temperature measurement experiments at a relevant buffer conductivity range commonly used for iDEP applications under applied electric potentials. To this aim, we employed an in-channel measurement method and an alternative method employing a thin film located slightly below the iDEP channel. We found that the temperature does not deviate significantly from room temperature at 100 μS/cm up to 3000 V applied such as in protein iDEP experiments. At a conductivity of 300 μS/cm, such as previously used for mitochondria iDEP experiments at 3000 V, the temperature never exceeds 34 °C. This observation suggests that temperature effects for iDEP of proteins and mitochondria under these conditions are marginal. However, at larger conductivities (1 mS/cm) and only at 3000 V applied, temperature increases were significant, reaching a regime in which degradation is likely to occur. Moreover, the thin layer method resulted in lower temperature enhancement which was also confirmed with numerical simulations. We thus conclude that the thin film method is preferable providing closer agreement with numerical simulations and further since it does not depend on the iDEP channel material. Overall, our study provides a thorough comparison of two experimental techniques for direct temperature measurement, which can be adapted to a variety of iDEP applications in the future. The good agreement between simulation and experiment will also allow one to assess temperature variations for iDEP devices prior to experiments.
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Affiliation(s)
- Asuka Nakano
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287, United States
| | - Jinghui Luo
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287, United States
| | - Alexandra Ros
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, Arizona 85287, United States
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LaLonde A, Gencoglu A, Romero-Creel MF, Koppula KS, Lapizco-Encinas BH. Effect of insulating posts geometry on particle manipulation in insulator based dielectrophoretic devices. J Chromatogr A 2014; 1344:99-108. [DOI: 10.1016/j.chroma.2014.03.083] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 03/25/2014] [Accepted: 03/30/2014] [Indexed: 10/25/2022]
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Luo J, Abdallah BG, Wolken GG, Arriaga EA, Ros A. Insulator-based dielectrophoresis of mitochondria. BIOMICROFLUIDICS 2014; 8:021801. [PMID: 24959306 PMCID: PMC4056684 DOI: 10.1063/1.4866852] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/28/2014] [Indexed: 05/03/2023]
Abstract
Isolated mitochondria display a wide range of sizes plausibly resulting from the coexistence of subpopulations, some of which may be associated with disease or aging. Strategies to separate subpopulations are needed to study the importance of these organelles in cellular functions. Here, insulator-based dielectrophoresis (iDEP) was exploited to provide a new dimension of organelle separation. The dielectrophoretic properties of isolated Fischer 344 (F344) rat semimembranosus muscle mitochondria and C57BL/6 mouse hepatic mitochondria in low conductivity buffer (0.025-0.030 S/m) at physiological pH (7.2-7.4) were studied using polydimethylsiloxane (PDMS) microfluidic devices. First, direct current (DC) and alternating current (AC) of 0-50 kHz with potentials of 0-3000 V applied over a channel length of 1 cm were separately employed to generate inhomogeneous electric fields and establish that mitochondria exhibit negative DEP (nDEP). DEP trapping potential thresholds at 0-50 kHz were also determined to be weakly dependent on applied frequency and were generally above 200 V. Second, we demonstrated a separation scheme using DC potentials <100 V to perform the first size-based iDEP sorting of mitochondria. Samples of isolated mitochondria with heterogeneous sizes (150 nm-2 μm diameters) were successfully separated into sub-micron fractions, indicating the ability to isolate mitochondria into populations based on their size.
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Affiliation(s)
- Jinghui Luo
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA
| | - Bahige G Abdallah
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA
| | - Gregory G Wolken
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Edgar A Arriaga
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Alexandra Ros
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA
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Gallo-Villanueva RC, Sano MB, Lapizco-Encinas BH, Davalos RV. Joule heating effects on particle immobilization in insulator-based dielectrophoretic devices. Electrophoresis 2014; 35:352-61. [PMID: 24002905 PMCID: PMC4114348 DOI: 10.1002/elps.201300171] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/31/2013] [Accepted: 08/01/2013] [Indexed: 11/10/2022]
Abstract
In this work, the temperature effects due to Joule heating obtained by application of a direct current electric potential were investigated for a microchannel with cylindrical insulating posts employed for insulator-based dielectrophoresis. The conductivity of the suspending medium, the local electric field, and the gradient of the squared electric field, which directly affect the magnitude of the dielectrophoretic force exerted on particles, were computationally simulated employing COMSOL Multiphysics. It was observed that a temperature gradient is formed along the microchannel, which redistributes the conductivity of the suspending medium leading to an increase of the dielectrophoretic force toward the inlet of the channel while decreasing toward the outlet. Experimental results are in good agreement with simulations on the particle-trapping zones anticipated. This study demonstrates the importance of considering Joule heating effects when designing insulator-based dielectrophoresis systems.
