1
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Rukundo JL, Kochmann S, Wang TY, Ivanov NA, Le Blanc JCY, Gorin BI, Krylov SN. Template Instrumentation for "Accurate Constant via Transient Incomplete Separation". Anal Chem 2021; 93:11654-11659. [PMID: 34410698 DOI: 10.1021/acs.analchem.1c02007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accurate Constant via Transient Incomplete Separation (ACTIS) is a new method for finding the equilibrium dissociation constant Kd of a protein-small molecule complex based on transient incomplete separation of the complex from the unbound small molecule in a capillary. This separation is caused by differential transverse diffusion of the complex and the small molecule in a pressure-driven flow. The advection-diffusion processes underlying ACTIS can be described by a system of partial differential equations allowing for a virtual ACTIS instrument to be built and ACTIS to be studied in silico. The previous in silico studies show that large variations in the fluidic system geometry do not affect the accuracy of Kd determination, thus, proving that ACTIS is conceptually accurate. The conceptual accuracy does not preclude, however, instrumental inaccuracy caused by run-to-run signal drifts. Here we report on assembling a physical ACTIS instrument with a fluidic system that mimics the virtual one and proving the absence of signal drifts. Furthermore, we confirmed method ruggedness by assembling a second ACTIS instrument and comparing the results of experiments performed with both instruments in parallel. Despite some unintentional differences between the instruments (caused by tolerances in sizes, positions, etc.) and noticeable differences in their respective separagrams, we found that the Kd values determined for identical samples with these instruments were equal. Conclusively, the fluidic system presented here can serve as a template for reliable ACTIS instrumentation.
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Affiliation(s)
- Jean-Luc Rukundo
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Sven Kochmann
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Tong Ye Wang
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Nikita A Ivanov
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | | | - Boris I Gorin
- Eurofins CDMO Alphora, Mississauga, Ontario L5K 1B3, Canada
| | - Sergey N Krylov
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
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2
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Sisavath N, Rukundo JL, Le Blanc JCY, Galievsky VA, Bao J, Kochmann S, Stasheuski AS, Krylov SN. Transient Incomplete Separation Facilitates Finding Accurate Equilibrium Dissociation Constant of Protein-Small Molecule Complex. Angew Chem Int Ed Engl 2019; 58:6635-6639. [PMID: 30901510 DOI: 10.1002/anie.201901345] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/21/2019] [Indexed: 01/18/2023]
Abstract
Current practical methods for finding the equilibrium dissociation constant, Kd , of protein-small molecule complexes have inherent sources of inaccuracy. Introduced here is "accurate constant via transient incomplete separation" (ACTIS), which appears to be free of inherent sources of inaccuracy. Conceptually, a short plug of the pre-equilibrated protein-small molecule mixture is pressure-propagated in a capillary, causing fast transient incomplete separation of the complex from the unbound small molecule. A superposition of signals from these two components is measured near the capillary exit and used to calculate a fraction of unbound small molecule, which, in turn, is used to calculate Kd . Herein the validity of ACTIS is proven theoretically, its accuracy is verified by computer simulation, and its practical use is demonstrated. ACTIS has the potential to become a reference-standard method for determining Kd values of protein-small molecule complexes.
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Affiliation(s)
- Nicolas Sisavath
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Jean-Luc Rukundo
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | | | - Victor A Galievsky
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Jiayin Bao
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Sven Kochmann
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Alexander S Stasheuski
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Sergey N Krylov
- Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, M3J 1P3, Canada
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3
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Sisavath N, Rukundo J, Le Blanc JCY, Galievsky VA, Bao J, Kochmann S, Stasheuski AS, Krylov SN. Transient Incomplete Separation Facilitates Finding Accurate Equilibrium Dissociation Constant of Protein–Small Molecule Complex. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Nicolas Sisavath
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | - Jean‐Luc Rukundo
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | | | - Victor A. Galievsky
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | - Jiayin Bao
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | - Sven Kochmann
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | - Alexander S. Stasheuski
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
| | - Sergey N. Krylov
- Centre for Research on Biomolecular InteractionsYork University Toronto Ontario M3J 1P3 Canada
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4
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Abstract
Microfluidics has been undergoing fast development in the past two decades due to its promising applications in biotechnology, medicine, and chemistry. Towards these applications, enhancing concentration sensitivity and detection resolution are indispensable to meet the detection limits because of the dilute sample concentrations, ultra-small sample volumes and short detection lengths in microfluidic devices. A variety of microfluidic techniques for concentrating analytes have been developed. This article presents an overview of analyte concentration techniques in microfluidics. We focus on discussing the physical mechanism of each concentration technique with its representative advancements and applications. Finally, the article is concluded by highlighting and discussing advantages and disadvantages of the reviewed techniques.
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Affiliation(s)
- Cunlu Zhao
- Key Laboratory of Thermo-Fluid Science and Engineering of MOE, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- Correspondence: (C.Z.); (C.Y.); Tel.: +86-29-8266-3222 (C.Z.); +65-6790-4883 (C.Y.)
| | - Zhengwei Ge
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;
| | - Chun Yang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;
- Correspondence: (C.Z.); (C.Y.); Tel.: +86-29-8266-3222 (C.Z.); +65-6790-4883 (C.Y.)
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5
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Gagliardi LG, Tascon M, Castells CB. Effect of temperature on acid–base equilibria in separation techniques. A review. Anal Chim Acta 2015; 889:35-57. [DOI: 10.1016/j.aca.2015.05.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 05/16/2015] [Accepted: 05/22/2015] [Indexed: 10/23/2022]
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6
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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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7
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Kenyon SM, Weiss NG, Hayes MA. Using electrophoretic exclusion to manipulate small molecules and particles on a microdevice. Electrophoresis 2012; 33:1227-35. [PMID: 22589099 DOI: 10.1002/elps.201100622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrophoretic exclusion, a novel separations technique that differentiates species in bulk solution using the opposing forces of electrophoretic velocity and hydrodynamic flow, has been adapted to a microscale device. Proof-of-principle experiments indicate that the device was able to exclude small particles (1 μm polystyrene microspheres) and fluorescent dye molecules (rhodamine 123) from the entrance of a channel. Additionally, differentiation of the rhodamine 123 and polystyrene spheres was demonstrated. The current studies focus on the direct observation of the electrophoretic exclusion behavior on a microchip.
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Affiliation(s)
- Stacy M Kenyon
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA
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Strychalski EA, Henry AC, Ross D. Expanding the Capabilities of Microfluidic Gradient Elution Moving Boundary Electrophoresis for Complex Samples. Anal Chem 2011; 83:6316-22. [DOI: 10.1021/ac2011894] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Elizabeth A. Strychalski
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Alyssa C. Henry
- Applied Research Associates, Incorporated, Arlington, Virginia 22203, United States
| | - David Ross
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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10
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Kenyon SM, Meighan MM, Hayes MA. Recent developments in electrophoretic separations on microfluidic devices. Electrophoresis 2011; 32:482-93. [DOI: 10.1002/elps.201000469] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/24/2010] [Accepted: 12/09/2010] [Indexed: 11/09/2022]
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11
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Meighan MM, Vasquez J, Dziubcynski L, Hews S, Hayes MA. Investigation of Electrophoretic Exclusion Method for the Concentration and Differentiation of Proteins. Anal Chem 2010; 83:368-73. [DOI: 10.1021/ac1025495] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michelle M. Meighan
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States, and Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania 19081, United States
| | - Jared Vasquez
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States, and Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania 19081, United States
| | - Luke Dziubcynski
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States, and Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania 19081, United States
| | - Sarah Hews
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States, and Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania 19081, United States
| | - Mark A. Hayes
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States, and Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania 19081, United States
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Breadmore MC, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2008-2010). Electrophoresis 2010; 32:127-48. [PMID: 21171119 DOI: 10.1002/elps.201000412] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 01/22/2023]
Abstract
Capillary electrophoresis 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 an update published in 2009 and covers material published through to June 2010. It includes developments in the fields of stacking, covering all methods from field-amplified sample stacking and large volume sample stacking, through to ITP, dynamic pH junction and sweeping. Attention is also given to on-line or in-line 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, TAS, Australia.
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13
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Ross D. Step width, spacing, and resolution in gradient elution moving boundary electrophoresis. Part 1. Theory and comparison with zone electrophoresis. Electrophoresis 2010; 31:3650-7. [DOI: 10.1002/elps.201000334] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Meighan MM, Keebaugh MW, Quihuis AM, Kenyon SM, Hayes MA. Electrophoretic exclusion for the selective transport of small molecules. Electrophoresis 2010; 30:3786-92. [PMID: 19810029 DOI: 10.1002/elps.200900340] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A novel method capable of differentiating and concentrating small molecules in bulk solution termed "electrophoretic exclusion" is described and experimentally investigated. In this technique, the hydrodynamic flow of the system is countered by the electrophoretic velocity to prevent a species from entering into the channel. The separation can be controlled by changing the flow rate or applied electric field in order to exclude certain species selectively while allowing others to pass through the capillary. Proof of principle studies employed a flow injection regime of the method and examined the exclusion of Methyl Violet dye in the presence of a neutral species. Methyl Violet was concentrated almost 40 times the background concentration in 30 s using 6 kV. Additionally, a threshold voltage necessary for exclusion was determined. The establishment of a threshold voltage enabled the differentiation of two similar cationic species: Methyl Green and Neutral Red.
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Strychalski EA, Henry AC, Ross D. Microfluidic Analysis of Complex Samples with Minimal Sample Preparation Using Gradient Elution Moving Boundary Electrophoresis. Anal Chem 2009; 81:10201-7. [DOI: 10.1021/ac902075c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Elizabeth A. Strychalski
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
| | - Alyssa C. Henry
- Applied Research Associates, Incorporated, Alexandria, Virginia 22314
| | - David Ross
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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Ross D, Kralj JG. Simple device for multiplexed electrophoretic separations using gradient elution moving boundary electrophoresis with channel current detection. Anal Chem 2009; 80:9467-74. [PMID: 19007187 DOI: 10.1021/ac801597e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new microfluidic electrophoresis device and technique is described that is designed specifically for multiplexed, high-throughput separations. The device consists of an array of short (3 mm) capillaries connecting individual sample reservoirs to a common buffer reservoir. Each capillary in the array functions as both a separation channel and as a conductivity-based detection cell. The new technique is based upon the recently described gradient elution moving boundary electrophoresis (GEMBE) technique, which uses a combination of an electric field and buffer counterflow to achieve electrophoretic separations in short capillaries or microfluidic channels. A high voltage drives electrophoresis of the sample analytes through each separation channel. At the start of a separation, the bulk counterflow of buffer through the channel is high, and none of the analytes of interest can enter the channel. The counterflow is then gradually reduced until each analyte, in turn, is able to enter the channel where it is detected as a moving boundary or step. With very short capillaries, only one step at a time is present in each capillary, and the electric current through the channels can then be used as the detector signal, without any extra detector hardware. The current vs time signal for each channel is then smoothed and differentiated to produce a set of simultaneous electropherograms. Because there is no light source or other added hardware required for detection, the system is simple and can be easily and inexpensively scaled up to perform large numbers of simultaneous analyses. As a first demonstration, a 16-channel array device is used for high-throughput, time-series measurements of enzyme activity and inhibition.
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Affiliation(s)
- David Ross
- Biochemical Science Division, National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
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17
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Ross D, Romantseva EF. Gradient Elution Moving Boundary Electrophoresis with Channel Current Detection. Anal Chem 2009; 81:7326-35. [DOI: 10.1021/ac901189y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David Ross
- National Institute of Standards and Technology 100 Bureau Drive, Gaithersburg, Maryland 20899
| | - Eugenia F. Romantseva
- National Institute of Standards and Technology 100 Bureau Drive, Gaithersburg, Maryland 20899
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18
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Meighan MM, Staton SJR, Hayes MA. Bioanalytical separations using electric field gradient techniques. Electrophoresis 2009; 30:852-65. [DOI: 10.1002/elps.200800614] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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19
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Performance optimization in electric field gradient focusing. J Chromatogr A 2009; 1216:159-64. [DOI: 10.1016/j.chroma.2008.11.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 11/11/2008] [Accepted: 11/13/2008] [Indexed: 11/19/2022]
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Munson MS, Meacham JM, Ross D, Locascio LE. Development of aptamer-based affinity assays using temperature gradient focusing: minimization of the limit of detection. Electrophoresis 2008; 29:3456-65. [PMID: 18646283 DOI: 10.1002/elps.200800210] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A method is described for an aptamer-based affinity assay using a combination of two nonconventional techniques, temperature gradient focusing (TGF) and field-amplified continuous sample injection TGF (FACSI-TGF), with fluorescence detection. Human immunodeficiency virus reverse transcriptase (HIVRT) is used as the protein target for the assay. The TGF and FACSI-TGF assays are compared to similar results obtained with conventional CE. A range of starting aptamer concentrations are used to determine the optimal LOD for human immunodeficiency virus reverse transcriptase (HIVRT) using each approach. The results indicate that the LODs for HIVRT obtained with TGF and FACSI-TGF are comparable to or even lower than the LODs obtained with conventional CE in spite of the inferior detector used for the TGF and FACSI-TGF assays (arc lamp and low-cost CCD for TGF versus LIF with PMT for CE). It is hypothesized that this is due to the greater reproducibility of the TGF and FACSI-TGF techniques since they do not employ a defined sample injection. The lowest LOD achieved with the new aptamer assay approach is more than an order of magnitude lower than that reported for a similar CE-based aptamer assay for the same target.
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Affiliation(s)
- Matthew S Munson
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Mamunooru M, Jenkins RJ, Davis NI, Shackman JG. Gradient elution isotachophoresis with direct ultraviolet absorption detection for sensitive amino acid analysis. J Chromatogr A 2008; 1202:203-11. [DOI: 10.1016/j.chroma.2008.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 06/09/2008] [Accepted: 07/02/2008] [Indexed: 11/27/2022]
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Danger G, Ross D. Development of a temperature gradient focusing method for in situ extraterrestrial biomarker analysis. Electrophoresis 2008; 29:3107-14. [DOI: 10.1002/elps.200700778] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Molecular dispersion is caused by both molecular diffusion and non-uniform bulk fluid motion. While the Taylor–Aris dispersion regime is the most familiar regime in microfluidic systems, an oft-overlooked regime is that of purely kinematic (or ballistic) dispersion. In most microfluidic systems, this dispersion regime is transient and quickly gives way to Taylor–Aris dispersion. In electrophoretic focusing methods such as temperature gradient focusing (TGF), however, the characteristic time scales for dispersion are fixed, and focused peaks may never reach the Taylor limit. In this situation, generalized Taylor dispersion analysis is not applicable. A heuristic model is developed here which accounts for both molecular diffusion and advective dispersion across all dispersion regimes, from pure diffusion to Taylor dispersion to pure advection. This model is compared to results from TGF experiments and accurately captures both the initial decrease and subsequent increase in peak widths as electric field strength increases. The results of this combined analytical and experimental study provide a useful tool for estimation of dispersion and optimization of TGF systems.
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Affiliation(s)
- David E Huber
- Department of Mechanical Engineering, Stanford UniversityStanford, CA 94305-3030, USA
| | - Juan G Santiago
- Department of Mechanical Engineering, Stanford UniversityStanford, CA 94305-3030, USA
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