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Couceiro P, Alonso-Chamarro J. Fluorescence Imaging Characterization of the Separation Process in a Monolithic Microfluidic Free-Flow Electrophoresis Device Fabricated Using Low-Temperature Co-Fired Ceramics. MICROMACHINES 2022; 13:mi13071023. [PMID: 35888840 PMCID: PMC9324176 DOI: 10.3390/mi13071023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/22/2022] [Accepted: 06/24/2022] [Indexed: 11/26/2022]
Abstract
A monolithic microfluidic free-flow electrophoresis device, fabricated using low-temperature co-fired ceramic technology, is presented. The device integrates gold electrodes and a 20 µm thick transparent ceramic optical window, suitable for fluorescence imaging, into a multilevel microfluidic chamber design. The microfluidic chamber consists of a 60 µm deep separation chamber and two, 50 µm deep electrode chambers separated by 10 µm deep side channel arrays. Fluorescence imaging was used for in-chip, spatial-temporal characterization of local pH variations in separation conditions as well as to characterize the separation process. The device allowed baseline resolution separation of a sample mixture of Fluorescein, Rhodamine 6G, and 4-Methylumbelliferone at pH 7.0, in only 6 s, using 378 V.s/cm. The results demonstrate the possibility of studying a chemical process using fluorescence imaging within the traditional fields of low-temperature co-fired ceramics technology, such as high-electrical-field applications, while using a simple fabrication procedure suitable for low-cost mass production.
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Microfluidic free-flow electrophoresis: a promising tool for protein purification and analysis in proteomics. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.02.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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3
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Brandão EG, Perdigão SRW, Reis BF. A new flow cell design for chemiluminescence detection using an improved signal transduction network. Determination of hydrogen peroxide in pharmaceuticals. Microchem J 2021. [DOI: 10.1016/j.microc.2021.106789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Anciaux SK, Bowser MT. Reduced surface adsorption in 3D printed acrylonitrile butadiene styrene micro free-flow electrophoresis devices. Electrophoresis 2020; 41:225-234. [PMID: 31816114 PMCID: PMC7316087 DOI: 10.1002/elps.201900179] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 01/27/2023]
Abstract
We have 3D printed and fabricated micro free-flow electrophoresis (µFFE) devices in acrylonitrile butadiene styrene (ABS) that exhibit minimal surface adsorption without requiring additional surface coatings or specialized buffer additives. 2D, nano LC-micro free flow electrophoresis (2D nLC × µFFE) separations were used to assess both spatial and temporal broadening as peaks eluted through the separation channel. Minimal broadening due to wall adsorption was observed in either the spatial or temporal dimensions during separations of rhodamine 110, rhodamine 123, and fluorescein. Surface adsorption was observed in separations of Chromeo P503 labeled myoglobin and cytochrome c but was significantly reduced compared to previously reported glass devices. Peak widths of < 30 s were observed for both proteins. For comparison, Chromeo P503 labeled myoglobin and cytochrome c adsorb strongly to the surface of glass µFFE devices resulting in peak widths >20 min. A 2D nLC × µFFE separation of a Chromeo P503 labeled tryptic digest of BSA was performed to demonstrate the high peak capacity possible due to the low surface adsorption in the 3D printed ABS devices, even in the absence of surface coatings or buffer additives.
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Affiliation(s)
- Sarah K. Anciaux
- University of Minnesota, Department of Chemistry, 207 Pleasant St. SE, Minneapolis, MN, 55455
| | - Michael T. Bowser
- University of Minnesota, Department of Chemistry, 207 Pleasant St. SE, Minneapolis, MN, 55455
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Duarte-Junior GF, Lobo-Júnior EO, Medeiros Junior Í, da Silva JAF, do Lago CL, Coltro WKT. Separation of carbohydrates on electrophoresis microchips with controlled electrolysis. Electrophoresis 2019; 40:693-698. [DOI: 10.1002/elps.201800354] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 01/05/2023]
Affiliation(s)
| | | | - Íris Medeiros Junior
- Petróleo Brasileiro S.A.; Centro de Pesquisas e Desenvolvimento Leopoldo Américo Miguez de Mello (CENPES); Rio de Janeiro/RJ Brasil
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Abstract
Micro free-flow electrophoresis (μFFE) is a continuous separation technique in which analytes are streamed through a perpendicularly applied electric field in a planar separation channel. Analyte streams are deflected laterally based on their electrophoretic mobilities as they flow through the separation channel. A number of μFFE separation modes have been demonstrated, including free zone (FZ), micellar electrokinetic chromatography (MEKC), isoelectric focusing (IEF) and isotachophoresis (ITP). Approximately 60 articles have been published since the first μFFE device was fabricated in 1994. We anticipate that recent advances in device design, detection, and fabrication, will allow μFFE to be applied to a much wider range of applications. Applications particularly well suited for μFFE analysis include continuous, real time monitoring and microscale purifications.
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Affiliation(s)
- Alexander C Johnson
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
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Novo P, Janasek D. Current advances and challenges in microfluidic free-flow electrophoresis-A critical review. Anal Chim Acta 2017; 991:9-29. [PMID: 29031303 DOI: 10.1016/j.aca.2017.08.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 08/10/2017] [Accepted: 08/11/2017] [Indexed: 12/30/2022]
Abstract
The research field on microfluidic free-flow electrophoresis has developed vast amounts of devices, methods, applications and raised new questions, often in analogy to conventional techniques from which it derives. Most efforts have been employed on device development and a myriad of architectures and fabrication techniques have been reported using simple proof-of-principle separations. As technological aspects reach a quite mature state, researchers' new challenges include the development of protocols for the separation of complex mixtures, as required in the fields of application. The success of this effort is extremely dependent on the capability to transfer the device's fabrication to an industrial setting as well as to ensure interfacing simplicity, namely at the solutions' supply and collection, and actuation such as electric potential application and temperature control. Other advanced applications such as direct interfacing to downstream systems such as mass spectrometry, integration of sensing and feedback controls will require further development in the laboratory. In this review we provide an overview on the field, from basic concepts, through advanced developments both in the theoretical and experimental arenas, and addressing the above details. A comprehensive survey of designs, materials and applications is presented with particular highlights to most recent developments, namely the integration of electrodes, flow control and hyphenation of microfluidic free-flow electrophoresis with other techniques.
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Affiliation(s)
- Pedro Novo
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., 44227, Otto-Hahn-Str. 6b, Dortmund, Germany
| | - Dirk Janasek
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., 44227, Otto-Hahn-Str. 6b, Dortmund, Germany.
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9
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Abstract
The cost, time, and restrictions on creative flexibility associated with current fabrication methods present significant challenges in the development and application of microfluidic devices. Additive manufacturing, also referred to as three-dimensional (3D) printing, provides many advantages over existing methods. With 3D printing, devices can be made in a cost-effective manner with the ability to rapidly prototype new designs. We have fabricated a micro free-flow electrophoresis (μFFE) device using a low-cost, consumer-grade 3D printer. Test prints were performed to determine the minimum feature sizes that could be reproducibly produced using 3D printing fabrication. Microfluidic ridges could be fabricated with dimensions as small as 20 μm high × 640 μm wide. Minimum valley dimensions were 30 μm wide × 130 μm wide. An acetone vapor bath was used to smooth acrylonitrile-butadiene-styrene (ABS) surfaces and facilitate bonding of fully enclosed channels. The surfaces of the 3D-printed features were profiled and compared to a similar device fabricated in a glass substrate. Stable stream profiles were obtained in a 3D-printed μFFE device. Separations of fluorescent dyes in the 3D-printed device and its glass counterpart were comparable. A μFFE separation of myoglobin and cytochrome c was also demonstrated on a 3D-printed device. Limits of detection for rhodamine 110 were determined to be 2 and 0.3 nM for the 3D-printed and glass devices, respectively.
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Affiliation(s)
- Sarah K Anciaux
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Matthew Geiger
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Michael T Bowser
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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Fu X, Mavrogiannis N, Ibo M, Crivellari F, Gagnon ZR. Microfluidic free-flow zone electrophoresis and isotachophoresis using carbon black nano-composite PDMS sidewall membranes. Electrophoresis 2016; 38:327-334. [DOI: 10.1002/elps.201600104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/12/2016] [Accepted: 05/13/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Xiaotong Fu
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore MD USA
| | - Nicholas Mavrogiannis
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore MD USA
| | - Markela Ibo
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore MD USA
| | - Francesca Crivellari
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore MD USA
| | - Zachary R. Gagnon
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore MD USA
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Herzog C, Poehler E, Peretzki AJ, Borisov SM, Aigner D, Mayr T, Nagl S. Continuous on-chip fluorescence labelling, free-flow isoelectric focusing and marker-free isoelectric point determination of proteins and peptides. LAB ON A CHIP 2016; 16:1565-1572. [PMID: 27064144 DOI: 10.1039/c6lc00055j] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a microfluidic platform that contains a micro flow reactor for on-chip biomolecule labelling that is directly followed by a separation bed for continuous free-flow electrophoresis and has an integrated hydrogel-based near-infrared fluorescent pH sensor layer. Using this assembly, labelling of protein and peptide mixtures, their separation via free-flow isoelectric focusing and the determination of the isoelectric point (pI) of the separated products via the integrated sensor layer could be carried out within typically around 5 minutes. Spatially-resolved immobilization of fluidic and sensing structures was carried out via multistep photolithography. The assembly was characterized and optimized with respect to their fluidic and pH sensing properties and applied in the IEF of model proteins, peptides and a tryptic digest from physalaemine. We have therefore realized continuous sample preparation and preparative separation, analyte detection, process observation and analyte assignment capability based on pI on a single platform the size of a microscope slide.
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Affiliation(s)
- Christin Herzog
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany.
| | - Elisabeth Poehler
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany.
| | - Andrea J Peretzki
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany.
| | - Sergey M Borisov
- Institut für Analytische Chemie und Lebensmittelchemie, Technische Universität Graz, Stremayrgasse 9/III, 8010 Graz, Austria
| | - Daniel Aigner
- Institut für Analytische Chemie und Lebensmittelchemie, Technische Universität Graz, Stremayrgasse 9/III, 8010 Graz, Austria
| | - Torsten Mayr
- Institut für Analytische Chemie und Lebensmittelchemie, Technische Universität Graz, Stremayrgasse 9/III, 8010 Graz, Austria
| | - Stefan Nagl
- Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany.
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Dzido TH, Łopaciuk E, Płocharz PW, Chomicki A, Zembrzycka M, Frank H. Equipment and preliminary results for orthogonal pressurized planar electrochromatography. J Chromatogr A 2014; 1334:149-55. [DOI: 10.1016/j.chroma.2014.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/30/2014] [Accepted: 02/02/2014] [Indexed: 11/28/2022]
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14
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Yin XY, Dong JY, Wang HY, Li S, Fan LY, Cao CX. A simple chip free-flow electrophoresis for monosaccharide sensing via supermolecule interaction of boronic acid functionalized quencher and fluorescent dye. Electrophoresis 2013; 34:2185-92. [DOI: 10.1002/elps.201300104] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/07/2013] [Accepted: 04/17/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Xiao-Yang Yin
- Laboratory of Bio-Separation and Analytical Biochemistry; State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology; Shanghai Jiao Tong University; Shanghai; P. R. China
| | | | - Hou-Yu Wang
- Laboratory of Bio-Separation and Analytical Biochemistry; State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology; Shanghai Jiao Tong University; Shanghai; P. R. China
| | - Si Li
- Laboratory of Bio-Separation and Analytical Biochemistry; State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology; Shanghai Jiao Tong University; Shanghai; P. R. China
| | - Liu-Yin Fan
- Laboratory of Bio-Separation and Analytical Biochemistry; State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology; Shanghai Jiao Tong University; Shanghai; P. R. China
| | - Cheng-Xi Cao
- Laboratory of Bio-Separation and Analytical Biochemistry; State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology; Shanghai Jiao Tong University; Shanghai; P. R. China
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15
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Jezierski S, Belder D, Nagl S. Microfluidic free-flow electrophoresis chips with an integrated fluorescent sensor layer for real time pH imaging in isoelectric focusing. Chem Commun (Camb) 2013; 49:904-6. [DOI: 10.1039/c2cc38093e] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Jezierski S, Tehsmer V, Nagl S, Belder D. Integrating continuous microflow reactions with subsequent micropreparative separations on a single microfluidic chip. Chem Commun (Camb) 2013; 49:11644-6. [DOI: 10.1039/c3cc46548a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Walowski B, Hüttner W, Wackerbarth H. Generation of a miniaturized free-flow electrophoresis chip based on a multi-lamination technique—isoelectric focusing of proteins and a single-stranded DNA fragment. Anal Bioanal Chem 2011; 401:2465-71. [DOI: 10.1007/s00216-011-5353-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/01/2022]
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18
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Multistep liquid-phase lithography for fast prototyping of microfluidic free-flow-electrophoresis chips. Anal Bioanal Chem 2011; 401:2651-6. [DOI: 10.1007/s00216-011-5351-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/17/2011] [Accepted: 08/19/2011] [Indexed: 10/17/2022]
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Abstract
Micro free flow electrophoresis (micro-FFE) is a continuous micro-separation or preparation technique, which has been applied in the analysis of biomolecules, such as cells, sub cell organics and proteins. In this review, the recent progresses in micro FFE are summarized, with emphasis on the design of microchips, the separation modes and the applications of micro-FFE. Furthermore, the further developments of micro-FFE are prospected.
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Affiliation(s)
- Pingli Wang
- National Chromatographic R. & A. Center, Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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Duarte GRM, Price CW, Augustine BH, Carrilho E, Landers JP. Dynamic Solid Phase DNA Extraction and PCR Amplification in Polyester-Toner Based Microchip. Anal Chem 2011; 83:5182-9. [DOI: 10.1021/ac200292m] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gabriela R. M. Duarte
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos-SP 13566-590, Brazil
- Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Campinas-SP 13083-970, Brazil
- Universidade Estadual de Goiás, Anápolis-GO 75132-903, Brazil
| | | | - Brian H. Augustine
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Emanuel Carrilho
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos-SP 13566-590, Brazil
- Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Campinas-SP 13083-970, Brazil
| | - James P. Landers
- Department of Pathology, University of Virginia Health Science Center, Charlottesville, Virginia 22904, United States
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Coltro WKT, de Jesus DP, da Silva JAF, do Lago CL, Carrilho E. Toner and paper-based fabrication techniques for microfluidic applications. Electrophoresis 2010; 31:2487-98. [DOI: 10.1002/elps.201000063] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Frost NW, Bowser MT. Using buffer additives to improve analyte stream stability in micro free flow electrophoresis. LAB ON A CHIP 2010; 10:1231-6. [PMID: 20445874 PMCID: PMC2903047 DOI: 10.1039/b922325h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Micro free flow electrophoresis (microFFE) is a separation technique that continuously separates analyte streams as they travel through an electric field applied perpendicularly to the flow in a microdevice. Application of the technique has been limited by the generation of electrolysis bubbles at the electrodes, which results in unstable flow paths through the device. The current paper introduces the use of surfactants and nonaqueous solvents in the carrier buffer as a means of increasing stability of separated analyte streams. Adding surfactant or nonaqueous solvents lowers the surface tension of the carrier buffer, which we hypothesize promotes the formation of smaller electrolysis bubbles. A 6-fold improvement in the standard deviation of analyte stream position was observed upon addition of 10 mM SDS. Likewise, an approximately 12-fold improvement in stability was observed upon addition of 300 microM Triton X-100. Similar stability improvements were found in carrier buffers containing nonaqueous solvents. An 8-fold improvement in stability was found with a carrier buffer containing 50% methanol and a 6-fold improvement was found with a carrier buffer containing 37.5% acetonitrile. Long term use was demonstrated with a carrier buffer containing 300 microM Triton X-100 in which separated analyte streams remained stable for nearly two hours.
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Affiliation(s)
- Nicholas W Frost
- University of Minnesota, Department of Chemistry, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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Microfluidic chip: Next-generation platform for systems biology. Anal Chim Acta 2009; 650:83-97. [DOI: 10.1016/j.aca.2009.04.051] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 04/16/2009] [Accepted: 04/27/2009] [Indexed: 12/30/2022]
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24
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Micro free-flow electrophoresis: theory and applications. Anal Bioanal Chem 2009; 394:187-98. [PMID: 19290514 DOI: 10.1007/s00216-009-2656-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 01/23/2009] [Accepted: 01/26/2009] [Indexed: 10/21/2022]
Abstract
Free-flow electrophoresis (FFE) is a technique that performs an electrophoretic separation on a continuous stream of analyte as it flows through a planar flow channel. The electric field is applied perpendicularly to the flow to deflect analytes laterally according to their mobility as they flow through the separation channel. Miniaturization of FFE (microFFE) over the past 15 years has allowed analytical and preparative separation of small volume samples. Advances in chip design have improved separations by reducing interference from bubbles generated by electrolysis. Mechanisms of band broadening have been examined theoretically and experimentally to improve resolution in microFFE. Separations using various modes such as zone electrophoresis, isoelectric focusing, isotachophoresis, and field-step electrophoresis have been demonstrated.
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Coltro WKT, Lunte SM, Carrilho E. Comparison of the analytical performance of electrophoresis microchannels fabricated in PDMS, glass, and polyester-toner. Electrophoresis 2008; 29:4928-37. [PMID: 19025869 PMCID: PMC2672913 DOI: 10.1002/elps.200700897] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This paper compares the analytical performance of microchannels fabricated in PDMS, glass, and polyester-toner for electrophoretic separations. Glass and PDMS chips were fabricated using well-established photolithographic and replica-molding procedures, respectively. PDMS channels were sealed against three different types of materials: native PDMS, plasma-oxidized PDMS, and glass. Polyester-toner chips were micromachined by a direct-printing process using an office laser printer. All microchannels were fabricated with similar dimensions according to the limitations of the direct-printing process (width/depth 150 microm/12 microm). LIF was employed for detection to rule out any losses in separation efficiency due to the detector configuration. Two fluorescent dyes, coumarin and fluorescein, were used as model analytes. Devices were evaluated for the following parameters related to electrophoretic separations: EOF, heat dissipation, injection reproducibility, separation efficiency, and adsorption to channel wall.
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Affiliation(s)
- Wendell Karlos Tomazelli Coltro
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
- Ralph N. Adams Institute for Bioanalytical Chemistry, The University of Kansas, Lawrence, Kansas, USA
| | - Susan M. Lunte
- Ralph N. Adams Institute for Bioanalytical Chemistry, The University of Kansas, Lawrence, Kansas, USA
| | - Emanuel Carrilho
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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Zalewski DR, Kohlheyer D, Schlautmann S, Gardeniers HJGE. Synchronized, continuous-flow zone electrophoresis. Anal Chem 2008; 80:6228-34. [PMID: 18620428 DOI: 10.1021/ac800567n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method for performing continuous electrophoretic separation of complex mixtures in microscale devices is proposed. Unlike in free-flow electrophoresis devices, no mechanical pumping is required--both fluid transport and separation are driven electrokinetically. This gives the method great potential for on-a-chip integration in multistep analytical systems. The method enables us to collect fractionated sample and tenfold purification is possible. The model of the operation is presented and a detailed description of the optimal conditions for performing purification is given. The chip devices with 10-microm-deep separation chamber of 1.5 mm x 4 mm in size were fabricated in glass. A standard microchip electrophoresis setup was used. Continuous separation of rhodamine B, rhodamine 6G, and fluorescein was accomplished. Purification was demonstrated on a mixture containing rhodamine B and fluorescein, and the recovery of both fractions was achieved. The results show the feasibility of the method.
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Affiliation(s)
- Dawid R Zalewski
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
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27
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Coltro WKT, da Silva JAF, Carrilho E. Fabrication and integration of planar electrodes for contactless conductivity detection on polyester-toner electrophoresis microchips. Electrophoresis 2008; 29:2260-5. [DOI: 10.1002/elps.200700761] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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West J, Becker M, Tombrink S, Manz A. Micro Total Analysis Systems: Latest Achievements. Anal Chem 2008; 80:4403-19. [PMID: 18498178 DOI: 10.1021/ac800680j] [Citation(s) in RCA: 351] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jonathan West
- ISAS, Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, D-44139 Dortmund, Germany
| | - Marco Becker
- ISAS, Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, D-44139 Dortmund, Germany
| | - Sven Tombrink
- ISAS, Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, D-44139 Dortmund, Germany
| | - Andreas Manz
- ISAS, Institute for Analytical Sciences, Bunsen-Kirchhoff-Strasse 11, D-44139 Dortmund, Germany
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29
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Fonslow BR, Bowser MT. Fast electrophoretic separation optimization using gradient micro free-flow electrophoresis. Anal Chem 2008; 80:3182-9. [PMID: 18351751 DOI: 10.1021/ac702367m] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The continuous nature of micro free-flow electrophoresis (mu-FFE) was used to monitor the effect of a gradient of buffer conditions on the separation. This unique application has great potential for fast optimization of separation conditions and estimation of equilibrium constants. COMSOL was used to model pressure profiles in the development of a new mu-FFE design that allowed even application of a buffer gradient across the separation channel. The new design was fabricated in an all glass device using our previously published multiple-depth etch method (Fonslow, B. R.; Barocas, V. H.; Bowser, M. T. Anal. Chem. 2006, 78, 5369-5374, ref 1). Fluorescein solutions were used to characterize the applied gradients in the separation channel. Linear gradients were observed when buffer conditions were varied over a period of 5-10 min. The effect of a gradient of 0-50 mM hydroxypropyl-beta-cyclodextrin (HP-beta-CD) on the separation of a group of 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) labeled primary amines was monitored as a proof of concept experiment. Direct comparisons to capillary electrophoresis (CE) separations performed under the same conditions were made. Gradient mu-FFE recorded 60 separations during a 5 min gradient allowing nearly complete coverage across a range of HP-beta-CD concentrations. In comparison, 4 h were required to assess 15 sets of conditions across the same range of HP-beta-CD concentrations using CE. Qualitatively, mu-FFE separations were predictive of the migration order and spacing of peaks in CE electropherograms measured under the same conditions. Data were fit to equations describing 1:1 analyte-additive binding to allow a more quantitative comparison between gradient mu-FFE and CE.
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Affiliation(s)
- Bryan R Fonslow
- University of Minnesota, Department of Chemistry, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
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Kohlheyer D, Eijkel JCT, van den Berg A, Schasfoort RBM. Miniaturizing free-flow electrophoresis – a critical review. Electrophoresis 2008; 29:977-93. [DOI: 10.1002/elps.200700725] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
Biochemical sample mixtures are commonly separated in batch processes, such as filtration, centrifugation, chromatography or electrophoresis. In recent years, however, many research groups have demonstrated continuous flow separation methods in microfluidic devices. Such separation methods are characterised by continuous injection, real-time monitoring, as well as continuous collection, which makes them ideal for combination with upstream and downstream applications. Importantly, in continuous flow separation the sample components are deflected from the main direction of flow, either by means of a force field (electric, magnetic, acoustic, optical etc.), or by intelligent positioning of obstacles in combination with laminar flow profiles. Sample components susceptible to deflection can be spatially separated. A large variety of methods has been reported, some of these are miniaturised versions of larger scale methods, others are only possible in microfluidic regimes. Researchers now have a diverse toolbox to choose from and it is likely that continuous flow methods will play an important role in future point-of-care or in-the-field analysis devices.
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Affiliation(s)
- Nicole Pamme
- The University of Hull, Department of Chemistry, Cottingham Road, Hull, UK HU6 7RX.
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Kohlheyer D, Eijkel JCT, Schlautmann S, van den Berg A, Schasfoort RBM. Microfluidic High-Resolution Free-Flow Isoelectric Focusing. Anal Chem 2007; 79:8190-8. [PMID: 17902700 DOI: 10.1021/ac071419b] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A microfluidic free-flow isoelectric focusing glass chip for separation of proteins is described. Free-flow isoelectric focusing is demonstrated with a set of fluorescent standards covering a wide range of isoelectric points from pH 3 to 10 as well as the protein HSA. With respect to an earlier developed device, an improved microfluidic FFE chip was developed. The improvements included the usage of multiple sheath flows and the introduction of preseparated ampholytes. Preseparated ampholytes are commonly used in large-scale conventional free-flow isoelectric focusing instruments but have not been used in micromachined devices yet. Furthermore, the channel depth was further decreased. These adaptations led to a higher separation resolution and peak capacity, which were not achieved with previously published free-flow isoelectric focusing chips. An almost linear pH gradient ranging from pH 2.5 to 11.5 between 1.2 and 2 mm wide was generated. Seven isoelectric focusing markers were successfully and clearly separated within a residence time of 2.5 s and an electrical field of 20 V mm-1. Experiments with pI markers proved that the device is fully capable of separating analytes with a minimum difference in isoelectric point of Delta(pI) = 0.4. Furthermore, the results indicate that even a better resolution can be achieved. The theoretical minimum difference in isoelectric point is Delta(pI) = 0.23 resulting in a peak capacity of 29 peaks within 1.8 mm. This is an 8-fold increase in peak capacity to previously published results. The focusing of pI markers led to an increase in concentration by factor 20 and higher. Further improvement in terms of resolution seems possible, for which we envisage that the influence of electroosmotic flow has to be further reduced. The performance of the microfluidic free-flow isoelectric focusing device will enable new applications, as this device might be used in clinical analysis where often low sample volumes are available and fast separation times are essential.
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Affiliation(s)
- Dietrich Kohlheyer
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
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Chen Y, Guo Z, Wang X, Qiu C. Sample preparation. J Chromatogr A 2007; 1184:191-219. [PMID: 17991475 DOI: 10.1016/j.chroma.2007.10.026] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 10/08/2007] [Accepted: 10/10/2007] [Indexed: 11/17/2022]
Abstract
A panorama of sample preparation methods has been composed from 481 references, with a highlight of some promising methods fast developed during recent years and a somewhat brief introduction on most of the well-developed methods. All the samples were commonly referred to molecular composition, being extendable to particles including cells but not to organs, tissues and larger bodies. Some criteria to evaluate or validate a sample preparation method were proposed for reference. Strategy for integration of several methods to prepare complicated protein samples for proteomic studies was illustrated and discussed.
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Affiliation(s)
- Yi Chen
- Beijing National Laboratory of Molecular Science, Laboratory of Analytical Chemistry for Life Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
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Coltro WKT, Piccin E, Fracassi da Silva JA, Lucio do Lago C, Carrilho E. A toner-mediated lithographic technology for rapid prototyping of glass microchannels. LAB ON A CHIP 2007; 7:931-4. [PMID: 17594016 DOI: 10.1039/b702931d] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A simple, fast, and inexpensive masking technology without any photolithographic step to produce glass microchannels is proposed in this work. This innovative process is based on the use of toner layers as mask for wet chemical etching. The layouts were projected in graphic software and printed on wax paper using a laser printer. The toner layer was thermally transferred from the paper to cleaned glass surfaces (microscope slides) at 130 degrees C for 2 min. After thermal transference, the glass channel was etched using 25% (v/v) hydrofluoric acid (HF) solution. The toner mask was then removed by cotton soaked in acetonitrile. The etching rate was approximately 7.1 +/- 0.6 microm min(-1). This process is economically more attractive than conventional methods because it does not require any sophisticated instrumentation and it can be implemented in any chemical/biochemical laboratory. The glass channel was thermally bonded against a flat glass cover and its analytical feasibility was investigated using capacitively coupled contactless conductivity detection (C(4)D) and laser-induced fluorescence (LIF) detection.
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Affiliation(s)
- Wendell Karlos Tomazelli Coltro
- Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador SãoCarlense 400, P.O. Box 780, 13566-590, São Carlos-SP, Brazil
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