Papers - Fujimoto, Keiji

Core−shell Particle Embedding into Human Hair: A Novel Approach for Surface Modification and Long-Lasting Hair Coloration

Keiji Fujimoto, Megumi Nishimura, Yuuka Fukui

ACS OMEGA (ACS)   2025.05

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted

Preparation of a CNF porous membrane and in situ synthesis of silver nanoparticles (AgNPs)

Fukui Y., Baba E., Fujimoto K.

RSC Advances 15 ( 2 ) 1115 - 1124 2025.01

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We prepared a cellulose nanofiber (CNF)-based porous membrane with three dimensional cellular structures. CNF was concentrated via a surfactant-induced assembly by mixing CNF with a cationic surfactant, domiphen bromide (DB). Furthermore, they were accumulated by centrifugation to obtain a CNF-DB sol. Next, when the CNF-DB sol was naturally dried, a membrane composed of densely packed CNF was obtained. On the other hand, when the CNF-DB sol was freeze-dried, a porous membrane with the anisotropic cellular structure could be obtained. The interspace between layered CNF sheets was tunable by the DB concentration in the assembly process and the centrifugal force in the accumulation process. FT-IR analysis of the porous membrane showed the formation of hydrogen bonds between the CNF, resulting in facilitation of crosslinking of the CNF and formation of the cellular structures. The obtained CNF-DB membrane exhibited high water resistance. They showed a high ability to absorb hydrophobic dyes such as Nile red and rhodamine B (RhB) due to the presence of the hydrophobic core of DB micelles. Then, the release of RhB could be controlled by the ionic strength in the medium. In addition, they possessed a high ability to adsorb cationic metals such as Ag ions due to the presence of carboxyl moieties of CNF. Next, in situ synthesis of silver nanoparticles (AgNPs) was carried out by employing the CNF-DB membrane as a template for Ag ion adsorption and reduction. Deposition of AgNPs could be observed on the CNF-DB membrane, which suppressed aggregation of AgNPs. Almost all AgNPs were arrayed apart from each other to generate the hotspots, which could enhance surface-enhanced Raman scattering (SERS) of AgNPs. Such an AgNPs-CNF composite membrane could be applied for a label-free analysis of adsorbed RhB.

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Preparation of a robust and degradable nanocapsule by polymer deposition over the liposome for loading and release of cargos

Yuuka Fukui, Junna Ito, Masatoshi Takeiri, Keiji Fujimoto

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier B.V.)  676   132160 2023.11

Research paper (scientific journal), Last author, Accepted,  ISSN  09277757

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We prepared biobased nanocapsules by the polymer deposition over the ceramide-containing liposomes to render abilities to load versatile substances and to release them in response to enzymatic degradation of the capsule wall. First, we carried out phosphorylation of chitosan (CHI) to make it amphoteric. Then, we prepared a liposome containing glucosylceramide (GlcCer) and carried out deposition of phosphorylated chitosan (PCHI). The obtained capsule showed high structural stability against solubilization by surfactants and organic solvents, where it maintained its size even in 90 vol% DMSO. Next, we attempted to load various substances into the capsule. A lipophilic Nile red dissolved in 50 vol% DMSO could be loaded into the capsule without rupturing. The loading capacity of PCHI-deposited liposomes was almost three times higher than that of bare liposomes. Its release was suppressed to less than 10 % in an aqueous solution, whereas it could be released to more than 40 % when a small amount of surfactant was added to mimic a lipophilic environment. Also, an amphoteric nature of the capsule derived from PCHI allowed for loading of both cationic and anionic substances. Furthermore, lysozyme (Lyso) was deposited onto the capsule to provide the capsule wall with the enzymatic degradability. Although the release of substances from the capsule was suppressed to less than 10 % without Lyso, it was increased to approximately 50 % by enzymatic degradation of the PCHI layer.

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One-pot generation of gold-polymer hybrid nanoparticles using a miniemulsion reactor system

Fukui Y., Fujino K., Fujimoto K.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  666 2023.06

ISSN  09277757

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We investigated one-pot synthesis of gold nanoparticles (AuNPs) and AuNPs-polymer hybrid nanoparticles in a water-in-oil (W/O) miniemulsion. Water nanodroplets were dispersed as a reactor in cyclohexane using dimethicone as a surfactant. First, we intended to generate AuNPs in water nanodroplets, which contained HAuCl4 with a mixture of 1-vinylpyrrolidone (VP) and N,N’-methylenebisacrylamide (MBAAm). Several AuNPs with the size of approximately 10–20 nm were generated in each nanodroplet via reduction of AuCl4- by dimethicone. On the other hand, AuNPs was scarcely generated in water nanodroplets containing HAuCl4 with 2-hydroxyethyl methacrylate (HEMA). Next, we carried out polymerization in water nanodroplets to encapsulate AuNPs into polymer nanoparticles. Several AuNPs were encapsulated within polymer particles by copolymerization of VP and MBAAm with an oil-soluble initiator (V-601), and some AuNPs were present in the oil phase. The encapsulation efficiency of AuNPs was 34%. The encapsulation efficiency of AuNPs was dramatically increased by increasing the concentration of the initiator. The same result was obtained by increasing the concentration of the crosslinker due to rapid gelation of nanodroplets. On the other hand, monodisperse particles could be obtained by polymerization of HEMA using a water-soluble initiator (V-65). After polymerization for 5 d at 65ºC, the color of the suspension changed from opaque blue to blue purple and the encapsulation efficiency of AuNPs (5–20 nm) increased to 99 wt%. The average number of AuNPs encapsulated in a PHEMA nanoparticle increased from 1.5 to 4.6 particle. Furthermore, the size of AuNPs could be tuned by increasing the HAuCl4 concentration, and the corresponding color of the suspensions such as blue, purple, and red could be observed. The number and location of AuNPs in polymer nanoparticles could also be tuned by additives such as L-histidine and polyvinylpyrrolidone. By drop-casting the obtained hybrid nanoparticles, we could obtain gold-polymer hybrid films where AuNPs were evenly distributed within a film. The films exhibited different colors corresponding to their LSPR of AuNPs.

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Control in Coloration and Estimation of the Refractive Index by Porous Polymeric Membranes Prepared by the "Miniemulsion" Templating Method

Fukui Y., Sumida H., Sugaya Y., Fujimoto K.

ACS Applied Polymer Materials (ACS Applied Polymer Materials)  4 ( 10 ) 7547 - 7553 2022.10

ISSN  2637-6105

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We fabricated porous polymeric membranes using the miniemulsion templating method to investigate the transmitted and scattered lights in terms of the Christiansen filter effect. This method made it possible to produce porous polymeric membranes with different refractive indices by polymerization of different monomers and copolymerization of monomers. When a membrane with an open-cellular structure was immersed in a liquid, the transmitted light was observed at a wavelength where the refractive indices of the polymeric phase and the liquid matched. Angle-independent color derived from the scattered light could also be observed. When the porous membrane of poly(2-ethylhexyl methacrylate) (EHMA) was immersed in a mixture of different kinds of liquids, the maximum wavelength of the transmission (λmax) changed according to the refractive index matching of the polymeric phase and the liquid, resulting in the change in coloration. Next, when the P(EHMA-co-EGDMA) membrane was immersed in a mixture of toluene and d-limonene, λmax and color varied depending on their mixing ratios. This coloration was controlled by temperature and the refractive indices of the polymeric phase and the liquid. Furthermore, we could estimate the refractive index of PEGDMA using λmax values obtained by immersing it into liquids with different refractive indices.

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Functionalization of keratin nanoparticles by their internal modifications

Yuuka Fukui, Kaori Ito, Keiji Fujimoto

Polymer Journal (Springer Nature )  54 ( 11 ) 1367 - 1375 2022.06

Joint Work, Last author, Accepted,  ISSN  00323896

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We prepared keratin nanoparticles, which could respond to temperature and pH changes and to redox reactions, by electrostatic association of keratin and a cationic surfactant, dioctadecyl dimethyl ammonium chloride (DODAC). Solubilized keratin chains were assembled into nanoparticles (Ker-DODAC) and then crosslinked by disulfide formation. The resultant nanoparticles (Ker-DODACss) possessed a hydrophobic core composed of DODAC, enabling hydrophobic compounds to be loaed and retained in the core. By increasing the temperature, the fluidity of the core was increased, resulting in Ker-DODACss swelling and burst release of loaded compounds. Next, cholesterol was loaded into Ker-DODACss to modify the inner environment, such as the hydrophobicity and fluidity of the core. The nanoparticles (Ker-DODACss-Chol) exhibited reduced fluidity of the core and suppressed release of the payload. Furthermore, the release could be triggered by decreasing the electrostatic interaction between keratin and DODAC at pH values lower than 7.4. It was also found that Ker-DODACss-Chol possessed the ability to release payloads by breaking disulfide bonds. As a further internal modification, we incorporated a lipophilic antioxidant, α-tocopherol, into Ker-DODACss-Chol. It was confirmed that Ker-DODACss-Chol could act as a physical barrier to prevent α-tocopherol from undergoing oxidative degradation.

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Preparation of a deformable nanocapsule by living radical polymerization in a liposome

Fukui Y., Fukui A., Fujimoto K.

Polymer Journal (Polymer Journal)  54 ( 7 ) 893 - 901 2022

ISSN  00323896

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We aimed to prepare an elastic nanocapsule by internal modification of a liposome with living radical polymerization. First, monomers and photoiniferters were encapsulated in liposomes. Then, UV light irradiation was used to conduct living radical polymerization in the liposomes. The obtained nanocapsules showed good absorption and retention of chemical substances depending on the binding ability to the incorporated polymers, and the absorption capacity could be controlled by the length and dissolved state of the polymer chains. In addition, dynamic morphological changes in the capsules were observed when liposomes with high membrane fluidity were employed. Morphological changes in the nanocapsules were induced by altering the pH value and ionic strength, resulting in the release of cargo in response to these environmental conditions.

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Preparation of agarose xerogel nanoparticles by solvent evaporation from water nanodroplets

Yuuka Fukui, Ryutaro Inamura & Keiji Fujimoto

Polymer Journal (Springer Nature)  53 ( 7 ) 815 - 821 2021.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00323896

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We developed a W/O miniemulsion reactor system enabling the preparation of biopolymer nanoparticles and control of their morphologies and inner microstructures. First, the W/O miniemulsion was prepared by suspending water nanodroplets containing agarose in oil. Then, we produced agarose hydrogel nanoparticles (AgarH) by the gelation of agarose in nanodroplets. Next, we prepared agarose xerogel nanoparticles (AgarX) by precisely tuning the water evaporation from AgarH. We controlled the morphologies (solid and hollow) and crystal structure of AgarX by changing the pressure and temperature during water evaporation. In fact, AgarX with a hollow structure was generated through rapid evaporation at a low pressure. AgarH was dissolved in Milli-Q water when the temperature was raised to 90 °C. On the other hand, AgarX remained a solid particle under the same conditions, likely because of its high crystallinity. We expect that this technique can be applied to prepare xerogels of diverse biomass-based polymers for the replacement of synthetic polymers.

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Creation of porous polymeric membranes by accumulation of water nanodroplets in a miniemulsion system

Fukui Y., Fujino R., Sugaya Y., Fujimoto K.

Polymer Journal (Polymer Journal)  52 ( 9 ) 1077 - 1083 2020.05

Research paper (scientific journal), Accepted,  ISSN  00323896

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© 2020, The Society of Polymer Science, Japan. We developed a miniemulsion templating method to prepare porous polymeric membranes. First, water nanodroplets were suspended in an oil phase by using a nonionic and polymeric surfactant to form a water-in-oil (W/O) miniemulsion. After the nanodroplets accumulated by centrifugation, a small amount of monomer was added as an oil phase to resuspend the water nanodroplets in a monomer phase. Then, photopolymerization of the monomer phase was conducted to generate pores in the polymeric matrix. The size of the nanodroplets was tuned by the surfactant concentration to control the pore size of the membranes. We could produce pore morphologies such as closed-cellular, open-cellular, and bicontinuous structures by tuning the volume fraction of the nanodroplets. Alternatively, nanodroplets were accumulated by centrifugation, and then further surfactants were added to the monomer to suppress the coalescence of nanodroplets. This enabled us to generate a highly porous open-cellular structure while maintaining the size and spherical shape. Next, HAuCl4 was reduced by using the surfactant displayed at the inner surface of the pore wall as the reducing agent. Gold nanoparticles were produced in the inner pores of the polymeric membrane, showing coloration derived from local surface plasmon resonance.

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Tuning of particle indentation by surface modification of polymer particles and substrates

Fukui Y., Yamamoto K., Yamamoto T., Fujimoto K.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  588 2020.03

Research paper (scientific journal), Accepted,  ISSN  09277757

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© 2019 Elsevier B.V. We studied the influence of the chemical properties of the polymer particle and the polymer substrate on particle indentation. The polymer particles were arrayed over the polymer substrate and heat treatment (annealing) was conducted above the glass transition temperature (Tg) of bulk polymer to indent polymer particles into the polymer substrate. Surface topologies of particle-indented surfaces were observed with a field-emission scanning electron microscope (FE-SEM) and the degree of particle indentation (DI) was evaluated with a scanning probe microscope (SPM). The particle-arrayed substrate was placed upside down and then heat treatment was carried out. It was found that there was no effect of gravity on particle indentation. To prepare polymer particles with different chemical properties, surface grafting of hydrophobic, hydrophilic, cationic and anionic polymer chains was carried out by iniferter-initiated living radical polymerization. We found that the indentation of these particles was influenced by the outermost surface of the particle. Next, to investigate the effect of the substrate surface on particle indentation, sulfonation of the polystyrene (PS) substrate was carried out with concentrated sulfuric acid. We found that the surface property of the substrate also influenced particle indentation. From these results, we concluded that particle indentation would be determined by the interaction between the particle surface and the substrate surface. Finally, we intended to analyze the viscoelastic property of the substrate surface by particle indentation. We could estimate Tg values of PS and polyvinyl chloride (PVC) substrates by observing the particle indentation at the different annealing temperatures.

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Controlled release and targeting of polypeptide-deposited liposomes by enzymatic degradation

Fukui Y., Otsuka H., Fujimoto K.

Polymer Journal (Polymer Journal)  51 ( 11 ) 1223 - 1230 2019

Research paper (scientific journal), Accepted,  ISSN  00323896

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© 2019, The Society of Polymer Science, Japan. We prepared biobased nanocapsules with enzymatic degradability, which were generated by the layer-by-layer deposition of enzymes and polypeptide over the liposomal surface. Here, we demonstrate two different systems based on the enzymatic degradation of polymer layers. First, the deposition of trypsin and polyarginine (PArg), which is cleavable by trypsin, was carried out over a negatively charged liposome. The enzymatic cleavage of PArg resulted in exposure of the lipid membrane, which facilitated release of the cargo. Next, we attempted to degrade the outer polymer layer of the multilayered capsule wall to display the inner polymer layer by enzymatic degradation. This approach enabled the accumulation and targeting of the nanocapsules through the affinity between the displayed polymer layer and the target hydroxyapatite (HAp). The polymer wall was constructed with an inner layer consisting of poly-L-glutamic acid (PGlu) and an outer layer consisting of trypsin and PArg onto the liposome. The degradation of the outer PArg by trypsin allowed the surface to display the inner PGlu, which has bone-targeting ability. In addition, the polymer wall was constructed from an inner layer of PArg and an outer layer of pepsin and PGlu. The degradation of the outer PGlu by pepsin led to inner PArg on the surface to achieve cell-penetrating activity.

