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Kinoshita M, Nakatani Y, Yamada K, Yamamoto S, Suzuki S. A rapid and facile preparation of APTS-labeled N-glycans by combination of ion pair-assisted extraction and HILIC-SPE for routine glycan analysis. J Pharm Biomed Anal 2020; 195:113875. [PMID: 33418442 DOI: 10.1016/j.jpba.2020.113875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/26/2020] [Accepted: 12/26/2020] [Indexed: 11/26/2022]
Abstract
Glycoanalytical technology is required for a wide variety of scientific research, including basic glycobiological pharmaceutical, and biomarker research. Although several innovative analytical techniques have been developed for these purposes, quantitative glycan analysis based on electrophoretic separation, has often been impeded by the lack of cost-effective and facile sample preparation approaches. Here, we developed a rapid and facile sample preparation workflow for cost-effective glycan analysis and demonstrated its use with fully automated microchip electrophoresis (ME). Purification of 8-aminopyrene-1,3,6-trisulfonate (APTS)-labeled glycans was based on the combination of ion-pair assisted extraction (IPAE) with hydrophilic interaction chromatography-solid phase extraction (HILIC-SPE). Compared to commonly used sample preparation methods, the IPAE/HILIC-SPE method undergoes minimal nonspecific loss and undesirable degradation of N-glycans during the purification step. Furthermore, our method required only 10 min, and the entire workflow, including glycan release, labeling, and concentration processes was completed within 4 h. Although the present system should be improved to enable analysis of more complex mixtures, ME-based separation of APTS-labeled N-glycans offers a fully automated operation including conditioning, sample loading, separation, and can be analyzed with a sample-to-sample throughput of 120 s in parallel processes. The present workflow is easy to implement, does not require expensive reagents and instruments and may be useful for glycoscientists across disciplines.
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Affiliation(s)
- Mitsuhiro Kinoshita
- Department of Pharmaceutical Sciences, Kindai University, Kowakae 3-4-1, Higashi-osaka, Osaka, 577-8502, Japan.
| | - Yumi Nakatani
- Department of Pharmaceutical Sciences, Kindai University, Kowakae 3-4-1, Higashi-osaka, Osaka, 577-8502, Japan
| | - Keita Yamada
- Faculty of Pharmacy, Osaka Ohtani University, Nishikiori-Kita 3-11-1, Tondabayashi, Osaka, 584-8540, Japan
| | - Sachio Yamamoto
- Department of Pharmaceutical Sciences, Kindai University, Kowakae 3-4-1, Higashi-osaka, Osaka, 577-8502, Japan
| | - Shigeo Suzuki
- Department of Pharmaceutical Sciences, Kindai University, Kowakae 3-4-1, Higashi-osaka, Osaka, 577-8502, Japan
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2
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Rapid serial diluting biomicrofluidic provides EC50 in minutes. MICRO AND NANO ENGINEERING 2019. [DOI: 10.1016/j.mne.2019.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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3
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Kitagawa F, Tanigawa-Joh K, Terashita S, Fujiki R, Nukatsuka I, Sueyoshi K, Otsuka K. On-line sample preconcentration by polarity switching in floating electrode-integrated microchannel. Electrophoresis 2019; 40:2478-2483. [PMID: 30637781 DOI: 10.1002/elps.201800501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 11/09/2022]
Abstract
In this study, we found that the polarity switching was effective to enrich and separate fluorescent analytes which have weakly-dissociated groups in a floating platinum electrode (width, 50 µm; thickness, 2.5 µm)-integrated straight-channel in microchip electrophoresis (MCE). In the straight channel filled with an Alexa Flour 488 (AF488) solution, a sharp peak was observed after the polarity inversion with a 530-fold enhancement of the sensitivity relative to the conventional MCE analysis. By using a fluorescent pH indicator, we verified that a sharp high-pH zone was generated nearby the floating electrode and moved toward the anode with maintaining the high pH, which induced the sample enrichment like a dynamic pH junction mechanism. In the floating electrode-embedded channel, the mixture of AF488-labeled proteins was also well concentrated and separated within 100 s.
