Mitsuru Akashi

Osaka University, Suika, Ōsaka, Japan

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Publications (559)2055.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the present research was to study the thermal stability of ferulic acid after coupling onto chitosan, and the possibility of using ferulic acid-coupled chitosan (FA-CTS) as an antioxidant for biodegradable active packaging film. FA-CTS was incorporated into biodegradable film via a two-step process, i.e. compounding extrusion at temperatures up to 150°C followed by blown film extrusion at temperatures up to 175°C. Although incorporation of FA-CTS with a content of 0.02-0.16% (w/w) caused decreased water vapor barrier property and reduced extensibility, the biodegradable films possessed improved oxygen barrier property and antioxidant activity. Radical scavenging activity and reducing power of film containing FA-CTS were higher than those of film containing naked ferulic acid, by about 254% and 94%, respectively. Tensile strength and rigidity of the films were not significantly affected by the addition of FA-CTS with a content of 0.02-0.08% (w/w). The above results suggested that FA-CTS could potentially be used as an antioxidant for active packaging film. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Carbohydrate Polymers 01/2015; 115:744-51. · 3.92 Impact Factor
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    ABSTRACT: Although many rhodamine based fluorescence sensors were reported to detect metal ions with high sensitivity and selectivity, there are very few reports available to study the mechanisms of detection and the interaction between probe and metal ions. This paper aims to detect ferric ions by novel fluorescence chemosensors and study the mechanisms in detail. A novel probe AD-MAH-RhB was designed and synthesized from rhodamine B (RhB), adamantyl (AD), ethylene diamine and maleic anhydride (MAH). AD-MAH-RhB could detect Fe(3+) in aqueous solutions. The mechanism was explored by the HSAB principle, FTIR and mass spectra. The results suggested that Fe(3+) bound with amine and oxygen atoms in AD-MAH-RhB to form a complex composed of a 2 : 1 stoichiometry of Fe(3+) and the probe. Moreover, computational simulations were employed to further investigate the detection mechanism. The calculated results showed that Fe(3+) could conjugate with AD-MAH-RhB probe to form a stable complex, which was induced by synergetic effects of the suitable space and distance of van der Waals forces. However, Hg(2+) was found to disturb this detection and form a complex with 1 : 2 stoichiometry of Hg(2+) and AD-MAH-RhB. Then, another probe, β-cyclodextrin modified polymaleic anhydride (PMAH-CD) including AD-MAH-RhB (PMAH-CD/AD-MAH-RhB) was fabricated by inclusion interaction between CD and AD. PMAH-CD@AD-MAH-RhB showed high selectivity and sensitivity to Fe(3+) in the aqueous solution by eliminating the interruption of Hg(2+) possibly due to the high hydrogen interaction among the probes to inhibit the stable form complex with Hg(2+).
    The Analyst. 01/2015;
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    ABSTRACT: When bio-molecular recognition between nanofilms and proteins occurs on cell surfaces, rapid cellular assembly takes place. Cells coated with layer-by-layer nanofilms composed of fibronectin and heparin form aggregates after centrifugation and nanofilms induce attractive forces between cells through bio-molecular recognition between membrane proteins and heparin. Cell aggregates display network structures of cells as seen in colloidal gels with high viscosity. Cell—cell crosslinking allows for the construction of 3D-tissues with rich glycosaminoglycan. This cell—cell crosslinking process that uses a layer-by-layer technique has enormous potential for in vitro tissue applications in regenerative medicine and cell signaling assays.
    Macromolecular Bioscience 01/2015; · 3.65 Impact Factor
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    ABSTRACT: Caco-2, human colon carcinoma cell line, has been widely used as a model system for intestinal epithelial permeability because Caco-2 cells express tight-junctions, microvilli, and a number of enzymes and transporters characteristic of enterocytes. However, the functional differentiation and polarization of Caco-2 cells to express sufficient tight-junctions (a barrier) usually takes over 21 days in culture. This may be due to the cell culture environment, for example inflammation induced by plastic petri dishes. Three-dimensional (3D) sufficient cell microenvironments similar to in vivo natural conditions (proteins and cells), will promote rapid differentiation and higher functional expression of tight junctions. Herein we report for the first time an enhancement in tight-junction formation by 3D-cultures of Caco-2 cells on monolayered (1L) and eight layered (8L) normal human dermal fibroblasts (NHDF). Trans epithelial electric resistance (TEER) of Caco-2 cells was enhanced in the 3D-cultures, especially 8L-NHDF tissues, depending on culture times and only 10 days was enough to reach the same TEER value of Caco-2 monolayers after a 21 day incubation. Relative mRNA expression of tight-junction proteins of Caco-2 cells on 3D-cultures showed higher values than those in monolayer structures. Transporter gene expression patterns of Caco-2 cells on 3D-constructs were almost the same as those of Caco-2 monolayers, suggesting that there was no effect of 3D-cultures on transporter protein expression. The expression correlation between carboxylesterase 1 and 2 in 3D-cultures represented similar trends with human small intestines. The results of this study clearly represent a valuable application of 3D-Caco-2 tissues for pharmaceutical applications. Copyright © 2015. Published by Elsevier Inc.
