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219 results on '"Nakahata, Masaki"'

3. Switchable Wetting of Stimulus Responsive Polymer Brushes by Lipid Vesicles: Experiments and Simulations

Author

Weissenfeld, Felix, Wesenberg, Lucia, Nakahata, Masaki, Müller, Marcus, and Tanaka, Motomu

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

We grafted polyacrylic acid brushes containing cysteine side chains at a defined surface density on planar lipid membranes. Specular X-ray reflectivity data indicated that the addition of Cd2+ ions induces the compaction of the polymer brush layer and modulates the adhesion of lipid vesicles. The critical threshold level inducing the switch from non-wetting to partial wetting state, [Cd2+] = 0.25 mM, was determined by microinterferometry. The interactions between vesicles and brushes were evaluated by height fluctuations of the membrane in contact with brushes and the shape of vesicles near the surface. To analyze these experiments, we have studied adhesion of axially symmetric vesicles for finite-range membrane-substrate interaction and buoyancy through simulations. We found that the local transversality condition that relates the maximal curvature at the edge of the adhesion zone to the adhesion strength remains rather accurate. Thus, although it is not experimentally possible to prepare vesicles at zero buoyancy, we can use the transversality condition to estimate the adhesion strength. However, the adhesion diagram is significantly modified by a finite range of membrane-substrate interaction and buoyancy. For downward buoyancy, vesicles merely sediment onto the substrate and there is no mean-field adhesion transition. For upward buoyancy, adhered vesicles are metastable at best. Thus, a mean-field adhesion transition can only occur at vanishing buoyancy. Only for zero-range membrane-substrate interaction does a second-order adhesion transition occur at finite interaction strength. For any finite-range interaction, the transition occurs when the membrane-substrate interaction changes from repulsive to attractive. We present a adhesion diagram as a function of adhesion strength and buoyancy and compare the adhesion behavior of vesicles to the wetting behavior of droplets of liquids., Comment: 15 pages, 17 figures

Published
2022

8. Reversible Host–Guest Crosslinks in Supramolecular Hydrogels for On‐Demand Mechanical Stimulation of Human Mesenchymal Stem Cells (Adv. Healthcare Mater. 10/2024)

Author

Linke, Philipp, primary, Munding, Natalie, additional, Kimmle, Esther, additional, Kaufmann, Stefan, additional, Hayashi, Kentaro, additional, Nakahata, Masaki, additional, Takashima, Yoshinori, additional, Sano, Masaki, additional, Bastmeyer, Martin, additional, Holstein, Thomas, additional, Dietrich, Sascha, additional, Müller‐Tidow, Carsten, additional, Harada, Akira, additional, Ho, Anthony D., additional, and Tanaka, Motomu, additional

Published
2024
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11. Synthesis of an Alternating Polycation with the Dense 1,2,3-Triazole Backbone.

Author

Omae, Tomoki, Nakahata, Masaki, Kamon, Yuri, and Hashidzume, Akihito

Subjects
*WATER-soluble polymers, *SPINE
Abstract

This article explores the synthesis and properties of two different types of polymers. The first polymer is an alternating polycation with a dense 1,2,3-triazole backbone, which is important for gene therapy. The authors used a specific method to synthesize this polycation and studied its characteristics and ability to form complexes with polyanions. The second polymer discussed is poly(ethylene glycol)-b-poly(2-oxazoline) (PEG-b-POx), which has potential applications in drug delivery systems and biomaterials. The authors describe the synthesis process and highlight the unique properties of PEG-b-POx, such as its ability to self-assemble and its biocompatibility. This article provides valuable information for researchers interested in developing new polymers for biomedical purposes. [Extracted from the article]

Published
2024
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14. Density Function Theory Study on the Energy and Circular Dichroism Spectrum for Methylene-Linked Triazole Diads Depending on the Substitution Position and Conformation.

Author

Nakahata, Masaki and Hashidzume, Akihito

Subjects
*CIRCULAR dichroism, *TRIAZOLES, *OLIGOMERS, *CYCLIC compounds, *DENSITY functional theory
Abstract

Since the discovery of metal-catalyzed azide–alkyne cycloadditions, 1,2,3-triazoles have been widely used as linkers for various residues. 1,2,3-Triazole is an aromatic five-membered cyclic compound consisting of three nitrogen and two carbon atoms with large dipoles that absorb UV light. In the past decade, we have been working on the synthesis of dense triazole polymers possessing many 1,2,3-triazole residues linked through a carbon atom in their backbone as a new type of functional polymer. Recently, we reported that stereoregular dense triazole uniform oligomers exhibit a circular dichroism signal based on the chiral arrangement of two neighboring 1,2,3-triazole residues. In this study, to investigate the chiral conformation of two neighboring 1,2,3-triazole residues in stereoregular dense triazole uniform oligomers, density functional theory (DFT) calculations were performed using 1,2,3-triazole diads with different substitution positions and conformations as model compounds and compared with our previous results. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Synthesis of an alternating copolymer of the dense 1,2,3‐triazole backbone carrying t‐butyl ester and nitrile side chains.

Author

Xu, Linlin, Nakahata, Masaki, Kamon, Yuri, and Hashidzume, Akihito

Subjects
COPOLYMERS, TRIAZOLES, RING formation (Chemistry), METAL ions, HETERODIMERS
Abstract

In these decades, synthesis of polymers with controlled monomer sequences has been of increasing importance in polymer chemistry. When we tested synthesis of a heterodimer of 4‐azido‐5‐hexynoic acid derivatives carrying t‐butyl (tBu) ester and tBu amide side chains for preparation of an alternating copolymer, we unexpectedly obtained a heterodimer precursor carrying tBu ester and nitrile side chains, in a high yield. Since dense 1,2,3‐triazole polymers carrying nitrile side chains are expected as a new functional polymer, the heterodimer is polymerized by copper(I)‐catalyzed azide–alkyne cycloaddition polymerization to obtain an alternating copolymer carrying tBu ester and nitrile side chains in this study. Since 1,2,3‐triazole and nitrile moieties are known to be ligands for metal ions, the complex formation of the alternating copolymer with PdCl2 is also investigated by NMR. In the presence of PdCl2, 1H NMR spectra show broad and separated signals due to the free and complexed copolymers, indicative of slow exchange. Pulse‐field‐gradient spin‐echo NMR data indicated that the coordination of alternating copolymer to PdCl2 made the copolymer chains take a more compact conformation under dilute conditions. The density functional theory calculations indicated that the alternating copolymer coordinated to PdCl2 preferentially through the 1,2,3‐triazole nitrogen and nitrile nitrogen atoms. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Self-Healable and Conductive Hydrogel Coatings Based on Host-Guest Complexation between β-Cyclodextrin and Adamantane

Author

Park, Junsu, primary, Tamura, Hiroki, additional, Nakahata, Masaki, additional, Kobayashi, Yuichiro, additional, Yamaguchi, Hiroyasu, additional, Nakajima, Katsuhiko, additional, Takahashi, Hiroaki, additional, Takata, Satoshi, additional, Kayano, Kengo, additional, Harada, Akira, additional, Hatano, Kazuhiro, additional, and Takashima, Yoshinori, additional

Published
2023
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24. Synthesis of an alternating copolymer of the dense 1,2,3‐triazolebackbone carrying t‐butylester and nitrile side chains

Author

Xu, Linlin, Nakahata, Masaki, Kamon, Yuri, and Hashidzume, Akihito

Abstract

In these decades, synthesis of polymers with controlled monomer sequences has been of increasing importance in polymer chemistry. When we tested synthesis of a heterodimer of 4‐azido‐5‐hexynoic acid derivatives carrying t‐butyl (tBu) ester and tBu amide side chains for preparation of an alternating copolymer, we unexpectedly obtained a heterodimer precursor carrying tBu ester and nitrile side chains, in a high yield. Since dense 1,2,3‐triazole polymers carrying nitrile side chains are expected as a new functional polymer, the heterodimer is polymerized by copper(I)‐catalyzed azide–alkyne cycloaddition polymerization to obtain an alternating copolymer carrying tBu ester and nitrile side chains in this study. Since 1,2,3‐triazole and nitrile moieties are known to be ligands for metal ions, the complex formation of the alternating copolymer with PdCl2is also investigated by NMR. In the presence of PdCl2, 1H NMR spectra show broad and separated signals due to the free and complexed copolymers, indicative of slow exchange. Pulse‐field‐gradient spin‐echo NMR data indicated that the coordination of alternating copolymer to PdCl2made the copolymer chains take a more compact conformation under dilute conditions. The density functional theory calculations indicated that the alternating copolymer coordinated to PdCl2preferentially through the 1,2,3‐triazole nitrogen and nitrile nitrogen atoms.

Published
2024
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29. Selective Formose Reaction under Microwave Irradiation

Author

Hashidzume, Akihito, primary, Imai, Toru, additional, Deguchi, Nanako, additional, Tanibayashi, Takashi, additional, Ikeda, Takumi, additional, Michitaka, Tomohiro, additional, Kuwahara, Satoki, additional, Nakahata, Masaki, additional, Kamon, Yuri, additional, and Todokoro, Yasuto, additional

Published
2022
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31. Ion-specific nanoscale compaction of cysteine-modified poly(acrylic acid) brushes revealed by 3D scanning force microscopy with frequency modulation detection

Author

90706805, 10768071, 00706814, Yamamoto, Akihisa, Ikarashi, Takahiko, Fukuma, Takeshi, Suzuki, Ryo, Nakahata, Masaki, Miyata, Kazuki, Tanaka, Motomu, 90706805, 10768071, 00706814, Yamamoto, Akihisa, Ikarashi, Takahiko, Fukuma, Takeshi, Suzuki, Ryo, Nakahata, Masaki, Miyata, Kazuki, and Tanaka, Motomu

Abstract

Stimuli-responsive polyelectrolyte brushes adapt their physico-chemical properties according to pH and ion concentrations of the solution in contact. We synthesized a poly(acrylic acid) bearing cysteine residues at side chains and a lipid head group at the terminal, and incorporated them into a phospholipid monolayer deposited on a hydrophobic silane monolayer. The ion-specific, nanoscale response of polyelectrolyte brushes was detected by using three-dimensional scanning force microscopy (3D-SFM) combined with frequency modulation detection. The obtained topographic and mechanical landscapes indicated that the brushes were uniformly stretched, undergoing a gradual transition from the brush to the bulk electrolyte in the absence of divalent cations. When 1 mM calcium ions were added, the brushes were uniformly compacted, exhibiting a sharper brush-to-bulk transition. Remarkably, the addition of 1 mM cadmium ions made the brush surface significantly rough and the mechanical landscape highly heterogeneous. Currently, cadmium-specific nanoscale compaction of the brushes is attributed to the coordination of thiol and carboxyl side chains with cadmium ions, as suggested for naturally occurring, heavy metal binding proteins.

Published
2022

32. One-Step Synthesis of Gelatin-Conjugated Supramolecular Hydrogels for Dynamic Regulation of Adhesion Contact and Morphology of Myoblasts

Author

00706814, Hayashi, Kentaro, Matsuda, Mami, Mitake, Nodoka, Nakahata, Masaki, Munding, Natalie, Harada, Akira, Kaufmann, Stefan, Takashima, Yoshinori, Tanaka, Motomu, 00706814, Hayashi, Kentaro, Matsuda, Mami, Mitake, Nodoka, Nakahata, Masaki, Munding, Natalie, Harada, Akira, Kaufmann, Stefan, Takashima, Yoshinori, and Tanaka, Motomu

Abstract

Hydrogels possessing fine-adjustable and switchable elasticity emulate the mechanical microenvironments of biological cells, which are known to change dynamically during development and disease progression. In this study, a supramolecular hydrogel conjugated with gelatin side chains was synthesized. By systematically screening the molar fraction of supramolecular host/guest cross-linkers, Young’s modulus of the substrate was fine-adjusted to the level for myoblasts, E ≈ 10 kPa. C₂C₁₂ myoblasts reproducibly and firmly adhered to the gelatin-conjugated hydrogel via focal adhesion contacts consisting of integrin clusters, whereas only a few cells adhered to the gel without gelatin side chains. The elasticity of the gelatin-conjugated hydrogel was switchable to desired levels by simply adding and removing free guest molecules in appropriate concentrations without interfering with cell viability. Immunofluorescence confocal microscopy images of fixed cells confirmed the adaptation of focal adhesions and remodeling of actin cytoskeletons on the gelatin-conjugated hydrogel. Time-lapse phase-contrast images demonstrated the dynamic response of the cells, manifested in their morphology, to an abrupt change in the substrate elasticity. Gelatin-conjugated hydrogels with switchable elasticity enable the direct and reversible mechanical stimulation of cells in one step without tedious surface functionalization with adhesion ligands.

Published
2022

33. A Bio-synthetic Hybrid Hydrogel Formed under Physiological Conditions Consisting of Mucin and a Synthetic Polymer Carrying Boronic Acid

Author

1000040755641, Nakahata, Masaki, Tominaga, Naoki, Saito, Keishi, 1000040756029, Nishiyama, Keita, Tanino, Yuya, Saiki, Kiyoshiro, 1000000533647, Kojima, Masaru, 1000020359938, Sakai, Shinji, 1000040755641, Nakahata, Masaki, Tominaga, Naoki, Saito, Keishi, 1000040756029, Nishiyama, Keita, Tanino, Yuya, Saiki, Kiyoshiro, 1000000533647, Kojima, Masaru, 1000020359938, and Sakai, Shinji

Abstract

This is the peer reviewed version of the following article: Nakahata, M., Tominaga, N., Saito, K., Nishiyama, K., Tanino, Y., Saiki, K., Kojima, M. and Sakai, S. (2022), A Bio-synthetic Hybrid Hydrogel Formed under Physiological Conditions Consisting of Mucin and a Synthetic Polymer Carrying Boronic Acid. Macromol. Biosci., 22: 2200055, which has been published in final form at https://doi.org/10.1002/mabi.202200055. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited., Mucin-containing bio-synthetic hybrid hydrogel is successfully formed under physiological conditions upon mixing aqueous solutions of native mucin and synthetic polymers carrying boronic acids. The mechanical properties and stability of the hydrogel in physiological solutions, e.g., cell culture media, are tunable depending on the boronic acid content of polymers. The hydrogel dissolved in the physiological solutions releases native mucin and boronic acid-containing polymer, which can control the adhesion of mammalian cells to the surface.

Published
2022

44. Self-healable and Conductive Hydrogel Coatings Based on Host-guest Complexation between ß-Cyclodextrin and Adamantane

Author

Park, Junsu, Tamura, Hiroki, Nakahata, Masaki, Kobayashi, Yuichiro, Yamaguchi, Hiroyasu, Nakajima, Katsuhiko, Takahashi, Hiroaki, Takata, Satoshi, Kayano, Kengo, Harada, Akira, Hatano, Kazuhiro, and Takashima, Yoshinori

Abstract

Simultaneously self-healable and conductive materials are desirable because of their lightness, long lifetime, and flexibility. Although supramolecular chemistry has been employed to prepare these desired materials, in many cases, additional conductive agents are required. Herein, we incorporated the host-guest complexation between cyclodextrin and adamantane into an intrinsically conductive polymer system. The obtained polymeric materials showed simultaneous self-healing properties and electrical conductivities solely as coatings without addition of any conductive agents.We have prepared simultaneously self-healable and conductive polymeric materials based on host-guest chemistry between cyclodextrin and adamantane in poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonic acid) systems. The obtained polymeric materials were investigated as functional coatings. The anchor units employed in the polymer chains increased the electric conductivities as well as the adhesion force on the substrate.

Published
2023
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45. Mechanical stimulation of single cells by reversible host-guest interactions in 3D microscaffolds

Author

Hippler, Marc, primary, Weißenbruch, Kai, additional, Richler, Kai, additional, Lemma, Enrico D., additional, Nakahata, Masaki, additional, Richter, Benjamin, additional, Barner-Kowollik, Christopher, additional, Takashima, Yoshinori, additional, Harada, Akira, additional, Blasco, Eva, additional, Wegener, Martin, additional, Tanaka, Motomu, additional, and Bastmeyer, Martin, additional

Published
2020
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47. Stimuli-responsive hydrogels as a model of the dynamic cellular microenvironment

Author

00706814, Tanaka, Motomu, Nakahata, Masaki, Linke, Philipp, Kaufmann, Stefan, 00706814, Tanaka, Motomu, Nakahata, Masaki, Linke, Philipp, and Kaufmann, Stefan

Abstract

Ample evidence has demonstrated that biological cells not only react to biochemical cues from the surrounding microenvironments but also sensitively detect the mechanical properties of the extracellular matrix and neighboring cells to adapt their shape, function, and fate. Mechanical aspects in biology, called mechanobiology, have been attracting biologists, chemists, physicists, and mechanical engineers. However, most in vitro studies to date have heavily relied on covalently cross-linked hydrogels with prefixed and hence unchangeable mechanical properties, although the mechanical properties of the cellular microenvironment are never uniform or static. From this context, stimuli-responsive hydrogels are highly attractive as surrogate materials that can simulate dynamic physical microenvironments in vivo. This review tries to provide a comprehensive overview of previous achievements, present pitfalls and challenges, and future perspectives on the recent development of stimuli-responsive hydrogel materials for the dynamic control of cell behavior.

Published
2020

48. Mechanical stimulation of single cells by reversible host-guest interactions in 3D microscaffolds

Author

00706814, Hippler, Marc, Weißenbruch, Kai, Richler, Kai, Lemma, Enrico D., Nakahata, Masaki, Richter, Benjamin, Barner-Kowollik, Christopher, Takashima, Yoshinori, Harada, Akira, Blasco, Eva, Wegener, Martin, Tanaka, Motomu, Bastmeyer, Martin, 00706814, Hippler, Marc, Weißenbruch, Kai, Richler, Kai, Lemma, Enrico D., Nakahata, Masaki, Richter, Benjamin, Barner-Kowollik, Christopher, Takashima, Yoshinori, Harada, Akira, Blasco, Eva, Wegener, Martin, Tanaka, Motomu, and Bastmeyer, Martin

Published
2020

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