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Affiliation(s)
| | - Michael B. Sano
- School of Biomedical Engineering and Sciences, Virginia Tech
– Wake Forest University, Blacksburg, VA, USA
| | - Blanca H. Lapizco-Encinas
- Microscale Bioseparations Laboratory and Department of Chemical and
Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Rafael V. Davalos
- School of Biomedical Engineering and Sciences, Virginia Tech
– Wake Forest University, Blacksburg, VA, USA
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Gencoglu A, Olney D, LaLonde A, Koppula KS, Lapizco-Encinas BH. Dynamic microparticle manipulation with an electroosmotic flow gradient in low-frequency alternating current dielectrophoresis. Electrophoresis 2013; 35:362-73. [PMID: 24166858 DOI: 10.1002/elps.201300385] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 10/07/2013] [Accepted: 10/16/2013] [Indexed: 11/07/2022]
Abstract
In this study, the potential of low-frequency AC insulator-based DEP (iDEP) was explored for the separation of polystyrene microparticles and yeast cells. An EOF gradient was generated by employing an asymmetrical, 20 Hz AC electrical signal in an iDEP device consisting of a microchannel with diamond-shaped insulating posts. Two types of samples were analyzed, the first sample contained three types of polystyrene particles with different diameters (0.5, 1.0, and 2.0 μm) and the second sample contained two types of polystyrene particles (1.0 and 2 μm) and yeast cells (6.3 μm). This particular scheme uses a tapered AC signal that allows for all particles to be trapped and concentrated at the insulating post array, as the signal becomes asymmetrical (more positive), particles are selectively released. The smallest particles in each sample were released first, since they require greater dielectrophoretic forces to remain trapped. The largest particles in each sample were released last, when the applied signal became cyclical. A dielectropherogram, which is analogous to a chromatogram, was obtained for each sample, demonstrating successful separation of the particles by showing "peaks" of the released particles. These separations were achieved at lower applied potentials than those reported in previous studies that used solely direct current electrical voltages. Additionally, mathematical modeling with COMSOL Multiphysics was carried out to estimate the magnitude of the dielectrophoretic and EOF forces acting on the particles considering the low-frequency, asymmetrical AC signal used in the experiments. The results demonstrated the potential of low-frequency AC-iDEP systems for handling and separating complex mixtures of microparticles and biological cells.
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Affiliation(s)
- Aytug Gencoglu
- Microscale Bioseparations Laboratory, Department of Chemical and Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA
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Gan L, Chao TC, Camacho-Alanis F, Ros A. Six-Helix Bundle and Triangle DNA Origami Insulator-Based Dielectrophoresis. Anal Chem 2013; 85:11427-34. [DOI: 10.1021/ac402493u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Lin Gan
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, AZ 85287, U.S.A
| | - Tzu-Chiao Chao
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, AZ 85287, U.S.A
| | | | - Alexandra Ros
- Department of Chemistry and
Biochemistry, Arizona State University, Tempe, AZ 85287, U.S.A
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Nakano A, Ros A. Protein dielectrophoresis: advances, challenges, and applications. Electrophoresis 2013; 34:1085-96. [PMID: 23400789 PMCID: PMC3839426 DOI: 10.1002/elps.201200482] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 11/05/2022]
Abstract
Protein dielectrophoresis (DEP) has the potential to play an important role as a manipulation, fractionation, preconcentration, and separation method in bioanalysis and as manipulation tool for nanotechnological applications. The first demonstrations of protein DEP have been reported almost 20 years ago. Since then various experimental realizations to manipulate proteins by DEP as well as more targeted applications employing protein DEP have been demonstrated. This review summarizes the experimental studies in the field of protein DEP trapping and focusing as well as specific applications in separation, molecular patterning, on bioprobes and biosensors. While a comprehensive theoretical model describing protein DEP is still lacking we also attempt to provide an overview of the factors influencing protein DEP and relate to currently available theoretical models. We further point out the variations in experimental conditions used in the past to study the somewhat 20 proteins as well as the implications of protein molecular structure to the DEP response.
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Affiliation(s)
- Asuka Nakano
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA
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Yunus NAM, Nili H, Green NG. Continuous separation of colloidal particles using dielectrophoresis. Electrophoresis 2013; 34:969-78. [DOI: 10.1002/elps.201200466] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 10/22/2012] [Accepted: 11/07/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Nurul Amziah Md. Yunus
- Department of Electrical and Electronic Engineering, Faculty of Engineering; Universiti Putra Malaysia; Selangor; Malaysia
| | - Hossein Nili
- Nano Group, School of Electronics and Computer Science; University of Southampton; Highfield; Southampton; UK
| | - Nicolas G. Green
- Nano Group, School of Electronics and Computer Science; University of Southampton; Highfield; Southampton; UK
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