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Morikawa K, Takeuchi T, Kitamori T. Local nano-electrode fabrication utilizing nanofluidic and nano-electrochemical control. Electrophoresis 2024. [PMID: 38962855 DOI: 10.1002/elps.202300002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 05/23/2024] [Accepted: 06/19/2024] [Indexed: 07/05/2024]
Abstract
Miniaturized systems have attracted much attention with the recent advances in microfluidics and nanofluidics. From the capillary electrophoresis, the development of glass-based microfluidic and nanofluidic technologies has supported advances in microfluidics and nanofluidics. Most microfluidic systems, especially nanofluidic systems, are still simple, such as systems constructed with simple straight nanochannels and bulk-scale electrodes. One of the bottlenecks to the development of more complicated and sophisticated systems is to develop the locally integrated nano-electrodes. However, there are still issues with integrating nano-electrodes into nanofluidic devices because it is difficult to fit the nano-electrode size into a nanofluidic channel at the nanometer level. In this study, we propose a new method for the fabrication of local nano-electrodes in nanofluidic devices with nanofluidic and nano-electrochemistry-based experiments. An electroplating solution was introduced to a nanochannel with control of the flow and the electroplating reaction, by which nano-electrodes were successfully fabricated. In addition, a nanofluidic device was available for nanofluidic experiments with the application of 200 kPa. This method can be applied to any electroplating material such as gold and copper. The local nano-electrode will make a significant contribution to the development of more complicated and sophisticated nanofluidic electrophoresis systems and to local electric detection methods for various nanofluidic devices.
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Affiliation(s)
- Kyojiro Morikawa
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Tomoaki Takeuchi
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Takehiko Kitamori
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan
- Institute of Nanoengineering and Microsystems, Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan
- Collaborative Research Organization for Micro and Nano Multifunctional Devices, The University of Tokyo, Tokyo, Japan
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Bakhtiari N, Ihlemann J. Fabrication of fluidic submicron-channels by pulsed laser-induced buckling of SiO x films on fused silica. DISCOVER NANO 2024; 19:46. [PMID: 38485854 PMCID: PMC10940550 DOI: 10.1186/s11671-024-03987-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
Recently, considerable attention has been drawn to the field of micro/nanofluidic channels. However, current methods for fabricating micro/nanochannels are complex, costly, and time-intensive. In the present work, we successfully fabricated transparent submicron-channels on fused silica substrates (SiO2) using a straightforward laser process. To achieve this, a single-pulse excimer laser irradiation in a rear side configuration was employed to treat a thin film of UV-absorbing silicon suboxide (SiOx) through the transparent SiO2 substrate. A polydimethylsiloxane (PDMS) superstrate (coating layer) was applied over the SiOx film before laser exposure, serving as a confinement for controlled structure formation induced by the laser. Under optimal laser fluence, the thin SiOx film buckled, leading to the formation of channels with a width ranging from 10 to 20 µm and a height of 800 to 1200 nm, exhibiting a bell-like cross-sections following the so-called Euler buckling mode. Wider channels displayed morphologies resembling varicose or telephone cord modes. Subsequent high-temperature annealing led to the oxidation of SiOx, resulting transparent SiO2 channels on the fused silica substrate. The manufactured nanochannels exhibited promising potential for effectively transporting fluids of diverse viscosities. Various fluids were conveyed through these nanochannels via capillary action and in accordance with the Lucas-Washburn equation.
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Affiliation(s)
- Nastaran Bakhtiari
- Institut für Nanophotonik Göttingen e.V., Hans-Adolf-Krebs-Weg 1, 37077, Göttingen, Germany.
| | - Jürgen Ihlemann
- Institut für Nanophotonik Göttingen e.V., Hans-Adolf-Krebs-Weg 1, 37077, Göttingen, Germany
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Weise C, Westphal H, Warias R, Belder D. High-temperature ultrafast ChipHPLC-MS. Anal Bioanal Chem 2024; 416:1023-1031. [PMID: 38112789 PMCID: PMC10800301 DOI: 10.1007/s00216-023-05092-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/21/2023]
Abstract
Herein, we present a miniaturized chip-based HPLC approach coupled to electrospray ionization mass spectrometry utilizing temperature to achieve high-speed separations. The approach benefits from the low thermal mass of the microfluidic chip and can form an electrospray from the pre-heated mobile phase. With the help of this technology, isothermal and temperature-programmable operations up to 130°C were pursued to perform reversed-phase separations of pesticides in methanol and ethanol-containing eluents in less than 20 s.
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Affiliation(s)
- Chris Weise
- Institute of Analytical Chemistry, University Leipzig, Linnéstrasse 3, 04103, Leipzig, Germany
| | - Hannes Westphal
- Institute of Analytical Chemistry, University Leipzig, Linnéstrasse 3, 04103, Leipzig, Germany
| | - Rico Warias
- Institute of Analytical Chemistry, University Leipzig, Linnéstrasse 3, 04103, Leipzig, Germany
| | - Detlev Belder
- Institute of Analytical Chemistry, University Leipzig, Linnéstrasse 3, 04103, Leipzig, Germany.
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Sasaki S, Suzuki T, Morikawa K, Matsusaki M, Sato K. Fabrication of a Gelatin-Based Microdevice for Vascular Cell Culture. MICROMACHINES 2022; 14:107. [PMID: 36677169 PMCID: PMC9860854 DOI: 10.3390/mi14010107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
This study presents a novel technique for fabricating microfluidic devices with microbial transglutaminase-gelatin gels instead of polydimethylsiloxane (PDMS), in which flow culture simulates blood flow and a capillary network is incorporated for assays of vascular permeability or angiogenesis. We developed a gelatin-based device with a coverslip as the bottom, which allows the use of high-magnification lenses with short working distances, and we observed the differences in cell dynamics on gelatin, glass, and PDMS surfaces. The tubes of the gelatin microfluidic channel are designed to be difficult to pull out of the inlet hole, making sample introduction easy, and the gelatin channel can be manipulated from the cell introduction to the flow culture steps in a manner comparable to that of a typical PDMS channel. Human umbilical vein endothelial cells (HUVECs) and normal human dermal fibroblasts (NHDFs) were successfully co-cultured, resulting in structures that mimicked blood vessels with inner diameters ranging from 10 µm to 500 µm. Immunostaining and scanning electron microscopy results showed that the affinity of fibronectin for gelatin was stronger than that for glass or PDMS, making gelatin a suitable substrate for cell adhesion. The ability for microscopic observation at high magnification and the ease of sample introduction make this device easier to use than conventional gelatin microfluidics, and the above-mentioned small modifications in the device structure are important points that improve its convenience as a cell assay device.
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Affiliation(s)
- Satoko Sasaki
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo, Tokyo 112-8681, Japan
| | - Tomoko Suzuki
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo, Tokyo 112-8681, Japan
| | - Kyojiro Morikawa
- Institute of Nanoengineering and Microsystems, Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 300044, Taiwan
- Collaborative Research Organization for Micro and Nano Multifunctional Devices, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Michiya Matsusaki
- Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kae Sato
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo, Tokyo 112-8681, Japan
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Chantipmanee N, Xu Y. Nanofluidics for chemical and biological dynamics in solution at the single molecular level. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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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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