1
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Papadimitriou VA, Kruit SA, Segerink LI, Eijkel JCT. Droplet encapsulation of electrokinetically-focused analytes without loss of resolution. LAB ON A CHIP 2020; 20:2209-2217. [PMID: 32432628 DOI: 10.1039/d0lc00191k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lab-on-chip electrokinetic focusing and separation techniques are widely used in several scientific fields. In a number of cases, these techniques have been combined with a selective analyte extraction for off-chip analysis. Nevertheless, the usability of the extracts is limited by diffusion which reduces the separation resolution. In this paper we propose the integration of a droplet generator capable of continuous or on-demand generation and extraction of electrokinetically separated and focused analytes. We demonstrate the selective droplet extraction of model analytes separated and concentrated via ion concentration polarization focusing (ICPF). We report extracted droplets with 1000-fold increased concentration. Importantly, the droplet generator does not interrupt the ICPF process making it suitable for integration with the majority of electrokinetic separation techniques.
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Affiliation(s)
- Vasileios A Papadimitriou
- BIOS-Lab on a Chip Group, MESA+ Institute of Nanotechnology, Technical Medical Centre, Max Planck Center for Complex Fluid Dynamics, University of Twente, The Netherlands.
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2
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Abstract
Electrokinetic separation techniques in microfluidics are a powerful analytical chemistry tool, although an inherent limitation of microfluidics is their low sample throughput. In this article we report a free-flow variant of an electrokinetic focusing method, namely ion concentration polarization focusing (ICPF). The analytes flow continuously through the system via pressure driven flow while they separate and concentrate perpendicularly to the flow by ICPF. We demonstrate free flow ion concentration polarization focusing (FF-ICPF) in two operating modes, namely peak and plateau modes. Additionally, we showed the separation resolution could be improved by the use of an electrophoretic spacer. We report a concentration factor of 10 in human blood plasma in continuous flow at a flow rate of 15 μL min-1.
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Affiliation(s)
- Vasileios A Papadimitriou
- BIOS Lab on a Chip group, MESA+ Institute for Nanotechnology, Max Planck Centre for Complex Fluid Dynamics and Technical Medical Centre, University of Twente, Enschede 7500 AE, The Netherlands
| | - Loes I Segerink
- BIOS Lab on a Chip group, MESA+ Institute for Nanotechnology, Max Planck Centre for Complex Fluid Dynamics and Technical Medical Centre, University of Twente, Enschede 7500 AE, The Netherlands
| | - Jan C T Eijkel
- BIOS Lab on a Chip group, MESA+ Institute for Nanotechnology, Max Planck Centre for Complex Fluid Dynamics and Technical Medical Centre, University of Twente, Enschede 7500 AE, The Netherlands
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3
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Zhang C, Sun G, Senapati S, Chang HC. A bifurcated continuous field-flow fractionation (BCFFF) chip for high-yield and high-throughput nucleic acid extraction and purification. LAB ON A CHIP 2019; 19:3853-3861. [PMID: 31621762 PMCID: PMC6982425 DOI: 10.1039/c9lc00818g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We report a bifurcated continuous field-flow fractionation (BCFFF) chip for high-yield and high-throughput (20 min) extraction of nucleic acids from physiological samples. The design uses a membrane ionic transistor to sustain low-ionic strength in a localized region at a junction, such that the resulting high field can selectively isolate high-charge density nucleic acids from the main flow channel and insert them into a standardized buffer in a side channel that bifurcates from the junction. The high local electric field and the bifurcated field-flow design facilitate concentration reduction of both divalent cation (Ca2+) and molecular PCR inhibitors by more than two orders of magnitude, even with high-throughput continuous loading. The unique design with a large (>20 mM mm-1) on-chip ionic-strength gradient allows miniaturization into a high-throughput field-flow fractionation chip that can be integrated with upstream lysing and downstream PCR/sensor modules for various nucleic acid detection/quantification applications. A concentration-independent 85% yield for extraction and an overall post-PCR yield exceeding 60% are demonstrated for a 111 bp dsDNA in 10 μL of human plasma, compared to no amplification with the raw sample. A net yield four times larger than a commercial extraction kit is demonstrated for miR-39 in human plasma.
