1
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Choubey A, Dubey K, Bahga SS. Rapid prototyping of polydimethylsiloxane (PDMS) microchips using electrohydrodynamic jet printing: Application to electrokinetic assays. Electrophoresis 2023; 44:725-732. [PMID: 36774545 DOI: 10.1002/elps.202200241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023]
Abstract
Polydimethylsiloxane (PDMS) based microfluidic devices have found increasing utility for electrophoretic and electrokinetic assays because of their ease of fabrication using replica molding. However, the fabrication of high-resolution molds for replica molding still requires the resource-intensive and time-consuming photolithography process, which precludes quick design iterations and device optimization. We here demonstrate a low-cost, rapid microfabrication process, based on electrohydrodynamic jet printing (EJP), for fabricating non-sacrificial master molds for replica molding of PDMS microfluidic devices. The method is based on the precise deposition of an electrically stretched polymeric solution of polycaprolactone in acetic acid on a silicon wafer placed on a computer-controlled motion stage. This process offers the high-resolution (order 10 μ $\umu$ m) capability of photolithography and rapid prototyping capability of inkjet printing to print high-resolution templates for elastomeric microfluidic devices within a few minutes. Through proper selection of the operating parameters such as solution flow rate, applied electric field, and stage speed, we demonstrate microfabrication of intricate master molds and corresponding PDMS microfluidic devices for electrokinetic applications. We demonstrate the utility of the fabricated PDMS microchips for nonlinear electrokinetic processes such as electrokinetic instability and controlled sample splitting in ITP. The ability to rapid prototype customized reusable master molds with order 10 μ $\umu$ m resolution within a few minutes can help in designing and optimizing microfluidic devices for various electrokinetic applications.
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Affiliation(s)
- Anupam Choubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Kaushlendra Dubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Supreet Singh Bahga
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
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2
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Fluorescence signal amplification by optical reflection in metal-coated nanowells. Mikrochim Acta 2022; 189:478. [DOI: 10.1007/s00604-022-05577-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/14/2022] [Indexed: 11/29/2022]
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3
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Giri B, Dutta D. A compact microfluidic geometry for multiplexing enzyme‐linked immunosorbent assays. Electrophoresis 2022; 43:1399-1407. [DOI: 10.1002/elps.202100311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 02/03/2022] [Accepted: 03/22/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Basant Giri
- Department of Chemistry University of Wyoming Laramie Wyoming USA
| | - Debashis Dutta
- Department of Chemistry University of Wyoming Laramie Wyoming USA
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4
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Buyuktuncel E. Microchip Electrophoresis and Bioanalytical Applications. CURR PHARM ANAL 2019. [DOI: 10.2174/1573412914666180831100533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Microanalytical systems have aroused great interest because they can analyze extremely
small sample volumes, improve the rate and throughput of chemical and biochemical analysis in a way
that reduces costs. Microchip Electrophoresis (ME) represents an effective separation technique to perform
quick analytical separations of complex samples. It offers high resolution and significant peak
capacity. ME is used in many areas, including biology, chemistry, engineering, and medicine. It is established
the same working principles as Capillary Electrophoresis (CE). It is possible to perform electrophoresis
in a more direct and convenient way in a microchip. Since the electric field is the driving
force of the electrodes, there is no need for high pressure as in chromatography. The amount of the voltage
that is applied in some electrophoresis modes, e.g. Micelle Electrokinetic Chromatography (MEKC)
and Capillary Zone Electrophoresis (CZE), mainly determines separation efficiency. Therefore, it is
possible to apply a higher electric field along a considerably shorter separation channel, hence it is possible
to carry out ME much quicker.
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Affiliation(s)
- Ebru Buyuktuncel
- Faculty of Pharmacy, Department of Analytical Chemistry, Inonu University, 44280, Malatya, Turkey
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5
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Amphiphilic core-shell nanoparticles: Synthesis, biophysical properties, and applications. Colloids Surf B Biointerfaces 2018; 172:68-81. [DOI: 10.1016/j.colsurfb.2018.08.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/04/2018] [Accepted: 08/12/2018] [Indexed: 11/18/2022]
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6
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Mechref E, Jabbour J, Calas-Etienne S, Amro K, Mehdi A, Tauk R, Zaouk D, Etienne P. Synthesis and characterization of a photosensitive organic–inorganic, hybrid positive resin type material: application to the manufacture of microfluidic devices by laser writing. RSC Adv 2016. [DOI: 10.1039/c5ra21393b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A chemically amplified photosensitive organic–inorganic hybrid material based on PAA polymer, TVEB as a crosslinking dissolution inhibitor, a VEPTES pre-hydrolysed as an organic–inorganic material and a PAG photoacid generator was developed.
