1
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Qiu W, Lin X, Nagl S. In Situ Live Monitoring of Extracellular Acidosis near Cancer Cells Using Digital Microfluidics with an Integrated Optical pH Sensor Film. Anal Chem 2024. [PMID: 39171737 DOI: 10.1021/acs.analchem.4c02319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
We demonstrate the live monitoring of extracellular acidification on digital microfluidics using a chip-integrated fluorescent pH sensor film. The metabolism of various types of live cells including cancer and healthy cells were investigated through recording the extracellular pH (pHe) change. An optical pH sensor array was integrated onto a digital microfluidic (DMF) interface with a diameter of 2 mm per pH-sensing spot. Miniaturized, label-free, and noninvasive monitoring of extracellular acidosis on DMF was realized within a pH range of 5.0-8.0 with good sensitivity and rapid response. The pH sensitive probe fluorescein-5-isothiocyanate was covalently bound to poly-2-hydroxyethyl methacrylate and immobilized on a circularly exposed indium tin oxide interface on the DMF top plate. The surface of the fabricated pH sensor spots was modified with polydopamine via self-polymerization. Direct cell attachment on the sensor surfaces enabled rapid pH detection near the cell membranes. Automatic medium exchange on cell-attached pH sensing sites was achieved though solution passive dispensing on DMF. The developed DMF platform was used to monitor the pHe decrease during MCF-7 and A549 cancer cell proliferation due to abnormal glycolysis metabolism. A rapid pH decrease at the pH sensing area in the presence of cancer cells could be detected within 2 min after fresh medium exchange, while no obvious pHe change was observed with HUVEC healthy cells. Real-time detection of cell acidification and cellular response to different metabolic conditions such as higher glucose levels or administered anticancer drugs was possible.
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Affiliation(s)
- Wenting Qiu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, China
| | - Xuyan Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, China
| | - Stefan Nagl
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, China
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2
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Suarez GD, Bayer S, Tang YYK, Suarez DA, Cheung PPH, Nagl S. Rapid microfluidics prototyping through variotherm desktop injection molding for multiplex diagnostics. LAB ON A CHIP 2023; 23:3850-3861. [PMID: 37534874 DOI: 10.1039/d3lc00391d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
In this work, we demonstrate an inexpensive method of prototyping microfluidics using a desktop injection molding machine. A centrifugal microfluidic device with a novel central filling mechanism was developed to demonstrate the technique. We overcame the limitations of desktop machines in replicating microfluidic features by variotherm heating and cooling the mold between 50 °C and 110 °C within two minutes. Variotherm heating enabled good replication of microfeatures, with a coefficient of variation averaging only 3.6% attained for the measured widths of 100 μm wide molded channels. Using this methodology, we produced functional polystyrene centrifugal microfluidic chips, capable of aliquoting fluids into 5.0 μL reaction chambers with 97.5% accuracy. We performed allele-specific loop-mediated isothermal amplification (AS-LAMP) reactions for genotyping CYP2C19 alleles on these chips. Readouts were generated using optical pH sensors integrated onto chips, by drop-casting sensor precursor solutions into reaction chambers before final chip assembly. Positive reactions could be discerned by decreases in pH sensor fluorescence, thresholded against negative control reactions lacking the primers for nucleic acid amplification and with time-to-results averaging 38 minutes. Variotherm desktop injection molding can enable researchers to prototype microfluidic devices more cost-effectively, in an iterative fashion, due to reduced costs of smaller, in-house molds. Designs prototyped this way can be directly translated to mass production, enhancing their commercialization potential and positive impacts.