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Affiliation(s)
- Chenguang Zhang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA. and Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Gongchen Sun
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Satyajyoti Senapati
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA. and Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, IN 46556, USA and Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Hsueh-Chia Chang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA. and Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, IN 46556, USA and Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, USA and Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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4
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Sun G, Wan J, Lu H. Rapid and multi-cycle smFISH enabled by microfluidic ion concentration polarization for in-situ profiling of tissue-specific gene expression in whole C. elegans. BIOMICROFLUIDICS 2019; 13:064101. [PMID: 31700560 PMCID: PMC6824911 DOI: 10.1063/1.5124827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/15/2019] [Indexed: 06/10/2023]
Abstract
Understanding gene regulation networks in multicellular organisms is crucial to decipher many complex physiological processes ranging from development to aging. One technique to characterize gene expression with tissue-specificity in whole organisms is single-molecule fluorescence in situ hybridization (smFISH). However, this protocol requires lengthy incubation times, and it is challenging to achieve multiplexed smFISH in a whole organism. Multiplexing techniques can yield transcriptome-level information, but they require sequential probing of different genes. The inefficient macromolecule exchange through diffusion-dominant transport across dense tissues is the major bottleneck. In this work, we address this challenge by developing a microfluidic/electrokinetic hybrid platform to enable multicycle smFISH in an intact model organism, Caenorhabditis elegans. We integrate an ion concentration polarization based ion pump with a microfluidic array to rapidly deliver and remove gene-specific probes and stripping reagents on demand in individual animals. Using our platform, we can achieve rapid smFISH, an order of magnitude faster than traditional smFISH protocols. We also demonstrate the capability to perform multicycle smFISH on the same individual samples, which is impossible to do off-chip. Our method hence provides a powerful tool to study individual-specific, spatially resolvable, and large-scale gene expression in whole organisms.
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Affiliation(s)
- Gongchen Sun
- School of Chemical & Biomolecular Engineering,
Georgia Institute of Technology, Atlanta, Georgia
30332, USA
| | - Jason Wan
- Wallace H. Coulter Department of Biomedical
Engineering, Georgia Institute of Technology and Emory University,
Atlanta, Georgia 30332, USA
| | - Hang Lu
- School of Chemical & Biomolecular Engineering,
Georgia Institute of Technology, Atlanta, Georgia
30332, USA
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5
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Papadimitriou VA, Segerink LI, Eijkel JCT. Continuous focusing, fractionation and extraction of anionic analytes in a microfluidic chip. LAB ON A CHIP 2019; 19:3238-3248. [PMID: 31475716 DOI: 10.1039/c9lc00434c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrokinetic focusing and separation methods, specifically ion concentration polarization focusing (ICPF), provide a very powerful and easy to use analytical tool for several scientific fields. Nevertheless, the concentrated and separated analytes are effectively trapped inside the chip in picoliter volumes. In this article we propose an ICPF device that allows continuous and selective extraction of the focused analytes. A theoretical background is presented to understand the dynamics of the system and a 1D model was developed that describes the general behavior of the system. We demonstrate the selective extraction of three fluorescent model anionic analytes and we report selective extraction of the analytes at a 300-fold increased concentration.
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Affiliation(s)
- Vasileios A Papadimitriou
- BIOS Lab on a Chip group, MESA+ Institute for Nanotechnology, Max Planck Centre for Complex Fluid Dynamics and Technical Medical Centre, University of Twente, The Netherlands.
