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Stability of enzyme immobilized on the nanofluidic channel surface. ANAL SCI 2023; 39:251-255. [PMID: 36670328 DOI: 10.1007/s44211-023-00272-1] [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: 12/26/2022] [Accepted: 01/06/2023] [Indexed: 01/21/2023]
Abstract
The lifetime of an enzyme is critical to prevent system failure and optimize maintenance schedules in biological and analytical chemistry. The lifetime metrics of an enzyme can be evaluated from enzyme activity in terms of catalytic cycles per enzyme at various storage times. Trypsin, which is a gold-standard enzyme in proteomics, has been known to decrease activity due to self-digestion. To improve the activity of trypsin, enzyme reactors have developed by immobilizing in micro and nanospace. However, an evaluation method for the catalytic cycle has not been established due to major issues such as nonuniform space, unstable liquid transport, and self-digestion during immobilization in conventional work. To solve these issues, we have previously developed an ultra-fast enzyme reactor with a well-defined nanofabrication method, stable liquid transport, and partial enzyme modification. Here, we aimed to investigate catalytic cycles in a nanochannel. To extend enzyme lifetime efficiently, we have evaluated the optimal immobilization process and catalytic cycles of trypsin. As a result, immobilized enzyme densities by the trypsinogen immobilization process were increased at all concentrations compared to the trypsin immobilization process. To evaluate the lifetime of trypsin, the immobilized enzyme densities and activities were almost the same before and after 72 h of enzyme storage, and the calculated catalytic cycles were 1740. These results indicated that self-digestion of the immobilized enzyme was highly suppressed. Consequently, the reaction efficiency has been evaluated depending on the catalytic cycles from the substrate for the first time, while preventing self-digestion by trypsin.
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2
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Yamamoto K, Morikawa K, Imanaka H, Imamura K, Kitamori T. Kinetics of Enzymatic Reactions at the Solid/Liquid Interface in Nanofluidic Channels. Anal Chem 2022; 94:15686-15694. [DOI: 10.1021/acs.analchem.2c02878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Koki Yamamoto
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo113-8656, Japan
| | - Kyojiro Morikawa
- Institute of Nanoengineering and Microsystems, Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu300044, Taiwan, ROC
- Collaborative Research Organization for Micro and Nano Multifunctional Devices, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo113-8656, Japan
| | - Hiroyuki Imanaka
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama700-8530, Japan
| | - Koreyoshi Imamura
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama700-8530, Japan
| | - Takehiko Kitamori
- Institute of Nanoengineering and Microsystems, Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu300044, Taiwan, ROC
- Collaborative Research Organization for Micro and Nano Multifunctional Devices, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo113-8656, Japan
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Yamamoto K, Morikawa K, Shimizu H, Sano H, Kazoe Y, Kitamori T. Accelerated protein digestion and separation with picoliter volume utilizing nanofluidics. LAB ON A CHIP 2022; 22:1162-1170. [PMID: 35133382 DOI: 10.1039/d1lc00923k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Single cell analyses can provide critical biological insight into cellular heterogeneity. In particular, the proteome, which governs cell functions, is much more difficult to analyze because it is principally impossible to amplify proteins compared to nucleic acids. The most promising approach to single cell proteomics is based on the liquid chromatography mass spectrometry (LC-MS) platform. However, pretreatments before MS detection have two critical issues for single cell analysis: analyte loss as a result of adsorption and artifacts due to the duration of analysis. This is a serious problem because single cells have a limited number of protein molecules and a small volume. To solve these issues, we developed an integrated nanofluidic device to manipulate samples on a femtoliter to picoliter (fL-pL) scale to achieve high-throughput analysis via suppressing analyte loss. This device can perform tryptic digestion, chromatographic separation, and non-labeled detection with high consistency. In addition, we introduced an open/close valve by physical deformation of glass on a nanometer scale to independently modify the nanochannel surfaces and control sample aliquots. The injection system equipped with this valve achieved an injection volume of 1.0 ± 0.1 pL. By using this integrated device, we found that the chromatogram of bulk-digestion for 12 hours resembled that of 15 min-digestion in the nanochannel, which indicated that these conditions reached a similar state of digestion. Therefore, an integrated device for ultra-fast protein analysis was developed on a 1 pL scale for the first time.