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Affiliation(s)
- Fumihiko Kitagawa
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, Japan
| | - Kana Tanigawa-Joh
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Satomi Terashita
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, Japan
| | - Ryohei Fujiki
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, Japan
| | - Isoshi Nukatsuka
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, Japan
| | - Kenji Sueyoshi
- Department of Applied Chemistry, Osaka Prefecture University Graduate School of Engineering, Sakai, Japan
| | - Koji Otsuka
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
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4
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Khademi M, Wang W, Reitinger W, Barz DPJ. Zeta Potential of Poly(methyl methacrylate) (PMMA) in Contact with Aqueous Electrolyte-Surfactant Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10473-10482. [PMID: 28915350 DOI: 10.1021/acs.langmuir.7b02487] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The addition of surfactants can considerably impact the electrical characteristics of an interface, and the zeta potential measurement is the standard method for its characterization. In this article, a comprehensive study of the zeta potential of poly(methyl methacrylate) (PMMA) in contact with aqueous solutions containing an anionic, a cationic, or a zwitterionic surfactant at different pH and ionic strength values is conducted. Electrophoretic mobilities are inferred from electrophoretic light scattering measurements of the particulate PMMA. These values can be converted into zeta potentials using permittivity and viscosity measurements of the continuous phase. Different behaviors are observed for each surfactant type, which can be explained with the various adsorption mechanisms on PMMA. For the anionic surfactant, the absolute zeta potential value below the critical micelle concentration (CMC) increases with the concentration, while it becomes rather constant around the CMC. At concentrations above the CMC, the absolute zeta potential increases again. We propose that hydrophobic-based adsorption and, at higher concentrations, the competing micellization process drive this behavior. The addition of cationic surfactant results in an isoelectric point below the CMC where the negative surface charge is neutralized by a layer of adsorbed cationic surfactant. At concentrations near the CMC, the positive zeta potential is rather constant. In this case, we propose that electrostatic interactions combined with hydrophobic adsorption are responsible for the observed behavior. The zeta potential in the presence of zwitterionic surfactant is influenced by the adsorption, because of hydrophobic interactions between the surfactant tail and the PMMA surface. However, there is less influence, compared to the ionic surfactants. For all three surfactant types, the zeta potential changes to more-negative or less-positive values for alkaline pH values, because of hydroxide adsorption. An increase of the ionic strength decreases the absolute value of the zeta potential, because of the shielding effects.
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Affiliation(s)
- Mahmoud Khademi
- Department of Chemical Engineering, Queen's University , Kingston, Ontario, Canada K7L 3N6
| | - Wuchun Wang
- Department of Chemical Engineering, Queen's University , Kingston, Ontario, Canada K7L 3N6
| | - Wolfgang Reitinger
- Department of Chemical Engineering, Queen's University , Kingston, Ontario, Canada K7L 3N6
| | - Dominik P J Barz
- Department of Chemical Engineering, Queen's University , Kingston, Ontario, Canada K7L 3N6
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5
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Yamagami M, Matsui Y, Hayakawa T, Yamamoto S, Kinoshita M, Suzuki S. Plug-plug kinetic capillary electrophoresis for in-capillary exoglycosidase digestion as a profiling tool for the analysis of glycoprotein glycans. J Chromatogr A 2017; 1496:157-162. [PMID: 28356190 DOI: 10.1016/j.chroma.2017.03.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/03/2017] [Accepted: 03/10/2017] [Indexed: 01/31/2023]
Abstract
An online exoglycosidase digestion was combined with a plug-plug kinetic mode of capillary electrophoresis (CE) for the analysis of glycoprotein-derived oligosaccharides. An exoglycosidase solution and a solution of glycoprotein glycans derivatized with 8-aminopyrene-1,3,6-trisulfonic acid (APTS) were introduced to a neutrally coated capillary previously filled with electrophoresis buffer solution containing 0.5w/v% hydroxypropylcellulose. After immersion of both ends of the capillary in the buffer solutions, a negative voltage was applied for analysis. An APTS group of an oligosaccharide derivative has triply negative charges, which forced saccharide derivatives to anode with fast mobility and pass through the enzyme plug, which are detected at the anodic end. If the terminal monosaccharides of APTS-labeled oligosaccharides are released by the action of an exoglycosidase, the migration times of the oligosaccharides shift to those of digested oligosaccharides. We examined β-galactosidase, α-mannosidase, β-N-acetylhexosaminidase, α-neuraminidase, and α-fucosidase, and found only β-galactosidase and α-neuraminidase showed good reactivity toward APTS-labeled oligosaccharides; the reaction was completed by injecting a 3.6cm long plug of 200 and 50mU/mL concentration of exoglycosidases. In contrast, other exoglycosidases could not react with APTS labeled oligosaccharides at a concentration up to 5U/mL. The β-N-acetylhexosaminidase reaction was successively followed by the electrophoretic mobility of APTS oligosaccharides and stopped for 10min when saccharide derivatives were achieved in the enzyme plug. The reaction of α-fucosidase and α-mannosidase was completed by decreasing the electrophoretic voltage to -2kV when the APTS oligosaccharides were passing through an exoglycosidase plug. We established the CE conditions for all of the glycosidic linkage analysis of glycoprotein glycans.