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6
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Marczak S, Smith E, Senapati S, Chang HC. Selectivity enhancements in gel-based DNA-nanoparticle assays by membrane-induced isotachophoresis: thermodynamics versus kinetics. Electrophoresis 2017; 38:2592-2602. [PMID: 28726313 DOI: 10.1002/elps.201700146] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/10/2017] [Accepted: 07/14/2017] [Indexed: 12/17/2022]
Abstract
Selectivity against mutant nontargets with a few mismatches remains challenging in nucleic acid sensing. Sensitivity enhancement by analyte concentration does not improve selectivity because it affects targets and nontargets equally. Hydrodynamic or electrical shear enhanced selectivity is often accompanied by substantial losses in target signals, thereby leading to poor limits of detection. We introduce a platform based on depletion isotachophoresis in agarose gel generated by an ion-selective membrane that allows both selectivity and sensitivity enhancement with a two-step assay involving concentration polarization at an ion-selective membrane. By concentrating both the targets and probe-functionalized nanoparticles by ion enrichment at the membrane, the effective thermodynamic dissociation constant is lowered from 40 nM to below 500 pM, and the detection limit is 10 pM as reported previously. A dynamically optimized ion depletion front is then generated from the membrane with a high electrical shear force to selectively and irreversibly dehybridize nontargets. The optimized selectivity against a two-mismatch nontarget (in a 35-base pairing sequence) is shown to be better than the thermodynamic equilibrium selectivity by more than a hundred-fold, such that there is no detectable signal from the two-mismatch nontarget. We offer empirical evidence that irreversible cooperative dehybridization plays an important role in this kinetic selectivity enhancement and that mismatch location controls the optimum selectivity even when there is little change in the corresponding thermodynamic dissociation constant.
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Affiliation(s)
- Steven Marczak
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Elaine Smith
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Satyajyoti Senapati
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Hsueh-Chia Chang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, USA
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7
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Sun G, Pan Z, Senapati S, Chang HC. Concentration-Gradient Stabilization with Segregated Counter- and Co-Ion Paths: A Quasistationary Depletion Front for Robust Molecular Isolation or Concentration. PHYSICAL REVIEW APPLIED 2017; 7:064024. [PMID: 36936449 PMCID: PMC10021788 DOI: 10.1103/physrevapplied.7.064024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We study the spatiotemporal dynamics of a microfluidic system with a nonselective microfluidic channel gated by an ion-selective membrane which separates the ion flux paths of cations and anions. To preserve electroneutrality, the ionic concentration in the system is shown to converge to a specific inhomogeneous distribution with robust constant current fluxes. A circuit scaling theory that collapses measured asymptotic currents verifies that this is a generic and robust mechanism insensitive to channel geometry, ion selectivity, and electrolyte ionic strength. This first temporally stationary but spatially inhomogeneous depletion front can be used for modulating ionic current and for isotachophoretic isolation of low-mobility molecules and exosomes on small diagnostic chips for various medical applications that require robust high-throughput and integrated platforms.
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Affiliation(s)
- Gongchen Sun
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Zehao Pan
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Satyajyoti Senapati
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Hsueh-Chia Chang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
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8
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Induced nanoparticle aggregation for short nucleic acid quantification by depletion isotachophoresis. Biosens Bioelectron 2016; 86:840-848. [DOI: 10.1016/j.bios.2016.07.093] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/31/2016] [Accepted: 07/26/2016] [Indexed: 12/21/2022]
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9
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Startsev MA, Ostrowski M, Goldys EM, Inglis DW. A mobility shift assay for DNA detection using nanochannel gradient electrophoresis. Electrophoresis 2016; 38:335-341. [PMID: 27515373 DOI: 10.1002/elps.201600358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/18/2022]
Abstract
Conventional detection of pathogenic or other biological contamination relies on amplification of DNA using sequence-specific primers. Recent work in nanofluidics has shown very high concentration enhancement of biomolecules with some degree of simultaneous separation. This work demonstrates the combination of these two approaches by selectively concentrating a mobility-shifted hybridization product, potentially enabling rapid detection of rare DNA fragments such as highly specific 16S ribosomal DNA. We have performed conductivity gradient electrofocusing within nanofluidic channels and have shown concentration of hybridized peptide nucleic acids and DNA oligomers. We also show selectivity to single base-pair mismatch on 18-mer oligos. This approach may enable sensitive optical detection of small amounts of DNA.