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Affiliation(s)
- Gianmarco D Suarez
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - Steevanson Bayer
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - Yuki Yu Kiu Tang
- Quommni Technologies Limited, Tsuen Wan, New Territories, Hong Kong
| | | | - Peter Pak-Hang Cheung
- Department of Chemical Pathology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
| | - Stefan Nagl
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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3
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Shahriari S, Selvaganapathy PR. Integration of hydrogels into microfluidic devices with porous membranes as scaffolds enables their drying and reconstitution. BIOMICROFLUIDICS 2022; 16:054108. [PMID: 36313189 PMCID: PMC9616609 DOI: 10.1063/5.0100589] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Hydrogels are a critical component of many microfluidic devices. They have been used in cell culture applications, biosensors, gradient generators, separation microdevices, micro-actuators, and microvalves. Various techniques have been utilized to integrate hydrogels into microfluidic devices such as flow confinement and gel photopolymerization. However, in these methods, hydrogels are typically introduced in post processing steps which add complexity, cost, and extensive fabrication steps to the integration process and can be prone to user induced variations. Here, we introduce an inexpensive method to locally integrate hydrogels into microfluidic devices during the fabrication process without the need for post-processing. In this method, porous and fibrous membranes such as electrospun membranes are used as scaffolds to hold gels and they are patterned using xurography. Hydrogels in various shapes as small as 200 μm can be patterned using this method in a scalable manner. The electrospun scaffold facilitates drying and reconstitution of these gels without loss of shape or leakage that is beneficial in a number of applications. Such reconstitution is not feasible using other hydrogel integration techniques. Therefore, this method is suitable for long time storage of hydrogels in devices which is useful in point-of-care (POC) devices. This hydrogel integration method was used to demonstrate gel electrophoretic concentration and quantification of short DNA (150 bp) with different concentrations in rehydrated agarose embedded in electrospun polycaprolactone (PCL) membrane. This can be developed further to create a POC device to quantify cell-free DNA, which is a prognostic biomarker for severe sepsis patients.
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Affiliation(s)
- Shadi Shahriari
- Department of Mechanical Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada
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4
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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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5
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Konoplev G, Agafonova D, Bakhchova L, Mukhin N, Kurachkina M, Schmidt MP, Verlov N, Sidorov A, Oseev A, Stepanova O, Kozyrev A, Dmitriev A, Hirsch S. Label-Free Physical Techniques and Methodologies for Proteins Detection in Microfluidic Biosensor Structures. Biomedicines 2022; 10:207. [PMID: 35203416 PMCID: PMC8868674 DOI: 10.3390/biomedicines10020207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/01/2022] [Accepted: 01/11/2022] [Indexed: 12/25/2022] Open
Abstract
Proteins in biological fluids (blood, urine, cerebrospinal fluid) are important biomarkers of various pathological conditions. Protein biomarkers detection and quantification have been proven to be an indispensable diagnostic tool in clinical practice. There is a growing tendency towards using portable diagnostic biosensor devices for point-of-care (POC) analysis based on microfluidic technology as an alternative to conventional laboratory protein assays. In contrast to universally accepted analytical methods involving protein labeling, label-free approaches often allow the development of biosensors with minimal requirements for sample preparation by omitting expensive labelling reagents. The aim of the present work is to review the variety of physical label-free techniques of protein detection and characterization which are suitable for application in micro-fluidic structures and analyze the technological and material aspects of label-free biosensors that implement these methods. The most widely used optical and impedance spectroscopy techniques: absorption, fluorescence, surface plasmon resonance, Raman scattering, and interferometry, as well as new trends in photonics are reviewed. The challenges of materials selection, surfaces tailoring in microfluidic structures, and enhancement of the sensitivity and miniaturization of biosensor systems are discussed. The review provides an overview for current advances and future trends in microfluidics integrated technologies for label-free protein biomarkers detection and discusses existing challenges and a way towards novel solutions.