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Affiliation(s)
- Koki Yamamoto
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Kyojiro Morikawa
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
| | - Hisashi Shimizu
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
| | - Hiroki Sano
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
| | - Yutaka Kazoe
- Department of System Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Kanagawa 223-8522, Japan
| | - Takehiko Kitamori
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
- Collaborative Research Organization for Micro and Nano Multifunctional Devices, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Institute of Nanoengineering and Microsystems, Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan, Republic of China
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Morikawa K, Kazumi H, Tsuyama Y, Ohta R, Kitamori T. Surface Patterning of Closed Nanochannel Using VUV Light and Surface Evaluation by Streaming Current. MICROMACHINES 2021; 12:mi12111367. [PMID: 34832779 PMCID: PMC8623798 DOI: 10.3390/mi12111367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 11/16/2022]
Abstract
In nanofluidics, surface control is a critical technology because nanospaces are surface-governed spaces as a consequence of their extremely high surface-to-volume ratio. Various surface patterning methods have been developed, including patterning on an open substrate and patterning using a liquid modifier in microchannels. However, the surface patterning of a closed nanochannel is difficult. In addition, the surface evaluation of closed nanochannels is difficult because of a lack of appropriate experimental tools. In this study, we verified the surface patterning of a closed nanochannel by vacuum ultraviolet (VUV) light and evaluated the surface using streaming-current measurements. First, the C18 modification of closed nanochannels was confirmed by Laplace pressure measurements. In addition, no streaming-current signal was detected for the C18-modified surface, confirming the successful modification of the nanochannel surface with C18 groups. The C18 groups were subsequently decomposed by VUV light, and the nanochannel surface became hydrophilic because of the presence of silanol groups. In streaming-current measurements, the current signals increased in amplitude with increasing VUV light irradiation time, indicating the decomposition of the C18 groups on the closed nanochannel surfaces. Finally, hydrophilic/hydrophobic patterning by VUV light was performed in a nanochannel. Capillary filling experiments confirmed the presence of a hydrophilic/hydrophobic interface. Therefore, VUV patterning in a closed nanochannel was demonstrated, and the surface of a closed nanochannel was successfully evaluated using streaming-current measurements.
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Affiliation(s)
- Kyojiro Morikawa
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan; (H.K.); (R.O.)
- Correspondence: (K.M.); (T.K.)
| | - Haruki Kazumi
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan; (H.K.); (R.O.)
| | - Yoshiyuki Tsuyama
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan;
| | - Ryoichi Ohta
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan; (H.K.); (R.O.)
| | - Takehiko Kitamori
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan; (H.K.); (R.O.)
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Institute of Nanoengineering and Microsystems (iNEMS), Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan
- Correspondence: (K.M.); (T.K.)
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5
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Morikawa K, Ohta R, Mawatari K, Kitamori T. Metal-Free Fabrication of Fused Silica Extended Nanofluidic Channel to Remove Artifacts in Chemical Analysis. MICROMACHINES 2021; 12:mi12080917. [PMID: 34442539 PMCID: PMC8399996 DOI: 10.3390/mi12080917] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022]
Abstract
In microfluidics, especially in nanofluidics, nanochannels with functionalized surfaces have recently attracted attention for use as a new tool for the investigation of chemical reaction fields. Molecules handled in the reaction field can reach the single-molecule level due to the small size of the nanochannel. In such surroundings, contamination of the channel surface should be removed at the single-molecule level. In this study, it was assumed that metal materials could contaminate the nanochannels during the fabrication processes; therefore, we aimed to develop metal-free fabrication processes. Fused silica channels 1000 nm-deep were conventionally fabricated using a chromium mask. Instead of chromium, electron beam resists more than 1000 nm thick were used and the lithography conditions were optimized. From the results of optimization, channels with 1000 nm scale width and depth were fabricated on fused silica substrates without the use of a chromium mask. In nanofluidic experiments, an oxidation reaction was observed in a device fabricated by conventional fabrication processes using a chromium mask. It was found that Cr6+ remained on the channel surfaces and reacted with chemicals in the liquid phase in the extended nanochannels; this effect occurred at least to the micromolar level. In contrast, the device fabricated with metal-free processes was free of artifacts induced by the presence of chromium. The developed fabrication processes and results of this study will be a significant contribution to the fundamental technologies employed in the fields of microfluidics and nanofluidics.
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Affiliation(s)
- Kyojiro Morikawa
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Ryoichi Ohta
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Kazuma Mawatari
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Takehiko Kitamori
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Institute of Nanoengineering and Microsystems (iNEMS), Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
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Ouchi K, Tsukahara T, Brandt A, Muto Y, Nabatame N, Kitatsuji Y. Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium. ANAL SCI 2021; 37:1789-1794. [PMID: 34305053 DOI: 10.2116/analsci.21p110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We present a resin-packed microchannel that can reduce the radiation exposure risk and secondary radioactive wastes during uranium (U) separation by downscaling the separation using a microchip. Two types of microchips were designed to densely pack the microchannels with resins. The microchannels had almost the same cross-sectional area, but different outer circumferences. A satisfactory separation performance could be obtained by arranging more than ca. 10 resins along the depth and width of the microchannels. A resin-packed microchannel is an effective separation technique for determining the U concentration via inductively coupled plasma mass spectrometry owing to its ability to avoid the contamination of equipment by cesium, and to reduce the matrix effect. The size of the separation site was scaled down to <1/5000 compared to commonly used counterparts. The radiation exposure risk and secondary radioactive wastes can be reduced by 10- and 800-fold, respectively, using a resin-packed microchannel.