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Affiliation(s)
- Michael A Startsev
- Department of Physics and Astronomy, Macquarie University, Sydney, Australia
| | - Martin Ostrowski
- Department of Chemistry and Bimolecular Sciences, Macquarie University, Sydney, Australia
| | - Ewa M Goldys
- Department of Physics and Astronomy, Macquarie University, Sydney, Australia
| | - David W Inglis
- Department of Engineering, Macquarie University, Sydney, Australia
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10
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Bahga SS, Moza R, Khichar M. Theory of multi-species electrophoresis in the presence of surface conduction. Proc Math Phys Eng Sci 2016; 472:20150661. [PMID: 27118893 DOI: 10.1098/rspa.2015.0661] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electrophoresis techniques are characterized by concentration disturbances (or waves) propagating under the effect of an electric field. These techniques are usually performed in microchannels where surface conduction through the electric double layer (EDL) at channel walls is negligible compared with bulk conduction. However, when electrophoresis techniques are integrated in nanochannels, shallow microchannels or charged porous media, surface conduction can alter bulk electrophoretic transport. The existing mathematical models for electrophoretic transport in multi-species electrolytes do not account for the competing effects of surface and bulk conduction. We present a mathematical model of multi-species electrophoretic transport incorporating the effects of surface conduction on bulk ion-transport and provide a methodology to derive analytical solutions using the method of characteristics. Based on the analytical solutions, we elucidate the propagation of nonlinear concentration waves, such as shock and rarefaction waves, and provide the necessary and sufficient conditions for their existence. Our results show that the presence of surface conduction alters the propagation speed of nonlinear concentration waves and the composition of various zones. Importantly, we highlight the role of surface conduction in formation of additional shock and rarefaction waves which are otherwise not present in conventional electrophoresis.
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Affiliation(s)
- Supreet Singh Bahga
- Department of Mechanical Engineering , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
| | - Romir Moza
- Department of Mechanical Engineering , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
| | - Mayank Khichar
- Department of Mechanical Engineering , Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
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11
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Abstract
Advancements in ion concentration polarization made over the past three years are highlighted.
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Affiliation(s)
- Min Li
- Department of Chemistry
- Iowa State University
- Ames
- USA
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12
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Present state of microchip electrophoresis: state of the art and routine applications. J Chromatogr A 2014; 1382:66-85. [PMID: 25529267 DOI: 10.1016/j.chroma.2014.11.034] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/07/2014] [Accepted: 11/12/2014] [Indexed: 12/20/2022]
Abstract
Microchip electrophoresis (MCE) was one of the earliest applications of the micro-total analysis system (μ-TAS) concept, whose aim is to reduce analysis time and reagent and sample consumption while increasing throughput and portability by miniaturizing analytical laboratory procedures onto a microfluidic chip. More than two decades on, electrophoresis remains the most common separation technique used in microfluidic applications. MCE-based instruments have had some commercial success and have found application in many disciplines. This review will consider the present state of MCE including recent advances in technology and both novel and routine applications in the laboratory. We will also attempt to assess the impact of MCE in the scientific community and its prospects for the future.
