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Abstract
Isotachophoresis (ITP) is a versatile electrophoretic technique that can be used for sample preconcentration, separation, purification, and mixing, and to control and accelerate chemical reactions. Although the basic technique is nearly a century old and widely used, there is a persistent need for an easily approachable, succinct, and rigorous review of ITP theory and analysis. This is important because the interest and adoption of the technique has grown over the last two decades, especially with its implementation in microfluidics and integration with on-chip chemical and biochemical assays. We here provide a review of ITP theory starting from physicochemical first-principles, including conservation of species, conservation of current, approximation of charge neutrality, pH equilibrium of weak electrolytes, and so-called regulating functions that govern transport dynamics, with a strong emphasis on steady and unsteady transport. We combine these generally applicable (to all types of ITP) theoretical discussions with applications of ITP in the field of microfluidic systems, particularly on-chip biochemical analyses. Our discussion includes principles that govern the ITP focusing of weak and strong electrolytes; ITP dynamics in peak and plateau modes; a review of simulation tools, experimental tools, and detection methods; applications of ITP for on-chip separations and trace analyte manipulation; and design considerations and challenges for microfluidic ITP systems. We conclude with remarks on possible future research directions. The intent of this review is to help make ITP analysis and design principles more accessible to the scientific and engineering communities and to provide a rigorous basis for the increased adoption of ITP in microfluidics.
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Affiliation(s)
- Ashwin Ramachandran
- Department
of Aeronautics and Astronautics, Stanford
University, Stanford, California 94305, United States
| | - Juan G. Santiago
- Department
of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
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2
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Thormann W, Mosher RA. Dynamic computer simulations of electrophoresis: 2010-2020. Electrophoresis 2021; 43:10-36. [PMID: 34287996 PMCID: PMC9292373 DOI: 10.1002/elps.202100191] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 02/05/2023]
Abstract
The transport of components in liquid media under the influence of an applied electric field can be described with the continuity equation. It represents a nonlinear conservation law that is based upon the balance laws of continuous transport processes and can be solved in time and space numerically. This procedure is referred to as dynamic computer simulation. Since its inception four decades ago, the state of dynamic computer simulation software and its use has progressed significantly. Dynamic models are the most versatile tools to explore the fundamentals of electrokinetic separations and provide insights into the behavior of buffer systems and sample components of all electrophoretic separation methods, including moving boundary electrophoresis, CZE, CGE, ITP, IEF, EKC, ACE, and CEC. This article is a continuation of previous reviews (Electrophoresis 2009, 30, S16–S26 and Electrophoresis 2010, 31, 726–754) and summarizes the progress and achievements made during the 2010 to 2020 time period in which some of the existing dynamic simulators were extended and new simulation packages were developed. This review presents the basics and extensions of the three most used one‐dimensional simulators, provides a survey of new one‐dimensional simulators, outlines an overview of multi‐dimensional models, and mentions models that were briefly reported in the literature. A comprehensive discussion of simulation applications and achievements of the 2010 to 2020 time period is also included.
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Affiliation(s)
- Wolfgang Thormann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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3
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He M, Luo P, Hong J, Wang X, Wu H, Zhang R, Qu F, Xiang Y, Xu W. Structural Analysis of Biomolecules through a Combination of Mobility Capillary Electrophoresis and Mass Spectrometry. ACS OMEGA 2019; 4:2377-2386. [PMID: 31459477 PMCID: PMC6648644 DOI: 10.1021/acsomega.8b03224] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/24/2019] [Indexed: 05/08/2023]
Abstract
The 3D structures of biomolecules determine their biological function. Established methods in biomolecule structure determination typically require purification, crystallization, or modification of target molecules, which limits their applications for analyzing trace amounts of biomolecules in complex matrices. Here, we developed instruments and methods of mobility capillary electrophoresis (MCE) and its coupling with MS for the 3D structural analysis of biomolecules in the liquid phase. Biomolecules in complex matrices could be separated by MCE and sequentially detected by MS. The effective radius and the aspect ratio of each separated biomolecule were simultaneously determined through the separation by MCE, which were then used as restraints in determining biomolecule conformations through modeling. Feasibility of this method was verified by analyzing a mixture of somatostatin and bradykinin, two peptides with known liquid-phase structures. Proteins could also be structurally analyzed using this method, which was demonstrated for lysozyme. The combination of MCE and MS for complex sample analysis was also demonstrated. MCE and MCE-MS would allow us to analyze trace amounts of biomolecules in complex matrices, which has the potential to be an alternative and powerful biomolecule structure analysis technique.