    Biochemical and Biophysical Research Communications 01/2015; · 2.28 Impact Factor
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    ABSTRACT: Monolayers of endothelial cells (1L-ECs) have been generally used as in vitro vascular wall models to study the vascular mechanisms and transport of substances. However, these two-dimensional (2D-) system cannot represent the properties of native vascular wall which has 3D-structure and composed of not only ECs, but also smooth muscle cells (SMCs) and other surround tissues. Here in, five-layered (5L) 3D-arterial wall models (5L-AWMs) composed of EC monolayer and 4-layered SMCs were constructed by hierarchical cell manipulation. We applied the 5L-AWMs to evaluate their barrier function and permeability to nano-materials in order to analyze drug, or drug nanocarrier permeability to the blood vessel in vitro. Barrier property of the 3D-AWMs was confirm by Zonula occludens (ZO-1) staining and their transendothelial electrical resistance (TEER), which was comparable to 1L-ECs, while the SMCs showed close to zero. The effect of substance size to permeability across the 5L-AWMs was clearly observed from dextrans with various molecular weights, which agreed well with phenomena of the in vivo blood vessels. Importantly, transport of nano-materials could be observed across the depth of 5L-AWMs, suggesting the advantage of 3D-AWMs over general 2D-systems. By using this system, we evaluate the transport of 35 nm phenylalanine-modified poly(γ-Glutamic Acid) nanoparticles (γ-PGA-Phe NPs) as a candidate of biodegradable drug carrier. Interestingly, despite of having comparable size to dextran-2000k (28 nm), the γ-PGA-Phe NPs distinctly showed approximately 20 times faster transport across the 5L-AWMs, suggesting the effect of substance intrinsic properties to the transport. This in vitro evaluation system using the 3D-AWMs is therefore useful for the design and development of nano-drug carriers for treatment of vascular diseases, such as atherosclerosis. Copyright © 2014. Published by Elsevier Inc.
    Biochemical and Biophysical Research Communications 12/2014; · 2.28 Impact Factor
  • Hiroharu Ajiro, Kazuya Takemura, Mitsuru Akashi
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    ABSTRACT: The surface polyion complex gel (sPIC gel), which possesses chemically bonded nonionic gel moiety, was designed using N-vinylacetamide (NVA), N-vinylforamide (NVF), and vinyl phosphonic acid (VPA). Taking advantage of the property of NVF as vinylamine (VAm) precursor, the cationic moiety was introduced only onto the surface of poly(NVA-co-NVF), producing surface hydrolyzed poly(NVA-co-NVF-co-VAm), and the successive polymerization of VPA inside the gel successfully produced sPIC gel. The swelling ratio of the sPIC gel was investigated under various pH conditions, and compared with that of the fully polyion complex gel (PIC gel), using totally hydrolyzed poly(NVA-co-VAm). The swelling ratio of sPIC gel ranged between 14 and 25, while that of the PIC gel ranged between 2 and 5. The anionic compound, AR, showed a sustained release from sPIC gel at pH 2, due to the electrostatic interactions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014
    Journal of Polymer Science Part A Polymer Chemistry 12/2014; · 3.54 Impact Factor
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    ABSTRACT: We described an assembly technique and perfusion culture system for constructing artery tissue models. This technique differed from previous studies in that it does not require a solid biodegradable scaffold; therefore, using sheet-like tissues, this technique allowed the facile fabrication of tubular tissues can be used as model. The fabricated artery tissue models had a multilayer structure. The assembly technique and perfusion culture system were applicable to many different sizes of fabricated arteries. The shape of the fabricated artery tissue models was maintained by the perfusion culture system; furthermore, the system reproduced the in vivo environment and allowed mechanical stimulation of the arteries. The multilayer structure of the artery tissue model was observed using fluorescent dyes. The equivalent Young's modulus was measured by applying internal pressure to the multilayer tubular tissues. The aim of this study was to determine whether fabricated artery tissue models maintained their mechanical properties with developing. We demonstrated both the rapid fabrication of multilayer tubular tissues that can be used as model arteries and the measurement of their equivalent Young's modulus in a suitable perfusion culture environment.