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Affiliation(s)
- Kazuki Ouchi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency
| | - Takehiko Tsukahara
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology
| | - Aileen Brandt
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology
| | - Yoshiki Muto
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology
| | - Nozomi Nabatame
- Graduate School of Science and Engineering, Ibaraki University
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Morikawa K, Kazoe Y, Takagi Y, Tsuyama Y, Pihosh Y, Tsukahara T, Kitamori T. Advanced Top-Down Fabrication for a Fused Silica Nanofluidic Device. MICROMACHINES 2020; 11:E995. [PMID: 33182488 PMCID: PMC7697862 DOI: 10.3390/mi11110995] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/29/2020] [Accepted: 10/29/2020] [Indexed: 02/07/2023]
Abstract
Nanofluidics have recently attracted significant attention with regard to the development of new functionalities and applications, and producing new functional devices utilizing nanofluidics will require the fabrication of nanochannels. Fused silica nanofluidic devices fabricated by top-down methods are a promising approach to realizing this goal. Our group previously demonstrated the analysis of a living single cell using such a device, incorporating nanochannels having different sizes (102-103 nm) and with branched and confluent structures and surface patterning. However, fabrication of geometrically-controlled nanochannels on the 101 nm size scale by top-down methods on a fused silica substrate, and the fabrication of micro-nano interfaces on a single substrate, remain challenging. In the present study, the smallest-ever square nanochannels (with a size of 50 nm) were fabricated on fused silica substrates by optimizing the electron beam exposure time, and the absence of channel breaks was confirmed by streaming current measurements. In addition, micro-nano interfaces between 103 nm nanochannels and 101 μm microchannels were fabricated on a single substrate by controlling the hydrophobicity of the nanochannel surfaces. A micro-nano interface for a single cell analysis device, in which a nanochannel was connected to a 101 μm single cell chamber, was also fabricated. These new fabrication procedures are expected to advance the basic technologies employed in the field of nanofluidics.
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Affiliation(s)
- Kyojiro Morikawa
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; (Y.K.); (Y.T.); (Y.P.)
| | - Yutaka Kazoe
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; (Y.K.); (Y.T.); (Y.P.)
| | - Yuto Takagi
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; (Y.K.); (Y.T.); (Y.P.)
| | - Yoshiyuki Tsuyama
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;
| | - Yuriy Pihosh
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; (Y.K.); (Y.T.); (Y.P.)
| | - Takehiko Tsukahara
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1-6, Ookayama, Meguro-ku, Tokyo 152-8550, Japan;
| | - Takehiko Kitamori
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; (Y.K.); (Y.T.); (Y.P.)
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;
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8
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Shoda K, Tanaka M, Mino K, Kazoe Y. A Simple Low-Temperature Glass Bonding Process with Surface Activation by Oxygen Plasma for Micro/Nanofluidic Devices. MICROMACHINES 2020; 11:E804. [PMID: 32854246 PMCID: PMC7570177 DOI: 10.3390/mi11090804] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/11/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022]
Abstract
The bonding of glass substrates is necessary when constructing micro/nanofluidic devices for sealing micro- and nanochannels. Recently, a low-temperature glass bonding method utilizing surface activation with plasma was developed to realize micro/nanofluidic devices for various applications, but it still has issues for general use. Here, we propose a simple process of low-temperature glass bonding utilizing typical facilities available in clean rooms and applied it to the fabrication of micro/nanofluidic devices made of different glasses. In the process, the substrate surface was activated with oxygen plasma, and the glass substrates were placed in contact in a class ISO 5 clean room. The pre-bonded substrates were heated for annealing. We found an optimal concentration of oxygen plasma and achieved a bonding energy of 0.33-0.48 J/m2 in fused-silica/fused-silica glass bonding. The process was applied to the bonding of fused-silica glass and borosilicate glass, which is generally used in optical microscopy, and revealed higher bonding energy than fused-silica/fused-silica glass bonding. An annealing temperature lower than 200 °C was necessary to avoid crack generation by thermal stress due to the different thermal properties of the glasses. A fabricated micro/nanofluidic device exhibited a pressure resistance higher than 600 kPa. This work will contribute to the advancement of micro/nanofluidics.