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Affiliation(s)
- Georgii Konoplev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Darina Agafonova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Liubov Bakhchova
- Institute for Automation Technology, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany;
| | - Nikolay Mukhin
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marharyta Kurachkina
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marc-Peter Schmidt
- Faculty of Electrical Engineering, University of Applied Sciences Dresden, 01069 Dresden, Germany;
| | - Nikolay Verlov
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute Named by B.P. Konstantinov, National Research Centre Kurchatov Institute, 188300 Gatchina, Russia;
| | - Alexander Sidorov
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Fuculty of Photonics, ITMO University, 197101 Saint Petersburg, Russia
| | - Aleksandr Oseev
- FEMTO-ST Institute, CNRS UMR-6174, University Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Oksana Stepanova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Andrey Kozyrev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Alexander Dmitriev
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution “Institute of Experimental Medicine” (FSBSI “IEM”), 197376 Saint Petersburg, Russia;
| | - Soeren Hirsch
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
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6
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Jiang L, Qu X, Sun W, Zhang M, Wang Y, Wang Y, Zhao Y, Zhang F, Leng Y, Liu S, Yu J, Huang J. A three-dimensional dynamic DNA walker-mediated branching hybridization chain reaction for the ultrasensitive fluorescence sensing of ampicillin. Analyst 2021; 146:5413-5420. [PMID: 34346408 DOI: 10.1039/d0an02226h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In this study, a novel, rapid and ultrasensitive fluorescence strategy using the three-dimensional (3D) dynamic DNA walker (DW)-induced branched hybridization chain reaction (bHCR) has been proposed for the detection of ampicillin (AMP). The sensing system was composed of an Nt·Bbvcl-powered DNA walker blocked by an AMP aptamer, hairpin-shaped DNA track probe (TP) and four kinds of metastable hairpin probes as the substrates of bHCR, which triggered the formation of the split G-quadruplex as the signal molecule. Due to the reasonable design, the specific binding between AMP and its aptamer activated the DW, and the DW moved on the surface of the gold nanoparticles (AuNPs) with the help of Nt·Bbvcl to produce primer probes (PPs), which induced bHCR. The products of the bHCR gathered two split G-quadruplex sequences together to form one complete G-quadruplex. The formed G-quadruplex emitted a strong fluorescence signal in the presence of thioflavin-T (ThT) to achieve the purpose of detecting AMP. The sensitivity of this method was greatly improved by the use of the 3D DNA walker and bHCR. The split G-quadruplex enhanced the signal-to-noise ratio (SNR). Under the optimal experimental conditions, a good correlation was obtained between the fluorescence intensity of the sensing system and the concentration of AMP ranging from 5 pM to 500 nM with a limit of detection (LOD) of 3.68 pM. Simultaneously, the method has been applied to the detection of antibiotics in spiked milk samples with satisfactory results.
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Affiliation(s)
- Long Jiang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, P.R. China
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7
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Farmerie L, Rustandi RR, Loughney JW, Dawod M. Recent advances in isoelectric focusing of proteins and peptides. J Chromatogr A 2021; 1651:462274. [PMID: 34090060 DOI: 10.1016/j.chroma.2021.462274] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 05/13/2021] [Accepted: 05/16/2021] [Indexed: 12/18/2022]
Abstract
This review article describes the significant recent advances in Isoelectric Focusing from the period 2015-2020. The review highlights the principles and common challenges faced in Isoelectric Focusing as well as its applications. This review also details the recent advances in various modes of Isoelectric Focusing in various platforms and future directions for the technique.
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Affiliation(s)
- Lily Farmerie
- Analytical Research & Development, Merck & Co., Inc., Kenilworth, NJ, USA; Pennsylvania State University, College of Engineering, University Park, PA, USA
| | - Richard R Rustandi
- Analytical Research & Development, Merck & Co., Inc., Kenilworth, NJ, USA
| | - John W Loughney
- Analytical Research & Development, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Mohamed Dawod
- Analytical Research & Development, Merck & Co., Inc., Kenilworth, NJ, USA.
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8
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Jender M, Höving S, Novo P, Freier E, Janasek D. Coupling Miniaturized Free-Flow Electrophoresis to Mass Spectrometry via a Multi-Emitter ESI Interface. Anal Chem 2021; 93:7204-7209. [PMID: 33939916 DOI: 10.1021/acs.analchem.1c00200] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a novel multi-emitter electrospray ionization (ESI) interface for the coupling of microfluidic free-flow electrophoresis (μFFE) with mass spectrometry (MS). The effluents of the μFFE outlets are analyzed in near real-time, allowing a direct optimization of the electrophoretic separation and an online monitoring of qualitative sample compositions. The short measurement time of just a few seconds for all outlets even enables a reasonable time-dependent monitoring. As a proof of concept, we employ the multi-emitter ESI interface for the continuous identification of analytes at 15 μFFE outlets via MS to optimize the μFFE separation of important players of cellular respiration in operando. The results indicate great potential of the presented system in downstream processing control, for example, for the monitoring and purification of products in continuous-flow microreactors.