    Biomicrofluidics 11/2014; 8(6):064113. · 3.77 Impact Factor
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    ABSTRACT: We found that cyclodextrins (CDs) have a high solubility in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Evaporating HFIP from CD solutions on a glass plate prepared crystalline solids composed of channel-type CD assemblies, and electrospinning with an HFIP solution of CDs fabricated CD microfibers.
    Chemical Communications 09/2014; · 6.38 Impact Factor
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    ABSTRACT: Conclusion: Amphiphilic biodegradable nanoparticles (NPs) composed of poly(γ-glutamic acid) conjugated with L-phenylalanine ethylester (γ-PGA-Phe NPs) applied on the rat middle ear mucosa produce an inflammatory type 1 response. The observation is of relevance for the use of γ-PGA-Phe NPs as a concomitant antigen delivery system and adjuvant measure in the context of vaccinations. Objectives: To examine effects of topical mucosal administration of γ-PGA-Phe NPs as a potentially combined antigen delivery system and adjuvant. Methods: γ-PGA-Phe NPs were administered on rat middle ear mucosa in a sham-controlled design and the response was monitored, focusing on soluble markers in mucosal surface liquids and on overall histopathology. Results: γ-PGA-Phe NPs produced a dose- and time-dependent inflammatory response characterized by generation of proinflammatory cytokines (IL-1α, IL-1β, IL-6, MIP-1α, and TNF-α) and associated histopathological changes.
    Acta Oto-Laryngologica 09/2014; 134(10). · 0.99 Impact Factor
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    Chunyen Liu, Michiya Matsusaki, Mitsuru Akashi
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    ABSTRACT: Type I collagen fibers were coated onto single cell surfaces by capitalizing on the formation of collagen microfibers at a neutral pH and exploiting cell membrane interactions between collagen fibers and integrin receptors. Collagen fibers coat thicknesses were controllable from 3 to 30 μm. Multi-layered tissues with controllable thicknesses and cell densities were successfully constructed depending on the thickness of micrometer-sized collagen matrices.
    RSC Advances 09/2014; · 3.71 Impact Factor
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    Biochemical and Biophysical Research Communications 08/2014; 451(1):107–111. · 2.28 Impact Factor
  • Hiroharu Ajiro, Tatsuaki Ueyama, Mitsuru Akashi
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    ABSTRACT: The radical polymerization of methacrylic acid (MAA) at 0, 20, 40, and 70 °C was achieved in porous isotactic (it-) poly(methyl methacrylate) (PMMA) films on quartz crystal microbalance (QCM) substrates, which were prepared by layer-by-layer assembled stereocomplex films of it-PMMA and syndiotactic (st-) poly(methacrylic acid) (PMAA), followed by the subsequent extraction of st-PMAA. The MAA polymerization yields increased from 35 to 75%, as the polymerization temperature increased from 0 to 70 °C. Furthermore, infrared spectroscopy revealed that a higher polymerization temperature is necessary to form it-PMMA/st-PMAA stereocomplexes via stereoregular polymerization manner that resemble native it-PMMA/st-PMAA stereocomplexes. X-ray diffraction pattern of porous it-PMMA were also investigated for reaction fields. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014
    Journal of Polymer Science Part A Polymer Chemistry 08/2014; · 3.54 Impact Factor
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    ABSTRACT: Three-dimensional (3D) hepatocyte cultures have attracted much attention to obtain high biological functions of hepatocyte for pharmaceutical drug assessment. However, maintaining the high functions for over one month is still a key challenge although many approaches have been reported. In this study, we demonstrate for the first time simple and rapid construction of 3D-hepatocyte constructs by our cell accumulation technique and their high biological functions for one month, without any medium change. The human hepatocyte carcinoma (HepG2) cells were coated with approximately 7 nm-sized extracellular matrix (ECM) films consisting of fibronectin (FN) and gelatin (G), and then incubated in cell culture insert to construct 3D-tissue constructs for 24 hours. The thickness of obtained 3D-HepG2 constructs was easily controlled by altering seeding cell number and the maximum is over 100 μm. When a large volume of culture media was employed, the 3D-constructs showed higher mRNA expression of albumin and some cytochrome P450 (CYP) enzymes as compared to general two-dimensional (2D) culture. Surprisingly, their high cell viabilities (over 80%) and high mRNA expressions were successfully maintained without medium change for at least 27 days. These results demonstrate novel easy and rapid technique to construct 3D-human liver tissue models which can maintain their high functions and viability for 1 month without medium change.