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Affiliation(s)
- Elias Mechref
- Charles Coulomb Laboratory
- University of Montpellier
- 34095 Montpellier Cedex 5
- France
- Platform for Research in Nanosciences and Nanotechnology
| | - Jihane Jabbour
- Platform for Research in Nanosciences and Nanotechnology
- Faculty of Sciences 2
- Lebanese University
- BP90239. Jdedeit
- Lebanon
| | - Sylvie Calas-Etienne
- Charles Coulomb Laboratory
- University of Montpellier
- 34095 Montpellier Cedex 5
- France
| | - Kassem Amro
- Charles Coulomb Laboratory
- University of Montpellier
- 34095 Montpellier Cedex 5
- France
| | - Ahmad Mehdi
- Institute Charles Gerhardt
- Chimie Moléculaire et Organisation du solide
- UMR 5253
- University of Montpellier
- 34095 Montpellier Cedex 5
| | - Rabih Tauk
- Platform for Research in Nanosciences and Nanotechnology
- Faculty of Sciences 2
- Lebanese University
- BP90239. Jdedeit
- Lebanon
| | - Doumit Zaouk
- Applied Physics Laboratory
- Faculty of Sciences 2
- Lebanese University
- BP 90656 Jdedeit
- Lebanon
| | - Pascal Etienne
- Charles Coulomb Laboratory
- University of Montpellier
- 34095 Montpellier Cedex 5
- France
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7
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Mechref E, Jabbour J, Calas-Etienne S, Amro K, Mehdi A, Tauk R, Etienne P. New organic–inorganic hybrid material based on a poly(amic acid) oligomer: a promising opportunity to obtain microfluidic devices by a photolithographic process. RSC Adv 2016. [DOI: 10.1039/c6ra10584j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Miniaturized total analysis systems are becoming a powerful tool for analytical and bioanalytical applications.
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Affiliation(s)
- Elias Mechref
- Charles Coulomb Laboratory
- University of Montpellier
- UMR 5221
- 34095 Montpellier Cedex 5
- France
| | - Jihane Jabbour
- Platform for Research in Nanosciences and Nanotechnology
- Faculty of Sciences 2
- Lebanese University
- Lebanon
| | - Sylvie Calas-Etienne
- Charles Coulomb Laboratory
- University of Montpellier
- UMR 5221
- 34095 Montpellier Cedex 5
- France
| | - Kassem Amro
- Charles Coulomb Laboratory
- University of Montpellier
- UMR 5221
- 34095 Montpellier Cedex 5
- France
| | - Ahmad Mehdi
- Institute Charles Gerhardt
- Chimie Moléculaire et Organisation du Solide
- University of Montpellier
- UMR 5253
- 34095 Montpellier Cedex 5
| | - Rabih Tauk
- Platform for Research in Nanosciences and Nanotechnology
- Faculty of Sciences 2
- Lebanese University
- Lebanon
| | - Pascal Etienne
- Charles Coulomb Laboratory
- University of Montpellier
- UMR 5221
- 34095 Montpellier Cedex 5
- France
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8
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Recent applications of microchip electrophoresis to biomedical analysis. J Pharm Biomed Anal 2015; 113:72-96. [DOI: 10.1016/j.jpba.2015.03.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 02/28/2015] [Accepted: 03/03/2015] [Indexed: 11/22/2022]
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9
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Cerqueira MRF, Santos MSF, Matos RC, Gutz IGR, Angnes L. Use of poly(methyl methacrylate)/polyethyleneimine flow microreactors for enzyme immobilization. Microchem J 2015. [DOI: 10.1016/j.microc.2014.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Cerqueira MRF, Grasseschi D, Matos RC, Angnes L. A novel functionalisation process for glucose oxidase immobilisation in poly(methyl methacrylate) microchannels in a flow system for amperometric determinations. Talanta 2014; 126:20-6. [DOI: 10.1016/j.talanta.2014.02.048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 02/18/2014] [Accepted: 02/19/2014] [Indexed: 10/25/2022]
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11
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Pena J, McAllister SJ, Dutta D. A glass microchip device for conducting serological survey of West Nile viral antibodies. Biomed Microdevices 2014; 16:737-43. [PMID: 24908138 DOI: 10.1007/s10544-014-9878-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Serological surveys are vital to determining the prevalence of a disease and/or the immunity status against it in any population. However, the relatively large sample volume requirement (1-10 mL) in traditional serum-based assays demands that blood draw camps be set up by medical professionals to obtain samples for these studies which significantly increases the time and cost associated with them. Here we address these drawbacks of a serosurvey by reducing the whole blood requirement in its diagnostic procedures down to 10 μL using the microfluidic platform. Such a miniaturization approach was demonstrated in our current work by developing a microchip based serological device for determining the serum levels of West Nile (WN) viral antibodies (IgG and IgM) to assess the immunity status against WN virus in Fremont County, Wyoming. Enzyme-linked immunosorbent assays (ELISA) were developed for these target analytes in glass microchannels to accomplish this task using antibodies/assay reagents purchased from commercial sources. The reported assays were directly quantitated using a fluorescence microplate reader which to our knowledge is the first account of signal measurement in a microchip based ELISA procedure using this standard instrument. To enable this quantitation method, the assay channels on our device were spaced identically as the wells on a commercial microplate, and a holder having the dimensions of this plate was used to accommodate the microchips. Our microfluidic assays showed an excellent correlation with the results from the microwell plate based experiments for significantly lower incubation periods and using only 3 μL of the ELISA reagents.
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Affiliation(s)
- Javier Pena
- Department of Chemistry (Dept. # 3838), University of Wyoming, 1000 East University Avenue, Laramie, WY, 82071, USA
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12
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Thurmann S, Dittmar A, Belder D. A low pressure on-chip injection strategy for high-performance chip-based chromatography. J Chromatogr A 2014; 1340:59-67. [DOI: 10.1016/j.chroma.2014.03.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/21/2014] [Accepted: 03/04/2014] [Indexed: 12/11/2022]
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13
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Giri B, Dutta D. Improvement in the sensitivity of microfluidic ELISA through field amplified stacking of the enzyme reaction product. Anal Chim Acta 2013; 810:32-8. [PMID: 24439502 DOI: 10.1016/j.aca.2013.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/02/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022]
Abstract
In this article, we demonstrate a novel approach to enhancing the sensitivity of enzyme-linked immunosorbent assays (ELISA) through pre-concentration of the enzyme reaction product (resorufin/4-methylumbelliferone) in free solution. The reported pre-concentration was accomplished by transporting the resorufin/4-methylumbelliferone molecules produced in the ELISA process towards a high ionic-strength buffer stream in a microfluidic channel while applying a voltage drop across this merging region. A sharp change in the electric field around the junction of the two liquid streams was observed to abruptly slow down the negatively charged resorufin/4-methylumbelliferone species leading to the reported pre-concentration effect based on the field amplified stacking (FAS) technique. It has been shown that the resulting enhancement in the detectability of the enzyme reaction product significantly improves the signal-to-noise ratio in the system thereby reducing the smallest detectable analyte concentration in the ELISA method. Applying the above-described approach, we were able to detect mouse anti-BSA and human TNF-α at concentrations nearly 60-fold smaller than that possible on commercial microwell plates. For the human TNF-α sample, this improvement in assay sensitivity corresponded to a limit of detection (LOD) of 0.102pg mL(-1) using the FAS based microfluidic ELISA method as compared to 7.03pg mL(-1) obtained with the traditional microwell plate based approach. Moreover, because our ELISAs were performed in micrometer sized channels, they required sample volumes about two orders of magnitude smaller than that consumed in the latter case (1μL versus 100μL).
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Affiliation(s)
- Basant Giri
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA
| | - Debashis Dutta
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA.
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14
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Yanagisawa N, Dutta D. Enhancement in the sensitivity of microfluidic enzyme-linked immunosorbent assays through analyte preconcentration. Anal Chem 2012; 84:7029-36. [PMID: 22861072 DOI: 10.1021/ac3011632] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this Article, we describe a microfluidic enzyme-linked immunosorbent assay (ELISA) method whose sensitivity can be substantially enhanced through preconcentration of the target analyte around a semipermeable membrane. The reported preconcentration has been accomplished in our current work via electrokinetic means allowing a significant increase in the amount of captured analyte relative to nonspecific binding in the trapping/detection zone. Upon introduction of an enzyme substrate into this region, the rate of generation of the ELISA reaction product (resorufin) was observed to increase by over a factor of 200 for the sample and 2 for the corresponding blank compared to similar assays without analyte trapping. Interestingly, in spite of nonuniformities in the amount of captured analyte along the surface of our analysis channel, the measured fluorescence signal in the preconcentration zone increased linearly with time over an enzyme reaction period of 30 min and at a rate that was proportional to the analyte concentration in the bulk sample. In our current study, the reported technique has been shown to reduce the smallest detectable concentration of the tumor marker CA 19-9 and Blue Tongue Viral antibody by over 2 orders of magnitude compared to immunoassays without analyte preconcentration. When compared to microwell based ELISAs, the reported microfluidic approach not only yielded a similar improvement in the smallest detectable analyte concentration but also reduced the sample consumption in the assay by a factor of 20 (5 μL versus 100 μL).
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Affiliation(s)
- Naoki Yanagisawa
- Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA
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15
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Enzyme-immobilized microfluidic process reactors. Molecules 2011; 16:6041-59. [PMID: 21772235 PMCID: PMC6264325 DOI: 10.3390/molecules16076041] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/13/2011] [Accepted: 07/17/2011] [Indexed: 11/17/2022] Open
Abstract
Microreaction technology, which is an interdisciplinary science and engineering area, has been the focus of different fields of research in the past few years. Several microreactors have been developed. Enzymes are a type of catalyst, which are useful in the production of substance in an environmentally friendly way, and they also have high potential for analytical applications. However, not many enzymatic processes have been commercialized, because of problems in stability of the enzymes, cost, and efficiency of the reactions. Thus, there have been demands for innovation in process engineering, particularly for enzymatic reactions, and microreaction devices represent important tools for the development of enzyme processes. In this review, we summarize the recent advances of microchannel reaction technologies especially for enzyme immobilized microreactors. We discuss the manufacturing process of microreaction devices and the advantages of microreactors compared to conventional reaction devices. Fundamental techniques for enzyme immobilized microreactors and important applications of this multidisciplinary technology are also included in our topics.
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16
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Multiplex ELISA in a single microfluidic channel. Anal Bioanal Chem 2011; 401:1173-81. [DOI: 10.1007/s00216-011-5191-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 05/31/2011] [Accepted: 06/16/2011] [Indexed: 11/27/2022]
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17
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Yanagisawa N, Dutta D. Kinetic ELISA in microfluidic channels. BIOSENSORS-BASEL 2011; 1:58-69. [PMID: 25586828 PMCID: PMC4264342 DOI: 10.3390/bios1020058] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 05/26/2011] [Accepted: 06/15/2011] [Indexed: 11/16/2022]
Abstract
In this article, we describe the kinetic ELISA of Blue Tongue and Epizootic Hemorrhagic Disease viral antibodies in microfluidic channels by monitoring the rate of generation of the enzyme reaction product under static conditions. It has been shown that this format of the immunoassay allows very reliable quantitation of the target species using inexpensive glass microchips and a standard epifluorescence microscope system coupled to a CCD camera. For the viral antibodies assayed here, the limit of detection (LOD) for the analyte concentration in our microchips was established to be 3–5 times lower than that obtained on commercial microwell plates using a fiftieth of the sample volume and less than a third of the incubation time. Our analyses further show that when compared to the end-point ELISA format, the kinetic mode of this assay yields an improvement in the LOD by over an order of magnitude in microfluidic devices. This benefit is primarily realized as the observed variation in the background fluorescence (signal at the start of the enzyme reaction period) was significantly larger than that in the rate of signal generation upon repeating these assays in different microchannels/microchips. Because the kinetic ELISA results depend only on the latter quantity, the noise level in them was substantially lower compared to that in its end-point counterpart in which the absolute fluorescence measurements are of greater significance. While a similar benefit was also recorded through implementation of kinetic ELISAs on the microwell platform, the improvement in LOD registered in that system was not as significant as was observed in the case of microfluidic assays.
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Affiliation(s)
- Naoki Yanagisawa
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA.
| | - Debashis Dutta
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA.
