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376 results on '"Terakawa, Mitsuhiro"'

115. ナノ高強度散乱近接場光プロセスによる表面機能光学素子の開発

Author

慶應義塾大学・理工学部・名誉教授, 慶應義塾大学・理工学部・教授, 慶應義塾大学・理工学部・専任講師, オバラ, ミノル, サイキ, トシハル, ツダ, ヒロユキ, テラカワ, ミツヒロ, Obara, Minoru, Saiki, Toshiharu, Tsuda, Hiroyuki, Terakawa, Mitsuhiro, 小原, 實, 斎木, 敏治, 津田, 裕之, 寺川, 光洋, 慶應義塾大学・理工学部・名誉教授, 慶應義塾大学・理工学部・教授, 慶應義塾大学・理工学部・専任講師, オバラ, ミノル, サイキ, トシハル, ツダ, ヒロユキ, テラカワ, ミツヒロ, Obara, Minoru, Saiki, Toshiharu, Tsuda, Hiroyuki, Terakawa, Mitsuhiro, 小原, 實, 斎木, 敏治, 津田, 裕之, and 寺川, 光洋

Abstract

Research team head, Research team member, Publisher, 微小構造からの散乱近接場光は局在し、フェムト秒レーザー励起光強度より増強近接場強度となり、ナノプロセシングが可能となる。本研究は、照射方式、散乱体構造・サイズ、プロセス基板の種類から、近接場特性とアブレーション特性を明らかにした。プラズモニック散乱とMie散乱近接場の特徴を明確にした。散乱増強近接場光とともに、散乱遠方場光を使った表面微細周期構造の作製とその作製メカニズムを解明した。 An enhanced near-field scattered from nanostructures is localized to the nano-scale zone, and is then used for nano-ablation processing of a variety of advanced functional materials. This report presents theoretically and experimentally the characteristics of near-field and nano-ablation in terms of femtosecond laser polarization, irradiation angles, scattering structures, scattering materials, work materials. Near-fields from plasmonic scattering and Mie scattering are clearly explained. In addition to the enhanced near-field processing, the mechanism of surface ripples formed by the interference of the incident femtosecond laser and the scattered far-field light is well explained by using the 3D FDTD method. The nano-patterned surfaces fabricated these methods can potentially be used for surface photonic devices., 研究種目 : 基盤研究(B) 研究期間 : 2011～2013 課題番号 : 23360161 研究分野 : 工学 科研費の分科・細目 : 電気電子工学・電子デバイス・電子機器

Published
2014

116. Biodegradability of poly(lactic-co-glycolic acid) and poly( l-lactic acid) after deep-ultraviolet femtosecond and nanosecond laser irradiation.

Author

Shibata, Akimichi, Machida, Manan, Kondo, Naonari, and Terakawa, Mitsuhiro

Subjects
POLYMERS, IRRADIATION, POLYMER films, X-ray diffraction, PHOTOELECTRON spectroscopy
Abstract

In this study, we investigated the change in biodegradability of biodegradable polymer films by deep-ultraviolet laser irradiation with different pulse durations. Measurements of water absorption and mass change as well as microscopic observation revealed that the femtosecond laser irradiation significantly accelerated the degradation rate of the biodegradable polymer films, whereas the nanosecond laser irradiation did not induce a comparable degree of change. Analyses with X-ray photoelectron spectroscopy and X-ray diffraction indicate that the difference in the biodegradability following laser irradiation with different pulse durations is attributable to the difference in chemical structure for amorphous polymers including PLGA, while the difference in chemical structure as well as crystallinity affects the biodegradability for crystalline polymer including PLLA. The obtained results suggest that deep-ultraviolet laser processing enables the fabrication of a tissue scaffold with a desirable degradation rate. [ABSTRACT FROM AUTHOR]

Published
2017
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121. In vitro perforation of human epithelial carcinoma cell with antibody-conjugated biodegradable microspheres illuminated by a single 80 femtosecond near-infrared laser pulse

Author

Terakawa,Mitsuhiro, Tsunoi,Yasuyuki, Mitsuhashi,Tatsuki, Terakawa,Mitsuhiro, Tsunoi,Yasuyuki, and Mitsuhashi,Tatsuki

Abstract

Mitsuhiro Terakawa, Yasuyuki Tsunoi, Tatsuki MitsuhashiDepartment of Electronics and Electrical Engineering, Keio University, Yokohama, Kanagawa, JapanAbstract: Pulsed laser interaction with small metallic and dielectric particles has been receiving attention as a method of drug delivery to many cells. However, most of the particles are attended by many risks, which are mainly dependent upon particle size. Unlike other widely used particles, biodegradable particles have advantages of being broken down and eliminated by innate metabolic processes. In this paper, the perforation of cell membrane by a focused spot with transparent biodegradable microspheres excited by a single 800 nm, 80 fs laser pulse is demonstrated. A polylactic acid (PLA) sphere, a biodegradable polymer, was used. Fluorescein isothiocyanate (FITC)-dextran and short interfering RNA were delivered into many human epithelial carcinoma cells (A431 cells) by applying a single 80 fs laser pulse in the presence of antibody-conjugated PLA microspheres. The focused intensity was also simulated by the three-dimensional finite-difference time-domain method. Perforation by biodegradable spheres compared with other particles has the potential to be a much safer phototherapy and drug delivery method for patients. The present method can open a new avenue, which is considered an efficient adherent for the selective perforation of cells which express the specific antigen on the cell membrane.Keywords: femtosecond laser, drug delivery, transfection, biodegradable polymer

Published
2012

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