    Journal of Biomedical Materials Research Part A 08/2014; · 2.83 Impact Factor
  • Polymer 08/2014; 55(16):3591–3598. · 3.77 Impact Factor
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    ABSTRACT: Creation of superhydrophobic materials bio-inspired by nature fascinates many scientists. One of the most intriguing challenges in this field is the fabrication of these materials using biopolymers from the viewpoint of green chemistry and environmental chemistry. Here, superhydrophobic and biodegradable nonwovens are constructed by electrospinning from a naturally occurring poly(amino acid), poly(γ-glutamic acid) (γ-PGA), modified with a hydrophobic α-amino acid, l-phenylalanine. The contact angle of a water droplet on the materials is 154°, and the droplet remains stuck to the material surface even if it is inverted, clearly indicating a petal-type superhydrophobic property. Biodegradability and post-functionalization of the nonwovens as well as cell adhesion on the superhydrophobic materials are also evaluated. As far as we know, this is the first report on biodegradable materials exhibiting a petal-type superhydrophobicity. The material design and processing shown here can be applied to various bioresources and such functional materials will become a new class of functional materials satisfying some of the requirements in green science.
    Advanced Functional Materials 08/2014; · 10.44 Impact Factor
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    ABSTRACT: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered-integrin bindings link cells mechanically to the ECM. In order to quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin-substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types.
    Biochemical and Biophysical Research Communications 07/2014; · 2.28 Impact Factor
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    ABSTRACT: Oil gels made of low-toxic components were prepared using chemically cross-linked copolymer, which was composed of poly(trimethylene carbonate) derivative and poly(L-lactide). The poly(L-lactide) moiety in gels could form stereocomplexes with poly(D-lactide).
    RSC Advances 07/2014; · 3.71 Impact Factor
  • Fumiaki Shima, Takami Akagi, Mitsuru Akashi
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    ABSTRACT: For the development of safe and effective next-generation vaccine carriers, their physicochemical properties (size, shape, surface charge, and hydrophobic/hydrophilic balance) are crucial to control their interactions (cellular uptake, intracellular degradability of the loaded antigen, and intracellular localization) with immune cells. Recently, the hydrophobicity of carriers affected the cellular uptake and immune response, which demonstrated that hydrophobicity is one of the most important factors to control the behaviors of the loaded antigens and carriers. In this study, we investigated the effect of the hydrophobicity of nanoparticles (NPs) composed of amphiphilic poly(γ-glutamic acid)-graft-phenylalanine ethyl ester (γ-PGA-Phe) with various grafting degrees of hydrophobic side chains on cellular uptake of the encapsulated antigens, their degradability, and their release behavior in the endosomal environment. These NPs could encapsulate proteins, and the degradability of the encapsulated proteins was changed by the hydrophobicity of NPs. On the other hand, the release behavior of the encapsulated proteins was not changed by the hydrophobicity of NPs. These results suggest that the intracellular behaviors of the encapsulated protein could be controlled by the hydrophobicity of NPs, and could result in the manipulation of the antigen-specific immune responses.
    Biomater. Sci. 07/2014;
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    ABSTRACT: Objective: A novel 3D porous hyaluronic acid-hydroxyapatite (HA-Hap) scaffold has been developed. The aim of this study was to investigate the potential of using this novel scaffold for bone tissue engineering in vitro and in vivo. Method: Human dental pulp stromal cells (HDPSCs) were isolated from wisdom teeth. The cells were expanded in vitro and seeded statically onto sterile porous HA-Hap and poly L-lactic acid (PLLA, control) scaffolds. The cell-scaffold constructs were cultured in basal and osteogenic medium in vitro for up to 8 weeks. Live/dead fluorescent markers were used to check the cell viability. Confocal, SEM and histology were used for monitoring the cells attachment, growth and osteogenic differentiation on the scaffolds. For in vivostudy, the cells-scaffold constructs were sealed within diffusion chamber, which were implanted peritoneally in MF1 Nu/Nu mice for 8 weeks. The samples were assessed by histology and immunohistochemistry. Result: Confocal and SEM images showed that HA-Hap porous scaffold has highly inter-connectivity and supported HDPSCs attachment and in-growth. The majority of the cells remained viable on the scaffolds after 8 weeks in vitro. The cells maintained osteogenic phenotype and produced extracellular matrix through out the scaffolds, which were confirmed by histological staining of H/E, Alcian blue/Sirus Red, Von kossa and Type I collagen immunohistochemical assay. After 8 weeks of in vivoimplantation, new tissues were formed by HDPSCs on/within the HA-Hap scaffolds. Alcian blue/Sirus Red staining confirmed acid mucosubstances and collagen matrix formation. Type I collagen immunohistochemical staining indicated that the matrix were mainly Type I collagen. Von kossa staining showed mineralized bone nodules formation within the collagen matrix. Conclusion: This study shows that the HA-Hap scaffold is biocompatible and can support HDPSCs growth and bone matrix formation which indicates that this scaffold could be used as potential bone substitute for bone tissue repair/regeneration.