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18
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Ziółkowska K, Kwapiszewski R, Brzózka Z. Microfluidic devices as tools for mimicking the in vivo environment. NEW J CHEM 2011. [DOI: 10.1039/c0nj00709a] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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19
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Mao X, Reschke BR, Timperman AT. Analyte transport past a nanofluidic intermediate electrode junction in a microfluidic device. Electrophoresis 2010; 31:2686-94. [DOI: 10.1002/elps.201000068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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20
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Wang J, Huang W, Li L, Cheng J. [Microchip electrochromatography: the latest developments and applications]. Se Pu 2010; 28:264-72. [PMID: 20549978 DOI: 10.3724/sp.j.1123.2010.00264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
This review summarizes recent developments and applications of microchip electrochromatography (microCEC) mainly in the past five years between 2005 and 2009 with a focus on column technologies. In addition, some new improvements in the chip design and fabrication, sample preconcentration, electroosmotic flow control as well as mechanisms that govern electrochromatographic separation are described and reviewed. The features and limitations of several practical aspects of their applications are highlighted.
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Affiliation(s)
- Junhu Wang
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53705, USA.
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21
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Yanagisawa N, Dutta D. Pressure generation at the junction of two microchannels with different depths. Electrophoresis 2010; 31:2080-8. [DOI: 10.1002/elps.201000060] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Xu Y, Takai M, Ishihara K. Phospholipid Polymer Biointerfaces for Lab-on-a-Chip Devices. Ann Biomed Eng 2010; 38:1938-53. [DOI: 10.1007/s10439-010-0025-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 03/22/2010] [Indexed: 01/09/2023]
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23
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Asensio-Ramos M, Hernández-Borges J, Rocco A, Fanali S. Food analysis: A continuous challenge for miniaturized separation techniques. J Sep Sci 2009; 32:3764-800. [DOI: 10.1002/jssc.200900321] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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24
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Fu LM, Hong TF, Wen CY, Tsai CH, Lin CH. Electrokinetic instability effects in microchannels with and without nanofilm coatings. Electrophoresis 2009; 29:4871-9. [PMID: 19130549 DOI: 10.1002/elps.200800455] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This paper presents a parametric experimental investigation into the electrokinetic instability (EKI) phenomenon within three different types of microfluidic device, namely T-type, cross-shaped, and cross-form with an expansion configuration. The critical electric field strength at which the EKI phenomenon is induced is examined as a function of the conductivity ratio, the microchannel width, the expansion ratio, and the surface treatment of the microchannel walls. It is found that the critical electric field strength associated with the onset of EKI is strongly dependent on the conductivity ratio of the two samples within the microfluidic device and reduces as the channel width increases. The surfaces of the microchannel walls are coated with hydrophilic or hydrophobic organic-based spin-on-glass (SOG) nanofilms for glass-based microchips. The experimental results indicate that no significant difference exists in the critical electric field strengths in the hydrophilic or hydrophobic SOG-coated microchannels, respectively. However, for a given conductivity ratio and microchannel width, the critical strength of the electric field is slightly lower in the SOG-coated microchannels than in the non-coated channels. In general, the results presented in this study demonstrate the potential for designing and controlling on-chip assays requiring the manipulation of samples with high conductivity gradients, and provide a useful general reference for avoiding EKI effects in capillary electrophoresis analysis applications.
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Affiliation(s)
- Lung-Ming Fu
- Department of Materials Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan
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25
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Faure K, Albert M, Dugas V, Crétier G, Ferrigno R, Morin P, Rocca JL. Development of an acrylate monolith in a cyclo-olefin copolymer microfluidic device for chip electrochromatography separation. Electrophoresis 2009; 29:4948-55. [PMID: 19130574 DOI: 10.1002/elps.200800235] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An acrylate monolith has been synthesized into a cyclic olefin copolymer microdevice for reversed-phase electrochromatography purposes. Microchannels, designed by hot embossing, were filled up with an acrylate monolith to serve as a hydrophobic stationary phase. A lauryl acrylate monolith was formulated to suit the hydrophobic material, by implementing 100% organic porogenic solvent. This new composition was tested in capillary prior to its transfer into the microfluidic device. Surface functionalization of the cyclic olefin copolymer surface was applied using UV-grafting technique to improve the covalent attachment of this monolith to the plastic walls of the microfluidic chip. The on-chip performances of this monolith were evaluated in detail for the reversed-phase electrochromatographic separation of polycyclic aromatic hydrocarbons, with plate heights reaching down to 10 microm when working at optimal velocity.