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13
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Hsu WL, Harvie DJE, Davidson MR, Jeong H, Goldys EM, Inglis DW. Concentration gradient focusing and separation in a silica nanofluidic channel with a non-uniform electroosmotic flow. LAB ON A CHIP 2014; 14:3539-49. [PMID: 25027204 DOI: 10.1039/c4lc00504j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The simultaneous concentration gradient focusing and separation of proteins in a silica nanofluidic channel of various geometries is investigated experimentally and theoretically. Previous modelling of a similar device [Inglis et al., Angew. Chem. Int. Ed., 2011, 50, 7546] assumed a uniform velocity profile along the length of the nanochannel. Using detailed numerical analysis incorporating charge regulation and viscoelectric effects, we show that in reality the varying axial electric field and varying electric double layer thickness caused by the concentration gradient, induce a highly non-uniform velocity profile, fundamentally altering the protein trapping mechanism: the direction of the local electroosmotic flow reverses and two local vortices are formed near the centreline of the nanochannel at the low salt concentration end, enhancing trapping efficiency. Simulation results for yellow/red fluorescent protein R-PE concentration enhancement, peak focusing position and peak focusing width are in good agreement with experimental measurements, validating the model. The predicted separation of yellow/red (R-PE) from green (Dyl-Strep) fluorescent proteins mimics that from a previous experiment [Inglis et al., Angew. Chem. Int. Ed., 2011, 50, 7546] conducted in a slightly different geometry. The results will inform the design of new class of matrix-free particle focusing and separation devices.
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Affiliation(s)
- Wei-Lun Hsu
- Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
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14
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Cheow LF, Sarkar A, Kolitz S, Lauffenburger D, Han J. Detecting kinase activities from single cell lysate using concentration-enhanced mobility shift assay. Anal Chem 2014; 86:7455-62. [PMID: 25025773 PMCID: PMC4144746 DOI: 10.1021/ac502185v] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Electrokinetic preconcentration coupled with mobility shift assays can give rise to very high detection sensitivities. We describe a microfluidic device that utilizes this principle to detect cellular kinase activities by simultaneously concentrating and separating substrate peptides with different phosphorylation states. This platform is capable of reliably measuring kinase activities of single adherent cells cultured in nanoliter volume microwells. We also describe a novel method utilizing spacer peptides that significantly increase separation resolution while maintaining high concentration factors in this device. Thus, multiplexed kinase measurements can be implemented with single cell sensitivity. Multiple kinase activity profiling from single cell lysate could potentially allow us to study heterogeneous activation of signaling pathways that can lead to multiple cell fates.
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Affiliation(s)
- Lih Feng Cheow
- Department of Electrical Engineering and Computer Science and ‡Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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15
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Electrokinetics for sample preparation of biological molecules in biological samples using microfluidic systems. Bioanalysis 2014; 6:1961-74. [DOI: 10.4155/bio.14.140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Sample preparation is the first part of every analytical method, but is often considered only after the optimization of the method. It is traditionally performed using a range of techniques requiring extensive manual handling, with solid-phase extraction, liquid–liquid extraction, protein precipitation and ultracentrfiguation, among others, being used depending on the targets and the application. In this article, we will focus on alternatives based on electrokinetics for applications including sample clean-up, concentration and derivatization of large biological molecules (DNA, peptides and proteins) of diagnostic importance, as well as small molecules as a tool for therapeutic drug monitoring. This article describes these approaches in terms of mechanisms, applicability and potential to be integrated into a lab-on-a-chip device for directly processing biological samples. Examples dealing with treated or clean samples have been excluded except where they show exceptionally high value.
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16
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Hsu WL, Inglis DW, Jeong H, Dunstan DE, Davidson MR, Goldys EM, Harvie DJE. Stationary chemical gradients for concentration gradient-based separation and focusing in nanofluidic channels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5337-5348. [PMID: 24725102 DOI: 10.1021/la500206b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Previous work has demonstrated the simultaneous concentration and separation of proteins via a stable ion concentration gradient established within a nanochannel (Inglis Angew. Chem., Int. Ed. 2001, 50, 7546-7550). To gain a better understanding of how this novel technique works, we here examine experimentally and numerically how the underlying electric potential controlled ion concentration gradients can be formed and controlled. Four nanochannel geometries are considered. Measured fluorescence profiles, a direct indicator of ion concentrations within the Tris-fluorescein buffer solution, closely match depth-averaged fluorescence profiles calculated from the simulations. The simulations include multiple reacting species within the fluid bulk and surface wall charge regulation whereby the deprotonation of silica-bound silanol groups is governed by the local pH. The three-dimensional system is simulated in two dimensions by averaging the governing equations across the (varying) nanochannel width, allowing accurate numerical results to be generated for the computationally challenging high aspect ratio nanochannel geometries. An electrokinetic circuit analysis is incorporated to directly relate the potential drop across the (simulated) nanochannel to that applied across the experimental chip device (which includes serially connected microchannels). The merit of the thick double layer, potential-controlled concentration gradient as a particle focusing and separation tool is discussed, linking this work to the previously presented protein trapping experiments. We explain why stable traps are formed when the flow is in the opposite direction to the concentration gradient, allowing particle separation near the low concentration end of the nanochannel. We predict that tapered, rather than straight nanochannels are better at separating particles of different electrophoretic mobilities.
