Takamasa Sakai

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We have developed a novel form of granular artificial bone "Tetrabones" with a homogeneous tetrapod shape and uniform size. Tetrabones are four armed structures that accumulate to form the intergranular pores that allow invasion of cells and blood vessels. In this study we evaluated the physicochemical characteristics of Tetrabones in vitro, and compared(More)
BACKGROUND Early treatment of disseminated intravascular coagulation (DIC) can be associated with improved patient outcomes. The Japanese Ministry of Health and Welfare (JMHW) and the International Society on Thrombosis and Haemostasis (ISTH) criteria are the most specific for diagnosis of septic DIC. The revised Japanese Association for Acute Medicine(More)
A robust hydrogel with a reliable deformation region in an aqueous environment is proposed. The gel has a homogeneous network where hydrophilic/hydrophobic components are uniformly distributed. In an aqueous environment, aggregated hydrophobic segments serve as "mechanical fuse links," inhibiting sudden macroscopic fracture. The gel endures threefold(More)
We used a coarse-grained (CG) molecular dynamics model with potentials convertible to actual units to simulate the polymerization of a gel of a tetra-armed poly(ethylene glycol) derivative (MW ≈ 6000) under aqueous conditions and analysed its three-dimensional network structure. The radius of gyration of individual pre-polymers after gelation was slightly(More)
We investigated biodegradability and new bone formation after implantation of tetrapod-shaped granular artificial bone (Tetrabone®) or β-tricalcium phosphate granules (β-TCP) in experimental critical-size defects in dogs, which were created through medial and lateral femoral condyles. The defect was packed with Tetrabone® (Tetrabone group) or β-TCP (β-TCP(More)
Hydrogels are three-dimensional polymer networks that contain a large amount of water inside. Certain hydrogels can be injected in solution and transformed into the gel state with the required shape. Despite their potential biomedical applications, the use of hydrogels has been severely limited because all the conventional hydrogels inevitably "swell" under(More)
Self-oscillation of polymer chains in an aqueous solution has been achieved. The ruthenium catalyst for the Belousov-Zhabotinsky reaction was polymerized by using N-isopropylacrylamide and dissolved into the solution containing the BZ substrates. Periodical soluble-insoluble changes of the polymer chain were spontaneously induced by the BZ reaction. The(More)
A novel technique was developed to regulate the bulk water content of silk hydrogels by adjusting the concentrations of silk proteins, which is helpful to investigate the effects of the state of water in polymeric hydrogel on its biological functions, such as cytotoxicity. Gelation of the silk hydrogel was induced with ethanol and its gelation behavior was(More)
Stimuli-responsive polymers and their application to biomaterials have been widely studied. On the other hand, as a novel biomimetic polymer, we have been studying the polymer with an autonomous self-oscillating function by utilizing oscillating chemical reactions. So far, we succeeded in developing a novel self-oscillating polymer and gels by utilizing the(More)
A new type of self-oscillating polymer was prepared by utilizing the Belousov-Zhabotinsky reaction. In this study, capture sites with a positive charge for an oxidizing agent as a counterion were incorporated into the copolymer of N-isopropylacrylamide and the ruthenium complex as a catalyst. Soluble-insoluble self-oscillation of the polymer was first(More)