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Generation of mucin gel particles with self-degradable and -releasable properties

Yuuka Fukui, Megumi Fukuda, Keiji Fujimoto

J. Mater. Chem. B (RSC)  6 ( 5 ) 781 - 788 2018

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507518

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© The Royal Society of Chemistry 2018. Herein, we focused on mucin, which is a large viscous glycoprotein in terms of materials science, and reported preparation of mucin gel particles and incorporation of enzymes to provide the particle with self-degradable and releasable properties. To expose the hydrophobic peptide cores, trimming of sugar moieties was carried out by β-elimination reaction under alkaline conditions (tMucin). Nano-sized tMucin particles were prepared by the assembly of tMucin with the aid of a cationic surfactant. Then, cross-linking of tMucin particles was carried out via heat treatment (annealing) to induce thermal aggregation of the polypeptide chains. The hydrodynamic diameter of tMucin particles reversibly changed in response to calcium ions. Next, in an attempt to render the particle degradable, lysozyme was incorporated into the tMucin particles for the hydrolysis of oligosaccharide chains. These particles were gradually degraded upon enzymatic cleavage of the mucin molecules, facilitating the release of their incorporated substances. Also, the degradation of the mucin particles and the release of lysozyme were tunable by environmental conditions, such as temperature and calcium ions, in addition to the degree of cross-linking of the particles.

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Preparation of free-standing hybrid colloidal membranes via assembly of liponanocapsules

Y. Fukui, S. Kameyama, K. Fujimoto

J. Biomaterials Science, Polymer Edition (Taylor & Francis)  10-12 ( 10-12 ) 1010 - 1024 2017.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09205063

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© 2017 Informa UK Limited, trading as Taylor & Francis Group. We intended to create a free-standing and organic–inorganic hybrid colloidal membrane. The colloidal membrane was assembled from polymeric capsules, which were prepared by coating of polymer layers over a liposome (liponanocapsules). In this study, two approaches were employed for mineralization over the membrane with calcium phosphate (CaP) to control its mechanical robustness and biodegradability (hybrid bioscaffold). One approach was based on CaP deposition over the liponanocapsules and their assembly into the hybrid membrane. CaP deposition was conducted via the counter-diffusion of phosphate ions and calcium ions across the capsule wall to obtain hybrid nanocapsules. Then, free-standing hybrid membrane was obtained by utilizing hybrid nanocapsules as building blocks for drying-mediated assembly. The obtained hybrid membrane was degraded into individual nanocapsules and degradation could be tuned by the crystal structure of CaP. In another approach, the free-standing membrane was assembled from DNA-coated liponanocapsules and then the counter-diffusion of ions was carried out across each assembled nanocapsule for CaP mineralization. The mechanical robustness of the membrane was significantly improved and its degradation was suppressed by CaP mineralization. This is probably because mineral cross-linkages were formed in the interspace between each nanocapsule. Fluorescent substances could be incorporated in each nanocapsule of the membrane and their release could be tuned by the control in crystal properties of CaP.

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Creation of hybrid polymer particles through morphological tuning of CaCO<inf>3</inf> crystals in miniemulsion system

Fukui Y., Takamatsu H., Fujimoto K.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  516   1 - 8 2017.03

Research paper (scientific journal), Accepted,  ISSN  09277757

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© 2016 Elsevier B.V. We developed a miniemulsion-based nanoreactor system, which can allow for morphological tuning of CaCO3 crystals in nanodroplets and their high encapsulation efficiency in polymer particles. We first obtained nano-sized CaCO3 by using the aqueous nanodroplet as a nanoreactor. In addition, it was found that crystal growth and morphological transformation of CaCO3 from spherical to rod-like crystals were induced by adding 2-hydroxyethyl methacrylate (HEMA) in nanodroplets. Such transformation was also promoted by raising the incubation temperature or increasing the number of nanodroplets in the presence of HEMA. We speculated that crystal growth of CaCO3 crystals was induced by coalescence of nanodroplets and morphological transformation to rod-like shape was undertaken with an assistance of HEMA. In this way, we could tune the shapes of CaCO3 with the well-controlled size and aspect ratio by tuning environments in nanodroplets. Then, subsequent polymerization of HEMA, which was used as a monomer, was carried out for encapsulation of CaCO3 with rod-like morphologies inside polymer nanoparticles. As a result, spherical and spheroidal hybrid nanoparticles, which possessed homogeneity in size and shape, were obtained. Then, by spin-coating of hybrid nanoparticles onto the glass substrate, we could obtain a closely-packed particle monolayer.

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Creation of hybrid polymer particles through morphological tuning of CaCO3 crystals in miniemulsion system

Y. Fukui, H. Takamatsu, K. Fujimoto

Colloids and Surfaces A (Elsevier)  516   1 - 8 2017

Joint Work, Accepted

Preparation of protein nano-objects by assembly of polymer-grafted proteins

Y. Fukui, D. Sakai, K. Fujimoto

Colloids and Surfaces B (Elsevier)  148   503 - 510 2016

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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© 2016 Elsevier B.V. We carried out surface-grafting from proteins and their assembling into objects with unique nanostructured materials (nano-objects). To immobilize polymer-initiating sites, amino groups of bovine serum albumin (BSA) were allowed to react with iniferter groups (BSA-i). Then, graft polymerization of N-isopropyl acrylamide (NIPAM) was performed by light-initiated living radical polymerization from immobilized iniferter moieties of BSA-i. The polymer-grafted BSA (BSA-g-PNIPAM) was assembled into nano-objects through the precipitation of PNIPAM graft chains and their sizes and morphologies were tuned by the chain length, the density and the chemical structure of graft polymers in addition to the environmental conditions such as temperature and pH. It was possible to retain the structures of nano-objects by thermal denaturation via heat treatment. Fluorescent substances were encapsulated in particulate nano-objects (nanoparticles) assembled from PNIPAM-g-BSA and their release could be regulated by tuning pH and temperature. Next, further graft polymerization from PNIPAM-grafted BSA was carried out by living radical polymerization of a cationic monomer, N,N-dimethylamino propyl acrylamide methyl chloride quaternary (DMAPAAQ). The grafted polymer was composed of a block copolymer of PNIPAM and a cationic polymer (PDMAPAAQ) and the gel-like nano-object was generated by increasing temperature. In contrast to PNIPAM-g-BSA, it became insoluble even when the temperature decreased, probably due to the electrostatic association between anionic regions of BSA and cationic regions of graft polymers. Coating of BSA-g-P(NIPAM-b-DMAPAAQ) enabled to form a uniform thin layer over a human hair. A free-standing membrane could be obtained by peeling from a water repellent substrate to create a porous membrane.

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Fine-tuning in mineral cross-linking of biopolymer nanoparticle for incorporation and release of cargo

Y. Fukui, N. Kabayama and K.Fujimoto

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  136   168 - 174 2015

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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© 2015 Elsevier B.V. We developed a mineral cross-linking strategy to prepare a biopolymer-based nanoparticle using calcium phosphate (CaP) as a cross-linker. Nanoparticles were first formed by mixing deoxyribonucleic acid (DNA) with cationic surfactants, and were cross-linked by CaP precipitation. After removal of the surfactants, we carried out the alternative dialysis of nanoparticles against CaCl2 aqueous solution and phosphate buffered solution for further mineral cross-linking. XRD and FT-IR studies revealed that the resultant nanoparticles were produced by mineral cross-linkages of hydroxyapatite (HAp) and the crystal amount and properties such as morphology and crystallinity could be well-controlled by the reaction conditions. Chemical dyes could be incorporated into nanoparticles via their affinities with crystal faces of HAp and DNA. Their release was tunable by crystal amount and properties of mineral cross-linkages. Also, the release could be triggered by mineral dissolution in response to pH. Such a mineral cross-linking will open up a potential way to provide a nanoparticle with versatile functions such as cleavable cross-linking, binding affinity for cargos, and pH-responsive release.

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Development of a particle nano-imprinting technique by core-shell particles

Watanabe, H., Nishimura, M., Fukui, Y., Fujimoto, K.

Langmuir (Langmuir)  30 ( 6 ) 1630-1635 - 1635 2014

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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We developed a particle nanoimprinting technique assisted by the array of core-shell particles. Core-shell particles composed of a solid core of polystyrene and a soft shell were prepared by soap-free emulsion polymerization and subsequently seeded polymerization. By the Langmuir-Blodgett method, particles were arranged into a closely packed 2D array over the water surface and transferred onto a polystyrene (PS) substrate at a regular interval. The PS substrate was heated up above its glass transition temperature (Tg) by either UV irradiation using a high-pressure Hg lamp or heat treatment in a temperature-controlled incubator. It could be observed that a nanopatterned indented surface was formed through the denting of particles into the PS substrate (particle nanoindenting). By the detachment of particles from the substrate by ultrasonication in ethanol, nanoholes were produced over the surface (particle nanoimprinting). The depth and the wall of nanoholes and their interval were tunable by the shell thickness and the 2D packing ratio of core-shell particle monolayers. The contact angle decreased from 70 degrees of the pristine particle monolayer to 13 degrees by the particle nanoindenting, and again increased to 50 degrees by detaching the particles from the substrate to create the nanoholes. The use of nanoholes as zepto-litter volume vessels enabled us to produce and arrange nanocrystals, such as NaCl and CaCO 3 (zepto-reactor). © 2014 American Chemical Society.

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Preparation of nanometre-sized spiral calcium carbonate via controlled mineralization using gel particle as a template

Fukui, Y., Nakada, S., Fujimoto, K.

RSC Advances 4   6027-6030 2014

Research paper (scientific journal), Joint Work, Accepted

Photoreactive nanotool for cell aggregation and immobilization

Sachiko Kaihara, Ayaka Sumimoto, Keiji Fujimoto

Journal of Biomaterials Science-polymer Edition (Journal of Biomaterials Science, Polymer Edition)  24 ( 6 ) 714-725 - 725 2013.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09205063

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We developed a new method to prepare aggregates of specific cells and immobilize cells on a substrate with specific shapes by using a synthetic multifunctional tool, which consisted of a cell adhesive Arg-Gly-Asp (RGD) sequence, a photoreactive phenyl azido group and a biotin group. This chemical nanotool, RGD-2-(6-[biotinamido]-2-(p-azidobenzamido)-hexaneamido)ethyl-1, 3′-dithio-proprionate (RGD-BED) was added to human umbilical vein endothelial cells to bind to receptors via the ligand-receptor interaction. Next a photoimmobilization of the binding RGD-BED was carried out by UV irradiation to covalently couple a phenyl azido moiety of RGD-BED with the neighboring site of the integrin receptor. We found that not only the migration distance of RGD-BED immobilized cells was diminished, but also the cell morphology was fixed on the substrate due to the blocking of integrin receptors by RGD-BED. In contrast, the addition of biocytin-containing polymers, poly(N-methacryloyloxy biocytin-co-dimethylacrylamide), and avidin to the RGD-BED-immobilized cells led to restore cellular migration behavior, probably arising from the increase in the rigidity of the environment surrounding the cells. Furthermore, by the addition of avidin to the RGD-BED-immobilized cells, three-dimensional cell aggregates were formed due to the cross-linking of the biotin moieties of RGD-BED. These results show that RGD-BED is a potential nanotool not only to label and collect targeted cells by the formation of cell aggregates but also to suppress mobility and morphologies of specific cells to be applicable for medical treatments.

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One-pot synthesis of fluorescent hybrid nanoparticles and their assembly into transparent and multi-coloured nanofilms

Yuuka Fukui, Yui Ozawa and Keiji Fujimoto

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  1 ( 6 ) 1231-1237 - 1237 2013

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507534

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We developed a route for one-pot synthesis of fluorescent hybrid nanoparticles and their assembly into a nanofilm by utilizing a fusion and fission-triggered nanoreactor system based on water-in-oil "mini- emulsion". A fluorescent nanocrystal, ZnS:Mn²⁺, was produced in a confined system via fusion and fission of nanodroplets induced by ultrasonication and the amount of nanocrystals formed in each nanoreactor was easily controlled. Then, in situ polymerisation allowed for encapsulation of nanocrystals inside polymer nanoparticles, leading to an efficient surface capping of nanocrystals with polymers and hence a strong light emission under UV irradiation. Also, hybrid nanoparticles with different colours could be created by tuning of Mn²⁺ doping into ZnS nanocrystals, which can give rise to an energy transfer from carboxylic groups of surface capping polymers to the Mn²⁺. These hybrid nanoparticles were then spin-coated to form hybrid nanofilms where nanocrystals were uniformly distributed. The multicolour tuning of nanofilms was achieved simply by mixing nanoparticles with ZnS-derived blue emission and those with ZnS:Mn²⁺-derived orange emission. We believe that our nanoreactor system would offer a viable way in creating fluorescent nanomaterials. © 2013 The Royal Society of Chemistry.

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Preparation of thermosensitive polymer nanoparticles by protein-mimetic cross-linking.

Kaihara, Sachiko; Narikawa, Masatoshi; Fujimoto, Keiji.

Colloid and Polymer Science (Colloid and Polymer Science)  290 ( 13 ) 1317-1325 - 1325 2012.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0303402X

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Thermosensitive nanoparticles were prepared by mimicking protein folding where polymer aggregates were formed by precipitation of thermosensitive polymer chains followed by disulfide formation of their thiol groups. N-Isopropylacrylamide (NIPAM) and methacryloxy succini-mide (SuMA) were co-polymerized and then cysteamine was allowed to react with succinimide moieties of the polymer to render thiol moieties. A polymer aqueous solution precipitated to form nano-sized aggregates by increasing temperature above its lower critical solution temperature (LCST), and their sizes were monodispersed and tunable by the polymer concentration. The aggregates were cross-linked to produce nanoparticles by oxidation of thiol groups in a manner similar to formation of a disulfide bond of protein. As a result, the cross-linked nanoparticles exhibited swelling by decreasing temperature below the LCST of the copolymer. Fluorescein and bovine serum albumin (BSA) were chosen as a small and a large substance, respectively, and were encapsulated into the swollen nanoparticles at 25 °C. Fluorescein was rapidly released from both swollen and shrunken nanoparticles. Although BSA exhibited little release at any temperatures, it was released from nanopar-ticles by adding the reducing agent to dissociate the disul-fide cross-linking and incubating below the LCST. © Springer-Verlag 2012.

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Bio-inspired nanoreactor based on a miniemulsion system to create organic-inorganic hybrid nanoparticles and nanofilms

Fukui Y., Fujimoto K.

Journal of Materials Chemistry (Journal of Materials Chemistry)  22 ( 8 ) 3493 - 3499 2012.02

Research paper (scientific journal), Accepted,  ISSN  09599428

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We developed a novel route to control both mineralization and polymerization inside a nanoreactor based on a miniemulsion system to create organic-inorganic hybrid nanomaterials with diverse structures and morphologies. Nanodroplets of calcium nitrate (Ca(NO 3) 2)/monomer and nanodroplets of sodium carbonate (Na 2CO 3) were separately prepared and suspended in the oil phase. They were mixed through the fusion and fission process triggered by ultrasonication to precipitate a biomineral only inside the nanodroplets. In the presence of monomer, 2-hydroxyethyl methacrylate (HEMA), we could obtain unique structures of nano-sized CaCO 3 particles, which were crystalline with spherical or rod-like shapes or amorphous. By subsequent polymerization, we could encapsulate nano-CaCO 3 inside the polymeric nanoparticles at a desired stage of crystal growth. The preincubation period for CaCO 3 nucleation and growth and the polymerization rate were important factors to manipulate the structures and polymorphs of nano-CaCO 3 inside the hybrid nanoparticles, owing to inhibition of crystal growth and transformation by polymerization of HEMA. Also, the growth of rod-like CaCO 3 inside the nanoparticles led to formation of spheroidal hybrid nanoparticles. By using hybrid nanoparticles as building blocks, we could produce nanofilms containing nano-CaCO 3 with a variety of sizes and structures. Crystal transformation of amorphous CaCO 3 was induced inside the nanofilm by increasing the temperature to above the T g of PHEMA. © 2012 The Royal Society of Chemistry.

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Bio-inspired nanoreactor based on miniemulsion system to create organic-inorganic hybrid nanoparticles and nanofilms

Yuuka Fukui & Keiji Fujimoto

Journal of Materials Chemistry (RSC)  22 ( 8 ) 3493-3499 2012.01

Research paper (scientific journal), Joint Work, Accepted

Production of nanofibers by atto-incubator-assisted assembly of urea using the particle array

S. Watanabe, M. Yamazaki, S. Kaihara and K. Fujimoto

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  399   83-91 - 91 2012

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277757

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We exploited three approaches to fabricate urea nanofibers by using an array of core-shell particles as a template. Core-shell particles were prepared by seeded polymerization and used as an atto-liter scale incubator (atto-incubator) to form nanofibers of urea crystal. Firstly, the mixture of the particle suspension and a urea aqueous solution was spin-coated to promote arrangement of core-shell particles and urea crystallization simultaneously (mix-spin method). Secondly, core-shell particles were arranged by a Langmuir-Blodgett apparatus and then the spin-coating of a urea aqueous solution was performed (LB-spin method). Then, the nano-network of urea crystals was produced by heat treatment at 80 °C. The interparticle distance and the amount of the remaining solution were important to determine the shapes, orientation and amounts of urea crystals. In the LB-natural drying method, one-directionally oriented nanocrystals were obtained over the wide range of the interparticle distance. As preliminary attempts, the obtained nanofibers were used as a template for the production of nanoscale metallic materials. Au nanofibers, nanotubes and nanorods could be obtained by gold sputtering deposition on the urea nanofiber and dissolving urea crystals. Ag-urea hybrid nanofibers were also produced using a mixture of urea and Ag nanoparticles by the modified LB-spin method. © 2012 Elsevier B.V.

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Preparation and Assembly of Poly(arginine)-coated liposomes to Create a Free-standing Bio-scaffold

Yamamoto, Saika; Fukui, Yuuka; Kaihara, Sachiko; Fujimoto, Keiji

Langmuir (ACS)  27 ( 15 ) 9576-82 - 9582 2011.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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We created a free-standing membrane as a novel bioscaffold through the assembly of polymer-coated liposomes. Polyarginine (PArg) possessing a cell-penetrating activity was used to form the polymer layer onto a negatively charged liposome (lipo-PArg). The capsule wall of PArg over liposomes made it possible to improve the mechanical property of capsules and to display deoxyribonucleic acid (DNA) over the vesicle surface through the electrostatic attraction (lipo-PArg-DNA). The release rates of a fluorescent probe encapsulated in lipo-PArg and lipo-P Arg-DNA were tunable by the number of polymeric layers of the capsule walls. To investigate the cell-membrane permeability of lipo-P Arg-DNA, polymer-coated liposomes were incubated with human umbilical vein endothelial cells (HUVECs) at 4 °C. It was found that lipo-P Arg underwent a significant cellular uptake, whereas bare liposomes and liposomes modified with chitosan were incapable of overcoming the plasma membrane barrier. To prepare a free-standing membrane composed of polymer-coated liposomes, a suspension of lipo-PArg-DNA was cast over a mesh hole and dried up. SEM observation revealed that a free-standing membrane was obtained through drying-mediated assembly process without rupturing polymer-coated liposomes inside the membrane. On the other hand, it was not possible to obtain a complete membrane from a mixture of lipo-PArg and DNA. In summary, lipo-PArg-DNA capsules possess versatile functions as a drug carrier, and their assembly enables us to create a free-standing membrane applicable as a bioscaffold. © 2011 American Chemical Society.

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In situ synthesis of polysaccharide nanoparticles via polyion complex of carboxymethyl cellulose and chitosan

Kaihara,S, Suzuki,Y and Fujimoto,K.

Colloids & Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  85 ( 2 ) 343-348 - 348 2011.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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Biocompatible polymer-magnetite hybrid nanoparticles were prepared by means of in situ synthesis of magnetite within polysaccharide hydrogel nanoparticles. Hydrogel nanoparticles were first fabricated by blending high-molecular-weight carboxymethyl cellulose as an anionic polymer, and low-molecular-weight chitosan as a cationic polymer to form polyion complexes (CC particles). These polyion complexes were then chemically crosslinked using genipin, a bio-based cross-linker, to form stable nanoparticles having a semi-IPN structure (CCG particles). Magnetite was lastly synthesized within CCG particles by the coprecipitation method to obtain polymer-magnetite hybrid nanoparticles (CCGM particles). The formations of CC, CCG and CCGM particles were mainly observed by transmittance, absorbance of genipin and TEM, respectively, and their hydrodynamic diameters and zeta-potentials were analyzed. It was confirmed that the hydrodynamic diameters and the zeta-potentials of these particles were significantly influenced by pH of the suspension, which was attributed to the charges of polymers. The diameters of CCGM particles were smaller than 200. nm at any pH conditions, suggesting the possibility to apply them as drug delivery carriers. CCGM particles exhibited the responsiveness to a magnetic field in addition to their high dispersion stability, indicating their potential to be utilized as a biomaterial for hyperthermia. © 2011 Elsevier B.V.

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Control in Mineralization by the Polysaccharide-Coated Liposome via the Counter-Diffusion of ions

Yuuka Fukui and Keiji Fujimoto

Chemistry of Materials (ACS)  23 ( 21 ) 4701-4708 - 4708 2011

Research paper (scientific journal), Joint Work, Accepted,  ISSN  08974756

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We created an organic-inorganic hybrid nanocapsule by utilizing polysaccharide-coated liposomes as a reaction site for the deposition of calcium phosphate (CaP). Phosphate ions were encapsulated in a liposome, followed by the layer-by-layer deposition of chitosan (CHI), dextran sulfate (DXS), or DNA onto the liposome surface. Calcium ions were added to an aqueous suspension of the phosphate ion-incorporated nanocapsules to prepare the nanocapsules that provide a variety of walls for the counter-diffusion of ions and the surface for CaP deposition. As a result, control in biomineralization, such as thickness and crystal properties, over the nanocapsules was achieved by tuning the counter-diffusion of the calcium ions and the phosphate ions through the capsule wall and the surface chemical composition of nanocapsules. Furthermore, we carried out DNA adsorption onto CaP-coated liposomes. DNA was releasable from the nanocapsules because of the dissolution of CaP under acidic conditions. © 2011 American Chemical Society.

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The Preparation of Sugar Polymer-Coated Nanocapsules by the Layer-by-Layer Deposition on the Liposome

Fukui,Y. and Fujimoto,K.

Langmuir (Langmuir)  25 ( 17 ) 10020-10025 - 10025 2009.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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We intended to combine the liposomal preparation and the layer-by-layer deposition to prepare a nanosized capsule. Chitosan (CHI) was deposited to form the cationic polymeric layer onto a negatively charged liposomal surface and further deposition was carried out using anionic polymers dextran sulfate (DXS) or deoxyribonucleic acid (DNA). ζ-Potentials of nanocapsules changed between positive and negative charges at each deposition. FE-TEM revealed that the liposome remained a spherical shape even after the layer-by-layer (LbL) deposition. The capsule wall showed a dramatic increase in stability against the surfactant Triton X-100 compared to a bare liposome, and the stability was controllable by the adsorption amount of the polymer. These suggest that the polymer multilayer was generated on the liposome surface by the layer-by-layer depositions of polysaccharides. The three kinds of chemical substances with different charges, 1-hydroxy pyrene-3,6,8-trisulfonic acid (HPTS), alendronate, and glucose, were encapsulated into nanocapsules and the release was suppressed by the polymeric capsule wall irrespective of charges. The release from DNA-deposited nanocapsules (liponano-CHI-DNA) was clearly increased by raising temperature from 25 to 60 °C. This indicates that the temperature-dependent release was achieved by applying DNA denaturation as a temperaturedependent "switch", which influenced the permeability of the capsule wall. © 2009 American Chemical Society.

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Effect of nano-scale roughness on detachment of a cell sheet from a particle monolayer

Miura M., Fujimoto K.

8th World Biomaterials Congress 2008 (8th World Biomaterials Congress 2008)  1 2008.12

Research paper (scientific journal), Accepted,  ISSN  9781615670802

Formation and recovery of a cell sheet by a particle monolayer with the surface roughness

Manabu MIURA and Keiji FUJIMOTO

Colloids and Surfaces B: Biointerfaces (Elsevir)  66 ( 1 ) 125-133 - 133 2008

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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We studied the topographical effect of roughness displayed by a closely packed particle monolayer on formation of a cell monolayer (cell sheet). Particle monolayers were prepared by Langmuir-Blodgett deposition using particles, which were 527 nm (SA053) and 1270 nm (SA127) in diameter. Human umbilical vein endothelial cells (HUVECs) were seeded at a high density (2.0 × 105 cells/cm2) onto particle monolayers. It was found that cells gradually became into contact with adjacent cells on the SA053 monolayer and the formed cell sheet could be readily detached from the particle monolayer by gentle pipetting. On the other hand, cells adhering onto the tissue culture polystyrene (TCPS) and the SA127 particle monolayer were difficult to peel off. At a low cell seeding density (5.0 × 104 cells/cm2), pre-coating with bovine plasma fibronectin (FN) allowed cell growth on an SA053 particle monolayer, and a confluent monolayer was able to be peeled as a cell sheet from the particle monolayer just by pipetting. By immunostaining of human fibronectin, we found that fibronectin was secreted and concentrated onto the substrate side of a cell sheet. The obtained cell sheet adhered and grew on the TCPS again within 20 min. © 2008 Elsevier B.V. All rights reserved.

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Preparation of Bionanocapsules by the Layer-by-Layer Deposition of Polypeptides onto a Liposome

FUJIMOTO KEIJI,TOYODA TOMONORI,FUKUI YUUKA

Macromolecules (Macromolecules)  40 ( 14 ) 5122-5128 - 5128 2007.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00249297

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Hollow nanoparticles (bionanocapsules) were prepared using liposomes as a template for the layerby-layer deposition of biopolymers. We carried out the alternative deposition of poly-L-lysine (PLys) and poly-L-aspartic acid (PAsP) onto a negatively charged liposome, which was prepared from dilauroyl phosphatidic acid (DLPA) and dimyristoylphosphatidylcholine (DMPC). Efficient separation of nanocapsules from unbound polymers was achieved by ultrafiltration. ζ-Potentials of nanocapsules changed between positive and negative charges at each deposition. FE-TEM revealed that the liposome was covered with a thin polymeric layer. A fluorescent probe, l-hydroxypyrene-3,6,8- trisulfonic acid (HPTS), was encapsulated into nanocapsules. The release of HPTS was suppressed by the polymer deposition, and the release rate was tunable by coverage of the first PLys layer and the ratio of DLPA. © 2007 American Chemical Society.

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Producing and patterning of nanocrystals using "atto-incubators" composed of the core-shell particles

Fujimoto K., Katsuta I., Adachi T.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  290 ( 1-3 ) 118 - 124 2006.11

Research paper (scientific journal), Accepted,  ISSN  09277757

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We developed a small incubator of an atto-liter scale (atto-incubator) for producing and arraying nanosized materials. The core-shell particles with a hydrogel shell were used as an incubator to isolate individual droplets of the solution and to specify the nucleation sites for crystallizing NaCl and urea solutes. Their array was deposited on a polystyrene dish by the spin-coating of a particulate dispersion, and then dried to remove any residual solvent. When the array was exposed to a solution, the hydrogel shell absorbed the solution and swelled. Nucleation of the nanocrystals at the particles occurred as the arrays were dried again. We obtained single crystals as a rectangular solid with a uniform shape at 8 wt.% NaCl. By the use of atto-incubators for urea crystallization, we obtained nanosized fibers of a single crystal, which were aligned in the direction of the flow. The atto-incubator could allow us to control the nucleation region and the size and shape of the crystals. © 2006 Elsevier B.V. All rights reserved.

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Subcellular topological effect of particle monolayers on cell shapes and functions

Miura, M and Fujimoto, K

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  53 ( 2 ) 245-253 - 253 2006

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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We studied topological effects of subcellular roughness displayed by a closely packed particle monolayer on adhesion and growth of endothelial cells. Poly(styrene-co-acrylamide) (SA) particles were prepared by soap-free emulsion copolymerization. Particle monolayers were prepared by Langmuir-Blodgett deposition using particles, which were 527 (SA053) and 1270 nm (SA127) in diameter. After 24-h incubation, cells tightly adhered on a tissue culture polystyrene dish and randomly spread. On the other hand, cells attached on particle monolayers were stretched into a narrow stalk-like shape. Lamellipodia spread from the leading edge of cells attached on SA053 monolayer to the top of the particles and gradually gathered to form clusters. This shows that cell-cell adhesion became stronger than cell-substrate interaction. Cells attached to SA127 monolayer extended to the reverse side of a particle monolayer and engulfed particles. They remained immobile without migration 24 h after incubation. This shows that the inhibition of extensions on SA127 monolayer could inhibit cell migration and cell proliferation. Cell growth on the particle monolayers was suppressed compared with a flat TCPS dish. The number of cells on SA053 gradually increased, whereas that on SA127 decreased with time. When the cell seeding density was increased to 200,000 cells cm-2, some adherent cells gradually became into contact with adjacent cells. F-actin condensations were formed at the frame of adherent cells and the thin filaments grew from the edges to connect each other with time. For the cell culture on SA053 monolayer, elongated cells showed a little alignment. Cells showed not arrangement of actin stress fibers but F-actin condensation at the contact regions with neighboring cells. Interestingly, the formed cell monolayer could be readily peeled from the particle monolayer. These results indicate that endothelial cells could recognize the surface roughness displayed by particle monolayers and the response was dependent on the pitch of particle monolayers. © 2006 Elsevier B.V. All rights reserved.

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A reduction-triggered delivery by a liposomal carrier possessing membrane-permeable ligands and a detachable coating

Maeda, T. and Fujimoto, K.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  49 ( 1 ) 15-21 - 21 2006

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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To control the cellular uptake of drugs and genes, we synthesized a liposomal carrier possessing membrane-permeable ligands and a detachable poly(ethylene glycol) (PEG) coating. For the detachable coating, a lipid having a thiolytic cleavable spacer (PEG-S-S-DOPE) was synthesized by the reaction of dioleoylphosphatidylethanolamine (DOPE) with a PEG chain via a disulfide linkage. The liposomes were prepared from a mixture of dipalmitoylphosphatidylcholine (DPPC), DOPE, PEG-S-S-DOPE, and cholesteryl hemisuccinate (CHEMS). The octamer (R8 peptide) of arginine was chosen as the membrane-permeable ligand and covalently immobilized onto the CHEMS portion of the liposome surface (PEG-S-S-R8-liposome). The disulfide bond of the PEG chain was cleaved to display the R8 peptides on the liposome surface by adding a reducing agent such as l-cysteine, and thereby internalization of the liposomes was significantly facilitated. When l-cysteine was added to the mixture of cells and the liposome that incorporated plasmids encoding the enhanced green fluorescence protein (pEGFP), the expression of EGFP was low but could be observed in almost 100% of the cells. © 2006 Elsevier B.V. All rights reserved.

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Producing and patterning of nanocrystals using “atto-incubators” composed of the core-shell particles

Keiji FUJIMOTO*, Izumi KATSUTA and Tomoko ADACHI

Colloids and Surfaces A: Physicochemical and Engineering Aspects 290   118-124 2006

Research paper (scientific journal), Joint Work, Accepted

Preparation and functionalization of hollow nanoparticles fabricated by the layer-by-layer deposition

Toyoda T., Fujimoto K.

Polymer Preprints, Japan (Polymer Preprints, Japan)  54 ( 2 ) 5163 - 5164 2005.12

Research paper (scientific journal), Accepted

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To prepare hollow particles in a nano size, we used a layer-by-layer deposition. Liposomes were used as a template for this deposition. At first, negatively charged liposomes composed of dilauroyl phosphatidic acid (DLPA) and dimyristoyl phosphatidylcholine (DMPC) were prepared with the extrusion method. Then, polyelectrolytes were adsorbed on the liposomal template. Poly-L-lysine (PLys) and poly-L-aspartic acid (PAsp) were chosen as adsorbates to make a capsule of the biopolymers. When the alternative adsorption of PLys and PAsp on the liposomes was repeated for thickening the capsule layer, their ζ-potentials changed between positive and negative charges at each deposition. To investigate the release behavior from the liposomes and the liposome-polypeptide complexes, we prepared liposomes incorporating 1-hydroxypyrene-3,6,8-trisulfonic acid (HPTS). It was found that the release experiment to the buffered solutions was related to the adsorption of polymers. When the liposomes were completely covered with PLys, the release was suppressed.

Detection of a K-ras point mutation employing peptide nucleic acid at the surface of a SPR biosensor

Sato Y., Fujimoto K., Kawaguchi H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  27 ( 1 ) 23 - 31 2003.01

Research paper (scientific journal), Accepted,  ISSN  09277765

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A fundamental study of the usage of peptide nucleic acid (PNA) and DNA at the surface of a surface plasmon resonance (SPR) biosensor for detecting a specific point mutation in the K-ras gene for early detection of cancers is reported. The extents of hybridization using DNA analytes of different length which are targets were studied at 25 and 40°C. The 15mer PNA ligand immobilized to the surface of the sensor had a high ability to detect a 11mer DNA analyte point mutation at 25 and 40°C. On the contrary, when DNA was used as a ligand, detection was only confirmed at 40°C which indicates that the difference of melting temperature (Tm) between the complementary and mismatched analyte was a key factor for point mutation detection. This also implied the decrease of Tm by immobilizing a probe to a surface since it was below the one in solution. Therefore, effects from the surface are seen in this system and the surrounding environment makes a difference to the discrimination process. To understand the process in detail, kinetic analysis was performed and association constants were found to be larger for DNA ligands implying the effect coming from the sensor surface. In this case negative charges of the carboxyl groups of the matrix had a tendency to repel negatively charged DNA ligands. Affinity constants (KA) were calculated and as expected, the ratio of KA between the complementary and mismatched analyte was of the order of 102 for PNA interacting with 11mer analytes, making it a promising probe for genetic diagnosis. These results indicate the importance of the effect of analyte length, temperature and the environment surrounding the ligand for accomplishing an all or none single base mismatched detection system. © 2002 Elsevier Science B.V. All rights reserved.

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Thermosensitive two-dimensional arrays of hydrogel particles

Nakahama K., Fujimoto K.

Langmuir (Langmuir)  18 ( 26 ) 10095 - 10099 2002.12

Research paper (scientific journal), Accepted,  ISSN  07437463

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We prepared two-dimensional (2D) arrays composed of nanoscale hydrogel particles as a model of suprastructured assemblages. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel particles and the core-shell particles, which possess a rigid polystyrene core encased in a PNIPAM hydrogel shell, were selected as components for arrays. Below and above 32°C, these two kinds of particles swelled and shrank, respectively, due to temperature-dependent solubility of a PNIPAM chain. The particle dispersion was spread and then compressed to produce particle monolayers closely packed at the air-water interface. To study thermal behavior of 2D arrays, surface pressure and surface area for obtained 2D arrays were measured at 40 and 25°C with leaving the monolayer on the water surface. Both of them varied in response to temperature, indicating that each particle of 2D arrays swelled and shrank at the water surface. Although the pressure and the area for the 2D array of PNIPAM hydrogel particles exhibited great responses at the beginning, they gradually decreased and eventually disappeared with repeating the temperature cycle, due to particle coalescence. On the other hand, the 2D array of core-shell particles maintained the thermosensitive response without relaxation though its variation between 40 and 25°C was still small. By assembling the mixture of PNIPAM and core-shell particles into the monolayer, the 2D array with large and steady responses could be obtained.

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Changes in cell membrane and cellular lipids in apoptotic cells induced by dolichyl phosphate differ from findings in cells induced by etoposide

Horiuchi,A., Yasugi,E., Iwasaki,C., Fujimoto,K., and Oshima,M.

J. Oleo Sci. (Journal of Oleo Science)  51 ( 1 ) 35-42 - 42 2002

Research paper (scientific journal), Joint Work, Accepted,  ISSN  13458957

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Cell membrane fluidity and changes of cellular lipids of U937 cells during apoptosis are compared between the cells treated with dolichyl phosphate (dol-P) and etoposide. Dol-P induced lateral cell membrane perturbation immediately after addition and continued for at least 40 min. However, etoposide induced apoptosis without increase in cell membrane fluidity. Phosphatidylethanolamine was translocated together with phosphatidylserine after 4 hr of treatment in both dol-P and etoposide treated cells. The concentration of lipid levels changed in dol-P-induced cells and the cholesterol/phospholipid ratio almost doubled. Conversely, none of the phospholipid and cholesterol levels changed in etoposide treated cells. Although both dol-P and etoposide induce apoptosis, dol-P, but not etoposide, appeared to function as a modulator of membrane fluidity and to change membrane constituents and membrane physiology during the course of apoptosis.© 2002, Japan Oil Chemists’ Society. All rights reserved.

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Amphoteric initiators suitable for emulsifier-free emulsion polymerization and the properties of the resulting latices

Fang S., Fujimoto K., Kondo S., Shiraki K., Kawaguchi H.

Colloid and Polymer Science (Colloid and Polymer Science)  279 ( 6 ) 589 - 596 2001

Research paper (scientific journal), Accepted,  ISSN  0303402X

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The soap-free emulsion polymerizations of styrene (St) and acrylamide (AAm) or methyl methacrylate (MMA) were carried out in the presence of three kinds of amphoteric initiators, and the polymerization kinetics and the colloidal properties of the latices produced were emphatically investigated. It was found that the number of carbon atoms between the amidino and carboxyl groups in each initiator exhibited an appreciable effect on the dissociation as well as on the solubility of the initiator in water, and therefore, that the properties of the colloidal particles depended on the structure of the initiators used. All the copolymerization runs, except for the polymerization using (2,2′-azobis(N-(2-caboxyethyl)-2-methylpropionamidine) under a strongly alkali condition, gave amphoteric latices, which indicated higher critical flocculation concentrations at lower or higher pHs than at a medium pH. The surface charge density measured by titration for poly(St/MMA) particles was about 3-10 times as high as that for the poly(St/AAm) ones, though these were prepared under the same conditions other than the monomer composition. The influence of the polymerization pH on both the polymerization rate and the surface charge density of the resulting latices was negligible even if the constants of the decomposition rate and the dissociation of the amphoteric initiators strongly depended on the pH of the medium.

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Preparative techniques of nanoparticles for drug delivery

Fujimoto K.

Drug Delivery System 16 ( 3 ) 155 - 164 2001

ISSN  09135006

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This review presents the outstanding contributions and preparative techniques in mainly polymeric nanoparticles used as drug delivery systems. Nanoparticles discussed here vary in the diameter from 10 to 1000 nm. The formation of nanoparticles composed of one polymer chain and many polymer chains is reviewed in terms of the intrapolymer and interpolymer self-association and methods of preparation and drug loading are briefly described. Several methods to prepare nanoparticles by dispersing the preformed polymers are also demonstrated, e. g., solvent evaporation method and solvent diffusion method. Particles can be produced via a polymerization process from monomers. The preparative techniques for nanoparticles include emulsion polymerization, miniemulsion polymerization, and microemulsion polymerization. For drug incorporation, preparation of core-shell nanoparticles is also described. As a novel approach to fabricate nanoparticles, supra-molecular structured materials such as dendrimers are introduced. Finally, our attempts to utilize nanoparticles for cell-death induction are stated and the concept of ‘cell-death programmed cell’ is proposed in this literature. © 2001, THE JAPAN SOCIETY OF DRUG DELIVERY SYSTEM. All rights reserved.

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Novel preparation of nonsymmetrical microspheres using the Langmuir-Blodgett technique

Nakahama K., Kawaguchi H., Fujimoto K.

Langmuir (Langmuir)  16 ( 21 ) 7882 - 7886 2000.10

Research paper (scientific journal), Accepted,  ISSN  07437463

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We have utilized the Langmuir-Blodgett (L-B) technique to develop the generic technology that can prepare nonsymmetrical microspheres. The dispersion of the microspheres in butanol was spread on a water surface and compressed by a L-B apparatus to obtain a microsphere monolayer. Then, an amphiphilic and reactive polymer was prepared by terpolymerization of N-octadecyl acrylamide, p-nitrophenyl acrylate, and 2,2,2,-trifluoroethyl methacrylate. A stable polymer monolayer was transferred onto the microsphere monolayer by the L-B technique. It was found from contact angle measurement that the surface became hydrophobic with deposit of the terpolymer. X-ray photoelectron spectroscopy data demonstrated that only the top side of modified microspheres was covered with the terpolymer.

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Emulsifier-free emulsion copolymerization of styrene and acrylamide using an amphoteric initiator

Fang S., Fujimoto K., Kondo S., Shiraki K., Kawaguchi H.

Colloid and Polymer Science (Colloid and Polymer Science)  278 ( 9 ) 864 - 871 2000.09

Research paper (scientific journal), Accepted,  ISSN  0303402X

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Emulsifier-free emulsion copolymerization of styrene (St) and acrylamide (AAm) has been investigated in the presence of an amphoteric water-soluble initiator, 2,2'-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine]hydrate (VA057). The kinetics of polymerization and the colloidal properties of the resulting latices were studied and compared with the cases using ionic initiators. When adopting the amphoteric initiator at pHs lower than 10, stable amphoteric poly (St/AAm) latices, evidenced by the electrophoretic mobility, were prepared directly. Meanwhile, almost the same conversion versus time curves appeared and there were no apparent differences in the final particle sizes for those polymerizations, whereas in the polymerization at pH 10, a much lower rate of copolymerization and a larger size of particles were observed. The surface charge density and the growth rate of latex particles produced with VA057 at pH<10 were comparable to those of the particles with a cationic initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride, but were apparently lower than those with an anionic initiator, potassium persulfate, when the polymerizations were carried out under corresponding conditions. The number of initiator fragments incorporated onto the particle surfaces was independent of polymerization pH, except for pH 10. The abnormal performance of VA057 at pH 10 was attributed to its degradation due to hydrolysis.

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Inspiration provided by the living world and design of synthetic materials

Fujimoto K.

Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme 45 ( 11 ) 1859 - 1864 2000.08

ISSN  00399450

Modification and functionalization of cell surfaces by polymer chains

6th World Biomaterial Congress  2000.05

Single Work, Accepted

Emulsifier-free emulsion copolymerization of styrene and acrylamide using an amphoteric initiatorsl

Fang,S.-J., Fujimoto,K., Kondo,S., Shiraki,K., and Kawaguchi,H.,

Colloid Polym. Sci., 278,(2000)    864-871 2000

Joint Work, Accepted

Renaturation of Reduced Ribonuclease A with Microsphere-Induced Refolding System

Shimizu,H., Fujimoto,K., and Kawaguchi,H

Biotechnology Progress 16, (2000).    248-253 2000

Joint Work, Accepted

Improved refolding of denatured/reduced lysozyme using disulfide-carrying polymeric microspheres

Shimizu,H., Fujimoto,K., and Kawaguchi,H.,

Colloids and Surfaces B: Biointerfaces 18, (2000). (Colloids and Surfaces B: Biointerfaces)  18 ( 2 ) 137-144 - 144 2000

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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Many proteins tend to aggregate during refolding, especially at high protein concentrations. To reduce aggregation and improve the refolding yields, denatured/reduced lysozyme at 0.5 mg ml-1 was refolded using disulfide-carrying microspheres. The extent of renaturation was evaluated by measuring the content of recovered soluble protein and its enzymatic activity. Addition of the dispersion of the modified microspheres to the aqueous solution of reduced lysozyme resulted in the binding of the proteins on the microsphere surface, followed by the spontaneous release of the bound proteins. As a consequence, a 10% active enzyme was obtained. However, no renaturation occurred without the microspheres due to aggregation. Moreover, when glutathione was added 20 h after incubation with the microspheres, the refolding yields could increase to ~40%. These results indicate that the disulfide moieties of the microspheres play an important role in preventing the aggregation process and catalyzing the refolding reaction through the thiol-disulfide interchange reactions. Copyright (C) 2000 Elsevier Science B.V.

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A novel preparation of non-symmetrical microspheres using the Langmuir-Blodgett technique

Nakahama,K., Kawaguchi,H., and Fujimoto,K.,

Langmuir 16, (2000)    7882-7886 2000

Joint Work, Accepted

Control of cell death by the smart polymeric vehicle

Fujimoto,K., Iwasaki1,C., Arai1,C., Kuwako,M., and Yasugi,E.,

Biomacromolecules 1, (2000) (Biomacromolecules)  1 ( 4 ) 515-518 - 518 2000

Research paper (scientific journal), Joint Work, Accepted,  ISSN  15257797

　View Summary

We report a novel drug delivery system for apoptosis induction by a "smart" polymer vehicle possessing thermosensitivity and bioaffinity. The polymer chain was prepared by copolymerization of N-isopropyl-acrylamide and N-methacryloyloxysuccinimide. Cell-adhesive RGDS peptide was conjugated with the copolymer as a ligand model for bioaffinity. When the temperature was increased, nanoscale aggregates precipitated from a copolymer aqueous solution. Either dolichyl phosphate (dol-p), which is an apoptotic inducer, or dolichol was added to aggregates at around the precipitation temperature (31°C), and the temperature was raised to 37°C for incorporation. Aggregates incorporating dol-p or dolicol were added to a human promonocytic leukemia U937 cell suspension at 37°C. When the temperature was lowered to 25 °C, cells underwent apoptosis in the presence of Ca2+. Probably, copolymer vehicles were concentrated on a cell surface through the binding of RGDS and integrin and the release of lipid inducers was caused by the disruption of vehicles in response to temperature.

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Preparation of partly hydrophobized, crosslinked polyacrylamide particles by terpolymerization of acrylamide/ N,N-methylenebisacrylamide/styrene in inverse microemulsion

Bartoň J., Kawamoto S., Fujimoto K., Kawaguchi H., Capek I.

Polymer International (Polymer International)  49 ( 4 ) 358 - 366 2000

Research paper (scientific journal), Accepted,  ISSN  09598103

　View Summary

Free-radical polymerization of a termonomer system comprising acrylamide (AAm) N,N′-methylenebisacrylamide (MBAAm) and styrene (S) initiated by water-soluble ammonium peroxodisulphate (APS) or by toluene-soluble dibenzoyl peroxide (DBP) in inverse microemulsion (toluene/ S/AOT//water//AAm/MBAAm), leads to the formation of partly hydrophobized crosslinked polymer particles of tailored chemical composition, degree of crosslinking and polymer particle size. Styrene strongly decreases the rate of terpolymerization, while the presence of MBAAm has almost no effect on the polymerization rates observed. This conclusion is valid for both APS and DBP initiators. Increase of the S/T mass ratio (T is toluene) in inverse microemulsion leads to an increase of polymer particle diameter from about 20 nm to about 50 nm attributed to toluene swelling of the styrene-rich structural moieties of AAm-co-S copolymer located on the surface of polymer particles. Polymerization kinetics measurements pointed to the important role of exiting water soluble AAm and MBAAm monomer radicals generated by thermal decomposition of APS in water pools of inverse micelles for initiation of polymerization reactions of sparingly water-soluble S monomer in the oil-phase of the inverse microemulsion. It was shown that the polymerization and copolymerization reactions of S in the presence of AAm and/or MBAAm are effectively initiated by water-soluble APS and also by oil-soluble DBP initiators. During dialysis the polymerized single-phase water/oil Winsor IV inverse microemulsion gradually converts itself into a two-phase oil/water Winsor I dispersion system with volume fraction of aqueous phase Φaw≈0.950. The water phase contains water swelled, crosslinked polymer particles of diameters 80-300 nm. During dialysis, toluene and the sodium salt of bis(2-ethyl hexyl)sulphosuccinic acid (AOT) partition between the oil phase of the dialysed dispersion system and the water dialysate. After evaporation of water from the dialysed inverse microemulsion, solid, dried, crosslinked polymer particles in the form of a transparent film, almost uncontaminated by AOT surfactant, were obtained. © 2000 Society of Chemical Industry.

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Versatility of thermosensitive particles

Kawaguchi H., Kisara K., Takahashi T., Achiha K., Yasui M., Fujimoto K.

Macromolecular Symposia (Macromolecular Symposia)  151   591 - 598 2000

Research paper (scientific journal), Accepted,  ISSN  10221360

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Poly(N-isopropylacrylamide) (PNIPAM) particles are highly swollen below the transition temperature in water so that they become very soft and hydrophilic, but collapsed above the transition temperature to become hard and hydrophobic. Such changes bring about the discontinuous temperature dependence of adsorbability of protein, activity of immobilized enzyme, cell activating ability of the particles. The transition temperature of PNIPAM was changed by binding something to the chain end and this property was used to control the enzyme activity with temperature. Sudden change in the topology of the particle surface by quick temperature change gave excess stimulus to cells when the change was transmitted straightly to the cells.

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Renaturation of reduced ribonuclease A with a microsphere-induced refolding system

Shimizu H., Fujimoto K., Kawaguchi H.

Biotechnology Progress (Biotechnology Progress)  16 ( 2 ) 248 - 253 2000

Research paper (scientific journal), Accepted,  ISSN  87567938

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We intended to refold reduced ribonuclease A (RNase A) using polymeric microspheres. Polymeric microspheres were allowed to react with dithiothreitol (DTT) to immobilize the disulfide and thiol moieties on their surface. The fully reduced RNase A was added to the dispersion of the modified microspheres. Protein refolding and renaturation were estimated by the change in the number of disulfide bonds of RNase A and the recovery of the enzymatic activity, respectively. Without microspheres, the activity gradually recovered with the increase in the number of disulfide bonds. However, the formation of disulfide bonds of reduced RNase A was accelerated by adding the modified microspheres, and the rate of renaturation was increased depending on the amount of charged DTT and the reaction time of the immobilization. These results indicate that modified microspheres significantly catalyze the recovery of active RNase A from the reduced form. The protein adsorption data demonstrated that the disulfide moieties of the modified microspheres react with the thiol moieties of the reduced RNase A to form a mixed disulfide. The thiol/disulfide exchange reaction can possibly proceed at the microsphere/protein interface, resulting in the formation of a correct three-dimensional structure.

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Using Polymeric Microspheres for Renaturation of Reduced Proteins

The Fourth Asian Symposium on Biomedical Materials in Singapore (Kobunshi Kankokai)    106-107 1999.12

Joint Work, Accepted

Cell Surface Modification by Reactive Polymer Chains and Control of Cell Recognition and Response

The Fourth Asian Symposium on Biomedical Materials in Singapore (Kobunshi Kankokai)    106-107 1999.12

Joint Work, Accepted

DNA-carrying latex particles for DNA diagnosis 3. Detection of point mutant DNA using an indirect labeled probe

Hatakeyama M., Iwato S., Hanashita H., Nakamura K., Fujimoto K., Kawaguchi H.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  153 ( 1-3 ) 445 - 451 1999.08

Research paper (scientific journal), Accepted,  ISSN  09277757

　View Summary

We have developed DNA-carrying affinity latex particles for distinction of point-mutational genes, but point-mutational DNA was not full length in the sample obtained from patients and had to be labeled. To overcome this disadvantage, we used an indirect labeled probe in this study. The indirect labeled probe was complementary with a 5' end region of 70mer DNA involved in the K-ras gene. The indirect labeled probe did not play a role of direct detection of point-mutational DNA, but the complex of 70mer DNA and an indirect labeled probe hybridized with single-stranded DNA immobilized on latex particles. This study suggests practical DNA diagnosis by using DNA-carrying affinity latex. Copyright (C) 1999 Elsevier Science B.V. All rights reserved.

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Cell membrane dynamics and the induction of apoptosis by lipid compounds

Fujimoto,K., Iwasaki,C., Kawaguchi,H., Yasugi,E., and Oshima,M.

FEBS Letters (FEBS Letters)  vol.446 ( 1 ) 113-116 - 116 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00145793

　View Summary

特定の脂質は細胞にアポトーシスを誘導した。これらの脂質は培養液中でサブミクロンサイズのエマルションを形成して細胞膜に分配することがわかった。さらにこの分配に際して細胞膜の動的な変化が極めて短時間で起こり、アポトーシス発現のマーカーとなることがわかった。

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Refolding of protein using thiol-carrying latex particles

Shimizu H., Fujimoto K., Kawaguchi H.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier) (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  vol.153 ( 1-3 ) 421-427 - 427 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277757

　View Summary

Mis-folded ribonucleaseA (RNaseA) could be refolded by the use of microspheres onto which sulfhydryl and disulfide groups were introduced. Modified microspheres were first added to a mis-folded RNaseA aqueous solution. After incubation, proteins were separated from the solution by centrifugation and the enzymatic activity of recovered RNaseA was measured. The refolding was clearly induced by the modified microspheres. On the contrary, virtually no refolding was observed on the unmodified microspheres. Possibly, sulfhydryl groups on the microsphere can preferentially attack disulfide bonds in mis-folded RNaseA, and this attack can trigger protein refolding through thiol-disulfide exchange reactions at the microsphere-protein interface. Copyright (C) 1999 Elsevier Science B.V. All rights reserved.

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Cell response to micropatterned surfaces produced with polymeric microspheres

Miyaki M., Fujimoto K., Kawaguchi H.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier) (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  Vol.153 ( 1-3 ) 603-608 - 608 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277757

　View Summary

Surface topography plays an important role in cell function. We fabricated microstructured patterns from monolayers of polymeric microspheres, which were arranged on a flat polystyrene dish. Such patterns could be quickly formed by spin-coating microspheres and were easily controlled by changing the size of the settled microspheres. Polystyrene (PS) microspheres having different sizes were prepared by soap-free emulsion polymerization in the presence of sodium chloride with different concentrations. The zeta potential of these microspheres was approx. -25 mV regardless of their diameter. Electron microscopic observations revealed that the microspheres were deposited on a PS dish in hexagonally-packed monolayers with a pitch equal to the diameter of each microsphere. The water contact angles gradually decreased with an increase of the pitch. To investigate the topographical effect of these surfaces on the neutrophil-like cell function, microscopic observations and measurements of active oxygen released from cells were carried out. Microscopic observation revealed that spreading cells adhered on PS microsphere-settling surfaces as well as on a PS film. As for active oxygen release, cell response to a PS microsphere-settling surface depended on the diameter of settling microspheres and showed a maximum for diameters of approx. 1 μm. This tendency was observed in phosphate-buffered solutions both with and without serum. Continuous activation which followed by the initial attachment seems to relate to the change of cytoskeletal systems. These results indicate that cells recognize the roughness of the micropatterned surface covered with PS microspheres, and a pitch between the tops of settled microspheres is an important factor for cell recognition. Copyright (C) 1999 Elsevier Science B.V. All rights reserved.

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DNA-carring latex particles for DNA diagnosis 3. Detection of point mutation DNA using an indirect labeled probe

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier) vol.153   445-451 1999

Joint Work, Accepted

Dispersion polymerization of methyl methacrylate using macro-azo-initiator

Nakamura K., Fujimoto K., Kawaguchi H.

Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier) (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  vol.153 ( 1-3 ) 195-201 - 201 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277757

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Poly(dimethylsiloxane)-containing macro-azo-initiator was used in dispersion polymerization of methyl methacrylate. Stable microspheres were obtained when the solvents had solubility parameters in the range of 7.4-8.2. The microspheres were stabilized by a stabilizer formed in-situ, that is, polydimethylsiloxane-block-poly(methyl methacrylate). Copyright (C) 1999 Elsevier Science B.V. All rights reserved.

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Preparation of unsymmetrical microspheres at the interfaces

Fujimoto K., Nakahama K., Shidara M., Kawaguchi H.

Langmuir (Americal Chemical Society) (Langmuir)  vol.15 ( 13 ) 4630-4635 - 4635 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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Many synthetic microspheres are spherical and symmetrical because of the thermodynamical limitations of the reaction systems. We developed modification techniques to prepare spherical microspheres with intrinsic unsymmetry, for example, a microsphere with both an anionic and a cationic part. The modification was performed at the liquid-solid interface. Reactive microspheres with p-nitrophenyl moieties were settled onto the IgG-preadsorbed substrate, and the reaction between the activated ester moieties and IgG molecules proceeded only at the interface upon attachment. After the reaction, the modified microspheres were detached from the substrate with ultrasonication. In another modification at the air-water interface, the dispersion of reactive microspheres in ethanol was first spread on a water surface to produce the monolayer of microspheres, and then hydrolysis at the water side of the monolayer was performed by adding a NaOH aqueous solution to the subphase. After this unsymmetrical hydrolysis, we carried out IgG immobilization with the remaining reactive moieties. In both interface methods, the immobilized IgG molecules were labeled with colloidal gold particles conjugated with anti-IgG antibodies. Transmission electron microscopy indicated that gold particles could be observed on only the immobilized side. Small microspheres were coupled to the reactive microsphere, and its unsymmetry was confirmed by scanning electron microscopy. Such unsymmetrical microspheres will be applicable to the electrical rheology, diagnosis, display technology, and creation of functional devices through the assembling of microspheres.

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Smart latex es for bioseparation

Kawaguchi H., Fujimoto K.

Bioseparation (Kluwer Academic Publishers) (Bioseparation)  vol.7 ( 4-5 ) 253-258 - 258 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0923179X

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Monodisperse, thermosensitive microspheres with sub-micron diameters are used for separation and collection of proteins and other biomolecules. The thermosensitivity gives the microspheres two valuable features. One is the controllability of affinity between microsphere and protein with temperature. The quality and quantity of proteins to be adsorbed on the microspheres can be controlled with temperature. The other feature is reversible control of dispersion stability. Microspheres which have adsorbed target proteins in the dispersion can be easily recovered by changing temperature.

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Stimuli-Response of Microsphere Having Poly(N-isopropylacrylamide) Shell

Matsuoka H., Fujimoto K., Kawaguchi H.

Polymer Journal (The Society of Polymer Science, Japan) (Polymer Journal)  vol.31 ( 11 pt 2 ) 1139-1144 - 1144 1999

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00323896

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Several kinds of submicron-sized microspheres having environment-sensitive shells were prepared and the effect of shell structure on the properties of microspheres was studied. The shell was composed of crosslinked or hairy poly(N-isopropyl acrylamide) (PNIPAM) whose lower critical solution temperature was about 32 °C but depended on the architecture of the shell. The resposivity of the shell to the change in environmental condition was sluggish when the shell was crosslinked. The decrease in the crosslink density of the shell was slightly effective in sharpening the response. But even non-crosslinked, hairy PNIPAM shell did not exhibit discontinuous transition at the critical condition. The response of hairy PNIPAM shell to environmental change was drastically sharpened by incorporating a slight amount of acrylic acid (AAc) in the hair.

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異方性微粒子の作製とそのはたらき

藤本啓二、中濱数理、設楽美和子、川口春馬

ポバール会記録 vol.110   19-25 1998.12

Joint Work

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微粒子に新たな自由度を与えるための一つの方策として、微粒子への異方性の導入を提案した。このような異方性処理によって上半球がプラス、下半球がマイナスといったものや、ある部分にだけ特定の高分子鎖が生えたものといった両親媒性を有するものが作製できると考えられる。この両親媒性は一個の微粒子に運動性をはじめとする様々な特異性を付与するために有効であろう。

アニオン性ポリマーによるマクロファージの活性化

藤本啓二、向井章、川口春馬、竹内勤

高分子加工 vol.47 ( No.8 ) 11-15 1998.08

Research paper (scientific journal), Joint Work

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合成したアニオン性ポリマーについて、その免疫系（主にマクロファージ）への作用の一端を知ることができた。特に寄生虫感染の初期においてはこのポリマーはマクロファージ等の活性化を誘導して防御に努めている。しかしその効果は長くは続かず、その後は主に細胞性免疫系の活性化を通して本質的な抗寄生虫活性を発現できるようになると考えられた。

DNA-carrying latex particles for DNA diagnosis 2. Distinction of normal and point mutant DNA using S1 nuclease

Hatakeyama M., Nakamura K., Iwato S., Handa H., Fujimoto K., Kawaguchi H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  10 ( 3 ) 171 - 178 1998.02

Research paper (scientific journal), Accepted,  ISSN  09277765

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In our previous paper, we reported a DNA diagnosis system in which fully complementary DNA was selectively hybridized with a DNA immobilized on latex particles but one-point mutant DNA was not. The system, however, included a few disadvantages. To overcome them, a single-strand DNA cleaving enzyme (S1 nuclease) was used in this study. S1 nuclease cleaved the unhybridized and loosely hybridized DNA's on the particles and enabled the determination of the fully complementary hybrid. This method saved us a troublesome labeling of the samples.

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Monodisperse Microspheres Exhibiting Discontinuous Response to Temperature Change

Matsuoka,H., Fujimoto,K., Kawaguchi,H.

Polymer Gel Network, 6(1998) (Polymer Gels and Networks)  6 ( 5 ) 319-332 - 332 1998

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09667822

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これまで作製されてきた感温性ゲル微粒子のサイズ変化は連続的であった。そこで架橋点をなくするためにコア微粒子からのN-イソプロピルアクリルアミドのグラフト重合を行った。さらにモノマーにアクリル酸を少量加えることにより不連続なサイズ変化を示す微粒子の作製が出来るようになった。

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DNA-carrying latex particles for DNA diagnosis. 1. Separation of normal and point mutant DNAs according to the difference in hybridization efficiency

Hatakeyama,M., Iwato,S., Fujimoto,K., Handa,H., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces, (Colloids and Surfaces B: Biointerfaces)  vol.10 ( 3 ) 161-169 - 169 1998

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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正常なDNA鎖同士のハイブリダイゼーションと片方のDNAにだけ点変異がある場合のハイブリダイゼーションとでは、後者のほうが結合力が弱いことがわかった。そこで微粒子にDNA一本鎖を固定化して、点変異DNAだけが検出できるように種々の条件の設定を行い、その検出に成功した。

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DNA-carrying latex particles for DNA diagnosis. 2. Distinction of normal and point mutant DNAs using S1 nuclease

Hatakeyama,M., Nakamura,K., Iwato,S., Fujimoto,K., Handa,H., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces vol.10   171-178 1998

Joint Work, Accepted

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点変異があるDNAとその変異点以外は相補的なDNAとの間では不完全ではあるが二本鎖が形成される。この不完全部分を認識して切断する酵素を用いて、点変異をもつDNAの検出に成功した。

Activation of neutrophil-like cells stimulated by polymer surfaces

Fujimoto,K., Sasaki,J., Tomida,Y., Wakabayashi,Y., and Kawaguchi,H.

高分子論文集 (Kobunshi Ronbunshu)  vol.55 ( No.6 ) 367-371 - 371 1998

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  03862186

　View Summary

様々な高分子表面による好中球の活性化について検討を行った。電荷を導入した表面および疎水性の表面は一過性であるが強く細胞を活性化させ、親水性の表面は弱いが持続的に細胞を活性化させることがわかった。

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Inverse microemulsion polymerization of acrylamide in the presence of N,N-dimethylacrylamide

Juranicova,V., Kawamoto,S., Fujimoto,K., Kawaguchi,H., and Barton,J.

Die Angewandte Makromolekulare Chemie (Angewandte Makromolekulare Chemie)  vol.258   27-31 - 31 1998

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00033146

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N,N-ジメチルアクリルアミド存在下でアクリルアミドの逆相マイクロエマルジョン重合を行った。

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高分子表面によるタンパク質のリフォールディング制御

藤本啓二、清水秀信、川口春馬

化学と工業 vol.50 ( No.10 ) 1523-1525 1997.10

Research paper (scientific journal), Joint Work

　View Summary

生体内でつくられたタンパク質の鎖は、折り畳まれて活性を示す立体構造をとるようになる。最近、この折り畳みを助ける生体システムについて研究が進んでいる。我々は初めてこの折り畳みの人工システムを考案・作製し、実際にタンパク質を効率よくフォールディングさせることに成功した。

人工材料表面によるタンパク質のリフォールディング制御

藤本啓二、清水秀信、川口春馬

ポバール会記録 vol.110   19-25 1997.07

Joint Work

　View Summary

生体内でつくられたタンパク質の鎖は、折り畳まれて活性を示す立体構造をとるようになる。最近、この折り畳み（リフォールディング）を助ける生体システムについて研究が進んでいる。我々はこの折り畳みの人工システムを考案・作製し、タンパク質のリフォールディング反応を促進させることに成功した。

Cell activation by the micropatterned surface with settling particles

Fujimoto K., Takahashi T., Miyaki M., Kawaguchi H.

Journal of Biomaterials Science, Polymer Edition (Journal of Biomaterials Science, Polymer Edition)  8 ( 11 ) 879 - 891 1997.01

Research paper (scientific journal), Accepted,  ISSN  09205063

　View Summary

Surface topography plays an important role in cell orientation and morphogenesis. In this study, we prepared a micropatterned surface with settling particles to obtain more detailed information about the cell recognition against the microstructured surface. Core-shell type particles having a poly-(N-isopropylacrylamide) (polyNIPAM) shell were prepared by seeded polymerization. Particles were settled on a polystyrene (PSt) flat dish by the spinner to prepare a micropatterned surface with settling particles. It could be seen that the polyNIPAM shell shrunk above and swelled below the LCST. For comparison, a thermosensitive flat surface was prepared by the graft polymerization of NIPAM. No morphologic change of cells contacting the both surfaces was observed with either an optical or a scanning electron microscope. Moreover, particles could move or roll on these surfaces when shaking the dishes. The weak interaction between neutrophil-like cells and the micropatterned surface with settling particles or the polyNIPAM-grafted surface was estimated by measurement of active oxygen released by cells. A little release could be observed at both 25 and 35°C. The amount of released active oxygen at 35°C was slightly larger than at 25°C. When the temperature was suddenly changed, the dynamic changes of particle shape and size resulted in the excess release of active oxygen from cells contacting the micropatterned surface with settling particles. Meanwhile no stimulation could be observed in the polyNIPAM-grafted surface even if the temperature is suddenly changed. These results indicate that the micropatterned surface with settling particles can induce the dynamic stimulus at a patterned input mode. © VSP 1997.

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Preparation of dimerized polypeptide-carrying microspheres and purification of specific proteins bound to these microspheres.

Hatakeyama,M., Ogura,Y., Sawada,J., Fujimoto,K., Handa,H., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.10 ( 1 ) 41-49 - 49 1997

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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二量化したペプチド断片の微粒子への固定化を行った。この微粒子を用いて二量化ペプチド断片と結合する核内タンパク質の単離を試みた。

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Activity of enzymes immobilized on microspheres with thermosensitive hairs

Yasui,M., Shiroya,T., Fujimoto,K., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.8 ( 6 ) 311-319 - 319 1997

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

　View Summary

微粒子表面の感温性のポリマー鎖に酵素の固定化を行った。この微粒子は温度変化により３つのサイズに変化した。それぞれの状態で酵素活性は異なり、温度による制御の可能性が示唆された。

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Ex vivo and in vivo evaluation of the blood compatibility of surface-modified polyurethane catheters

Inoue,H., Fujimoto,K., Uyama,Y., and Ikada,Y.

Journal of Biomedical Materials Research (Journal of Biomedical Materials Research)  vol.35 ( 2 ) 255-264 - 264 1997

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219304

　View Summary

ポリエステルウレタンをオゾン処理し、水溶性でノニオン性のポリマーのグラフト化を行った。この改質ポリウレタンの血液適合性を調べたところ、良好な結果を得ることが出来た。

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Affinity Latex for DNA Diagnosis

Kawaguchi,H., Hatakeyama,M., Iwato,S., Fujimoto,K., Handa,H.

Advances in Polymeric Biomaterials Science,Akaike,T., Okano,T., Akashi,M., Terano,M., and Yui,N., eds.CMC Inc., Tokyo    355-362 1997

Joint Work, Accepted

　View Summary

微粒子にDNAを固定化することにより遺伝子診断のデバイスとしての応用を試みた。

Cell activation by the micro-patterned particle surface

Fujimoto,K., Takahashi,T., Miyaki,M., and Kawaguchi,H.

Journal of Biomaterials Science, Polymer Edition vol.8   879-891 1997

Joint Work, Accepted

　View Summary

細胞が材料表面の微細な形態を認識し、その影響のもとに自分自身の形態や性質を変化さ せているといった報告が数多くなされるようになってきた。我々は表面に微粒子を規則的に並べた凸状の表面構造を作製し、細胞に与える影響について検討を行った。

Preparation and Structural Characteristics of Stimuli-Responsive Hydrogel Microsphere

Nakazawa,Y., Kamijo,Y., Fujimoto,K., Kawaguchi,H., Yuguchi,Y., Urakawa,H., and Kajiwara,K.

Die Angewandte Makromolekulare Chemie, (Angewandte Makromolekulare Chemie)  vol.240   187-196 - 196 1996

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00033146

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アクリルアミドとメタアクリル酸から刺激応答性ゲル微粒子を作製した。この微粒子はpHに応答したサイズ変化を示した。

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Selective Isolation of DNA or RNA Using Single-Stranded DNA Affinity Latex Particles

Imai,T., Sumi,Y., Hatakeyama,M., Fujimoto,K., Kawaguchi,H., Hayashida,N., Shiozaki,K., Terada, K., Yajima,H., and Handa,H.

Journal of Colloid and Interface Science (Journal of Colloid and Interface Science)  vol.177 ( 1 ) 245-249 - 249 1996

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219797

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一本鎖のDNAを微粒子に固定化し、そのDNAと相補的なDNAあるいはRNAの単離を試みたところ、短時間で簡便に回収できることがわかった。

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Preparation and Structural Characterization of Hydrogel Microspheres

Kamijo,Y., Fujimoto,K., Kawaguchi,H., Yuguchi,Y., Urakawa,H., and Kajiwara,K.

Polymer Journal (Polymer Journal)  vol.28 ( 4 ) 309-316 - 316 1996

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00323896

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様々な溶媒を用いて沈殿重合によりゲル微粒子の作製を行った。ゲル微粒子の生成と溶媒の性質との関係を見いだし、さらに重合途中の微粒子の核形成の過程を検出することにより沈殿重合についての新しい知見を得ることが出来た。

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Modification and functionalization of hydrogel microspheres

Kawaguchi,H., Fujimoto,K., Nakazawa,Y., Sakagawa,M., Ariyoshi,Y., Shidara,M., Okazaki,H., and Ebisawa,Y.

Colloids and Surfaces, A: Physicochem. Eng. Aspects (Colloids and Surfaces A: Physicochemical and Engineering Aspects)  vol.109   147-154 - 154 1996

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277757

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沈殿重合により反応性ゲル微粒子を作製し、機能化を目指した様々な改質を行った。

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Chemical Properties of Water-Soluble, Nonionic Azo Compounds as Initiators for Emulsion Polymerization

Torii,H., Fujimoto,K., and Kawaguchi,H.

J. Polym. Sci., Polym. Chem. Ed. (Journal of Polymer Science, Part A: Polymer Chemistry)  vol.34 ( 7 ) 1237-1244 - 1243 1996

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0887624X

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ノニオン性の開始剤を用いた乳化重合を行った。この開始剤は水溶性であり、静電的な反発力に起因する分散安定化効果がなくとも、この水溶性に由来する立体反発力により微粒子の生成がなされたものと考えられた。

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Interactions between temperature‐sensitive hydrogel microspheres and granulocytes

Achiha K., Ojima R., Kasuya Y., Fujimoto K., Kawaguchi H.

Polymers for Advanced Technologies (Polymers for Advanced Technologies)  6 ( 7 ) 534 - 540 1995.07

Research paper (scientific journal), Accepted,  ISSN  10427147

　View Summary

Poly(N‐isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM‐containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature‐sensitive microspheres. Copyright © 1995 John Wiley & Sons, Ltd.

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Enzyme immobilization on thermosensitive hydrogel microspheres

Shiroya,T., Tamura,N., Yasui,M., Fujimoto,K., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.4 ( 5 ) 267-274 - 274 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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感温性ゲル微粒子に酵素を固定化し、温度変化による酵素活性の制御を行った。

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Control of enzymatic activity using thermosensitive polymers

Shiroya,T., Yasui,M., Fujimoto,K., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.4 ( 5 ) 275-285 - 285 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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感温性ポリマー鎖に酵素を固定化し、温度変化による酵素活性の制御を行った。

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Preparation of monodisperse, reactive hydrogel microspheres and their amphoterization

Kashiwabara,M., Fujimoto,K., and Kawaguchi,H.

Colloid & Polymer Science (Colloid and Polymer Science)  vol.273 ( 4 ) 339-345 - 345 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0303402X

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沈殿重合により粒子径が均一で、反応性部位を有する微粒子を作製した。その反応性部位を介して微粒子の両性化を行った。

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Interactions between temperature-sensitive hydrogel microspheres and granulocytes

Achiha,K., Ojima,R., Kasuya,Y., Fujimoto,K., and Kawaguchi,H.

Polymers for Advanced Technologies vol.6   534-540 1995

Joint Work, Accepted

　View Summary

感温性ゲル微粒子と顆粒球との相互作用を調べた。低温で水和状態の微粒子は顆粒球に付着すらしなかった。しかし、温度を上げて脱水和させると微粒子は顆粒球に付着するようになったが、貪食されることはなかった。

Purification of membrane receptors with peptide-carrying affinity latex particles

Inomata,Y., Kasuya,Y., Fujimoto,K., Handa,H., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.4 ( 4 ) 231-241 - 241 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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膜レセプターと特異的に接着するペプチド断片を微粒子に固定化した。その微粒子を用いて顆粒球の膜レセプターの分離に成功した。

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Purification of transcription factor 2A using yeast TATA-binding protein affinity latex particles

Shiroya,T., Hatakeyama,M., Fujimoto,K., Watanabe,H., Wada,T., Imai,T., Kawaguchi,H., and Handa,H.

IJBC vol.1   191-198 1995

Joint Work, Accepted

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DNA鎖のTATA配列部分を微粒子に固定化することにより転写制御因子TF2Aの分離精製を試みた。この微粒子によるバッチシステムは、非特異的な成分の吸着が非常に少なく、短時間で高効率の分離が可能であった。

Cytoplasmic calcium level and membrane fluidity of platelets contacting poly(acrylamide-co-methacrylic acid) particles with different surface properties

Yui,N., Suzuki,K., Okano,T., Sakurai,Y., Nakano,M., Ishikawa,C., Fujimoto,K., and Kawaguchi,H.

Journal of Biomaterials Science, Polymer Edition (Journal of Biomaterials Science, Polymer Edition)  vol.7 ( 3 ) 253-264 - 264 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09205063

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様々な組成比を有するアクリルアミドとメタクリル酸の共重合体からなる微粒子を作製した。これらの微粒子が血小板に与える作用を細胞内カルシウム濃度と膜の流動性の観点から検討を行った。

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Effects of surface modification of materials on human neutrophil activation

Wakabayashi,Y., Sasaki,J., Fujita,H., Fujimoto,K., Morita,I., Murota,S., and Kawaguchi,H.

Biochimica et Biophysica Acta (BBA - General Subjects)  vol.1243 ( 3 ) 521-528 - 528 1995

Research paper (scientific journal), Joint Work, Accepted,  ISSN  03044165

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好中球の非特異的な活性化についての知見を得るために、ポリスチレン表面の表面化学改質を行った。その表面と接触した細胞の活性酸素の放出やレセプター類の発現を調べた。

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Dipyridamole, an anti-platelet agent, reduces the vascular endothelial cell injury induced by active oxygen species

Wakabayashi Y., Fujita H., Fujimoto K., Kawaguchi H., Morita I., Murota S.

Platelets (Platelets)  6 ( 3 ) 176 - 182 1995

Research paper (scientific journal), Accepted,  ISSN  09537104

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The effects of the anti-platelet agent dipyridamole on vascular endothelial cells were assessed by measurement of the injury index induced by oxygen stress. Vascular endothelial cell injury was assayed by measuring 51 Cr release from labeled vascular endothelial cells. Leukocytes activated by phorbol 12-myristate 13-acetate (PMA) were used to induce the injury of endothelial cells. In this system, dipyridamole suppressed endothelial cell injury in a dose dependent manner (0.1-10 4mUM) while it had no effect on production of superoxide anion in PMA-activated leukocytes. Treatment of endothelial cells with hydrogen peroxide also induced endothelial cell injury in a dose dependent manner (50-150 μM). Dipyridamole also prevented the endothelial cell injury induced by hydrogen peroxide with a dose dependent fashion (1-10 μM). There were no significant changes in the activities of catalyzing enzymes such as catalase and glutathione peroxidase in the endothelial cells following dipyridamole treatment. In contrast, dipyridamole significantly increased the cyclic GMP content of endothelial cells in a dose dependent manner (1-10 μM). Addition of 8-bromo-cyclic GMP (1 mM) to the culture also protected endothelial cells from injury induced by hydrogen peroxide, but 8-bromo-cyclic AMP did not. These data suggest that the protective effect of dipyridamole against oxygen stress is correlated with the increase in the cyclic GMP content of the endothelial cells. © 1995 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

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Purification of transcription factor IIA using yeast TATA-binding protein affinity latex particles

Shiroya T., Hatakeyama M., Fujimoto K., Watanabe H., Wada T., Imai T., Kawaguchi H., Handa H.

International Journal of Bio-Chromatography (International Journal of Bio-Chromatography)  1 ( 3 ) 191 - 198 1995

Research paper (scientific journal), Accepted,  ISSN  10680659

Influence of the structure of support microspheres on leucocyte activation by RGDS-carrying microspheres

Kasuya Y., Fujimoto K., Kawaguchi H., Miyamoto M.

Biomaterials (Biomaterials)  15 ( 8 ) 570 - 576 1994.06

Research paper (scientific journal), Accepted,  ISSN  01429612

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A cell adhesive peptide, Arg-Gly-Asp-Ser (RGDS), enhances leucocyte response to stimuli when insolubilized or conjugated with proteins. In order to investigate the contribution of the microsphere structure to leucocyte response, RGDS was immobilized onto several polymeric microspheres. The respiratory burst of polymorphonuclear leucocytes (PMNs) contacting microspheres was enhanced by RGDS in cases where it was immobilized on polystyrene and, more effectively, a positively charged one. This was not observed in polyacrylamide-based or negative-charged microsphere systems. These results demonstrate that the property of supports strongly affects the regulation of the PMN response via an adhesive interaction. © 1994.

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Activation of human neutrophils by Arg‐Gly‐Asp‐Ser immobilized on microspheres

Kasuya Y., Fujimoto K., Miyamoto M., Kawaguchi H.

Journal of Biomedical Materials Research (Journal of Biomedical Materials Research)  28 ( 3 ) 397 - 404 1994.03

Research paper (scientific journal), Accepted,  ISSN  00219304

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The adhesive interaction of cells with extracellular matrix components is essential for a variety of cellular functions, and is frequently mediated by a tetra peptide, Arg‐Gly‐Asp‐Ser (RGDS), located within fibronectin and other proteins. In this study, the RGDS‐mediated activation of polymorphonuclear leukocytes accompanied by phagocytosis was investigated using monodisperse polymeric microspheres carrying RGDS. The parent and Arg‐Gly‐Glu‐Ser (RGES)‐carrying microspheres, which have no adhesion activity, were employed as controls. The ingestion of microspheres into PMN was not enhanced by immobilizing RGDS. However, PMNs exhibited unique oxygen consumption and enhanced liberation of reactive oxygen when RGDS‐carrying microspheres were phagocytosed. These PMN responses disappeared with the addition of soluble RGDS. Furthermore, cytochalasin D, which inhibits actin polymerization, showed a marked inhibitory effect on oxygen consumption in the RGDS‐carrying microsphere system, as compared with those in other systems. These findings show that RGDS‐carrying microspheres induced the biospecific activation of PMNs by the signal transduction via RGDS‐integrin binding without alteration in the degree of phagocytosis. © 1994 John Wiley & Sons, Inc. Copyright © 1994 John Wiley & Sons, Inc.

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Surface structure of latex particles covered with temperature-sensitive hydrogel layers

Makino,K., Yamamoto,S., Fujimoto,K., Kawaguchi,H., and Ohshima,H.

Journal of Colloid and Interface Science (Journal of Colloid And Interface Science)  vol.166 ( 1 ) 251-258 - 258 1994

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219797

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コア部に電荷を持ち、感温性のヘアを表面に有するコアシェル微粒子の泳動挙動を測定し、電荷導入によるヘア層の状態変化について検討を行った。

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Activation of human neutrophil by Arg-Gly-Asp-Ser immobilized on microspheres

Kasuya,Y., Fujimoto,K., Miyamoto,M., and Kawaguchi,H.

Journal of Biomedical Materials Research vol.28   397-404 1994

Joint Work, Accepted

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細胞接着性のArg-Gly-Asp-Serを結合させた微粒子は好中球に対して、特異的に接着し、活性化を誘導することがわかった。

Preparation of DNA-carrying affinity latex and purification of transcription factors with the latex

Inomata,Y., Wada,T., Handa,H., Fujimoto,K., and Kawaguchi,H.

Journal of Biomaterials Science, Polymer Edition (Journal of Biomaterials Science, Polymer Edition)  vol.5 ( 4 ) 293-302 - 302 1994

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09205063

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転写活性を制御する因子が特異的に結合する二本鎖DNA部分を微粒子に結合させてアフィニティ微粒子を作製した。この微粒子を用いて細胞から転写活性因子の単離を行ったところ、高収率で回収できた。

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Influence of the structure of the support microspheres on leucocytes activation by RGDS-carrying microspheres

Kasuya,Y., Fujimoto,K., Kawaguchi,H. and Miyamoto,M.

Biomaterials, vol.15   570-576 1994

Joint Work, Accepted

　View Summary

細胞接着性ペプチドを固定化させた微粒子の細胞の活性化に与える影響について調べたところ、担体としての構造が重要であることがわかった。

Application of cationic latex particles for protein separation

Sumi,Y., Shiroya,T., Fujimoto,K., Wada,T., Handa,H., and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.2 ( 4 ) 419-427 - 427 1994

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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タンパク質は両性高分子電解質であるために様々な等電点を持つ。カチオン性の微粒子は静電的な引力により、アニオン性のタンパク質を高収率で回収することができた。

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Phagocytosis of microspheres with modified surfaces

Urakami,Y., Kasuya,Y., Fujimoto,K., Miyamoto,M, and Kawaguchi,H.

Colloids and Surfaces B: Biointerfaces (Colloids and Surfaces B: Biointerfaces)  vol.3 ( 3 ) 183-190 - 190 1994

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09277765

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様々な化学組成および形態を有する微粒子を作製し、顆粒球による貪食作用を調べた。ある親疎水性の混合割合の時に貪食作用が抑制される結果を得た。補体成分の活性化の抑制によるものと考えられた。

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Permeation control by thermosensitive shell layer of submicron microspheres

Kato,T., Fujimoto,K., and Kawaguchi,H.

Polymer Gels and Networks (Polymer Gels and Networks)  vol.2 ( 3-4 ) 307-313 - 313 1994

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09667822

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コアとシェルを持つ微粒子のシェル部の変化によりコア部と外部との透過性を制御することが出来る。ここでは感温性シェルを持つ微粒子について電子の伝達を制御することに成功した。

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Activation of leukocytes by RGDS-carrying microspheres

Fujimoto,K., Kasuya,Y., Miyamoto,M., and Kawaguchi,H.

ACS Symposium Series vol.540   220-227 1994

Joint Work, Accepted

　View Summary

細胞接着性のテトラペプチド（ＲＧＤＳ）を結合させた微粒子は白血球に対して、特異的に接着し、活性化させることがわかった。

Poly(vinyl alcohol) hydrogels prepared under different annealing conditions and their interactions with blood components

Fujimoto,K., Minato,M., and Ikada,Y.

ACS Symposium Series vol.540   228-242 1994

Joint Work, Accepted

　View Summary

ポリビニルアルコールの表面状態を変化させるために、種々な熱処理を行った。次にこの表面と接触した血液成分の状態変化を測定した。その結果、適当な可塑剤量、熱処理温度、および時間の時に優れた生体適合性を示すような表面状態になることがわかった。

高分子ミクロスフェアと接触した細胞の応答

藤本啓二

ケミカル・エンジニアリング vol.39   408-415 1994

Research paper (scientific journal), Single Work

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種々な微粒子と細胞との相互作用に関するまとめ。

Protein adsorption and platelet adhesion onto polyurethane grafted with methoxy‐poly(ethylene glycol) methacrylate by plasma technique

Fujimoto K., Inoue H., Ikada Y.

Journal of Biomedical Materials Research (Journal of Biomedical Materials Research)  27 ( 12 ) 1559 - 1567 1993.12

Research paper (scientific journal), Accepted,  ISSN  00219304

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Graft polymerization of methoxy‐poly(ethylene glycol) methacrylate, an ester of methacrylic acid and monomethoxy‐poly(ethylene glycol) (PEO), was performed onto a polyetherurethane (PU) film and tube under different polymerization conditions by a plasma treatment technique. The surface of grafted PU film was characterized by staining with dye, x‐ray photoelectron spectroscopy, contact angle, and zeta potential. All these measurements indicated that water‐soluble chains were immobilized on the PU surface, their location being restricted to the film surface region. The PU surface showed reduced protein adsorption in vitro and reduced platelet adhesion in vitro and ex vivo. The optimum graft density suppressing the protein adsorption was as low as 5 μg cm−2. When a small amount of dimethacrylate was added to the monomer solution for graft polymerization to introduce crosslinking in the grafted layer, protein adsorption was further slightly reduced. The extent of reduction in serum albumin adsorption was always less than that of γ‐globulin. Although platelet adhesion was largely reduced by the surface graft polymerization, a definite amount of protein was always adsorbed to the grafted surface. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.

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Ozone‐induced graft polymerization onto polymer surface

Fujimoto K., Takebayashi Y., Inoue H., Ikada Y.

Journal of Polymer Science Part A: Polymer Chemistry (Journal of Polymer Science Part A: Polymer Chemistry)  31 ( 4 ) 1035 - 1043 1993.03

Research paper (scientific journal), Accepted,  ISSN  0887624X

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Ozone‐induced graft polymerization was carried out to improve polymer surfaces. The polymers were exposed to ozone and the surface density of peroxides formed was determined by three methods; iodide, DPPH, and peroxidase method. The peroxide production could be readily controlled by the ozone concentration and the ozone exposure time. In addition, it was dependent on the kind of polymer. Further, it seemed probable that the ozone oxidation introduced peroxides not only on the outermost surface but also into a layer deeper from the outermost surface. Such polymeric peroxides were capable of initiating graft polymerization onto PU. All the physical and biological measurements on the grafted surface indicated that ozone‐induced graft polymerization has effectively made the PU surface covered with the grafted water‐soluble chains, their location being restricted to the film surface region. The interaction of the PU surface with blood components could be greatly reduced by the surface graft polymerization. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.

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アメリカ化学会：生物学的および生医学的に重要な高分子に関するシンポジウム参加記

藤本啓二

海外高分子研究 vol.39   49-50 1993

Research paper (scientific journal), Single Work

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アメリカ化学会の学会に参加した際の報告で、生物学的および生医学的に重要な高分子に関する紹介とともにこの分野の展望について述べた。

Changes in platelet metabolism in contact with hydrophilic copolymer surfaces

Yui,N., Suzuki,K., Okano,T., Sakurai,Y., Ishikawa,C., Fujimoto,K., and Kawaguchi,H.

Heart Replacement Artificial Heart 4, Akutsu,T. and Koyanagi,H., Eds. Springer-Verlag, Tokyo    33-36 1993

Joint Work, Accepted

　View Summary

親水性の微粒子および高分子鎖が血小板の代謝に与える影響について検討を行った。

Electrophoretic mobility of latex particles covered with temperature-sensitive hydrogel layers

Ohshima,H., Makino,K., Kato,T., Fujimoto,K., Kondo,T., and Kawaguchi,H.

Journal of Colloid and Interface Science (Journal of Colloid And Interface Science)  vol.159 ( 2 ) 512-514 - 514 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219797

　View Summary

感温性のヘアを表面に有する微粒子の泳動挙動を測定し、ヘア層の状態を柔らかさの観点からとらえる試みを行った。

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Mechanism of cytoplasmic calcium changes in platelets in contact with polystyrene and poly(acrylamide-co-methacrylic acid) surfaces

Yui,N., Suzuki,K., Okada,T., Sakurai,Y., Ishikawa,C., Fujimoto,K., and Kawaguchi,H.

Journal of Biomaterials Science, Polym. Ed. (Journal of Biomaterials Science, Polymer Edition)  vol.4 ( 3 ) 199-215 - 215 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09205063

　View Summary

ポリスチレンの表面およびアクリルアミドとアクリル酸の共重合体表面が血小板に与える影響をその代謝機能変化から検出し、ポリマー鎖の動的な状態が重要な因子であることがわかった。

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ハイドロゲル粒子のラテックス診断薬担体としての応用

赤澤太朗、藤本啓二、川口春馬

高分子論文集 vol.50   431-435 1993

Research paper (conference, symposium, etc.), Joint Work

　View Summary

診断の感度を低下させるものに、担体への種々の成分の非特異的な吸着があげられる。ハイドロゲルは超親水性であり吸着量を低く抑えることができる。このゲル微粒子を診断薬担体として用いたところ、特異的な成分だけを検出することに優れていることがわかった。

細胞接着性を有するミクロスフェアの作製とその評価

粕谷裕司、宮本正樹、清水一弘、藤本啓二、 大高　章、船越　奨、藤井信孝、川口春馬

高分子論文集 vol.50   417-423 1993

Research paper (conference, symposium, etc.), Joint Work

　View Summary

アルギニン・グリシン・アスパラギン酸・セリンからなるテトラペプチドは細胞接着活性を有する。このテトラペプチドを合成し、反応性基を有する微粒子に結合させた。

Hybrid microspheres for biospecific recognition and separation

Kawaguchi,H. and Fujimoto, K.

New Functionality Materials, Volume B Synthesis and Function Control of Biofunctionality Materials Tsuruta,T., Doyama,M., Seno,M., and Imanishi,Y., Eds., Elsevier Science Publishers B.V.    29-36 1993

Joint Work

　View Summary

様々な微粒子を作製して、生体成分の固定化を行い、その生体認識能を用いて別の生体成分の分離を行うというシステムを開発した。

Preparation and modification of monodisperse hydrogel microspheres

Kawaguchi,H., Fujimoto,K., Saito,M., Kawasaki,T., and Urakami,Y.

Polymer International, 30 (Polymer International)  30 ( 2 ) 225-231 - 231 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  09598103

　View Summary

粒子径の揃ったヒドロゲル微粒子を沈殿重合により作製し、その生成過程の検討と更なる改良を行った。

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Fluorescence analysis for thermo-sensitive hydrogel microspheres

Fujimoto,K., Nakajima,Y., Kashiwabara,M., and Kawaguchi,H.

Polymer International vol.30   237-241 1993

Joint Work, Accepted

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ポリ（N-イソプロピルアクリルアミド）からなるゲル微粒子は温度によってその粒子径を変化させる。この変化に伴って、表面近傍での親疎水性がどのように変化するかを蛍光プローブを用いて検出した。

Interactions between thermosensitive hydrogel microspheres and proteins

Fujimoto,K., Mizuhara,Y., Tamura,N., and Kawaguchi,H.

Journal of Intelligent Material Systems and Structures (Journal of Intelligent Material Systems and Structures)  vol.4 ( 2 ) 184-189 - 189 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1045389X

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感温性ゲル微粒子への様々なタンパク質の吸着現象について検討を行った。

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Ozone-induced graft polymerization onto polymer surface

Fujimoto,K., Takebayashi,Y., Inoue,H., and Ikada,Y.

Journal of Polymer Science, Polymer Chemistry Edition vol.31   1035-1043 1993

Joint Work, Accepted

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オゾンで高分子物質を処理することによって、その表面への多種類のポリマー鎖のグラフト化が可能となった。

Polyurethane surface modification by graft polymerization of acrylamide for reduced protein adsorption and platelet adhesion

Fujimoto,K., Tadokoro,H., Ueda,Y., and Ikada,Y.

Biomaterials (Biomaterials)  vol.14 ( 6 ) 442-448 - 448 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  01429612

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ポリウレタンを低温プラズマ処理し、表面へのアクリルアミドのグラフト重合を行った。この改質により表面へのタンパク質の吸着および血小板の粘着は著しく抑制された。

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Protein adsorption and platelet adhesion onto polyurethane grafted with methoxy-poly(ethylene glycol)methacrylate by plasma technique

Fujimoto,K., Inoue,H., and Ikada,Y.

Journal of Biomedical Material Research vol.27   1559-1567 1993

Joint Work, Accepted

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ポリウレタンを低温プラズマ処理し、表面への側鎖にポリエチレンオキサイドを有するビニルモノマーのグラフト重合を行った。この改質により表面へのタンパク質の吸着および血小板の粘着は著しく抑制された。

Platelet deposition onto polymeric surfaces during shunting

Fujimoto,K., Minato,M., Tadokoro,H., and Ikada,Y.

Journal of Biomedical Material Research, (Journal of Biomedical Materials Research)  vol.27 ( 3 ) 335-343 - 343 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219304

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様々な高分子物質からなる小口径のチューブを用いて、動脈-静脈シャントを行い、主に血小板粘着挙動を調べた。

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Porous polyurethane tubes as vascular graft

Fujimoto,K., Minato,M., Miyamoto,S., Kaneko,T., Kikuchi,H., Sakai,K.,Okada,M., and Ikada,Y.

Journal of Applied Biomaterials (Journal of applied biomaterials : an official journal of the Society for Biomaterials)  vol.4 ( 4 ) 347-354 - 354 1993

Research paper (scientific journal), Joint Work, Accepted,  ISSN  10454861

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ポリウレタンから多孔性のチューブを作製し、そのポアサイズが大きいほど開存率が高いという結果を見いだした。

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Preparation of peptide-carrying microspheres with bioactivity on platelet

Kasuya,Y., Fujimoto,K., Miyamoto,M., Juji,T., Otaka,A., Funakoshi,S., Fujii,N., and Kawaguchi,H.

Journal of Biomaterials Science, Polymer Edition vol.4   369-380 1993

Joint Work, Accepted

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細胞接着成分であるテトラペプチドを結合させた微粒子を作製し、血小板への作用を見た。この微粒子は血小板を有為に凝集させることがわかった。

Application of Hydrogel Microspheres to Latex Diagnosis

Akazawa T., Fujimoto K., Kawaguchi H.

Kobunshi Ronbunshu (Kobunshi Ronbunshu)  50 ( 5 ) 431 - 435 1993

Research paper (scientific journal), Accepted,  ISSN  03862186

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Acrylamide, glycidyl methacrylate, and methylene bisacrylamide were copolymerized in an aqueous ethanol to form monodisperse hydrogel latex particles. Antibody of C-reactive protein (CRP) was immobilized on the particles through a hydrophilic spacer. The resulting particles were moderately stable, and the agglutination was proportional to the concentration of CRP. They were little susceptible to the nonspecific adsorption of proteins and the aggregation by rheumatoid factor. Therefore, it was concluded that the hydrogel particles are a promising carrier of antibodies for latex diagnosis. © 1993, The Society of Polymer Science, Japan. All rights reserved.

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Preparation of peptide-carrying microspheres with bioactivity on platelets

Kasuya Y., Fujimoto K., Kawaguchi H., Miyamoto M., Juji T., Otaka A., Funakoshi S., Fujii N.

Journal of Biomaterials Science, Polymer Edition (Journal of Biomaterials Science, Polymer Edition)  4 ( 3 ) 369 - 380 1993

Research paper (scientific journal), Accepted,  ISSN  09205063

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A tetrapeptide RGDS (Arg-Gly-Asp-Ser), which is one of the active sites of cell adhesive proteins, was synthesized according to the solution method and covalently coupled onto monodisperse microspheres. The biospecific activity of the RGDS-carrying microspheres was investigated by measuring the stimulatory effect of the microspheres on platelets. Large and tightly packed platelet aggregation accompanied with drastic ATP release was induced by the RGDS-carrying microspheres. It was confirmed that the specific platelet aggregation was attributed to the activity of the immobilized RGDS by comparison with those induced by other microspheres. © VSP 1993.

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Preparation Of Peptide-Carrying Microspheres With Bioactivity On Platelets

Kasuya Y., Fujimoto K., Kawaguchi H., Miyamoto M., Juji T., Otaka A., Funakoshi S., Fujii N.

Journal of Biomaterials Science, Polymer Edition (Journal of Biomaterials Science, Polymer Edition)  4 ( 4 ) 369 - 380 1993

Research paper (scientific journal), Accepted,  ISSN  09205063

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A tetrapeptide RGDS (Arg-Gly-Asp-Ser), which is one of the active sites of cell adhesive proteins, was synthesized according to the solution method and covalently coupled onto monodisperse microspheres. The biospecific activity of the RGDS-carrying microspheres was investigated by measuring the stimulatory effect of the microspheres on platelets. Large and tightly packed platelet aggregation accompanied with drastic ATP release was induced by the RGDS-carrying microspheres. It was confirmed that the specific platelet aggregation was attributed to the activity of the immobilized RGDS by comparison with those induced by other microspheres. © 1993, VSP. All rights reserved.

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Preparation and Evaluation of Polymer Microspheres with Cell Adhesion Activity

Kasuya Y., Shimizu K., Fujimoto K., Kawaguchi H., Miyamoto M., Otaka A., Funakoshi S., Fujii N.

Kobunshi Ronbunshu (Kobunshi Ronbunshu)  50 ( 5 ) 417 - 423 1993

Research paper (scientific journal), Accepted,  ISSN  03862186

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Microspheres having cell adhesion activity were prepared by immobilizing a tetrapeptide Arg-Gly-Asp-Ser (RGDS) onto the surface. Phagocytosis of the microspheres by leukocytes was not enhanced by immobilizing RGDS, but specific oxygen consumption was observed during the incubation of the RGDS-carrying microspheres with leukocytes. This was enhanced by a spacer introduced between RGDS and the microsphere. These results suggested that the immobilized RGDS could transduce the adhesion signal, resulting in the activation of leukocytes without enhancing phagocytosis of the microspheres. Furthermore, it was found that soluble RGDS did not induce oxygen consumption at all by itself. This result suggests that RGDS must be immobilized on solid carriers for the specific activation of leukocytes. Preparation and Evaluation of Polymer Microspheres with Cell Adhesion Activity. © 1993, The Society of Polymer Science, Japan. All rights reserved.

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Fluorescence analysis for thermo‐sensitive hydrogel microspheres

Fujimoto K., Nakajima Y., Kashiwabara M., Kawaguchi H.

Polymer International (Polymer International)  30 ( 2 ) 237 - 241 1993

Research paper (scientific journal), Accepted,  ISSN  09598103

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Poly(N‐isopropylacrylamide) (PNIPAM) hydrogel microspheres were prepared by precipitation polymerization above the polymer's lower critical solution temperature (LCST) in water. The hydrodynamic size of PNIPAM microspheres exhibited a thermo‐sensitive change around the LCST. In order to obtain information about the interface of the hydrogels, contact angle measurement, protein adsorption, and fluorescence analysis were performed. Contact angle measurement and protein adsorption showed a gradual change around the LCST similar to the change of the hydrodynamic size. However, fluorescence study exhibited a sharp change at the LCST. In addition, a quenching experiment was employed to elucidate the location of the fluorescent probes. In the PNIPAM latex, the probes were located where they were less quenchable as compared to the PNIPAM solution. It seems probable that the probes can penetrate into the crosslinked PNIPAM hydrogel and might reflect the inner environment of the hydrogel. The effect of salt on thermo‐sensitive behaviour was also detected by fluorescence analysis. On the other hand, the hydrogel microsphere prepared from poly(acryloyl pyrrolidine) (PAPr) showed a gradual change in fluorescence with temperature. Copyright © 1993 Society of Chemical Industry

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Hydrogel microspheres III. Temperature-dependent adsorption of proteins on poly-N-isopropylacrylamide hydrogel microspheres

Kawaguchi H., Fujimoto K., Mizuhara Y.

Colloid &amp; Polymer Science (Colloid &amp; Polymer Science)  270 ( 1 ) 53 - 57 1992.01

Research paper (scientific journal), Accepted,  ISSN  0303402X

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Precipitation polymerization of N-isopropylacrylamide (NIPAM) with methylenebisacrylamide (MBAAm) in water at 70°C gave thermosensitive hydrogel microspheres. The adsorbability of proteins on the poly-NIPAM microspheres was found to depend on temperature. Below the lower critical solution temperature (LCST) of poly-NIPAM in an aqueous medium, that is, around 32°C, the microspheres hold a large amount of water inside and their surface is hydrophilic enough to suppress the adsorption of proteins. On the contrary, above 32°C, the micropheres deswell and their surface becomes hydrophobic and, consequently, susceptible to adsorption of a large amount of proteins. Proteins once adsorbed on the microspheres at a high temperature could be desorbed more or less by lowering the temperature to below 32°C. The extent of desorption at low temperatures was found to depend on the incubation time for adsorption at high temperatures. © 1992 Steinkopff-Verlag.

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Hydrogel microspheres 3. Temperature-dependent adsorption of proteins on poly(N-isopropylacrylamide) hydrogel microspheres

Kawaguchi,H., Fujimoto,K., and Mizuhara,Y.

Colloid & Polymer Science vol.270   53-57 1992

Joint Work, Accepted

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温度変化によってポリマー鎖が収縮して粒子径が変化する微粒子を作製し、その表面へのタンパク質の吸着挙動を調べた。

Improvement in the mechanical properties of artificial blood vessel suitable for the extracranial cerebral artery

Miyamoto,S., Kikuchi,H., Ikada,Y., Minato,M., Fujimoto,K., Okada,M., Sakai,K., Nagata,I., Yamagata,S., Kaneko,T., and Kubo,H.

Neurological Surgery, (Neurological Surgery)  vol.18 ( 3 ) 253-258 - 258 1990

Research paper (scientific journal), Joint Work, Accepted,  ISSN  03012603

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ポリウレタンからなる人工血管を用いて埋植実験を行い、その機械的性質が重要である結果を得た。

Blood compatibility of polyurethane modified by surface graft polymerization

Fujimoto K., Tadokoro H., Minato M., Ikada Y.

Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering (Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering)  62   736 - 740 1990

Research paper (scientific journal), Accepted,  ISSN  07430515

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The purpose of this work is to modify PU by surface graft polymerization of acrylic monomers so as to reduce protein adsorption and platelet adhesion. It is shown that there is an optimum in the graft amount which leads to the minimum protein adsorption and thrombus formation.

Comparison between plasma- and ozone-induced graft polymerization

Fujimoto K., Ueda Y., Takebayashi Y., Ikada Y.

Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering (Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Materials Science and Engineering)  62   284 - 288 1990

Research paper (scientific journal), Accepted,  ISSN  07430515

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This paper describes the results of plasma- and ozone-induced graft polymerization of acrylamides, together with the amount of peroxides formed by the plasma treatment and the ozonization. It is concluded that both the treatments of polymer surfaces by plasma and ozone produce polymeric peroxides which are capable of initiating graft polymerization, even if the treatments are conducted under a mild condition. An advantage of the ozonization over the plasma treatment is easy and uniform introduction of peroxides on the surface of molded products even with complicated shapes.

New veno-venous bypass without systemic anticoagulation in canine liver transplantation

Kim,K.S., Ueda,J., Asonuma,K., Zaima,M.,Tanaka,K., Ozawa,K., Minato,M.,Fujimoto,K., and Ikada,Y.

Surgery Research Communication vol.6   287-298 1989

Joint Work, Accepted

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全身的な抗凝血剤処置を行わずに肝臓移植を行うための、新規の静脈-静脈バイパス技術を開発した。