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Affiliation(s)
- Muyi He
- College
of Information Science, Shenzhen University, Shenzhen 518060, China
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Pan Luo
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Jie Hong
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaofeng Wang
- Institute
of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Haimei Wu
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Rongkai Zhang
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Feng Qu
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Ye Xiang
- Beijing
Advanced Innovation Center for Structural Biology, Department of Basic
Medical Sciences, School of Medicine, Tsinghua
University, Beijing 100084, China
- E-mail: (Y.X.)
| | - Wei Xu
- College
of Information Science, Shenzhen University, Shenzhen 518060, China
- School
of Life Science, Beijing Institute of Technology, Beijing 100081, China
- E-mail: (W.X.)
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4
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van Kooten XF, Truman-Rosentsvit M, Kaigala GV, Bercovici M. Focusing analytes from 50 μL into 500 pL: On-chip focusing from large sample volumes using isotachophoresis. Sci Rep 2017; 7:10467. [PMID: 28874694 PMCID: PMC5585209 DOI: 10.1038/s41598-017-10579-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 08/09/2017] [Indexed: 11/12/2022] Open
Abstract
The use of on-chip isotachophoresis assays for diagnostic applications is often limited by the small volumes of standard microfluidic channels. Overcoming this limitation is particularly important for detection of 'discrete' biological targets (such as bacteria) at low concentrations, where the volume of processed liquid in a standard microchannel might not contain any targets. We present a novel microfluidic chip that enables ITP focusing of target analytes from initial sample volumes of 50 μL into a concentrated zone with a volume of 500 pL, corresponding to a 100,000-fold increase in mean concentration, and a 300,000-fold increase in peak concentration. We present design considerations for limiting sample dispersion in such large-volume focusing (LVF) chips and discuss the trade-off between assay time and Joule heating, which ultimately governs the scalability of LVF designs. Finally, we demonstrate a 100-fold improvement of ITP focusing performance in the LVF chip as compared to conventional microchannels, and apply this enhancement to achieve highly sensitive detection of both molecular targets (DNA, down to 10 fM) and whole bacteria (down to 100 cfu/mL).
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Affiliation(s)
- Xander F van Kooten
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
- IBM Research - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland
| | | | - Govind V Kaigala
- IBM Research - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
| | - Moran Bercovici
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel.
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5
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Breadmore MC, Wuethrich A, Li F, Phung SC, Kalsoom U, Cabot JM, Tehranirokh M, Shallan AI, Abdul Keyon AS, See HH, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2014–2016). Electrophoresis 2016; 38:33-59. [DOI: 10.1002/elps.201600331] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 01/02/2023]
Affiliation(s)
- Michael C. Breadmore
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
- ARC Centre of Excellence for Electromaterials Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
- ASTech, ARC Training Centre for Portable Analytical Separation Technologies, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Alain Wuethrich
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Feng Li
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Sui Ching Phung
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Umme Kalsoom
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Joan M. Cabot
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
- ARC Centre of Excellence for Electromaterials Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Masoomeh Tehranirokh
- ASTech, ARC Training Centre for Portable Analytical Separation Technologies, School of Physical Science University of Tasmania Hobart Tasmania Australia
| | - Aliaa I. Shallan
- Department of Analytical Chemistry, Faculty of Pharmacy Helwan University Cairo Egypt
| | - Aemi S. Abdul Keyon
- Department of Chemistry, Faculty of Science Universiti Teknologi Malaysia Johor Bahru Johor Malaysia
| | - Hong Heng See
- Department of Chemistry, Faculty of Science Universiti Teknologi Malaysia Johor Bahru Johor Malaysia
- Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and industrial Research Universiti Teknologi Malaysia Johor Bahru Johor Malaysia
| | - Mohamed Dawod
- Department of Chemistry University of Michigan Ann Arbor MI USA
| | - Joselito P. Quirino
- Australian Centre of Research on Separation Science, School of Physical Science University of Tasmania Hobart Tasmania Australia
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6
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Malá Z, Gebauer P, Boček P. Analytical capillary isotachophoresis after 50 years of development: Recent progress 2014-2016. Electrophoresis 2016; 38:9-19. [DOI: 10.1002/elps.201600289] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/15/2016] [Accepted: 07/15/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Zdena Malá
- Institute of Analytical Chemistry of the Czech Academy of Sciences; v.v.i; Brno Czech Republic
| | - Petr Gebauer
- Institute of Analytical Chemistry of the Czech Academy of Sciences; v.v.i; Brno Czech Republic
| | - Petr Boček
- Institute of Analytical Chemistry of the Czech Academy of Sciences; v.v.i; Brno Czech Republic
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