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Selemani MA, Martin RS. Use of 3D printing to integrate microchip electrophoresis with amperometric detection. Anal Bioanal Chem 2024; 416:4749-4758. [PMID: 38581532 DOI: 10.1007/s00216-024-05260-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/08/2024] [Accepted: 03/15/2024] [Indexed: 04/08/2024]
Abstract
This paper describes the use of PolyJet 3D printing to fabricate microchip electrophoresis devices with integrated microwire electrodes for amperometric detection. The fabrication process involves 3D printing of two separate pieces, a channel layer and an electrode layer. The channel layer is created by 3D printing on a pre-fabricated mold with a T-intersection. For the electrode layer, a stencil design is printed directly on the printing tray and covered with a piece of transparent glass. Microwire electrodes are adhered over the glass piece (guided by underlaying stencil) and a CAD design of the electrode layer is then printed on top of the microwire electrode. After delamination from the glass after printing, the microwire is embedded in the printed piece, with the stencil design ensuring that alignment and positioning of the electrode is reproducible for each print. After a thermal bonding step between the channel layer and electrode layer, a complete electrophoresis device with integrated microelectrodes for amperometric detection results. It is shown that this approach enables different microwire electrodes (gold or platinum) and sizes (100 or 50 µm) to be integrated in an end-channel configuration with no gap between the electrode and the separation channel. These devices were used to separate a mixture of catecholamines and the effect of separation voltage on the potential voltage applied on the working electrode was also investigated. In addition, the effect of electrode size on the number of theoretical plates and limit of detection was studied. Finally, a device that contains different channel heights and a detection electrode was 3D-printed to integrate continuous flow sampling with microchip electrophoresis and amperometric detection.
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Affiliation(s)
- Major A Selemani
- Department of Chemistry, Saint Louis University, Saint Louis, MO, USA
| | - R Scott Martin
- Department of Chemistry, Saint Louis University, Saint Louis, MO, USA.
- Center for Additive Manufacturing, Saint Louis University, Saint Louis, MO, USA.
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2
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Ward CL, Cornejo MA, Peli Thanthri SH, Linz TH. A review of electrophoretic separations in temperature-responsive Pluronic thermal gels. Anal Chim Acta 2023; 1276:341613. [PMID: 37573098 DOI: 10.1016/j.aca.2023.341613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 08/14/2023]
Abstract
Gel electrophoresis is a ubiquitous bioanalytical technique used in research laboratories to validate protein and nucleic acid samples. Polyacrylamide and agarose have been the gold standard gel materials for decades, but an alternative class of polymer has emerged with potentially superior performance. Pluronic thermal gels are water-soluble polymers that possess the unique ability to undergo a change in viscosity in response to changing temperature. Thermal gels can reversibly convert between low-viscosity liquids and high-viscosity solid gels using temperature as an adjustable parameter. The properties of thermal gels provide unmatched flexibility as a dynamic separations matrix to measure analytes ranging from small molecules to cells. This review article describes the physical and chemical properties of Pluronic thermal gels to provide a fundamental overview of polymer behavior. The performance of thermal gels is then reviewed to highlight their applications as a gel matrix for electrokinetic separations in capillary, microfluidic, and slab gel formats. The use of dynamic temperature-responsive gels in bioanalytical separations is an underexplored area of research but one that holds exciting potential to achieve performance unattainable with conventional static polymers.
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Affiliation(s)
- Cassandra L Ward
- Department of Chemistry, Wayne State University, Detroit, MI, USA; Lumigen Instrument Center, Wayne State University, Detroit, MI, USA.
| | - Mario A Cornejo
- Department of Chemistry, Wayne State University, Detroit, MI, USA
| | | | - Thomas H Linz
- Department of Chemistry, Wayne State University, Detroit, MI, USA.
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Lee NY. A review on microscale polymerase chain reaction based methods in molecular diagnosis, and future prospects for the fabrication of fully integrated portable biomedical devices. Mikrochim Acta 2018; 185:285. [PMID: 29736588 DOI: 10.1007/s00604-018-2791-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 04/05/2018] [Indexed: 02/06/2023]
Abstract
Since the advent of microfabrication technology and soft lithography, the lab-on-a-chip concept has emerged as a state-of-the-art miniaturized tool for conducting the multiple functions associated with micro total analyses of nucleic acids, in series, in a seamless manner with a miniscule volume of sample. The enhanced surface-to-volume ratio inside a microchannel enables fast reactions owing to increased heat dissipation, allowing rapid amplification. For this reason, PCR has been one of the first applications to be miniaturized in a portable format. However, the nature of the basic working principle for microscale PCR, such as the complicated temperature controls and use of a thermal cycler, has hindered its total integration with other components into a micro total analyses systems (μTAS). This review (with 179 references) surveys the diverse forms of PCR microdevices constructed on the basis of different working principles and evaluates their performances. The first two main sections cover the state-of-the-art in chamber-type PCR microdevices and in continuous-flow PCR microdevices. Methods are then discussed that lead to microdevices with upstream sample purification and downstream detection schemes, with a particular focus on rapid on-site detection of foodborne pathogens. Next, the potential for miniaturizing and automating heaters and pumps is examined. The review concludes with sections on aspects of complete functional integration in conjunction with nanomaterial based sensing, a discussion on future prospects, and with conclusions. Graphical abstract In recent years, thermocycler-based PCR systems have been miniaturized to palm-sized, disposable polymer platforms. In addition, operational accessories such as heaters and mechanical pumps have been simplified to realize semi-automatted stand-alone portable biomedical diagnostic microdevices that are directly applicable in the field. This review summarizes the progress made and the current state of this field.
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Affiliation(s)
- Nae Yoon Lee
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, South Korea.
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Zhu Y, Li Z, Wang P, Shen L, Zhang D, Yamaguchi Y. Factors affecting the separation performance of proteins in capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2018. [DOI: 10.1016/j.jchromb.2018.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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5
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Microfluidic chip-capillary electrophoresis device for the determination of urinary metabolites and proteins. Bioanalysis 2016; 7:907-22. [PMID: 25932524 DOI: 10.4155/bio.15.26] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Microfluidic chip-CE (MC-CE) devices have caught recent attention for diagnostic applications in urine. This is due to the successes reported in handling real urine samples by integrating microfluidic chips (MC) with analyte enrichment and sample cleanup to CE with high separation efficiency and sensitive analyte detection. Here, we review the determination of urinary metabolites and proteins by MC-CE devices within the past 7 years. The application scope for MC-CE integrated devices was found to exceed the use of either technique alone, showing comparable performance to laser-induced fluorescence detection using less sensitive UV detectors, offering the flexibility to handle difficult urine samples with on-chip dilution and online standard addition and delivering enhanced performance as compared with commercial microfluidic chip electrophoresis chips.
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6
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Fang XX, Li HY, Fang P, Pan JZ, Fang Q. A handheld laser-induced fluorescence detector for multiple applications. Talanta 2015; 150:135-41. [PMID: 26838391 DOI: 10.1016/j.talanta.2015.12.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/02/2015] [Accepted: 12/10/2015] [Indexed: 10/22/2022]
Abstract
In this paper, we present a compact handheld laser-induced fluorescence (LIF) detector based on a 450 nm laser diode and quasi-confocal optical configuration with a total size of 9.1 × 6.2 × 4.1 cm(3). Since there are few reports on the use of 450 nm laser diode in LIF detection, especially in miniaturized LIF detector, we systematically investigated various optical arrangements suitable for the requirements of 450 nm laser diode and system miniaturization, including focusing lens, filter combination, and pinhole, as well as Raman effect of water at 450 nm excitation wavelength. As the result, the handheld LIF detector integrates the light source (450 nm laser diode), optical circuit module (including a 450 nm band-pass filter, a dichroic mirror, a collimating lens, a 525 nm band-pass filter, and a 1.0mm aperture), optical detector (miniaturized photomultiplier tube), as well as electronic module (including signal recording, processing and displaying units). This detector is capable of working independently with a cost of ca. $2000 for the whole instrument. The detection limit of the instrument for sodium fluorescein solution is 0.42 nM (S/N=3). The broad applicability of the present system was demonstrated in capillary electrophoresis separation of fluorescein isothiocyanate (FITC) labeled amino acids and in flow cytometry of tumor cells as an on-line LIF detector, as well as in droplet array chip analysis as a LIF scanner. We expect such a compact LIF detector could be applied in flow analysis systems as an on-line detector, and in field analysis and biosensor analysis as a portable universal LIF detector.
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Affiliation(s)
- Xiao-Xia Fang
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Han-Yang Li
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Pan Fang
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Jian-Zhang Pan
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
| | - Qun Fang
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
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7
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Chung M, Kim D, Herr AE. Polymer sieving matrices in microanalytical electrophoresis. Analyst 2014; 139:5635-54. [DOI: 10.1039/c4an01179a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Han SI, Han KH. Microfluidic interface technology based on stereolithography for glass-based lab-on-a-chips. Methods Mol Biol 2013; 949:169-84. [PMID: 23329443 DOI: 10.1007/978-1-62703-134-9_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
As lab-on-a-chips are developed for on-chip integrated microfluidic systems with multiple functions, the development of microfluidic interface (MFI) technology to enable integration of complex microfluidic systems becomes increasingly important and faces many technical difficulties. Such difficulties include the need for more complex structures, the possibility of biological or chemical cross-contamination between functional compartments, and the possible need for individual compartments fabricated from different substrate materials. This chapter introduces MFI technology, based on rapid stereolithography, for a glass-based miniaturized genetic sample preparation system, as an example of a complex lab-on-a-chip that could include functional elements such as; solid-phase DNA extraction, polymerase chain reaction, and capillary electrophoresis. To enable the integration of a complex lab-on-a-chip system in a single chip, MFI technology based on stereolithography provides a simple method for realizing complex arrangements of one-step plug-in microfluidic interconnects, integrated microvalves for microfluidic control, and optical windows for on-chip optical processes.
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Affiliation(s)
- Song-I Han
- School of Nano Engineering, Inje University, Gimhae, Republic of Korea
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High-throughput analysis of therapeutic and diagnostic monoclonal antibodies by multicapillary SDS gel electrophoresis in conjunction with covalent fluorescent labeling. Anal Bioanal Chem 2012; 404:1485-94. [DOI: 10.1007/s00216-012-6213-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 12/13/2022]
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10
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A simple and compact blue diode laser powered excitation source for fluorescence detection in capillary electrochromatographic microchip separation. Microchem J 2011. [DOI: 10.1016/j.microc.2011.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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11
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Zhang S, Cao W, Li J, Su M. MCE enzyme immunoassay for carcinoembryonic antigen and alpha-fetoprotein using electrochemical detection. Electrophoresis 2009; 30:3427-35. [DOI: 10.1002/elps.200800805] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Liu X, Gomez FA. Microchip frontal affinity chromatography to study the binding of a ligand to teicoplanin-derivatized microbeads. Electrophoresis 2009; 30:1194-7. [DOI: 10.1002/elps.200800393] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Chen X, Tang K, Lee M, Flynn GC. Microchip assays for screening monoclonal antibody product quality. Electrophoresis 2008; 29:4993-5002. [DOI: 10.1002/elps.200800324] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Sloat AL, Roper MG, Lin X, Ferrance JP, Landers JP, Colyer CL. Protein determination by microchip capillary electrophoresis using an asymmetric squarylium dye: Noncovalent labeling and nonequilibrium measurement of association constants. Electrophoresis 2008; 29:3446-55. [DOI: 10.1002/elps.200700808] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Liu C, Mo YY, Chen ZG, Li X, Li OL, Zhou X. Dual fluorescence/contactless conductivity detection for microfluidic chip. Anal Chim Acta 2008; 621:171-7. [DOI: 10.1016/j.aca.2008.05.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 05/09/2008] [Accepted: 05/13/2008] [Indexed: 10/22/2022]
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16
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Okada H, Kaji N, Tokeshi M, Baba Y. Rinse and evaporation coating of poly(methyl methacrylate) microchip for separation of sodium dodecyl sulfate–protein complex. J Chromatogr A 2008; 1192:289-93. [DOI: 10.1016/j.chroma.2008.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 03/04/2008] [Accepted: 03/05/2008] [Indexed: 11/29/2022]
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17
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Peng Y, Pallandre A, Tran NT, Taverna M. Recent innovations in protein separation on microchips by electrophoretic methods. Electrophoresis 2008; 29:157-78. [DOI: 10.1002/elps.200700347] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Wu S, Lu JJ, Wang S, Peck KL, Li G, Liu S. Staining method for protein analysis by capillary gel electrophoresis. Anal Chem 2007; 79:7727-33. [PMID: 17874848 PMCID: PMC2753390 DOI: 10.1021/ac071055n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel staining method and the associated fluorescent dye were developed for protein analysis by capillary SDS-PAGE. The method strategy is to synthesize a pseudo-SDS dye and use it to replace some of the SDS in SDS-protein complexes so that the protein can be fluorescently detected. The pseudo-SDS dye consists of a long, straight alkyl chain connected to a negative charged fluorescent head and binds to proteins just as SDS. The number of dye molecules incorporated with a protein depends on the dye concentration relative to SDS in the sample solution, since SDS and dye bind to proteins competitively. In this work, we synthesized a series of pseudo-SDS dyes, and tested their performances for capillary SDS-PAGE. FT-16 (a fluorescein molecule linked with a hexadodecyl group) seemed to be the best among all the dyes tested. Although the numbers of dye molecules bound to proteins (and the fluorescence signals from these protein complexes) were maximized in the absence of SDS, high-quality separations were obtained when co-complexes of SDS-protein-dye were formed. The migration time correlates well with protein size even after some of the SDS in the SDS-protein complexes was replaced by the pseudo-SDS dye. Under optimized experimental conditions and using a laser-induced fluorescence detector, limits of detection of as low as 0.13 ng/mL (bovine serum albumin) and dynamic ranges over 5 orders of magnitude in which fluorescence response is proportional to the square root of analyte concentration were obtained. The method and dye were also tested for separations of real-world samples from E. coli.
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Affiliation(s)
| | | | | | | | | | - Shaorong Liu
- Corresponding author. Fax: 806 742 1289, E-mail:
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19
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Granzhan A, Ihmels H, Viola G. 9-Donor-Substituted Acridizinium Salts: Versatile Environment-Sensitive Fluorophores for the Detection of Biomacromolecules. J Am Chem Soc 2007; 129:1254-67. [PMID: 17263409 DOI: 10.1021/ja0668872] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The absorption and steady-state emission properties of a series of N-alkyl- and N-aryl-9-aminoacridizinium derivatives and two 9-sulfanyl-substituted acridizinium derivatives were investigated. The N-alkyl derivatives and the 9-methylsulfanylacridizinium have an intense intrinsic fluorescence (phi(f) = 0.2-0.6), whereas the N-aryl-substituted compounds are virtually nonfluorescent in liquid solutions (phi(f) < or = 0.01). The emission intensity of the latter compounds significantly increases with increasing viscosity of the medium. It is demonstrated that the excited-state deactivation of the N-aryl-9-aminoacridizinium derivatives is due to two nonradiative processes: (i) torsional relaxation by rotation about the N-aryl bond and (ii) an electron-transfer process from an electron-donor substituted phenyl ring to the photoexcited acridizinium chromophore. The binding of several representative acridizinium derivatives to double-stranded DNA was studied by the spectrophotometric titrations and linear dichroism spectroscopy. The results give evidence that the prevailing binding mode is intercalation with binding constants in the range (0.5-5.0) x 10(5) M(-1) (in base pairs). Notably, the binding of most of the N-aryl-9-aminoacridizinium derivatives leads to a fluorescence enhancement by a factor of up to 50 upon binding to the biomacromolecules. Moreover, the addition of selected proteins, namely albumins, to N-(halogenophenyl)-9-aminoacridizinium ions in the presence of an anionic surfactant (sodium dodecyl sulfate) results in a 20-fold fluorescence enhancement. In each case, the emission enhancement is supposed to result from the hindrance of the torsional relaxation in the corresponding binding site of the biomacromolecule, which in turn suppresses the excited-state deactivation pathway.
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Affiliation(s)
- Anton Granzhan
- University of Siegen, Organic Chemistry II, Adolf-Reichwein-Strasse 2, D-57068 Siegen, Germany
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Götz S, Karst U. Recent developments in optical detection methods for microchip separations. Anal Bioanal Chem 2007; 387:183-92. [PMID: 17031620 PMCID: PMC7080113 DOI: 10.1007/s00216-006-0820-8] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 08/18/2006] [Accepted: 08/31/2006] [Indexed: 10/26/2022]
Abstract
This paper summarizes the features and performances of optical detection systems currently applied in order to monitor separations on microchip devices. Fluorescence detection, which delivers very high sensitivity and selectivity, is still the most widely applied method of detection. Instruments utilizing laser-induced fluorescence (LIF) and lamp-based fluorescence along with recent applications of light-emitting diodes (LED) as excitation sources are also covered in this paper. Since chemiluminescence detection can be achieved using extremely simple devices which no longer require light sources and optical components for focusing and collimation, interesting approaches based on this technique are presented, too. Although UV/vis absorbance is a detection method that is commonly used in standard desktop electrophoresis and liquid chromatography instruments, it has not yet reached the same level of popularity for microchip applications. Current applications of UV/vis absorbance detection to microchip separations and innovative approaches that increase sensitivity are described. This article, which contains 85 references, focuses on developments and applications published within the last three years, points out exciting new approaches, and provides future perspectives on this field.
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Affiliation(s)
- Sebastian Götz
- Chemical Analysis Group and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Uwe Karst
- Chemical Analysis Group and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Present Address: Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstr. 30, 48149 Münster, Germany
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Liu X, Liang A, Shen Z, Liu X, Zhang Y, Dai Z, Xiong B, Lin B. Studying drug–plasma protein interactions by two-injector microchip electrophoresis frontal analysis. Electrophoresis 2006; 27:5128-31. [PMID: 17117388 DOI: 10.1002/elps.200600294] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We developed a simple, rapid, and sensitive two-injector microchip electrophoresis frontal analysis (MCE-FA) method for studying drug-plasma protein interactions. In this method, large volumes of a reference sample and drug-plasma protein mixture were simultaneously introduced into the respective sections of the microchannel through the separated injectors and then electrophoresed. Since the reference sample did not meet with the interacting species during migration, it could be used as an external standard. The interaction between heparin and HSA was quantitatively characterized as a model system. The binding constant was found to be (1.53 +/- 0.01) x 10(4) M(-1).
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Affiliation(s)
- Xiaojun Liu
- Dalian institute of Chemical Physics, Chinese Academy of Sciences, Dalian, PR China
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22
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Huynh BH, Fogarty BA, Nandi P, Lunte SM. A microchip electrophoresis device with on-line microdialysis sampling and on-chip sample derivatization by naphthalene 2,3-dicarboxaldehyde/2-mercaptoethanol for amino acid and peptide analysis. J Pharm Biomed Anal 2006; 42:529-34. [PMID: 16829012 DOI: 10.1016/j.jpba.2006.05.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Revised: 05/16/2006] [Accepted: 05/22/2006] [Indexed: 11/28/2022]
Abstract
The integration of rapid on-chip sample derivatization employing naphthalene 2,3-dicarboxaldehyde and 2-mercaptoethanol (NDA/2ME) with an easily assembled microdialysis/microchip electrophoresis device was carried out. The microchip device consisted of a glass layer with etched microfluidic channels that was sealed with a layer of poly(dimethylsiloxane) (PDMS) via plasma oxidation. This simple sealing procedure alleviated the need for glass thermal bonding and allowed the device to be re-sealed in the event of blockages within the channels. The device was used for analysis of a mixture of amino acids and peptides derivatized on-chip with NDA/2ME for laser-induced fluorescence (LIF) detection. A 0.6 mM NDA/1.2 mM 2ME mixture was simply added into the buffer reservoir for dynamic on-column derivatization of sample mixtures introduced at a flow rate of 1.0 microl/min. Using this scheme, sample injection plugs were derivatized and separated simultaneously. Injections of ca. 12 fmol of 5 mM amino acid and peptide samples were conducted using the system. Finally, a three-component mixture of Arg, Gly-Pro, and Asp was sampled from a vial using microdialysis, derivatized, separated and detected with the system. The ultimate goal of this effort is the creation of a micro-total analysis system for high-temporal resolution monitoring of primary amines in biological systems.
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Affiliation(s)
- Bryan H Huynh
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, USA
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Wang W, Xu X, Bin Q, Ling J, Chen G. A new method for fabrication of an integrated indium tin oxide electrode on electrophoresis microchips with amperometric detection and its application for determination of synephrine and hesperidin in pericarpium citri reticulatae. Electrophoresis 2006; 27:4174-81. [PMID: 17001742 DOI: 10.1002/elps.200600159] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new, simple, and fast method to integrate indium tin oxide electrode in an amperometric detection (AD) microchip is introduced. Without the help of photoresist and complicated apparatus, the microchip could be fabricated in most laboratories in a very short time by this method. The experiment indicated that the microchip was stable and had good reproducibility. On this microchip, a new method was established to separate and determine synephrine and hesperidin, which are the main electroactively bioactive ingredients of pericarpium citri reticulatae, by AD. Under the optimal conditions, the two compounds could be completely separated within 5.5 min and the detection limits were 0.13 and 0.57 microg/mL, respectively. The proposed method has been successfully used to determine synephrine and hesperidin in real pericarpium citri reticulatae sample, and the results show that the proposed method is sensitive, reliable, fast, and economical.
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Affiliation(s)
- Wei Wang
- Key Laboratory of Analysis and Detection Technology for Food Safety, Ministry of Education, Fuzhou University, Fuzhou, Fujian, China
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Giordano BC, Horsman KM, Burgi DS, Ferrance JP, Landers JP. Method for determining intracapillary solution temperatures: Application to sample zone heating for enhanced fluorescent labeling of proteins. Electrophoresis 2006; 27:1355-62. [PMID: 16518780 DOI: 10.1002/elps.200500633] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A fundamental premise in CE relies heavily on the assumption that temperature within the capillary is accurately known and controlled. Theoretical calculations for sample zone and BGE temperature during voltage application are presented. We propose that transient elevation of the sample zone temperature allowed for denaturing and renaturing of proteins in the presence of a fluorescent dynamic labeling reagent. Comparison with the extent of labeling possible with standard on-column dynamic labeling in the absence of elevated temperatures showed order-of-magnitude increases in the fluorescence detection sensitivity of proteins with low surface hydrophobicity. As a result, this represents an example where excess heating in the sample zone during electrophoresis can be exploited advantageously.
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Affiliation(s)
- Braden C Giordano
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
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Granzhan A, Ihmels H. N-Aryl-9-amino-Substituted Acridizinium Derivatives as Fluorescent “Light-Up” Probes for DNA and Protein Detection. Org Lett 2005; 7:5119-22. [PMID: 16268517 DOI: 10.1021/ol051624i] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] N-Arylamino-substituted acridizinium (benzo[b]quinolizinium) derivatives are almost nonfluorescent in water or organic solvents; however, upon addition of calf thymus DNA or bovine serum albumin the fluorescence intensity increases by a factor of 10 to 50. Thus, these dyes exhibit ideal properties to be used as DNA- and protein-sensitive "light-up probes".
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Affiliation(s)
- Anton Granzhan
- Institut für Organische Chemie, Universität Siegen, Adolf-Reichwein-Strasse 2, D-57068 Siegen, Germany
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Descroix S, Le Potier I, Niquet C, Minc N, Viovy JL, Taverna M. In-capillary non-covalent labeling of insulin and one gastrointestinal peptide for their analyses by capillary electrophoresis with laser-induced fluorescence detection. J Chromatogr A 2005; 1087:203-9. [PMID: 16130715 DOI: 10.1016/j.chroma.2005.01.095] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The potential of the commercially available dye sypro orange for in-capillary derivatization was evaluated for the detection of insulin and one gastrointestinal peptide (Arg-Arg-gastrin) by capillary electrophoresis with laser induced fluorescence (CE-LIF). The fluorescent emission intensity (lambda(ex) = 488 nm, lambda(em) = 610 nm) of this probe is very low in aqueous medium, and increases strongly in less polar solvent, e.g. methanol. The hydrophobic character of the two analyzed peptides is too low to induce sufficient interaction with the fluorescent probe for good sensitivity when the latter is alone in the background electrolyte. Thus, the potential of several neutral, zwitterionic, cationic and anionic surfactants to favor probe/peptide interactions has been evaluated. It was demonstrated that a borate buffer (pH 8.5) containing tetradecyltrimethylammonium bromide (TTAB) in sub-micellar conditions can be considered as the most suitable buffer for insulin CE-LIF analysis. In addition, the method showed a good linearity between insulin concentration and the peak area of the labeled insulin, allowing quantitative measurements. The sensitivity achieved so far is comparable with that achieved with UV absorption detection, but even at this level it is interesting for microchip analysis, in which fluorescence detection is much more commonly available than UV absorption detection.
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Affiliation(s)
- Stéphanie Descroix
- Faculté de Pharmacie, Groupe de Chimie Analytique, Université Paris-Sud, EA 3343, Rue J.B. Clément, 92290 Châtenay-Malabry, France
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Hofmann O, Wang X, Demello JC, Bradley DDC, Demello AJ. Towards microalbuminuria determination on a disposable diagnostic microchip with integrated fluorescence detection based on thin-film organic light emitting diodes. LAB ON A CHIP 2005; 5:863-8. [PMID: 16027938 DOI: 10.1039/b504551g] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
As a first step towards a fully disposable stand-alone diagnostic microchip for determination of urinary human serum albumin (HSA), we report the use of a thin-film organic light emitting diode (OLED) as an excitation source for microscale fluorescence detection. The OLED has a peak emission wavelength of 540 nm, is simple to fabricate on flexible or rigid substrates, and operates at drive voltages below 10 V. In a fluorescence assay, HSA is reacted with Albumin Blue 580, generating a strong emission at 620 nm when excited with the OLED. Filter-less discrimination between excitation light and generated fluorescence is achieved through an orthogonal detection geometry. When the assay is performed in 800 microm deep and 800 microm wide microchannels on a poly(dimethylsiloxane)(PDMS) microchip at flow rates of 20 microL min(-1), HSA concentrations down to 10 mg L(-1) can be detected with a linear range from 10 to 100 mg L(-1). This sensitivity is sufficient for the determination of microalbuminuria (MAU), an increased urinary albumin excretion indicative of renal disease (clinical cut-off levels: 15-40 mg L(-1)).
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Affiliation(s)
- Oliver Hofmann
- Molecular Vision Ltd., 90 Fetter Lane, London, EC4A 1JP, United Kingdom
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