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Affiliation(s)
| | | | | | - Yutaka Kazoe
- Department of System Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Kanagawa 223-8522, Japan; (K.S.); (M.T.); (K.M.)
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Fujiwara S, Morikawa K, Endo T, Hisamoto H, Sueyoshi K. Size Sorting of Exosomes by Tuning the Thicknesses of the Electric Double Layers on a Micro-Nanofluidic Device. MICROMACHINES 2020; 11:mi11050458. [PMID: 32354140 PMCID: PMC7281254 DOI: 10.3390/mi11050458] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 12/25/2022]
Abstract
Exosomes, a type of extracellular vesicle with a diameter of 30–150 nm, perform key biological functions such as intercellular communication. Recently, size sorting of exosomes has received increasing attention in order to clarify the correlation between their size and components. However, such sorting remains extremely difficult. Here, we propose to sort their size by controlling their electrokinetic migration in nanochannels in a micro-nanofluidic device, which is achieved by tuning the thickness of the electric double layers in the nanochannels. This approach was demonstrated experimentally for exosomes smaller than 250 nm. Using different running buffer concentrations (1 × 10−3, 1 × 10−4, and 1 × 10−5 M), most of the exosomes larger than 140, 110, and 80 nm were successfully cut off at the downstream of the nanochannels, respectively. Therefore, it is clarified that the proposed method is applicable for the size sorting of exosomes.
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Affiliation(s)
- Satoko Fujiwara
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan; (S.F.); (T.E.); (H.H.)
| | - Kyojiro Morikawa
- Department of Applied Chemistry, School of Engineering, University of Tokyo, Tokyo 113-0033, Japan;
| | - Tatsuro Endo
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan; (S.F.); (T.E.); (H.H.)
| | - Hideaki Hisamoto
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan; (S.F.); (T.E.); (H.H.)
| | - Kenji Sueyoshi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan; (S.F.); (T.E.); (H.H.)
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Tokyo 102-8666, Japan
- Correspondence: ; Tel.: +81-72-254-9477
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Yamamoto K, Morikawa K, Imanaka H, Imamura K, Kitamori T. Picoliter enzyme reactor on a nanofluidic device exceeding the bulk reaction rate. Analyst 2020; 145:5801-5807. [DOI: 10.1039/d0an00998a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A picoliter enzyme reactor using a trypsin immobilized nanochannel realized 25 times faster reaction than the bulk reaction.
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Affiliation(s)
- Koki Yamamoto
- Department of Bioengineering
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Kyojiro Morikawa
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Hiroyuki Imanaka
- Division of Chemistry and Biochemistry
- Graduate School of Natural Science and Technology
- Okayama University
- Okayama 700-8530
- Japan
| | - Koreyoshi Imamura
- Division of Chemistry and Biochemistry
- Graduate School of Natural Science and Technology
- Okayama University
- Okayama 700-8530
- Japan
| | - Takehiko Kitamori
- Department of Bioengineering
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
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Kazoe Y, Pihosh Y, Takahashi H, Ohyama T, Sano H, Morikawa K, Mawatari K, Kitamori T. Femtoliter nanofluidic valve utilizing glass deformation. LAB ON A CHIP 2019; 19:1686-1694. [PMID: 30942790 DOI: 10.1039/c8lc01340c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the field of micro/nanofluidics, the channel open/close valves are among the most important technologies for switching and partitioning actions and integration of various operations into fluidic circuits. While several types of valves have been developed in microfluidics, few are capable in nanofluidics. In this study, we proposed a femtoliter (fL) volume nanochannel open/close valve fabricated in glass substrates. The valve consists of a shallow, circular and stepped-bottom valve chamber connected to nanochannels and an actuator. Even with tiny deformation occurring at the nanolevel in glass, an open/closed state of a nanochannel (10-1000 nm) can be achieved. We designed a fL-valve based on an analytical material deformation model, and developed a valve fabrication process. We then verified the open/closed state of the valve using a 308 fL-valve chamber with a four-stepped nanostructure fitting an arc-shape of deflected glass, confirmed its stability and durability over 50 open/close operations, and succeeded in stopping/flowing an aqueous solution at 209 fL s-1 under a 100 kPa pressure in a 900 nm nanochannel with a fast response of ∼0.65 s. A leak flow from the closed valve was sufficiently small even at a 490 kPa pressure-driven flow. Since the developed fL-valve can be applied to various nanofluidic devices made of glass and other rigid materials such as plastic, it is expected that this work will contribute significantly to the development of novel integrated micro/nanofluidics chemical systems for use in various applications, such as single cell/single molecule analysis.
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Affiliation(s)
- Yutaka Kazoe
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
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