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Author

Kazunari Akiyoshi

Bio: Kazunari Akiyoshi is an academic researcher from Kyoto University. The author has contributed to research in topics: Nanogel & Pullulan. The author has an hindex of 59, co-authored 336 publications receiving 12219 citations. Previous affiliations of Kazunari Akiyoshi include Tokyo Medical and Dental University & Purdue University.


Papers
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TL;DR: In this article, the authors studied the aggregation properties of hydrophobized pullulan containing 1.6 cholesterol groups per 100 glucose units (CHP-55-1.6).
Abstract: Solution properties in water of hydrophobized pullulan containing 1.6 cholesterol groups per 100 glucose units (CHP-55-1.6) were studied. SEC measurements show that CHP (1.0 mg/mL, 0.10 wt %) intermolecularly aggregates and provides relatively monodispersive particles upon ultrasonication. Spherical particles with relatively uniform size (the diameter, 25±5 nm) were observed in the negatively stained electron microscopy of the aqueous CHP solution. The hydrodynamic radius of the CHP self-aggregate was approximately 13 nm and the aggregation number was approximately 13.

553 citations

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TL;DR: In this article, the authors developed hybrid exosomes by fusing their membranes with liposomes using the freeze-thaw method, which can be combined with genetic modification techniques to control and modify the performance of exosomal nanocarriers.
Abstract: Exosomes are a valuable biomaterial for the development of novel nanocarriers as functionally advanced drug delivery systems. To control and modify the performance of exosomal nanocarriers, we developed hybrid exosomes by fusing their membranes with liposomes using the freeze–thaw method. Exosomes embedded with a specific membrane protein isolated from genetically modified cells were fused with various liposomes, confirming that membrane engineering methods can be combined with genetic modification techniques. Cellular uptake studies performed using the hybrid exosomes revealed that the interactions between the developed exosomes and cells could be modified by changing the lipid composition or the properties of the exogenous lipids. These results suggest that the membrane-engineering approach reported here offers a new strategy for developing rationally designed exosomes as hybrid nanocarriers for use in advanced drug delivery systems.

420 citations

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TL;DR: Spontaneous dissociation of Ins from the complex was barely observed, except in the presence of bovine serum albumin, and the original physiological activity of complexed Ins was preserved in vivo after i.v. injection.

414 citations

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TL;DR: Results indicate that cCHP nanogel can be used as a universal protein-based antigen-delivery vehicle for adjuvant-free intranasal vaccination.
Abstract: Nanotechnology is an innovative method of freely controlling nanometre-sized materials. Recent outbreaks of mucosal infectious diseases have increased the demands for development of mucosal vaccines because they induce both systemic and mucosal antigen-specific immune responses. Here we developed an intranasal vaccine-delivery system with a nanometre-sized hydrogel ('nanogel') consisting of a cationic type of cholesteryl-group-bearing pullulan (cCHP). A non-toxic subunit fragment of Clostridium botulinum type-A neurotoxin BoHc/A administered intranasally with cCHP nanogel (cCHP-BoHc/A) continuously adhered to the nasal epithelium and was effectively taken up by mucosal dendritic cells after its release from the cCHP nanogel. Vigorous botulinum-neurotoxin-A-neutralizing serum IgG and secretory IgA antibody responses were induced without co-administration of mucosal adjuvant. Importantly, intranasally administered cCHP-BoHc/A did not accumulate in the olfactory bulbs or brain. Moreover, intranasally immunized tetanus toxoid with cCHP nanogel induced strong tetanus-toxoid-specific systemic and mucosal immune responses. These results indicate that cCHP nanogel can be used as a universal protein-based antigen-delivery vehicle for adjuvant-free intranasal vaccination.

406 citations

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TL;DR: Recent progress in the synthesis of nanogels and nanogel-integrated hydrogels (nanogel cross-linked gels) for drug-delivery systems (DDS), regenerative medicine, and bioimaging is described.
Abstract: Nanosize hydrogels (nanogels) are polymer nanoparticles with three-dimensional networks, formed by chemical and/or physical cross-linking of polymer chains. Recently, various nanogels have been designed, with a particular focus on biomedical applications. In this review, we describe recent progress in the synthesis of nanogels and nanogel-integrated hydrogels (nanogel cross-linked gels) for drug-delivery systems (DDS), regenerative medicine, and bioimaging. We also discuss chaperone-like functions of physical cross-linking nanogel (chaperoning engineering) and organic-inorganic hybrid nanogels.

308 citations


Cited by
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Journal ArticleDOI
TL;DR: This work reviews recent advances and challenges in the developments towards applications of stimuli-responsive polymeric materials that are self-assembled from nanostructured building blocks and provides a critical outline of emerging developments.
Abstract: Responsive polymer materials can adapt to surrounding environments, regulate transport of ions and molecules, change wettability and adhesion of different species on external stimuli, or convert chemical and biochemical signals into optical, electrical, thermal and mechanical signals, and vice versa. These materials are playing an increasingly important part in a diverse range of applications, such as drug delivery, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings and textiles. We review recent advances and challenges in the developments towards applications of stimuli-responsive polymeric materials that are self-assembled from nanostructured building blocks. We also provide a critical outline of emerging developments.

4,908 citations

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TL;DR: This work highlights recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for biomedical and biological applications and shows how such systems' intelligent behavior can be used in sensors, microarrays, and imaging.
Abstract: Hydrophilic polymers are the center of research emphasis in nanotechnology because of their perceived “intelligence”. They can be used as thin films, scaffolds, or nanoparticles in a wide range of biomedical and biological applications. Here we highlight recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for these applications. Natural, biohybrid, and synthetic hydrophilic polymers and hydrogels are analyzed and their thermodynamic responses are discussed. In addition, examples of the use of hydrogels for various therapeutic applications are given. We show how such systems’ intelligent behavior can be used in sensors, microarrays, and imaging. Finally, we outline challenges for the future in integrating hydrogels into biomedical applications.

3,524 citations

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TL;DR: The atomic force microscope (AFM) is not only used to image the topography of solid surfaces at high resolution but also to measure force-versus-distance curves as discussed by the authors, which provide valuable information on local material properties such as elasticity, hardness, Hamaker constant, adhesion and surface charge densities.

3,281 citations

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TL;DR: In this article, the authors focused on temperature and pH responsive polymer systems and additionally the other stimuli-based responsive polymers will be assessed, which is more helpful to design new approaches because the basic concepts and mechanisms are systematically connected.

2,233 citations

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TL;DR: The ability of pore size and porosity of scaffolds to direct cellular responses and alter the mechanical properties of scaffold will be reviewed, followed by a look at nature's own scaffold, the extracellular matrix.
Abstract: Tissue engineering applications commonly encompass the use of three-dimensional (3D) scaffolds to provide a suitable microenvironment for the incorporation of cells or growth factors to regenerate ...

2,075 citations