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Affiliation(s)
- Matthias Jender
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
| | - Stefan Höving
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
| | - Pedro Novo
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
| | - Erik Freier
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
| | - Dirk Janasek
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
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9
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Mikhail IE, Tehranirokh M, Gooley AA, Guijt RM, Breadmore MC. In‐Syringe Electrokinetic Protein Removal from Biological Samples prior to Electrospray Ionization Mass Spectrometry. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Ibraam E. Mikhail
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Australian Centre for Research on Separation Science (ACROSS) School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart Tasmania 7001 Australia
- Department of Analytical Chemistry Faculty of Pharmacy Mansoura University 35516 Mansoura Egypt
| | - Masoomeh Tehranirokh
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Trajan Scientific and Medical Ringwood VIC 3134 Australia
| | - Andrew A. Gooley
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Trajan Scientific and Medical Ringwood VIC 3134 Australia
| | - Rosanne M. Guijt
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Centre for Regional and Rural Futures Deakin University Geelong VIC 3220 Australia
| | - Michael C. Breadmore
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Australian Centre for Research on Separation Science (ACROSS) School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart Tasmania 7001 Australia
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10
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Steinegger A, Wolfbeis OS, Borisov SM. Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications. Chem Rev 2020; 120:12357-12489. [PMID: 33147405 PMCID: PMC7705895 DOI: 10.1021/acs.chemrev.0c00451] [Citation(s) in RCA: 181] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Indexed: 12/13/2022]
Abstract
This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.
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Affiliation(s)
- Andreas Steinegger
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Otto S. Wolfbeis
- Institute
of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040 Regensburg, Germany
| | - Sergey M. Borisov
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
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11
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Mikhail IE, Tehranirokh M, Gooley AA, Guijt RM, Breadmore MC. In‐Syringe Electrokinetic Protein Removal from Biological Samples prior to Electrospray Ionization Mass Spectrometry. Angew Chem Int Ed Engl 2020; 59:23162-23168. [DOI: 10.1002/anie.202006481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/24/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Ibraam E. Mikhail
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Australian Centre for Research on Separation Science (ACROSS) School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart Tasmania 7001 Australia
- Department of Analytical Chemistry Faculty of Pharmacy Mansoura University 35516 Mansoura Egypt
| | - Masoomeh Tehranirokh
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Trajan Scientific and Medical Ringwood VIC 3134 Australia
| | - Andrew A. Gooley
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Trajan Scientific and Medical Ringwood VIC 3134 Australia
| | - Rosanne M. Guijt
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Centre for Regional and Rural Futures Deakin University Geelong VIC 3220 Australia
| | - Michael C. Breadmore
- ARC Training Centre for Portable Analytical Separation Technologies (ASTech) Australia
- Australian Centre for Research on Separation Science (ACROSS) School of Natural Sciences (Chemistry) University of Tasmania Private Bag 75 Hobart Tasmania 7001 Australia
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12
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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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14
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LI N, LIU SG, HE YQ, MAI X. Resonance Rayleigh Scattering as a Tool for Isoelectric Point Monitoring and Iron(III) Cation Determination. ANAL SCI 2019; 35:1149-1153. [DOI: 10.2116/analsci.19p177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Na LI
- School of Pharmaceutical Science, Nanchang University
| | - Shi Gang LIU
- Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University
| | - Yong Qin HE
- School of Pharmaceutical Science, Nanchang University
| | - Xi MAI
- School of Pharmaceutical Science, Nanchang University
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15
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Wang S, Zhang L, Sun H, Chu Z, Chen H, Zhao Y, Zhang W. Carrier ampholyte-free free-flow isoelectric focusing for separation of protein. Electrophoresis 2019; 40:2610-2617. [PMID: 30977523 DOI: 10.1002/elps.201900148] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 04/06/2019] [Indexed: 01/20/2023]
Abstract
Free-flow isoelectric focusing (FFIEF) has the merits of mild separation conditions, high recovery and resolution, but suffers from the issues of ampholytes interference and high cost due to expensive carrier ampholytes. In this paper, a home-made carrier ampholyte-free FFIEF system was constructed via orientated migration of H+ and OH- provided by electrode solutions. When applying an electric field, a linear pH gradient from pH 4 to 9 (R2 = 0.994) was automatically formed by the electromigration of protons and hydroxyl ions in the separation chamber. The carrier ampholyte-free FFIEF system not only avoids interference of ampholyte to detection but also guarantees high separation resolution by establishing stable pH gradient. The separation selectivity was conveniently adjusted by controlling operating voltage and optimizing the composition, concentration and flow rate of the carrier buffer. The constructed system was applied to separation of proteins in egg white, followed by MADLI-TOF-MS identification. Three major proteins, ovomucoid, ovalbumin and ovotransferrin, were successfully separated according to their pI values with 15 mmol/L Tris-acetic acid (pH = 6.5) as carrier buffer at a flow rate of 12.9 mL/min.
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Affiliation(s)
- Shuai Wang
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Lingyi Zhang
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Haofan Sun
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Zhanying Chu
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Haihong Chen
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Yameng Zhao
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
| | - Weibing Zhang
- Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, P. R. China
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16
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Zhou W, Xia L, Xiao X, Li G, Pu Q. A microchip device to enhance free flow electrophoresis using controllable pinched sample injections. Electrophoresis 2019; 40:2165-2171. [DOI: 10.1002/elps.201900079] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Wanjun Zhou
- School of Chemistry Sun Yat‐sen University Guangzhou P. R. China
| | - Ling Xia
- School of Chemistry Sun Yat‐sen University Guangzhou P. R. China
| | - Xiaohua Xiao
- School of Chemistry Sun Yat‐sen University Guangzhou P. R. China
| | - Gongke Li
- School of Chemistry Sun Yat‐sen University Guangzhou P. R. China
| | - Qiaosheng Pu
- Department of Chemistry Lanzhou University Lanzhou Gansu P. R. China
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17
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Saar KL, Peter Q, Müller T, Challa PK, Herling TW, Knowles TPJ. Rapid two-dimensional characterisation of proteins in solution. MICROSYSTEMS & NANOENGINEERING 2019; 5:33. [PMID: 31636924 PMCID: PMC6799820 DOI: 10.1038/s41378-019-0072-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/25/2019] [Accepted: 03/21/2019] [Indexed: 05/20/2023]
Abstract
Microfluidic platforms provide an excellent basis for working with heterogeneous samples and separating biomolecular components at high throughput, with high recovery rates and by using only very small sample volumes. To date, several micron scale platforms with preparative capabilities have been demonstrated. Here we describe and demonstrate a microfluidic device that brings preparative and analytical operations together onto a single chip and thereby allows the acquisition of multidimensional information. We achieve this objective by using a free-flow electrophoretic separation approach that directs fractions of sample into an on-chip analysis unit, where the fractions are characterised through a microfluidic diffusional sizing process. This combined approach therefore allows simultaneously quantifying the sizes and the charges of components in heterogenous mixtures. We illustrate the power of the platform by describing the size distribution of a mixture comprising components which are close in size and cannot be identified as individual components using state-of-the-art solution sizing techniques on their own. Furthermore, we show that the platform can be used for two-dimensional fingerprinting of heterogeneous protein mixtures within tens of seconds, opening up a possibility to obtain multiparameter data on biomolecular systems on a minute timescale.