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Affiliation(s)
- Karine Faure
- Laboratoire des Sciences Analytiques, Université de Lyon, Villeurbanne, France.
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26
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Stephan K, Pittet P, Sigaud M, Renaud L, Vittori O, Morin P, Ouaini N, Ferrigno R. Amperometric quantification based on serial dilution microfluidic systems. Analyst 2009; 134:472-7. [DOI: 10.1039/b811629f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Derveaux S, Stubbe BG, Braeckmans K, Roelant C, Sato K, Demeester J, De Smedt SC. Synergism between particle-based multiplexing and microfluidics technologies may bring diagnostics closer to the patient. Anal Bioanal Chem 2008; 391:2453-67. [PMID: 18458889 PMCID: PMC2516543 DOI: 10.1007/s00216-008-2062-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 02/04/2008] [Accepted: 03/06/2008] [Indexed: 12/18/2022]
Abstract
In the field of medical diagnostics there is a growing need for inexpensive, accurate, and quick high-throughput assays. On the one hand, recent progress in microfluidics technologies is expected to strongly support the development of miniaturized analytical devices, which will speed up (bio)analytical assays. On the other hand, a higher throughput can be obtained by the simultaneous screening of one sample for multiple targets (multiplexing) by means of encoded particle-based assays. Multiplexing at the macro level is now common in research labs and is expected to become part of clinical diagnostics. This review aims to debate on the “added value” we can expect from (bio)analysis with particles in microfluidic devices. Technologies to (a) decode, (b) analyze, and (c) manipulate the particles are described. Special emphasis is placed on the challenges of integrating currently existing detection platforms for encoded microparticles into microdevices and on promising microtechnologies that could be used to down-scale the detection units in order to obtain compact miniaturized particle-based multiplexing platforms.
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Affiliation(s)
- S Derveaux
- Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000, Ghent, Belgium
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Fu LM, Tsai CH, Lin CH. A high-discernment microflow cytometer with microweir structure. Electrophoresis 2008; 29:1874-80. [DOI: 10.1002/elps.200700630] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Miyazaki M, Honda T, Yamaguchi H, Briones MPP, Maeda H. Enzymatic Processing in Microfluidic Reactors. Biotechnol Genet Eng Rev 2008; 25:405-28. [PMID: 21412364 DOI: 10.5661/bger-25-405] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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30
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Virus analysis by electrophoresis on a microfluidic chip. J Chromatogr B Analyt Technol Biomed Life Sci 2007; 860:173-9. [DOI: 10.1016/j.jchromb.2007.10.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 10/16/2007] [Accepted: 10/17/2007] [Indexed: 12/24/2022]
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Bishop SC, Lerch M, McCord BR. Detection of nitrated benzodiazepines by indirect laser-induced fluorescence detection on a microfluidic device. J Chromatogr A 2007; 1154:481-4. [PMID: 17499754 DOI: 10.1016/j.chroma.2007.05.004] [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] [Received: 11/05/2006] [Revised: 04/19/2007] [Accepted: 05/01/2007] [Indexed: 11/22/2022]
Abstract
Recently there has been concern regarding the use of flunitrazepam and other low-dose benzodiazepines in drug-facilitated sexual assault. These compounds are placed in drinks of unsuspecting victims and produce a sedative effect with anterorgrade amnesia. Chip-based microfluidic systems can provide a quick and disposable procedure for the detection of flunitrazepam and other nitrated benzodiazepines used in these crimes. This paper describes the application of indirect quenching of cyanine dye (Cy5) for detection of nitrated benzodiazepines. The separation is performed on a microfluidic device with a separation channel 8 cm long and 50 microm wide and utilizes indirect fluorescence detection with 635 nm laser excitation. The optimization of the separation using micellar electrokinetic chromatography with organic modifiers is described. A borate buffer containing 2.6 microM Cy5 dye, 15 mM sodium dodecyl sulphate (SDS) and 20% methanol is used. Complete separation of four target drugs occurs in under 2 min with limits of detection in the low microg/ml range. Overall the method provides a rapid and simple analysis for the presence of nitrated benzodiazepines in beverages and other similar preparations.