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Affiliation(s)
- Wei-Lun Hsu
- Department of Chemical and Biomolecular Engineering, University of Melbourne , Victoria 3010, Australia
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17
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Quist J, Vulto P, Hankemeier T. Isotachophoretic Phenomena in Electric Field Gradient Focusing: Perspectives for Sample Preparation and Bioassays. Anal Chem 2014; 86:4078-87. [DOI: 10.1021/ac403764e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Jos Quist
- Division of Analytical Biosciences, Leiden
Academic Centre for Drug Research (LACDR), Gorlaeus Laboratories, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Netherlands Metabolomics
Centre (NMC), Leiden University, Einsteinweg 55, Leiden, South Holland 2333CC, The Netherlands
| | - Paul Vulto
- Division of Analytical Biosciences, Leiden
Academic Centre for Drug Research (LACDR), Gorlaeus Laboratories, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Netherlands Metabolomics
Centre (NMC), Leiden University, Einsteinweg 55, Leiden, South Holland 2333CC, The Netherlands
| | - Thomas Hankemeier
- Division of Analytical Biosciences, Leiden
Academic Centre for Drug Research (LACDR), Gorlaeus Laboratories, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Netherlands Metabolomics
Centre (NMC), Leiden University, Einsteinweg 55, Leiden, South Holland 2333CC, The Netherlands
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18
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Quist J, Trietsch SJ, Vulto P, Hankemeier T. Elastomeric microvalves as tunable nanochannels for concentration polarization. LAB ON A CHIP 2013; 13:4810-4815. [PMID: 24158567 DOI: 10.1039/c3lc50658d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Elastomeric microvalves in poly(dimethylsiloxane) (PDMS) devices are today's paradigm for massively parallel microfluidic operations. Here, we report that such valves can act as nanochannels upon closure. When tuning nanospace heights between ~55 nm and ~7 nm, the nanofluidic phenomenon of concentration polarization could be induced. A wide range of concentration polarization regimes (anodic and cathodic analyte focusing and stacking) was achieved simply by valve pressure actuation. Electro-osmotic flow generated a counterpressure which also could be used to actuate between concentration polarization regimes. 1000-fold preconcentration of fluorescein was achieved in just 100 s in the anodic focusing regime. After valve opening, a concentrated sample plug could be transported through the valve, though at the cost of some defocusing. Reversible nanochannels open new avenues for integrating electrokinetic operations and assays in large scale integrated microfluidics.
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Affiliation(s)
- Jos Quist
- Netherlands Metabolomics Centre (NMC), Leiden Academic Centre for Drug Research (LACDR), Einsteinweg 55, 2333CC, Leiden, The Netherlands.
