Frontiers in Micromachines in Japan

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "C:Chemistry".

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 14973

Special Issue Editors

Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology (TUAT), 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588, Japan
Interests: nanopore; lipid bilayer; microfabrication; electrochemistry; molecular robotics; DNA computing
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Graduate School of Engineering, Tohoku University, 6-6-11 Aramaki-aza Aoba, Aoba-ku, Sendai 980-8579, Japan
Interests: cell analysis; electrochemical devices; bioMEMS/NEMS; organs on a chip; cell culture platforms; micro/nanochemistry
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Department of Physics and Electronics, Osaka Prefecture University, Room A4-07, B5 building, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
Interests: 2D material; FET; opt-electronics; molecular-inorganic device
Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Bldg. 25, Room 202, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
Interests: bioMEMS; microfluidics; tissue engineering; hydrogel; microrobot; self-assembly
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School of Computing, Tokyo Institute of Technology, Tokyo 152-8550, Japan
Interests: biophysics; nonlinear; non-equilibrium science; microfluidics; molecular computing/molecular robotics
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Special Issue Information

Dear Colleagues,

This Special Issue aims to publish the current trends and research results of outstanding and promising young Japanese investigators working on micromachines. The Special Issue welcomes reviews, original research articles, and communications in the field of micromachines, and provides young investigators from universities and research institutions in Japan an opportunity to present their latest research results. The "Excellent Papers Award"*, selected by the award committee, which is organized by the editorial office of Micromachines and the guest editors, will be granted to an excellent paper published in this Special Issue.

The contributions to this Special Issue will highlight the current frontiers in the extensive fields of micro-/nano-sciences, devices, and applications.

We are looking forward to receiving your submissions!

*This will be awarded to a paper that the first or the corresponding author is a young researcher whose Ph. D. degree is obtained within 15 years. This award will provide two free vouchers for MDPI journal publications.

Prof. Dr. Ryuji Kawano
Prof. Dr. Kosuke Ino
Prof. Dr. Masahiro Takinoue
Prof. Dr. Daisuke Kiriya
Prof. Dr. Hiroaki Onoe
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • MicroTAS
  • MEMS
  • Electrochemistry
  • Electrical engineering
  • Optics
  • Microrobot
  • Liposome
  • DNA nanotechnology
  • Nanopore
  • Lipid bilayer
  • 2D material
  • Gel

Published Papers (5 papers)

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Research

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11 pages, 3350 KiB  
Article
Electrochemical Glue for Binding Chitosan–Alginate Hydrogel Fibers for Cell Culture
by Yoshinobu Utagawa, Kosuke Ino, Tatsuki Kumagai, Kaoru Hiramoto, Masahiro Takinoue, Yuji Nashimoto and Hitoshi Shiku
Micromachines 2022, 13(3), 420; https://doi.org/10.3390/mi13030420 - 08 Mar 2022
Cited by 5 | Viewed by 3296
Abstract
Three-dimensional organs and tissues can be constructed using hydrogels as support matrices for cells. For the assembly of these gels, chemical and physical reactions that induce gluing should be induced locally in target areas without causing cell damage. Herein, we present a novel [...] Read more.
Three-dimensional organs and tissues can be constructed using hydrogels as support matrices for cells. For the assembly of these gels, chemical and physical reactions that induce gluing should be induced locally in target areas without causing cell damage. Herein, we present a novel electrochemical strategy for gluing hydrogel fibers. In this strategy, a microelectrode electrochemically generated HClO or Ca2+, and these chemicals were used to crosslink chitosan–alginate fibers fabricated using interfacial polyelectrolyte complexation. Further, human umbilical vein endothelial cells were incorporated into the fibers, and two such fibers were glued together to construct “+”-shaped hydrogels. After gluing, the hydrogels were embedded in Matrigel and cultured for several days. The cells spread and proliferated along the fibers, indicating that the electrochemical glue was not toxic toward the cells. This is the first report on the use of electrochemical glue for the assembly of hydrogel pieces containing cells. Based on our results, the electrochemical gluing method has promising applications in tissue engineering and the development of organs on a chip. Full article
(This article belongs to the Special Issue Frontiers in Micromachines in Japan)
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14 pages, 4521 KiB  
Article
3D Culture Platform for Enabling Large-Scale Imaging and Control of Cell Distribution into Complex Shapes by Combining 3D Printing with a Cube Device
by Atsushi Takano, Isabel Koh and Masaya Hagiwara
Micromachines 2022, 13(2), 156; https://doi.org/10.3390/mi13020156 - 21 Jan 2022
Cited by 4 | Viewed by 3482
Abstract
While organoid differentiation protocols have been widely developed, local control of initial cell seeding position and imaging of large-scale organoid samples with high resolution remain challenging. 3D bioprinting is an effective method to achieve control of cell positioning, but existing methods mainly rely [...] Read more.
While organoid differentiation protocols have been widely developed, local control of initial cell seeding position and imaging of large-scale organoid samples with high resolution remain challenging. 3D bioprinting is an effective method to achieve control of cell positioning, but existing methods mainly rely on the use of synthetic hydrogels that could compromise the native morphogenesis of organoids. To address this problem, we developed a 3D culture platform that combines 3D printing with a cube device to enable an unrestricted range of designs to be formed in biological hydrogels. We demonstrated the formation of channels in collagen hydrogel in the cube device via a molding process using a 3D-printed water-soluble mold. The mold is first placed in uncured hydrogel solution, then easily removed by immersion in water after the gel around it has cured, thus creating a mold-shaped gap in the hydrogel. At the same time, the difficulty in obtaining high-resolution imaging on a large scale can also be solved as the cube device allows us to scan the tissue sample from multiple directions, so that the imaging quality can be enhanced without having to rely on higher-end microscopes. Using this developed technology, we demonstrated (1) mimicking vascular structure by seeding HUVEC on the inner walls of helix-shaped channels in collagen gels, and (2) multi-directional imaging of the vascular structure in the cube device. Thus, this paper describes a concerted method that simultaneously allows for the precise control of cell positioning in hydrogels for organoid morphogenesis, and the imaging of large-sized organoid samples. It is expected that the platform developed here can lead to advancements in organoid technology to generate organoids with more sophisticated structures. Full article
(This article belongs to the Special Issue Frontiers in Micromachines in Japan)
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9 pages, 1573 KiB  
Article
Ion Conductance-Based Perfusability Assay of Vascular Vessel Models in Microfluidic Devices
by Rise Akasaka, Masashi Ozawa, Yuji Nashimoto, Kosuke Ino and Hitoshi Shiku
Micromachines 2021, 12(12), 1491; https://doi.org/10.3390/mi12121491 - 30 Nov 2021
Cited by 2 | Viewed by 1928
Abstract
We present a novel methodology based on ion conductance to evaluate the perfusability of vascular vessels in microfluidic devices without microscopic imaging. The devices consisted of five channels, with the center channel filled with fibrin/collagen gel containing human umbilical vein endothelial cells (HUVECs). [...] Read more.
We present a novel methodology based on ion conductance to evaluate the perfusability of vascular vessels in microfluidic devices without microscopic imaging. The devices consisted of five channels, with the center channel filled with fibrin/collagen gel containing human umbilical vein endothelial cells (HUVECs). Fibroblasts were cultured in the other channels to improve the vascular network formation. To form vessel structures bridging the center channel, HUVEC monolayers were prepared on both side walls of the gel. During the culture, the HUVECs migrated from the monolayer and connected to the HUVECs in the gel, and vascular vessels formed, resulting in successful perfusion between the channels after culturing for 3–5 d. To evaluate perfusion without microscopic imaging, Ag/AgCl wires were inserted into the channels, and ion currents were obtained to measure the ion conductance between the channels separated by the HUVEC monolayers. As the HUVEC monolayers blocked the ion current flow, the ion currents were low before vessel formation. In contrast, ion currents increased after vessel formation because of creation of ion current paths. Thus, the observed ion currents were correlated with the perfusability of the vessels, indicating that they can be used as indicators of perfusion during vessel formation in microfluidic devices. The developed methodology will be used for drug screening using organs-on-a-chip containing vascular vessels. Full article
(This article belongs to the Special Issue Frontiers in Micromachines in Japan)
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11 pages, 1300 KiB  
Article
Simple Fabrication of Solid-State Nanopores on a Carbon Film
by Natsumi Takai, Kan Shoji, Tei Maki and Ryuji Kawano
Micromachines 2021, 12(9), 1135; https://doi.org/10.3390/mi12091135 - 21 Sep 2021
Cited by 4 | Viewed by 2486
Abstract
Solid-state nanopores are widely used as a platform for stochastic nanopore sensing because they can provide better robustness, controllable pore size, and higher integrability than biological nanopores. However, the fabrication procedures, including thin film preparation and nanopore formation, require advanced micro-and nano-fabrication techniques. [...] Read more.
Solid-state nanopores are widely used as a platform for stochastic nanopore sensing because they can provide better robustness, controllable pore size, and higher integrability than biological nanopores. However, the fabrication procedures, including thin film preparation and nanopore formation, require advanced micro-and nano-fabrication techniques. Here, we describe the simple fabrication of solid-state nanopores in a commercially available material: a flat thin carbon film-coated micro-grid for a transmission electron microscope (TEM). We attempted two general methods for nanopore fabrication in the carbon film. The first method was a scanning TEM (STEM) electron beam method. Nanopores were fabricated by irradiating a focused electron beam on the carbon membrane on micro-grids, resulting in the production of nanopores with pore diameters ranging from 2 to 135 nm. The second attempt was a dielectric breakdown method. In this method, nanopores were fabricated by applying a transmembrane voltage of 10 or 30 V through the carbon film on micro-grids. As a result, nanopores with pore diameters ranging from 3.7 to 1345 nm were obtained. Since these nanopores were successfully fabricated in the commercially available carbon thin film using readily available devices, we believe that these solid-state nanopores offer great utility in the field of nanopore research. Full article
(This article belongs to the Special Issue Frontiers in Micromachines in Japan)
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Review

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13 pages, 1602 KiB  
Review
Identifying and Manipulating Giant Vesicles: Review of Recent Approaches
by Taro Toyota and Yiting Zhang
Micromachines 2022, 13(5), 644; https://doi.org/10.3390/mi13050644 - 19 Apr 2022
Cited by 5 | Viewed by 2364
Abstract
Giant vesicles (GVs) are closed bilayer membranes that primarily comprise amphiphiles with diameters of more than 1 μm. Compared with regular vesicles (several tens of nanometers in size), GVs are of greater scientific interest as model cell membranes and protocells because of their [...] Read more.
Giant vesicles (GVs) are closed bilayer membranes that primarily comprise amphiphiles with diameters of more than 1 μm. Compared with regular vesicles (several tens of nanometers in size), GVs are of greater scientific interest as model cell membranes and protocells because of their structure and size, which are similar to those of biological systems. Biopolymers and nano-/microparticles can be encapsulated in GVs at high concentrations, and their application as artificial cell bodies has piqued interest. It is essential to develop methods for investigating and manipulating the properties of GVs toward engineering applications. In this review, we discuss current improvements in microscopy, micromanipulation, and microfabrication technologies for progress in GV identification and engineering tools. Combined with the advancement of GV preparation technologies, these technological advancements can aid the development of artificial cell systems such as alternative tissues and GV-based chemical signal processing systems. Full article
(This article belongs to the Special Issue Frontiers in Micromachines in Japan)
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