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Affiliation(s)
- Kadi L. Saar
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
| | - Quentin Peter
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Ave, Cambridge, CB3 0HE UK
| | | | - Pavan K. Challa
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Ave, Cambridge, CB3 0HE UK
| | - Therese W. Herling
- 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
- Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Ave, Cambridge, CB3 0HE UK
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18
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Dalfen I, Dmitriev RI, Holst G, Klimant I, Borisov SM. Background-Free Fluorescence-Decay-Time Sensing and Imaging of pH with Highly Photostable Diazaoxotriangulenium Dyes. Anal Chem 2018; 91:808-816. [PMID: 30518209 DOI: 10.1021/acs.analchem.8b02534] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic-receptor groups inducing fluorescence quenching via a photoinduced-electron-transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent p Ka' values of ∼5 and 7.5 for the p, p-dichlorophenol- and p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetimes (17-20 ns), high quantum yields (∼60%), and high photostabilities. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behavior, which makes them suitable for studying 2D pH distributions with the help of fluorescence-lifetime-imaging techniques. The lifetime response is particularly pronounced for the sensors with high dye concentrations (0.5-1 wt % with respect to the polymer) and is attributed to the efficient homo-FRET mechanism.
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Affiliation(s)
- Irene Dalfen
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Ruslan I Dmitriev
- School of Biochemistry and Cell Biology , University College Cork , T12 K8AF Cork , Ireland.,Institute for Regenerative Medicine , I.M. Sechenov First Moscow State University , 119146 Moscow , Russian Federation
| | | | - Ingo Klimant
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Sergey M Borisov
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
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19
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Nagl S. Microfluidic Free-Flow Isoelectric Focusing with Real-Time pI Determination. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2018; 1906:113-124. [PMID: 30488389 DOI: 10.1007/978-1-4939-8964-5_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Free-flow electrophoresis (FFE) may be used for continuous and preparative separation of a wide variety of biomolecules. Isoelectric focusing (IEF) provides for the separation of compounds according to their isoelectric point (pI). Here we describe a microfluidic chip-based protocol for the fabrication, application, and optical monitoring of free-flow isoelectric focusing (FFIEF) of proteins and peptides on the microscale with optical surveillance of the microscopic pH gradient provided by an integrated pH sensing layer. This protocol may be used with modifications also for the FFIEF of other biomolecules and may serve as template for the fabrication of microfluidic chips with integrated fluorescent or luminescent pH sensor layers for FFE and other applications.
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Affiliation(s)
- Stefan Nagl
- Department of Chemistry, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China.
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20
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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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21
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Greño M, Castro-Puyana M, García MÁ, Marina ML. Analysis of antibiotics by CE and CEC and their use as chiral selectors: An update. Electrophoresis 2017; 39:235-259. [PMID: 28941242 DOI: 10.1002/elps.201700306] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/12/2017] [Accepted: 09/12/2017] [Indexed: 12/11/2022]
Abstract
Natural, synthetic or semisynthetic antibiotics are highly used to prevent or treat diseases in humans and animals, and to promote animal growth. This fact makes that antibiotics residues or their transformation products may be present in food or in the environment after human or animal excretion. For this reason, it is imperative to develop reliable and sensitive analytical methodologies for their analysis. The main aim of this work is to present and discuss the most recent applications of capillary electromigration methods for the analysis of antibiotics, including the developments and applications of their use as chiral selectors in CE. The literature published from June 2015 to June 2017 is included following the previous review by Domínguez-Vega et al. (Electrophoresis, 2016, 37, 189-211). Information about the use of different detection systems, off-line and on-line strategies to improve sensitivity, and microchip devices for the analysis of antibiotics is provided and properly discussed.
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Affiliation(s)
- Maider Greño
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - María Castro-Puyana
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - María Ángeles García
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
| | - María Luisa Marina
- Departamento de Química Analítica, Química Física e Ingeniería Química, Universidad de Alcalá, Alcalá de Henares (Madrid), Spain
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22
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Continuous purification of reaction products by micro free-flow electrophoresis enabled by large area deep-UV fluorescence imaging. Anal Bioanal Chem 2017; 410:853-862. [DOI: 10.1007/s00216-017-0697-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/18/2017] [Accepted: 10/06/2017] [Indexed: 10/18/2022]
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23
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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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24
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Nagl S. Micro free-flow isoelectric focusing with integrated optical pH sensors. Eng Life Sci 2017; 18:114-123. [PMID: 32624893 DOI: 10.1002/elsc.201700035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 02/07/2017] [Accepted: 07/13/2017] [Indexed: 01/12/2023] Open
Abstract
Recently, a new observation method for monitoring of pH gradients in microfluidic free-flow electrophoresis has emerged. It is based on the use of chip-integrated fluorescent or luminescent micro sensor layers. These are able to monitor pH gradients in miniaturized separations in real time and spatially resolved; this is particularly useful in isoelectric focusing. Here these multifunctional microdevices that feature continuous separation, monitoring, and in some instances other functionalities, are reviewed. The employed microfabrication procedures to produce these devices are discussed and the different pH sensor matrices that were integrated and their applications in the separation of different types of biomolecules. The procedures for obtaining spatially resolved information about the separated molecules and the pH at the same time and different detection modalities to achieve this such as deep UV fluorescence as well as time-resolved referenced pH sensing and the integration of a precolumn labeling step into these platforms are also highlighted.
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Affiliation(s)
- Stefan Nagl
- Department of Chemistry The Hong Kong University of Science and Technology Kowloon Hong Kong SAR P. R. China
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25
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Kochmann S, Krylov SN. Image processing and analysis system for development and use of free flow electrophoresis chips. LAB ON A CHIP 2017; 17:256-266. [PMID: 27957577 DOI: 10.1039/c6lc01381c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present an image processing and analysis system to facilitate detailed performance analysis of free flow electrophoresis (FFE) chips. It consists of a cost-effective self-built imaging setup and a comprehensive customizable software suite. Both components were designed modularly to be accessible, adaptable, versatile, and automatable. The system provides tools for i) automated identification of chip features (e.g. separation zone and flow markers), ii) extraction and analysis of stream trajectories, and iii) evaluation of flow profiles and separation quality (e.g. determination of resolution). Equipped with these tools, the presented image processing and analysis system will enable faster development of FFE chips and applications. It will also serve as a robust detector for fluorescence-based analytical applications of FFE.
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Affiliation(s)
- Sven Kochmann
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, 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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26
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Pfeiffer SA, Borisov SM, Nagl S. In-line monitoring of pH and oxygen during enzymatic reactions in off-the-shelf all-glass microreactors using integrated luminescent microsensors. Mikrochim Acta 2016. [DOI: 10.1007/s00604-016-2021-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Štěpánová S, Kašička V. Analysis of proteins and peptides by electromigration methods in microchips. J Sep Sci 2016; 40:228-250. [PMID: 27704694 DOI: 10.1002/jssc.201600962] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 11/07/2022]
Abstract
This review presents the developments and applications of microchip electromigration methods in the separation and analysis of peptides and proteins in the period 2011-mid-2016. The developments in sample preparation and preconcentration, microchannel material, and surface treatment are described. Separations by various microchip electromigration methods (zone electrophoresis in free and sieving media, affinity electrophoresis, isotachophoresis, isoelectric focusing, electrokinetic chromatography, and electrochromatography) are demonstrated. Advances in detection methods are reported and novel applications in the areas of proteomics and peptidomics, quality control of peptide and protein pharmaceuticals, analysis of proteins and peptides in biomatrices, and determination of physicochemical parameters are shown.
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Affiliation(s)
- Sille Štěpánová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Václav Kašička
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
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28
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Ehgartner J, Strobl M, Bolivar JM, Rabl D, Rothbauer M, Ertl P, Borisov SM, Mayr T. Simultaneous Determination of Oxygen and pH Inside Microfluidic Devices Using Core–Shell Nanosensors. Anal Chem 2016; 88:9796-9804. [DOI: 10.1021/acs.analchem.6b02849] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Josef Ehgartner
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9/3, 8010 Graz, Austria
| | - Martin Strobl
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9/3, 8010 Graz, Austria
| | - Juan M. Bolivar
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/1, 8010 Graz, Austria
| | - Dominik Rabl
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9/3, 8010 Graz, Austria
| | - Mario Rothbauer
- Institute
of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt
9/163, 1060 Wien, Austria
| | - Peter Ertl
- Institute
of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt
9/163, 1060 Wien, Austria
| | - Sergey M. Borisov
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9/3, 8010 Graz, Austria
| | - Torsten Mayr
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9/3, 8010 Graz, Austria
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29
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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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