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Affiliation(s)
- Maki Yamagami
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
| | - Yurie Matsui
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
| | - Takao Hayakawa
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
| | - Sachio Yamamoto
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
| | - Mitsuhiro Kinoshita
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan; Antiaging Center, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
| | - Shigeo Suzuki
- Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan; Antiaging Center, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, Japan.
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6
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Li N, Hai X, Yu X, Dang F. Carbohydrate analysis on hybrid poly(dimethylsiloxane)/glass chips dynamically coated with ionic complementary peptide. J Chromatogr A 2017; 1481:152-157. [DOI: 10.1016/j.chroma.2016.12.049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 11/26/2022]
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7
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BABA Y. Nano- and Microbiodevices for High-Performance Separation of Biomolecules. CHROMATOGRAPHY 2015. [DOI: 10.15583/jpchrom.2015.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoshinobu BABA
- Department of Applied Chemistry, Graduate School of Engineering, ImPACT Research Center for Advanced Nanobiodevices, Department of Advanced Medical Science, Graduate School of Medicine, Nagoya University, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
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8
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Mittermayr S, Bones J, Guttman A. Unraveling the Glyco-Puzzle: Glycan Structure Identification by Capillary Electrophoresis. Anal Chem 2013; 85:4228-38. [DOI: 10.1021/ac4006099] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Stefan Mittermayr
- Horváth
Laboratory of
Bioseparation Sciences, Regional Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Jonathan Bones
- NIBRT−The National Institute for Bioprocessing Research and Training, Fosters Avenue, Mount Merrion, Blackrock, Co. Dublin, Ireland
| | - András Guttman
- Horváth
Laboratory of
Bioseparation Sciences, Regional Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary
- MTA-PE Translational Glycomics
Group, University of Pannonia, Veszprem,
Hungary
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9
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Wongkaew N, Kirschbaum SEK, Surareungchai W, Durst RA, Baeumner AJ. A Novel Three-Electrode System Fabricated on Polymethyl Methacrylate for On-Chip Electrochemical Detection. ELECTROANAL 2012. [DOI: 10.1002/elan.201200336] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Azadi G, Tripathi A. Surfactant-induced electroosmotic flow in microfluidic capillaries. Electrophoresis 2012; 33:2094-101. [DOI: 10.1002/elps.201100633] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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11
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Sheng J, Ping Q, Lei J, Ju H, Song C, Zhang D. Fast and High-Performance Screening of Narcotic Drugs on a Microfluidic Device by Micellar Electrokinetic Capillary Chromatography. ANAL LETT 2012. [DOI: 10.1080/00032719.2011.653894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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12
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Highly sensitive oligosaccharide analysis in capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump. J Chromatogr A 2012; 1232:52-8. [DOI: 10.1016/j.chroma.2011.09.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/10/2011] [Accepted: 09/13/2011] [Indexed: 11/19/2022]
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13
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Yasui T, Reza Mohamadi M, Kaji N, Okamoto Y, Tokeshi M, Baba Y. Characterization of low viscosity polymer solutions for microchip electrophoresis of non-denatured proteins on plastic chips. BIOMICROFLUIDICS 2011; 5:44114-441149. [PMID: 22685502 PMCID: PMC3368831 DOI: 10.1063/1.3668233] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/17/2011] [Indexed: 06/01/2023]
Abstract
In this paper, we study characteristics of polymers (methylcellulose, hypromellose ((hydroxypropyl)methyl cellulose), poly(vinylpyrrolidone), and poly(vinyl alcohol)) with different chemical structures for microchip electrophoresis of non-denatured protein samples in a plastic microchip made of poly(methyl methacrylate) (PMMA). Coating efficiency of these polymers for controlling protein adsorption onto the channel surface of the plastic microchip, wettability of the PMMA surface, and electroosmotic flow in the PMMA microchannels in the presence of these polymers were compared. Also relative electrophoretic mobility of protein samples in solutions of these polymers was studied. We showed that when using low polymer concentrations (lower than the polymer entanglement point) where the sieving effect is substantially negligible, the interaction of the samples with the polymer affected the electrophoretic mobility of the samples. This effect can be used for achieving better resolution in microchip electrophoresis of protein samples.
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14
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Viefhues M, Manchanda S, Chao TC, Anselmetti D, Regtmeier J, Ros A. Physisorbed surface coatings for poly(dimethylsiloxane) and quartz microfluidic devices. Anal Bioanal Chem 2011; 401:2113-22. [PMID: 21847528 DOI: 10.1007/s00216-011-5301-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 07/22/2011] [Accepted: 07/28/2011] [Indexed: 01/20/2023]
Abstract
Surface modifications of microfluidic devices are of essential importance for successful bioanalytical applications. Here, we investigate three different coatings for quartz and poly(dimethylsiloxane) (PDMS) surfaces. We employed a triblock copolymer with trade name F(108), poly(L-lysine)-g-poly(ethylene glycol) (PLL-PEG), as well as the hybrid coating n-dodecyl-β-D-maltoside and methyl cellulose (DDM/MC). The impact of these coatings was characterized by measuring the electroosmotic flow (EOF), contact angle, and prevention of protein adsorption. Furthermore, we investigated the influence of static coatings, i.e., the incubation with the coating agent prior to measurements, and dynamic coatings, where the coating agent was present during the measurement. We found that all coatings on PDMS as well as quartz reduced EOF, increased reproducibility of EOF, reduced protein adsorption, and improved the wettability of the surfaces. Among the coating strategies tested, the dynamic coatings with DDM/MC and F(108) demonstrated maximal reduction of EOF and protein adsorption and simultaneously best long-term stability concerning EOF. For PLL-PEG, a reversal in the EOF direction was observed. Interestingly, the static surface coating strategy with F(108) proved to be as effective to prevent protein adsorption as dynamic coating with this block copolymer. These findings will allow optimized parameter choices for coating strategies on PDMS and quartz microfluidic devices in which control of EOF and reduced biofouling are indispensable.
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Affiliation(s)
- M Viefhues
- Experimental Biophysics and Applied Nanoscience, Bielefeld University, 33615 Bielefeld, Germany
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15
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Baba Y. Nanobiodevices for Genome Analysis, Proteome Analysis, and Biomedical Applications. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2011. [DOI: 10.1246/bcsj.20100341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Le NCH, Gubala V, Gandhiraman RP, Daniels S, Williams DE. Evaluation of different nonspecific binding blocking agents deposited inside poly(methyl methacrylate) microfluidic flow-cells. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9043-9051. [PMID: 21648475 DOI: 10.1021/la2011502] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Poly(methyl methacrylate) (PMMA) flow-cells containing microwells were deposited with different nonspecific binding blocking agents, namely, bovine serum albumin (BSA), cationic lipid (DOTAP:DOPE) and diethylene glycol dimethyl ether (DEGDME). Water contact angle (WCA) and atomic force microscope (AFM) measurements were carried out to confirm the successful depositions of BSA, DOTAP, and DEGDME onto the PMMA surfaces. Fluorescent intensity measurements were performed to evaluate the degree of nonspecific adsorption of Cy5-labeled anti-IgG proteins onto plain and oxygen plasma-treated (PT) PMMA flow-cells as well as PMMA flow-cells deposited with different above-mentioned blocking agents. We then employed a label-free detection method called total internal reflection ellipsometry (TIRE) to evaluate the stability of the deposited blocking agents inside the PMMA flow-cells. It was found that, while DOTAP:DOPE was the best agent for blocking the nonspecific adsorption, it could be removed from the PMMA surfaces of the flow-cells upon rinsing with phosphate buffered saline (PBS) and later deposited back onto the Au-coated glass sensing substrate of the TIRE. The removal of the blocking agents from PMMA surfaces and their deposition onto the sensing substrate were further manifested by measuring the kinetics and the amount of adsorbed anti-α-hCG proteins. Overall, the dry DEGDME coating by plasma-enhanced chemical vapor deposition (PECVD) showed very good blocking and excellent stability for subsequent assay inside the microwells. Our results could be useful when one considers what blocking agents should be used for PMMA-based microfluidic immunosensor or biosensor devices by looking at both the blocking efficiency and the stability of the blocking agent.
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Affiliation(s)
- Nam Cao Hoai Le
- Biomedical Diagnostics Institute (BDI), Dublin City University, Dublin, Republic of Ireland.
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17
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Rapid ultraviolet monitoring of multiple psychotropic drugs with a renewable microfluidic device. Anal Chim Acta 2010; 679:1-6. [DOI: 10.1016/j.aca.2010.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 08/10/2010] [Accepted: 08/16/2010] [Indexed: 02/05/2023]
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18
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Maeda E, Urakami K, Shimura K, Kinoshita M, Kakehi K. Charge heterogeneity of a therapeutic monoclonal antibody conjugated with a cytotoxic antitumor antibiotic, calicheamicin. J Chromatogr A 2010; 1217:7164-71. [PMID: 20932526 DOI: 10.1016/j.chroma.2010.09.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 09/01/2010] [Accepted: 09/08/2010] [Indexed: 12/28/2022]
Abstract
A robust and highly reproducible capillary isoelectric focusing (cIEF) method for the evaluation of charge heterogeneity of monoclonal antibody (mAb) pharmaceutical which contains covalently bound antitumor compounds was developed using a combination of commercially available dimethylpolysiloxane-coated capillary and carrier ampholyte. In order to optimize major analytical parameters for robust mobilization, experimental responses from three pI markers were selected. The optimized method gave excellent repeatability and intermediate precision in estimated pI values of charge variants with relative standard deviations (RSDs) of not more than 0.06% and 0.95%, respectively, when using IgG(4) as a model. Furthermore, RSDs of charge variant compositions were less than 5.0%. These results suggest that the proposed method can be a powerful tool for reproducible evaluation of charge variants of both naked mAbs and their conjugates with high resolution, and it is applicable to quality testing and detailed characterization in the pharmaceutical industry. In addition, it should be noticed that the method provided non-linear pH gradient within the tested ranges, from pI 9.50 to 3.78, and the pH gradient caused the inconsistency of estimated pI ranges between cIEF and gel IEF. This result indicates that selecting appropriate pI markers based on the target pI ranges of charge variants for each mAb related pharmaceutical is highly recommended for the precise determination of pI values.
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Affiliation(s)
- Eiki Maeda
- Analytical Development Laboratories, CMC Center, Takeda Pharmaceutical Company Limited, Juso-honmachi 2-17-85, Yodogawa-ku, Osaka 532-8686, Japan. maeda
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19
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Kawai T, Sueyoshi K, Kitagawa F, Otsuka K. Microchip Electrophoresis of Oligosaccharides Using Large-Volume Sample Stacking with an Electroosmotic Flow Pump in a Single Channel. Anal Chem 2010; 82:6504-11. [DOI: 10.1021/ac1008145] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Takayuki Kawai
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kenji Sueyoshi
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Fumihiko Kitagawa
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Koji Otsuka
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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20
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Luo R, Archer-Hartmann SA, Holland LA. Transformable Capillary Electrophoresis for Oligosaccharide Separations Using Phospholipid Additives. Anal Chem 2010; 82:1228-33. [PMID: 20078030 DOI: 10.1021/ac902052m] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ruijuan Luo
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| | | | - Lisa A. Holland
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
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21
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Pretreatment-free fast ultraviolet detection of melamine in milk products with a disposable microfluidic device. J Chromatogr A 2010; 1217:785-9. [DOI: 10.1016/j.chroma.2009.12.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 11/21/2009] [Accepted: 12/01/2009] [Indexed: 11/21/2022]
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22
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Guijt RM, Candish E, Breadmore MC. Dry film microchips for miniaturised separations. Electrophoresis 2009; 30:4219-24. [DOI: 10.1002/elps.200900233] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Dang F, Maeda E, Osafune T, Nakajima K, Kakehi K, Ishikawa M, Baba Y. Carbohydrate−Protein Interactions Investigated on Plastic Chips Statically Coated with Hydrophobically Modified Hydroxyethylcellulose. Anal Chem 2009; 81:10055-60. [DOI: 10.1021/ac902014c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fuquan Dang
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Eiki Maeda
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Tomo Osafune
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Kazuki Nakajima
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Kazuaki Kakehi
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Mitsuru Ishikawa
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
| | - Yoshinobu Baba
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, and Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka 577-850, Japan
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Dang F, Hasegawa T, Biju V, Ishikawa M, Kaji N, Yasui T, Baba Y. Spontaneous adsorption on a hydrophobic surface governed by hydrogen bonding. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9296-9301. [PMID: 19459684 DOI: 10.1021/la900850u] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Spontaneous adsorption from solution onto solid surface is a common phenomenon in nature, but the force that governs adsorption is still a matter of considerable debate. (1, 2) We found that surfactants and cellulose adsorb from solution onto a poly(methyl methacrylate) (PMMA) surface in an ordered and cooperative way governed by hydrogen bonding. The glucose rings of n-dodecyl-beta-D-maltoside (DDM) and hydroxyethylcellulose (HEC) stand perpendicular to the surface, H-bond to the surface COOMe groups with their C=O and Me-O bonds parallel to the surface, and form a tight monolayer. The non-H-bonded COOMe groups orient their C=O bonds perpendicular to the surface. In contrast, the glucose rings of hydrophobically modified hydroxyethylcellulose (HMHEC) lie flat with the side chains perpendicular to the surface and H-bond to the perpendicular-oriented C=O groups. The non-H-bonded COOMe groups orient their C=O bonds parallel but Me-O bonds near-perpendicular to the surface for stabilizing HMHEC. The current work provides a detailed picture of how surface-active molecules interact with a solid surface and self-assemble into greatly different architectures.
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Affiliation(s)
- Fuquan Dang
- Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Japan.
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25
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Microchip micellar electrokinetic chromatography based on one functionalized ionic liquid and its excellent performance on proteins separation. J Chromatogr A 2008; 1207:175-80. [DOI: 10.1016/j.chroma.2008.08.062] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 08/10/2008] [Accepted: 08/12/2008] [Indexed: 11/21/2022]
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26
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Xu Y, Li B, Li J, Wang E. Ionic liquids supported growth of highly ordered microdroplets induced by fluidic leakage at poly(dimethylsiloxane) interfaces. Anal Chim Acta 2008; 625:35-40. [PMID: 18721537 DOI: 10.1016/j.aca.2008.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 07/03/2008] [Indexed: 11/29/2022]
Abstract
"Fluidic leakage" caused by vacuum force at the reversible sealing poly(dimethylsiloxane) (PDMS) interfaces was converted to one useable avenue, which led to formation of highly ordered surfactant microdroplets functionalized with ionic liquids (ILs). Vacuum force is the prerequisite to lead constant microsolutions to diffuse to the PDMS interfaces. Imidazolium ions of ILs rendered structural rearrangement of the surfactant aggregates and the ordered droplets formation. The anion tetrafluoroborate of ILs possessed indispensable functions in affecting the polarity of the microdroplets and was discovered to have enhanced effect on encapsulation of hydrophilic molecules in surfactant microdroplets. These interesting phenomena were characterized by various analytical methods such as confocal laser scanning microscopy, atomic force microscopy, luminescence spectroscopy and UV-vis spectroscopy.
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Affiliation(s)
- Yuanhong Xu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Changchun, Jilin 130022, China
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27
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Kamoda S, Kakehi K. Evaluation of glycosylation for quality assurance of antibody pharmaceuticals by capillary electrophoresis. Electrophoresis 2008; 29:3595-604. [DOI: 10.1002/elps.200700940] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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28
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Greif D, Galla L, Ros A, Anselmetti D. Single cell analysis in full body quartz glass chips with native UV laser-induced fluorescence detection. J Chromatogr A 2008; 1206:83-8. [PMID: 18657818 DOI: 10.1016/j.chroma.2008.07.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/20/2008] [Accepted: 07/08/2008] [Indexed: 01/09/2023]
Abstract
In order to investigate the individual and inhomogenous cellular response, e.g. to external stimuli, single cell analysis is mandatory and may provide new cognitions in proteomics as well as in other fields of systems biology in the future. Here, we report on novel chip architectures for single cell analysis based on full body quartz glass microfluidic chips (QG chips) that extend our previous studies in polydimethylsiloxane (PDMS) chips, and enhance the detection sensitivity of native UV laser-induced fluorescence (UV-LIF) detection. Detection of a 10nM tryptophan solution with an S/N ratio of 11.9, which gives a theoretical limit of detection of 2.5 nM (with S/N=3), was possible. With these optimizations the three proteins alpha-chymotrypsinogen A, ovalbumin and catalase each at a concentration of 100 microg/mL (equal to 4 microM, 0.4 microM and 2.2 microM) were injected electrokinetically and could be separated with nearly baseline resolution. Furthermore, fluorescence spectra (excitation wavelength, lambda(ex) = 266 nm) clearly demonstrate the favourable properties like the very high UV transparency and the nearly vanishing background fluorescence of the QG chips as compared to PDMS chips and to PDMS quartz window (PQW) chips. Finally we exploit the improved sensitivity for single cell electropherograms of Spodoptera frugiperda (Sf9) insect cells.
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Affiliation(s)
- Dominik Greif
- Experimental Biophysics and Applied Nanoscience, Physics Department, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, NRW, Germany.
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29
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Xu Y, Li J, Wang E. Sensitive, label-free protein assay using 1-ethyl-3-methylimidazolium tetrafluoroborate-supported microchip electrophoresis with laser-induced fluorescence detection. Electrophoresis 2008; 29:1852-8. [DOI: 10.1002/elps.200700499] [Citation(s) in RCA: 17] [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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30
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Chen Y, Zhang L, Chen G. Fabrication, modification, and application of poly(methyl methacrylate) microfluidic chips. Electrophoresis 2008; 29:1801-14. [DOI: 10.1002/elps.200700552] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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31
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Wu D, Qin J, Lin B. Electrophoretic separations on microfluidic chips. J Chromatogr A 2008; 1184:542-59. [PMID: 18207148 PMCID: PMC7094303 DOI: 10.1016/j.chroma.2007.11.119] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 11/17/2007] [Accepted: 11/30/2007] [Indexed: 02/07/2023]
Abstract
This review presents a brief outline and novel developments of electrophoretic separation in microfluidic chips. Distinct characteristics of microchip electrophoresis (MCE) are discussed first, in which sample injection plug, joule heat, channel turn, surface adsorption and modification are introduced, and some successful strategies and recognized conclusions are also included. Important achievements of microfluidic electrophoresis separation in small molecules, DNA and protein are then summarized. This review is aimed at researchers, who are interested in MCE and want to adopt MCE as a functional unit in their integrated microsystems.
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Affiliation(s)
| | - Jianhua Qin
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Bingcheng Lin
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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32
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Xu Y, Jiang H, Wang E. Ionic liquid-assisted PDMS microchannel modification for efficiently resolving fluorescent dye and protein adsorption. Electrophoresis 2007; 28:4597-605. [DOI: 10.1002/elps.200700261] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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33
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Zhai C, Li C, Qiang W, Lei J, Yu X, Ju H. Amperometric Detection of Carbohydrates with a Portable Silicone/Quartz Capillary Microchip by Designed Fracture Sampling. Anal Chem 2007; 79:9427-32. [DOI: 10.1021/ac701869z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chun Zhai
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Chen Li
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Wei Qiang
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Jianping Lei
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Xiaodong Yu
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Huangxian Ju
- Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, Department of Chemistry, Nanjing University, Nanjing 210093, China
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34
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Roman GT, Kennedy RT. Fully integrated microfluidic separations systems for biochemical analysis. J Chromatogr A 2007; 1168:170-88; discussion 169. [PMID: 17659293 DOI: 10.1016/j.chroma.2007.06.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 06/05/2007] [Indexed: 10/23/2022]
Abstract
Over the past decade a tremendous amount of research has been performed using microfluidic analytical devices to detect over 200 different chemical species. Most of this work has involved substantial integration of fluid manipulation components such as separation channels, valves, and filters. This level of integration has enabled complex sample processing on miniscule sample volumes. Such devices have also demonstrated high throughput, sensitivity, and separation performance. Although the miniaturization of fluidics has been highly valuable, these devices typically rely on conventional ancillary equipment such as power supplies, detection systems, and pumps for operation. This auxiliary equipment prevents the full realization of a "lab-on-a-chip" device with complete portability, autonomous operation, and low cost. Integration and/or miniaturization of ancillary components would dramatically increase the capability and impact of microfluidic separations systems. This review describes recent efforts to incorporate auxiliary equipment either as miniaturized plug-in modules or directly fabricated into the microfluidic device.
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Affiliation(s)
- Gregory T Roman
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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35
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Mohamadi MR, Mahmoudian L, Kaji N, Tokeshi M, Baba Y. Dynamic coating using methylcellulose and polysorbate 20 for nondenaturing electrophoresis of proteins on plastic microchips. Electrophoresis 2007; 28:830-6. [PMID: 17274100 DOI: 10.1002/elps.200600373] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A dynamic coating using methylcellulose (MC) and a nonionic detergent (polysorbate 20) was developed, which controlled protein adsorption onto the surface of microchannels on a microchip made of poly(methyl methacrylate) (PMMA). Optimum concentration of polysorbate 20 in combination with the range of MC concentrations controlled the protein adsorption onto the microchannel surface, and increased the solubility of the protein samples while facilitating the injection of high concentrations of MC solutions into the microchannels. Higher concentrations of nonionic detergent increased the EOF mobility as opposed to the electrophoretic mobility and caused the electrophoresis to fail. Nondenaturing microchip electrophoresis of protein samples with molecular masses ranging from 20 to 100 kDa were completed in 100 s. Also, successful separation of a BSA sample and its complex with anti-BSA mAb ( 220 kDa) was achieved on a PMMA microchip. The separation exhibited high reproducibility in both migration time (RSD = 1%) and peak area (RSD = 10-15%).
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Affiliation(s)
- Mohamad Reza Mohamadi
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan.
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36
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Wang AJ, Xu JJ, Chen HY. In-situ grafting hydrophilic polymer on chitosan modified poly(dimethylsiloxane) microchip for separation of biomolecules. J Chromatogr A 2007; 1147:120-6. [PMID: 17320888 DOI: 10.1016/j.chroma.2007.02.030] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 02/03/2007] [Accepted: 02/07/2007] [Indexed: 11/27/2022]
Abstract
In this paper, a simple and green modification method is developed for biomolecules analysis on poly(dimethylsiloxane) (PDMS) microchip with successful depression of nonspecific biomolecules adsorption. O-[(N-succinimdyl)succiny]-o'-methyl-poly(ethylene glycol) was explored to form hydrophilic surface via in-situ grafting onto pre-coated chitosan (Chit) from aqueous solution in the PDMS microchannel. The polysaccharide chains backbone of Chit was strongly attracted onto the surface of PDMS via hydrophobic interaction combined with hydrogen bonding in an alkaline medium. The methyl-poly(ethylene glycol) (mPEG) could produce hydrophilic domains on the mPEG/aqueous interface, which generated brush-like coating in this way and revealed perfect resistance to nonspecific adsorption of biomolecules. This strategy could greatly improve separation efficiency and reproducibility of biomolecules. Amino acids and proteins could be efficiently separated and successfully detected on the coated microchip coupled with end-channel amperometric detection at a copper electrode. In addition, it offered an effective means for preparing biocompatible and hydrophilic surface on microfluidic devices, which may have potential use in the biological analysis.
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Affiliation(s)
- Ai-Jun Wang
- Key Lab of Analytical Chemistry for Life Science (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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37
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Zhang Y, Ping G, Zhu B, Kaji N, Tokeshi M, Baba Y. Enhanced electrophoretic resolution of monosulfate glycosaminoglycan disaccharide isomers on poly(methyl methacrylate) chips. Electrophoresis 2007; 28:414-21. [PMID: 17361462 DOI: 10.1002/elps.200600339] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
To improve the separation of monosulfate glycosaminoglycan disaccharide isomers by microchip electrophoresis, we found that addition of 1,4-dioxane (DO) dramatically improved analyte resolution, probably due to solvation effects. Methylcellulose (MC) was tested for the ability to suppress EOF and analyte adsorption to the chip. To improve analyte resolution, buffer pH, beta-CD, and DO were systematically investigated. Fast separation was achieved by increasing the electric field strength, and field-amplified sample stacking occurred with increasing buffer concentrations. Therefore, based on our findings, we describe an efficient method for the separation of monosulfate and trisulfate unsaturated disaccharides (DeltaDi-UA2S, DeltaDi-4S, DeltaDi-6S, and DeltaDi-triS) derivatized with 2-aminoacridone hydrochloride. A mixture of monosulfate disaccharide isomers (DeltaDi-UA2S, DeltaDi-4S, and DeltaDi-6S) was baseline-separated within 75 s on a poly(methyl methacrylate) chip using a mixed buffer (DO/running buffer 57:43 v:v), 0.5% MC, pH 6.81, with an E(sep) of 558 V/cm. The theoretical plate was in the range of 5 x 10(5) to 1 x 10(6) m-1.
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Affiliation(s)
- Yong Zhang
- Graduate School of Pharmaceutical Sciences, the University of Tokushima, Tokushima, Japan.
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