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Affiliation(s)
- Sandra C Bishop
- Department of Chemistry and Biochemistry, Ohio University, 136 Clippinger Laboratories, Athens, OH 45701, USA
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Abstract
This review is concerned with the phenomenological fluid dynamics in capillary and chip electrochromatography (EC) using high-surface-area random porous media as stationary phases. Specifically, the pore space morphology of packed beds and monoliths is analyzed with respect to the nonuniformity of local and macroscopic EOF, as well as the achievable separation efficiency. It is first pointed out that the pore-level velocity profile of EOF through packed beds and monoliths is generally nonuniform. This contrasts with the plug-like EOF profile in a single homogeneous channel and is caused by a nonuniform distribution of the local electrical field strength in porous media due to the continuously converging and diverging pores. Wall effects of geometrical and electrokinetic nature form another origin for EOF nonuniformities in packed beds which are caused by packing hard particles against a hard wall with different zeta potential. The influence of the resulting, systematic porosity fluctuations close to the confining wall over a distance of a few particle diameters becomes aggravated at low column-to-particle diameter ratio. Due to the hierarchical structure of the pore space in packed beds and silica-based monoliths which are characterized by discrete intraparticle (intraskeleton) mesoporous and interparticle (interskeleton) macroporous spatial domains, charge-selective transport prevails within the porous particles and the monolith skeleton under most general conditions. It forms the basis for electrical field-induced concentration polarization (CP). Simultaneously, a finite and -- depending on morphology -- often significant perfusive EOF is realized in these hierarchically structured materials. The data collected in this review show that the existence of CP and its relative intensity compared to perfusive EOF form fundamental ingredients which tune the fluid dynamics in EC employing monoliths and packed beds as stationary phases. This addresses the (electro)hydrodynamics, associated hydrodynamic dispersion, as well as the migration and retention of charged analytes.
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Affiliation(s)
- Ivo Nischang
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität, Magdeburg, Germany
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Xu Y, Takai M, Konno T, Ishihara K. Microfluidic flow control on charged phospholipid polymer interface. LAB ON A CHIP 2007; 7:199-206. [PMID: 17268622 DOI: 10.1039/b616851p] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A type of charged phospholipid polymer biointerface was constructed on a quartz microfluidic chip to control the electroosmotic flow (EOF) and to suppress non-specific protein adsorption through one-step modification. A negatively charged phospholipid copolymer containing 2-methacryloyloxyethyl phosphorylcholine (MPC), n-butyl methacrylate (BMA), potassium 3-methacryloyloxypropyl sulfonate (PMPS) and 3-methacryloxypropyl trimethoxysilane (MPTMSi) moieties (referred to as PMBSSi) was synthesized to introduce such phosphorylcholine segments as well as surface charges onto the silica-based microchannels via chemical bonding. At neutral pH, the homogenous microchannel surface modified with 0.3 wt% PMBSSi in alcoholic solution, retained a significant cathodic EOF ((1.0 +/- 0.1) x 10(-4) cm(2) V(-1) s(-1)) with approximately one-half of the EOF of the unmodified microchannel ((1.9 +/- 0.1) x 10(-4) cm(2) V(-1) s(-1)). Along with another non-charged copolymer (poly(MPC-co-MPTMSi), PMSi), the regulation of the surface charge density can be realized by adjusting the concentration of PMBSSi or PMSi initial solutions for modification. Coincidently, the zeta-potential and the EOF mobility at neutral pH showed a monotonically descending trend with the decrease in the charge densities on the surfaces. This provides a simple but feasible approach to controlling the EOF, especially with regard to satisfying the requisites of miniaturized systems for biological applications requiring neutral buffer conditions. In addition, the EOF in microchannels modified with PMBSSi and PMSi could maintain stability for a long time at neutral pH. In contrast to the EOF in the unmodified microchannel, the EOF in the modified microchannel was only slightly affected by the change in pH (from 1 to 10). Most importantly, although PMBSSi possesses negative charges, the non-specific adsorptions of both anionic and cationic proteins (considering albumin and cytochrome c, respectively, as examples) were effectively suppressed to a level of 0.15 microg cm(-2) and lesser in the case of the 0.3 wt% PMBSSi modification. Consequently, the variation in the EOF mobility resulting from the protein adsorption was also suppressed simultaneously. To facilitate easy EOF control with compatibility to biomolecules delivered in the microfluidic devices, the charged interface described could provide a promising option.
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Affiliation(s)
- Yan Xu
- Department of Materials Engineering, School of Engineering and Center for NanoBio Integration, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Ou J, Dong J, Dong X, Yu Z, Ye M, Zou H. Recent progress in polar stationary phases for CEC. Electrophoresis 2007; 28:148-63. [PMID: 17136736 DOI: 10.1002/elps.200600298] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This review summarizes most of the recent developments in the preparation and application of polar stationary phases for CEC covering the literature published since the year 2004. These polar stationary phases have been adopted for separation of analytes by the modes of packing column CEC, open-tubular CEC (o-CEC) and monolithic column CEC. Currently, development of o-CEC using biomolecules, such as protein and DNA, as the immobilized ligands is highlighted partly due to the simplicity of preparation. Furthermore, monolithic columns have been extended quickly, particularly inorganic materials-based monoliths, such as silica, zirconia, hafnium, etc., as an alternative to packed columns have been developed quickly.
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Affiliation(s)
- Junjie Ou
- National Chromatographic R & A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
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Abstract
This paper reviews recent methodological and instrumental advances in MEKC. Improvements in sensitivity arising from the use of on-line sample concentration (sweeping, stacking, and combination of both protocols) and derivatization (in-capillary reactions and coupling with flow-injection systems) and improvements in resolution obtained by changing the composition of the BGE (e.g., with organic modifiers, ionic liquids, nonionic and zwitterionic surfactants, mixed micelles, and vesicles) or using coated capillaries are discussed in detail. In addition, MS and LIF spectroscopy are examined in relation to their advantages and restrictions as applied to MEKC analysis. Some thoughts on potential future directions are also expressed.
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Affiliation(s)
- Manuel Silva
- Department of Analytical Chemistry, University of Cordoba, Cordoba, Spain.
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Lee CY, Chen CM, Chang GL, Lin CH, Fu LM. Fabrication and characterization of semicircular detection electrodes for contactless conductivity detector – CE microchips. Electrophoresis 2006; 27:5043-50. [PMID: 17117383 DOI: 10.1002/elps.200600113] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This study uses simple and reliable microfabrication techniques to fabricate CE biochips, integrating a novel contactless conductivity detector in a miniaturized detection system in a microfluidic biochip. The off-channel electrodes are deposited around side channels by Au sputtering and patterned using a standard "lift-off" process. A vacuum fusion bonding process is employed to seal the lower substrate containing the microchannels and the electrodes to an upper glass cover plate. The variations in the capacitance between the semicircular detection electrodes in the side channels are measured as different samples and ions pass through the detection region of the CE separation channel. Samples of Rhodamine B, commercial sports drinks, mineral waters, and a red wine, respectively, are mixed in different buffer solutions, separated, and successfully detected using the developed device. The semicircular detection electrodes for the contactless conductivity detector have microscale dimensions and provide a valuable contribution to the realization of the lab-on-a-chip concept.
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Affiliation(s)
- Chia-Yen Lee
- Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua, Taiwan
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Miyazaki M, Maeda H. Microchannel enzyme reactors and their applications for processing. Trends Biotechnol 2006; 24:463-70. [PMID: 16934892 DOI: 10.1016/j.tibtech.2006.08.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 05/19/2006] [Accepted: 08/15/2006] [Indexed: 10/24/2022]
Abstract
Microreaction technology is an interdisciplinary field combining science and engineering. It has attracted the attention of researchers from different fields for the past few years, resulting in the development of several microreactors. Enzymes are one of the catalysts used in microreactors: they are useful for substance production in an environmentally friendly way and have high potential for analytical applications. However, few enzymatic processes have been commercialized because of problems with stability and the cost and efficiency of the reactions. Thus, there have been demands for innovation in process engineering, particularly for enzymatic reactions, and microreaction devices can serve as efficient tools for the development of enzyme processes. In this review, we summarize the recent advances of enzyme-immobilized microchannel reactors; fundamental techniques for micro enzyme-reactor design and important applications of this multidisciplinary technology in chemical processing are also included in our topics.
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Affiliation(s)
- Masaya Miyazaki
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tosu, Saga 841-0052, Japan
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