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19
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Ramautar R, Berger R, van der Greef J, Hankemeier T. Human metabolomics: strategies to understand biology. Curr Opin Chem Biol 2013; 17:841-6. [PMID: 23849548 DOI: 10.1016/j.cbpa.2013.06.015] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 06/14/2013] [Accepted: 06/14/2013] [Indexed: 12/21/2022]
Abstract
Metabolomics provides a direct functional read-out of the physiological status of an organism and is in principle ideally suited to describe someone's health status. Whereas only a limited number of small metabolites are used in the clinics, in inborn errors of metabolism an extensive repertoire of metabolites are used as biomarkers. We discuss that the proper clinical phenotyping is crucial to find biomarkers and obtain biological insights for multifactorial diseases. This requires to study the phenotype dynamics including the concepts of homeostasis and allostasis, that is, the ability to adapt and cope with a challenge. We also elaborate that biology-driven metabolomics platforms (i.e. development of metabolomics technology driven by the need of studying and answering important biomedical questions) addressing clinically relevant pathways and at the same time providing absolute concentrations are key to allow discovery and validation of biomarkers across studies and labs. Following individuals over years will require high throughput metabolomics approaches, which are emerging for nuclear magnetic resonance spectroscopy and direct-infusion mass spectrometry, but should also include the biochemical networks needed for personalized health monitoring.
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Affiliation(s)
- Rawi Ramautar
- Leiden Academic Center for Drug Research, Division of Analytical Biosciences, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands; The Netherlands Metabolomics Centre, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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20
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Breadmore MC, Shallan AI, Rabanes HR, Gstoettenmayr D, Abdul Keyon AS, Gaspar A, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2010-2012). Electrophoresis 2013; 34:29-54. [PMID: 23161056 DOI: 10.1002/elps.201200396] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 12/21/2022]
Abstract
CE has been alive for over two decades now, yet its sensitivity is still regarded as being inferior to that of more traditional methods of separation such as HPLC. As such, it is unsurprising that overcoming this issue still generates much scientific interest. This review continues to update this series of reviews, first published in Electrophoresis in 2007, with updates published in 2009 and 2011 and covers material published through to June 2012. It includes developments in the field of stacking, covering all methods from field amplified sample stacking and large volume sample stacking, through to isotachophoresis, dynamic pH junction and sweeping. Attention is also given to online or inline extraction methods that have been used for electrophoresis.
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Affiliation(s)
- Michael C Breadmore
- Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
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Malá Z, Gebauer P, Boček P. Recent progress in analytical capillary isotachophoresis. Electrophoresis 2012; 34:19-28. [DOI: 10.1002/elps.201200323] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 07/23/2012] [Accepted: 07/23/2012] [Indexed: 12/18/2022]
Affiliation(s)
- Zdena Malá
- Institute of Analytical Chemistry; Academy of Sciences of the Czech Republic; Brno; Czech Republic
| | - Petr Gebauer
- Institute of Analytical Chemistry; Academy of Sciences of the Czech Republic; Brno; Czech Republic
| | - Petr Boček
- Institute of Analytical Chemistry; Academy of Sciences of the Czech Republic; Brno; Czech Republic
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Quist J, Vulto P, van der Linden H, Hankemeier T. Tunable Ionic Mobility Filter for Depletion Zone Isotachophoresis. Anal Chem 2012; 84:9065-71. [DOI: 10.1021/ac301612n] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jos Quist
- Leiden/Amsterdam Centre for Drug Research (LACDR), Division of Analytical
Biosciences, Einsteinweg 55, 2333CC, Leiden, The Netherlands
- Netherlands Metabolomics Centre (NMC), Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Paul Vulto
- Leiden/Amsterdam Centre for Drug Research (LACDR), Division of Analytical
Biosciences, Einsteinweg 55, 2333CC, Leiden, The Netherlands
- Netherlands Metabolomics Centre (NMC), Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Heiko van der Linden
- Leiden/Amsterdam Centre for Drug Research (LACDR), Division of Analytical
Biosciences, Einsteinweg 55, 2333CC, Leiden, The Netherlands
- Netherlands Metabolomics Centre (NMC), Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Thomas Hankemeier
- Leiden/Amsterdam Centre for Drug Research (LACDR), Division of Analytical
Biosciences, Einsteinweg 55, 2333CC, Leiden, The Netherlands
- Netherlands Metabolomics Centre (NMC), Einsteinweg 55, 2333CC, Leiden, The Netherlands
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