    IADR General Session and Exhibition 2014; 06/2014
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    ABSTRACT: 179 countries (parties) ratified the Stockholm Convention on Persistent Organic Pollutants (POPs), and agreed to destroy polychlorobiphenyls (PCBs) and develop a sound management plan by 2028. Currently still 3 million tons of PCB-contaminated oil and equipment need to be managed under the Convention. Thus, the development of a facile and environmentally benign method to treat large amounts of oil stockpiles contaminated with PCBs is a crucial subject. Herein we report that cyclodextrin (CD) polymers, which are easily prepared by crosslinking the renewable cyclic oligosaccharide γ-cyclodextrin (γ-CD) with dibasic acid dichlorides, are a new selective and powerful adsorbent to remove PCBs contaminants in oil. When PCB (100 ppm)-contaminated oil was passed through a column packed with the terephthaloyl-crosslinked γ-CD polymer (TP-γ-CD polymer) at 80-110 °C, the PCB contaminants were completely removed from the oil. Additionally, methyl esterification of the free carboxylic groups of the TP-γ-CD polymer enabled the complete recovery of the PCBs adsorbed on the polymer (with >99.9% recovery efficiency) by simply washing with acetone. The methyl-esterified TP-γ-CD polymer could be recycled at least ten times for PCB adsorption without any loss in the adsorption capability. These results revealed that the γ-CD polymers can function as highly effective and powerful adsorbents for the removal and recovery of PCBs from PCB-contaminated oil and thus, significantly contribute to the protection of the global environment.
    Environmental Science and Technology 06/2014; · 5.48 Impact Factor

Publication Stats

6k Citations
2,055.82 Total Impact Points

Institutions

  • 2003–2014
    • Osaka University
      • • Division of Applied Chemistry
      • • School of Pharmaceutical Sciences
      • • Division of Molecular Biology and Biochemistry
      • • Division of Biochemistry
      Suika, Ōsaka, Japan
  • 2013
    • University of Leeds
      Leeds, England, United Kingdom
  • 2008–2012
    • Setsunan University
      • Faculty of Pharmaceutical Sciences
      Ōsaka-shi, Osaka-fu, Japan
  • 2007–2011
    • National Institute of Biomedical Innovation
      • Laboratory of Virology and Vaccinology
      Ibaraki, Osaka-fu, Japan
  • 2005–2011
    • Japan Science and Technology Agency (JST)
      Edo, Tōkyō, Japan
    • The University of Tokyo
      • Research Center for Advanced Science and Technology
      Tokyo, Tokyo-to, Japan
    • Yangtze University
      Hu-pei-ts’un, Shanxi Sheng, China
    • Kyoto Institute of Technology
      Kioto, Kyōto, Japan
    • Osaka Institute of Technology
      • Department of Applied Chemistry
      Ōsaka, Ōsaka, Japan
  • 1984–2011
    • Kagoshima University
      • • Graduate School of Medical and Dental Sciences
      • • Graduate School of Science and Engineering
      • • Faculty of Engineering
      • • Division of Human Retroviruses
      Kagoshima-shi, Kagoshima-ken, Japan
  • 2010
    • Kyoto University
      • Institute for Virus Research
      Kyoto, Kyoto-fu, Japan
  • 2009
    • Jiangnan University
      • School of Chemical and Material Engineering
      Wuxi, Jiangsu Sheng, China
    • Kasetsart University
      Krung Thep, Bangkok, Thailand
  • 2006–2007
    • Nanjing Normal University
      • College of Chemistry and Environmental Science
      Hsin-ching, Jilin Sheng, China
  • 2003–2006
    • Chulalongkorn University
      Krung Thep, Bangkok, Thailand
  • 2001
    • Bangkok University
      Krung Thep, Bangkok, Thailand
  • 1999
    • National Institute for Agro-Environmental Sciences in Japan
      Tsukuba, Ibaraki, Japan
  • 1998
    • The University of Tokushima
      • Department of Medicinal Biochemistry
      Tokusima, Tokushima, Japan
  • 1997
    • Slovak Academy of Sciences
      • Polymer Institute
      Presburg, Bratislavský, Slovakia
  • 1991
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan