Mitsuru Akashi

Osaka University, Suika, Ōsaka, Japan

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Publications (599)2199.38 Total impact

  • Hiroharu Ajiro · Ayaka Kuroda · Kai Kan · Mitsuru Akashi
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    ABSTRACT: The stereocomplex formation of poly(L,L-lactide) (PLLA) and poly(D,D-lactide) (PDLA) using an inkjet system was expanded to the amphiphilic copolymers, using poly(ethylene glycol) (PEG) as hydrophilic polymer. The diblock copolymers which are composed of PEG and PLLA (MPEG-co-PLLA) and PEG and PDLA (MPEG-co-PDLA) were employed for thin film preparation using an aqueous inkjet system. The solvent and temperature conditions were optimized for the stereocomplex formation between MPEG-co-PLLA and MPEG-co- PDLA. As a result, the stereocomplex was adequately formed in acetonitrile/water (1/1, v/v) at 40 ºC. The aqueous conditions improved the stereocomplex film preparation, which have suffered from clogging when using the organic solvents in previous work. The triblock copolymers, PLLA-co-PEG-co-PLLA and PDLA-co-PEG-co-PDLA, were employed for square patterning with the inkjet system, which produced thin films. The amphiphilic polymer film was able to retain hydrophobic compounds inside. The present result contributed to the rapid film preparation by inkjet, retaining drugs with difficult solubility in water, such as paclitaxel within the films.
    Langmuir 09/2015; 31(38). DOI:10.1021/acs.langmuir.5b03169 · 4.46 Impact Factor
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    ABSTRACT: Surface modification can play a crucial role in enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering applications. Here, we report a novel approach for layer-by-layer (LbL) fabrication of nanometer-size fibronectin and gelatin (FN-G) layers on electrospun fibrous poly(carbonate urethane)urea (PCUU) scaffolds. Alternate immersions into the solutions of fibronectin and gelatin provided thickness-controlled FN-G nano-layers (PCUU(FN-G) ) which maintained the scaffold's 3D structure and width of fibrous bundle of PCUU as evidenced by scanning electron miscroscopy. The PCUU(FN-G) scaffold improved cell adhesion and proliferation of bladder smooth muscles (BSMCs) when compared to uncoated PCUU. The high affinity of PCUU(FN-G) for cells was further demonstrated by migration of adherent BSMCs from culture plates to the scaffold. Moreover, the culture of UROtsa cells, human urothelium-derived cell line, on PCUU(FN-G) resulted in an 11-15 μm thick multilayered cell structure with cell-to-cell contacts although many UROtsa cells died without forming cell connections on PCUU. Together these results indicate that this approach will aid in advancing the technology for engineering bladder tissues in vitro. Because FN-G nano-layers formation is based on nonspecific physical adsorption of fibronectin onto polymer and its subsequent interactions with gelatin, this technique may be applicable to other polymer-based scaffold systems for various tissue engineering/regenerative medicine applications. This article is protected by copyright. All rights reserved. © 2015 Wiley Periodicals, Inc.
    Journal of Biomedical Materials Research Part A 07/2015; DOI:10.1002/jbm.a.35544 · 3.37 Impact Factor
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    ABSTRACT: The cellular uptake of biodegradable particles as drug or vaccine carriers was observed by scanning electron microscopy employing an ionic liquid. The samples were observed by simply dipping them into the ionic liquid, and high-resolution images (sub-nanometer order) were achieved. The cellular uptake of polymeric nanoparticles (NPs) composed of biodegradable amphiphilic polymers was observed using an ionic liquid method for the first time. In particular, these NPs were observed when the quantum dots were immobilized on the NPs. In addition, when the cells were incubated with microparticles (MPs), the filopodia that covered the MPs were observed, and the cellular uptake of the MPs was evaluated in a time-dependent manner. This ionic liquid method is a promising technique for evaluating the cellular uptake behavior of drug or vaccine carriers. This method also provides a strategy for observing carriers that are sensitive to conventional pretreatment conditions by choosing a suitable ionic liquid.
    Polymer Journal 07/2015; DOI:10.1038/pj.2015.40 · 1.65 Impact Factor
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    ABSTRACT: Hydroxyapatite (HA) or calcium carbonate (CaCO3) formed on an organic polymer of agarose gel is a biomaterial that can be used for bone tissue regeneration. However, in critical bone defects, the regeneration capability of these materials is limited. Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into bone forming osteoblasts. In this study, we loaded MSCs on HA- or CaCO3-formed agarose gel and cultured them with dexamethasone, which triggers the osteogenic differentiation of MSCs. High alkaline phosphatase activity was detected on both the HA- and CaCO3-formed agarose gels; however, basal activity was only detected on bare agarose gel. Bone-specific osteocalcin content was detected on CaCO3-formed agarose gel on Day 14 of culture, and levels subsequently increased over time. Similar osteocalcin content was detected on HA-formed agarose on Day 21 and levels increased on Day 28. In contrast, only small amounts of osteocalcin were found on bare agarose gel. Consequently, osteogenic capability of MSCs was enhanced on CaCO3-formed agarose at an early stage, and both HA- and CaCO3-formed agarose gels well supported the capability at a later stage. Therefore, MSCs loaded on either HA- or CaCO3-formed agarose could potentially be employed for the repair of critical bone defects.
    International Journal of Molecular Sciences 06/2015; 16(6):14245-58. DOI:10.3390/ijms160614245 · 2.86 Impact Factor
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    ABSTRACT: Phase-sensitive vibrational sum frequency generation (SFG) spectroscopy has been utilized to study the molecular orientation of molecules adsorbed on dielectric solid substrates. Our results show that the complex second-order nonlinear susceptibility χ(2) spectra of various organic thin films can be obtained by using a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) as a standard sample for the phase correction and a gold thin film as a local oscillator. Furthermore, by using the present phase-sensitive SFG setup, the orientation flipping of water molecules on positively and negatively charged solid/liquid interface can be distinguished.
    Physical Chemistry Chemical Physics 06/2015; 17(27). DOI:10.1039/C5CP02702K · 4.49 Impact Factor
  • Yukie Takemoto · Hiroharu Ajiro · Mitsuru Akashi
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    ABSTRACT: Layer-by-layer (LbL) assembly based on hydrogen-bonding interactions is generating great interest for biomedical applications because it is composed of neutral polymers, while LbL assembly based on electrostatic interaction requires polycations which may induce toxicity issues. As a neutral polymer, poly(N-vinylamide), which has low toxicity compared to poly(acrylamide), has the potential to fabricate LbL thin films via hydrogen-bonding interactions. Herein we report interpolymer complexes of poly(N-vinylamide)s and natural polyphenol tannic acid to form the multilayered thin film. Poly(N-vinylformamide) and poly(N-vinylacetamide), which are water-soluble and insoluble in acetonitrile, could not form complexes with TA in water. On the other hand, N-alkylated poly(N-vinylamide) such as poly(N-ethyl-N-vinylformamide) and poly(N-methyl-N-vinylacetamide) was soluble in acetonitrile and allowed the LbL assembly to proceed with TA. Furthermore, the QCM frequency shift with films composed of poly(N-ethyl-N-vinylformamide) and TA were stable in water, while those of poly(N-methyl-N-vinylacetamide) and TA were instable in water, possibly because formamide has lower steric hindrance compared to acetamide to allow stronger hydrogen-bonding interactions to take place. Thus, LbL assembly reactions with alkylated poly(N-vinylamide)s and TA were investigated and revealed that poly(N-ethyl-N-formamide) and TA, which are water-soluble, effectively interacted with one another to generate water-stable hydrogen-bonded multilayered films.
    Langmuir 06/2015; 31(24). DOI:10.1021/acs.langmuir.5b00767 · 4.46 Impact Factor
  • Fumiaki Shima · Takami Akagi · Mitsuru Akashi
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    ABSTRACT: The new generation vaccines are safe but poorly immunogenic, and thus they require the use of adjuvants, and adjuvants which can control the balance and induction level of cellular and humoral immunities are urgently required for the treatment and/or protection of infectious diseases and cancers. Although, there have no adjuvants which can achieve these requirements. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA) with various kinds of hydrophobic amino acid ethyl esters (AAE), was synthesized (γ-PGA-AAE) and prepared antigen-encapsulated nanoparticles (NPs). γ-PGA-graft-Leu (γ-PGA-Leu, Leu; leucine ethyl ester), γ-PGA-graft-Phe (γ-PGA-Phe, Phe; phenylalanine ethyl ester), and γ-PGA-graft-Trp (γ-PGA-Trp, Trp; tryptophan ethyl ester) formed monodispersed NPs that encapsulated ovalbumin (OVA). The type and the induction level of the antigen-specific cellular and humoral immunities could be controlled by the kinds of hydrophobic segments and vaccine formulation (encapsulation or mixture). When OVA was encapsulated into NPs, the cellular immunity was dominantly induced, while humoral immunity was dominant when OVA was mixed with NPs. These results are a first report that demonstrated the balance and induction level of cellular and humoral immunities could be controlled by modifying compositions of NPs and vaccine formulation. Our results suggest that γ-PGA-AAE NPs can provide safe and efficient nanoparticle-based vaccine adjuvants, and provide guidelines in the rational design of amphiphilic polymers as vaccine adjuvants which can control the balance of immune responses.
    Bioconjugate Chemistry 04/2015; 26(5). DOI:10.1021/acs.bioconjchem.5b00106 · 4.51 Impact Factor
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    ABSTRACT: Urethane-crosslinked β-cyclodextrin polymers are prepared by crosslinking heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) with various diisocyanate linkers, such as 4,4′-methylenebis(phenyl isocyanate) (MDI), 1,4-phenylene diisocyanate (PDI) and hexamethylene diisocyanate (HMDI), in DMF. Among these polymers, MDI- and PDI-crosslinked polymers have high adsorption capabilities toward polychlorobiphenyls (PCBs), such as tetra, penta and hexachlorobiphenyl, in isooctane. Toward hexachlorobiphenyl in insulating oil, the adsorption capability of the MDI-crosslinked polymer increases with the adsorption temperature. In addition, using acetone as a washing solvent gives the highest recovery percentage of the PCB from the PCB-adsorbed polymer.
    Polymer Journal 04/2015; 47(6). DOI:10.1038/pj.2015.13 · 1.65 Impact Factor
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    ABSTRACT: The androgen testosterone is less expensive than bone morphogenetic proteins and has been shown to effectively repair bone fractures. However, testosterone is lipophilic and insoluble in water, making it difficult to load into hydrogels, which are common drug carriers. In this study, we prepared a novel oil gel composed of poly(L-lactide) and a poly(trimethylene carbonate) derivative and studied the release of testosterone from the gel. Dimethyl sulfoxide and dimethyl carbonate, which are organic solvents with relatively low toxicities, were used as dispersion media. The oil gel in dimethyl sulfoxide released testosterone faster than that in dimethyl carbonate. In addition, the dimethyl carbonate oil gel was vacuum-dried to reduce the gel porosity and thus slow testosterone release. Therefore, oil gel is a promising substrate for lipophilic drugs, including testosterone.
    Polymer Journal 04/2015; 47(6). DOI:10.1038/pj.2015.17 · 1.65 Impact Factor
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    ABSTRACT: We developed a human skin equivalent (HSE) containing blood and lymph-like capillary networks using a cell coating technique, which is a rapid fabrication technology of three-dimensional cellular constructs by cell surface coating using layer-by-layer assembled nanofilms of extracellular matrices. The thickness of dermis consisting of normal human dermal fibroblasts was easily controlled from approximately 5 to 100 µm by altering the seeded cell number. Keratinocytes as a major cell population showed homogeneous differentiation on the surface of the dermis by lifting to air-liquid interface. Histological analysis revealed four distinct layers such as basal layer, spinous layer, granular layer and cornified cell layer in the epidermis. Interestingly, the measurement of trans-epithelial electrical resistance (TEER) indicated prolongation of the attainment time for maximum value by increasing the number of the dermal fibroblasts, and the HSEs with six-layers of dermis revealed the longest period maintaining over 500 Ω·cm(2) of TEER. The co-sandwich culture of human umbilical vein endothelial cells and normal human dermal lymphatic microvascular endothelial cells within eight-layered dermis showed in vitro co-network formation of individual blood and lymph-like capillaries inside the dermis. This is the first report for homogeneous full-thickness HSEs with blood and lymph capillary networks, which will be useful for biomedical and pharmaceutical applications. This article is protected by copyright. All rights reserved. © 2015 Wiley Periodicals, Inc.
    Journal of Biomedical Materials Research Part A 04/2015; 103(10). DOI:10.1002/jbm.a.35473 · 3.37 Impact Factor
  • Tomofumi Uto · Takami Akagi · Mitsuru Akashi · Masanori Baba
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    ABSTRACT: Development of effective and simple vaccine preparation is desired for prophylaxis and treatment of a variety of infectious diseases and cancers. We have created novel polyion complex (PIC) nanoparticle (NPs) composed of amphiphilic anionic biodegradable poly(γ-glutamic acid) (γ-PGA) and cationic polymers as a vaccine adjuvant. PIC NPs can be prepared by mixing γ-PGA-graft-l-phenylalanine ethylester (γ-PGA-Phe) polymer with cationic polymer in phosphate buffered saline. We examined the efficacy of PIC NPs for their antigen delivery and immunostimulatory activity in vitro and in vivo. PIC NPs enhanced the uptake of ovalbumin (OVA) by dendritic cells (DCs) and subsequently induced DC maturation. The immunization of mice with OVA-carrying PIC NPs could induce potent and antigen-specific cellular and humoral immunity. Since PIC NPs can be created with water-soluble anionic γ-PGA-Phe and a cationic polymer by simple mixing in the absence of any organic solvents, PIC NPs may have potential as a novel candidate for an effective antigen carrier and vaccine adjuvant. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Clinical and vaccine Immunology: CVI 03/2015; 22(5). DOI:10.1128/CVI.00080-15 · 2.47 Impact Factor
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    ABSTRACT: Cyclic l-lactic acid octamer (l-COLA-8) shows a unique complexing capability towards alkali and alkali earth metal cations in acetonitrile-d3/chloroform-d (9/1). The valence of the cation affects the stoichiometry of the complexes between l-COLA-8 and the cation; l-COLA-8 forms a 2:1 complex with alkali metal cations, but forms a 1:1 complex with alkali earth metal cations. Additionally, l-COLA-8 shows a binding selectivity for Rb+ and Ba2+, which have a diameter about 3 Å.
    Tetrahedron Letters 03/2015; 56(13). DOI:10.1016/j.tetlet.2015.02.037 · 2.38 Impact Factor
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    Akihiro Nishiguchi · Michiya Matsusaki · Mitsuru Akashi
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    ABSTRACT: Front Cover: Heparin-based ECM nanofilms formed on living cells by layer-by-layer assembly induce cell-cell crosslinking through bio-molecular recognition between highly-sulfated polymers and membrane proteins. Cell aggregates display network structures of cells and the cell-cell crosslinking process leads to in vitro 3D-tissue construction with rich glycosaminoglycan. The cellular assembly technique presented by M. Akashi and co-workers on page 312 has potential for tissue engineering and intercellular signalling assay. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Macromolecular Bioscience 03/2015; 15(3):293. DOI:10.1002/mabi.201570009 · 3.85 Impact Factor
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    ABSTRACT: Surface polyion complex (sPIC) gels were prepared with a nonionic hydrogel interior core, composed of poly(N-vinylformamide and poly(N-vinylacetamide), and a chemically bounded polyion complex layer on the outer surface, composed of poly(vinylamine) and poly(acrylic acid). The gels were investigated as controlled drug release models based on electrostatic interactions depending on pH. Methylene blue and allura red were employed as cationic and anionic drug models, respectively, and resulted in the selective adsorption depending on pH conditions. Monovalent and multivalent anionic drug models, allura red and 1,3,6-naphthalenetrisulfonate were observed for their releasing behavior from the sPIC gel. The results indicated that the multivalent anionic drug effectively controlled release depending on pH conditions. We further investigated sPIC gels regarding their ability to control the release of ionic molecules as a function of pH-driven changes in electrostatic interactions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42081.
    Journal of Applied Polymer Science 03/2015; 132(24). DOI:10.1002/app.42081 · 1.77 Impact Factor
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    Chun-Yen Liu · Michiya Matsusaki · Mitsuru Akashi
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    ABSTRACT: Collagen molecules are widely used in the field of tissue engineering, especially as cell culture hydrogels. However, the cellular effects on collagen fiber formation inside collagen gels have not been reported. Here, we evaluated the effect of cells on collagen triple helix fiber formation at a molecular level in collagen hydrogels or on cell surfaces. Swelling ratios of collagen gels decreased with increasing cell numbers, most likely because of interactions between cell surface integrin molecules and collagen fibers. Circular dichroism and ultraviolet–visible spectroscopic analyses revealed aggregations of cells and collagen molecules because of their strong interaction. X-ray diffraction analyses suggested that cells did not affect the weak molecular orientation of collagen fibers inside collagen gels because the collagen gels usually do not have as dense molecular packing as natural collagen fibers in tendons. Scanning electron microscopy showed aggregations of submicrometer-sized spherical collagen structures mainly around cells inside collagen gels. The results suggest that interactions between cell surfaces and collagen molecules induce the formation of spherical constructs rather than microfiber formation, which in turn indicates that interactions between cells and collagen molecules induce the adsorption of collagen molecules onto cell surfaces and lead to the formation of spherical constructs in hydrogels.
    Polymer Journal 02/2015; 47(5). DOI:10.1038/pj.2015.2 · 1.65 Impact Factor
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    ABSTRACT: Hydroxyapatite agarose composite gel (HAp gel) is a radiolucent and absorbable bone–graft material that differs from hydroxyapatite ceramic; it is more rapidly absorbed and replaced by new bone than existing materials. This study examined the usefulness of HAp gel in the repair of alveolar bone defects due to cleft lip and palate.
    02/2015; DOI:10.1016/j.ajoms.2015.01.003
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    ABSTRACT: Functional 3D-engineered tissues are successfully harvested from a substrate using stimuli-responsive hydrogel films with dynamic nano-interface. The dynamic wettability control at the interfaces allows cellular detachment, leading to tissue harvesting without serious damage and remaining polymers. This method can be applied to various types of organs and used for tissue transplantation in regenerative medicine. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Advanced Healthcare Materials 02/2015; 4(8). DOI:10.1002/adhm.201500065 · 5.80 Impact Factor
  • Sarekha Woranuch · Rangrong Yoksan · Mitsuru Akashi
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    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. DOI:10.1016/j.carbpol.2014.06.074 · 4.07 Impact Factor
  • Dongjian Shi · Ming Ni · Jing Luo · Mitsuru Akashi · Xiaoya Liu · Mingqing Chen
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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; 140(4). DOI:10.1039/c4an01991a · 4.11 Impact Factor
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    Akihiro Nishiguchi · Michiya Matsusaki · Mitsuru Akashi
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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; 15(3). DOI:10.1002/mabi.201400415 · 3.85 Impact Factor

Publication Stats

9k Citations
2,199.38 Total Impact Points


  • 2003–2015
    • Osaka University
      • • Division of Applied Chemistry
      • • Division of Molecular Biochemistry
      • • Graduate School of Engineering
      Suika, Ōsaka, Japan
  • 2006–2013
    • Japan Science and Technology Agency (JST)
      Edo, Tōkyō, Japan
    • Nanjing University of Science and Technology
      Nan-ching, Jiangsu Sheng, China
  • 2012
    • RWTH Aachen University
      • Institute of Inorganic Chemistry
      Aachen, North Rhine-Westphalia, Germany
  • 1984–2010
    • Kagoshima University
      • • Faculty of Engineering
      • • Center for Educational Research and Development
      • • Graduate School of Science and Engineering
      Kagosima, Kagoshima, Japan
  • 2009
    • Jiangnan University
      • School of Chemical and Material Engineering
      Wuxi, Jiangsu Sheng, China
  • 2007
    • Kyoto Institute of Technology
      Kioto, Kyōto, Japan
  • 2005
    • Yangtze University
      Hu-pei-ts’un, Shanxi Sheng, China
  • 2004
    • Chulalongkorn University
      • Petroleum and Petrochemical College
      Krung Thep, Bangkok, Thailand
  • 1997
    • Slovak Academy of Sciences
      • Polymer Institute
      Presburg, Bratislavský, Slovakia
  • 1991
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan