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Courtney M, Thompson E, Glawdel T, Ren CL. Counterflow Gradient Focusing in Free-Flow Electrophoresis for Protein Fractionation. Anal Chem 2020; 92:7317-7324. [PMID: 32336087 DOI: 10.1021/acs.analchem.0c01024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew Courtney
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada
| | - Ethan Thompson
- Department of Nanotechnology Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada
| | - Tomasz Glawdel
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada
| | - Carolyn L. Ren
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada
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2
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Wang H, Zhang YL, Zhu R, Chen DL, Jin GX, Sun HB. Femtosecond laser direct writing of ion exchangeable multifunctional microstructures. OPTICS LETTERS 2018; 43:1139-1142. [PMID: 29489799 DOI: 10.1364/ol.43.001139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 01/31/2018] [Indexed: 06/08/2023]
Abstract
We report on the fabrication of ion exchangeable microstructures by femtosecond laser direct writing of an ion exchange photopolymer, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The resultant microstructures are negatively charged in aqueous solution, and can adsorb positively charged species, such as metal ions, nanoparticles, and proteins by electrostatic interaction, forming functional components for chip functionalization. In addition, it is possible to modify the microstructures with positively charged species that make the microstructures sensitive to negatively charged species. As a typical example, a crossed 3D microvessel functionalized with antibodies was fabricated, which reveals great potential for organ-on-a-chip systems. The fabrication of ion exchangeable microstructures holds great promise for flexible chip functionalization.
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Łapińska U, Saar KL, Yates EV, Herling TW, Müller T, Challa PK, Dobson CM, Knowles TPJ. Gradient-free determination of isoelectric points of proteins on chip. Phys Chem Chem Phys 2018; 19:23060-23067. [PMID: 28817152 DOI: 10.1039/c7cp01503h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isoelectric point (pI) of a protein is a key characteristic that influences its overall electrostatic behaviour. The majority of conventional methods for the determination of the isoelectric point of a molecule rely on the use of spatial gradients in pH, although significant practical challenges are associated with such techniques, notably the difficulty in generating a stable and well controlled pH gradient. Here, we introduce a gradient-free approach, exploiting a microfluidic platform which allows us to perform rapid pH change on chip and probe the electrophoretic mobility of species in a controlled field. In particular, in this approach, the pH of the electrolyte solution is modulated in time rather than in space, as in the case for conventional determinations of the isoelectric point. To demonstrate the general approachability of this platform, we have measured the isoelectric points of representative set of seven proteins, bovine serum albumin, β-lactoglobulin, ribonuclease A, ovalbumin, human transferrin, ubiquitin and myoglobin in microlitre sample volumes. The ability to conduct measurements in free solution thus provides the basis for the rapid determination of isoelectric points of proteins under a wide variety of solution conditions and in small volumes.
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Affiliation(s)
- Urszula Łapińska
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Kadi L Saar
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Emma V Yates
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Therese W Herling
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Thomas Müller
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. and Fluidic Analytics, Unit 5 Chesterton Mill, French's Road, Cambridge CB4 3NP, UK
| | - Pavan K Challa
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Christopher M Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. and Department of Physics, Cavendish Laboratory, 19 J J Thomson Avenue, Cambridge CB3 0HE, UK
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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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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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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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Exploring Gradients in Electrophoretic Separation and Preconcentration on Miniaturized Devices. SEPARATIONS 2016. [DOI: 10.3390/separations3020012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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8
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Emitter-assigned multi-dielectric barrier-nano-electrospray ionization mass spectrometry. Anal Bioanal Chem 2015; 407:6537-42. [DOI: 10.1007/s00216-015-8821-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
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Song YA, Wu L, Tannenbaum SR, Wishnok JS, Han J. Tunable membranes for free-flow zone electrophoresis in PDMS microchip using guided self-assembly of silica microbeads. Anal Chem 2013; 85:11695-9. [PMID: 24251795 DOI: 10.1021/ac402169x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we evaluate the strategy of using self-assembled microbeads to build a robust and tunable membrane for free-flow zone electrophoresis in a PDMS microfluidic chip. To fabricate a porous membrane as a salt bridge for free-flow zone electrophoresis, we used silica or polystyrene microbeads between 3-6 μm in diameter and packed them inside a microchannel. After complete evaporation, we infiltrated the porous microbead structure with a positively or negatively charged hydrogel to modify its surface charge polarity. Using this device, we demonstrated binary sorting (separation of positive and negative species at a given pH) of peptides and dyes in standard buffer systems without using sheath flows. The sample loss during sorting could be minimized by using ion selectivity of hydrogel-infiltrated microbead membranes. Our fabrication method enables building a robust membrane for pressure-driven free-flow zone electrophoresis with tunable pore size as well as surface charge polarity.
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Affiliation(s)
- Yong-Ak Song
- Department of Electrical Engineering and Computer Science, ‡Department of Biological Engineering, §Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, United States
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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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Kitagawa F, Kawai T, Sueyoshi K, Otsuka K. Recent progress of on-line sample preconcentration techniques in microchip electrophoresis. ANAL SCI 2012; 28:85-93. [PMID: 22322799 DOI: 10.2116/analsci.28.85] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review highlights recent developments and applications of on-line sample preconcentration techniques to enhance the detection sensitivity in microchip electrophoresis (MCE); references are mainly from 2008 and later. Among various developed techniques, we focus on the sample preconcentration based on the changes in the migration velocity of analytes in two or three discontinuous solutions system, since they can provide the sensitivity enhancement with relatively easy experimental procedures and short analysis times. The characteristic features of the on-line sample preconcentration applied to microchip electrophoresis (MCE) are presented, categorized on the basis of "field strength-" or "chemically" induced changes in the migration velocity. The preconcentration techniques utilizing field strength-induced changes in the velocity include field-amplified sample stacking, isotachophoresis and transient-isotachophoresis, whereas those based on chemically induced changes in the velocity are sweeping, transient-trapping and dynamic pH junction.
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Affiliation(s)
- Fumihiko Kitagawa
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo, Hirosaki, Aomori 036–8561, Japan.
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Köhler S, Nagl S, Fritzsche S, Belder D. Label-free real-time imaging in microchip free-flow electrophoresis applying high speed deep UV fluorescence scanning. LAB ON A CHIP 2012; 12:458-463. [PMID: 22011722 DOI: 10.1039/c1lc20558g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on label-free monitoring of microfluidic free-flow electrophoresis (μFFE) separations in real-time using a custom built high speed deep UV laser scanner. In combination with a novel layout realized in fused silica (FS) FFE chips the setup was successfully applied for continuous separations and detection of unlabeled analytes including native proteins by space-resolved intrinsic deep UV fluorescence scanning.
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Affiliation(s)
- Stefan Köhler
- Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, 04103 Leipzig, Germany
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Ding H, Li X, Lv X, Xu J, Sun X, Zhang Z, Wang H, Deng Y. Fabrication of micro free-flow electrophoresis chip by photocurable monomer binding microfabrication technique for continuous separation of proteins and their numerical simulation. Analyst 2012; 137:4482-9. [DOI: 10.1039/c2an35535c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Agostino FJ, Evenhuis CJ, Krylov SN. Milli-free flow electrophoresis: I. Fast prototyping of mFFE devices. J Sep Sci 2011; 34:556-64. [DOI: 10.1002/jssc.201000758] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 11/06/2022]
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