| 1. |
Kenta Temma, Ryosuke Oketani, Toshiki Kubo, Kazuki Bando, Shunsuke Maeda, Kazunori Sugiura, Tomoki Matsuda, Rainer Heintzmann, Tatsuya Kaminishi, Koki Fukuda, Maho Hamasaki, Takeharu Nagai, Katsumasa Fujita, Selective-plane-activation structured illumination microscopy, Nature Methods, 10.1038/s41592-024-02236-3, 2024.04. |
| 2. |
YUSUKE MURAKAMI, Minami Yoshimura, W.J. Klement, Atsuki Oda, Ryo Sakamoto, Miho Yakabe, Atsushi Matsumoto, Ryosuke Oketani, Philippe Leproux, Junichi Ikenouchi, Wesley Browne, Hideaki Kano, Backward multiplex coherent anti-Stokes Raman (CARS) spectroscopic imaging with electron-multiplying CCD (EMCCD) camera, Optics Continuum, 10.1364/optcon.497869, 2, 9, 2044-2054, 2023.09. |
| 3. |
Kyosuke Tanaka, Ryosuke Oketani, Takeshi Terada, Philippe Leproux, Yuki Morono, Hideaki Kano, Label-Free Identification of Spore-Forming Bacteria Using Ultrabroadband Multiplex Coherent Anti-Stokes Raman Scattering Microspectroscopy, The Journal of Physical Chemistry B, 10.1021/acs.jpcb.2c07291, 127, 9, 1940-1946, 2023.02. |
| 4. |
Kazuki Bando, Shumpei Yabuuchi, Menglu Li, Toshiki Kubo, Ryosuke Oketani, Nicholas I. Smith, Katsumasa Fujita, Bessel-beam illumination Raman microscopy, Biomedical Optics Express, 10.1364/BOE.456138, 13, 6, 3161-3170, 2022.05, We demonstrate the use of Bessel beams for side illumination slit-scanning Raman imaging for label-free and hyperspectral analysis of cell spheroids. The background elimination by the side illumination and the aberration-resistant Bessel beam drastically improves the image contrast in Raman observation, allowing label-free investigation of intracellular molecules in thick biological samples. Live cell spheroids were observed to confirm the improvement in image contrast and background reduction with Bessel illumination compared to conventional epi-line illumination.. |
| 5. |
Kenta Temma, Ryosuke Oketani, René Lachmann, Toshiki Kubo, Nicholas I. Smith, Rainer Heintzmann, Katsumasa Fujita, Saturated-excitation image scanning microscopy, Optics Express, 10.1364/oe.455621, 30, 8, 13825-13838, 2022.04. |
| 6. |
Yusuke Murakami, Minori Masaki, Shinichi Miyazaki, Ryosuke Oketani, Yu Hayashi, Masashi Yanagisawa, Sakiko Honjoh, Hideaki Kano, Spectroscopic second and third harmonic generation microscopy using a femtosecond laser source in the third near-infrared (NIR-III) optical window, Biomedical Optics Express, 10.1364/boe.446273, 13, 2, 694-708, 2022.01, In this study, second harmonic generation (SHG) and third harmonic generation (THG) spectroscopic imaging were performed on biological samples using a femtosecond laser source in the third near-infrared (NIR) optical window (NIR-III). Using a visible-NIR spectrometer, the SHG and THG signals were simultaneously detected and were extracted using spectral analysis. Visualization of biological samples such as cultured cells (HEK293 T), mouse brain slices, and the nematode Caenorhabditis elegans was performed in a label-free manner. In particular, in an SHG image of an entire coronal brain section (8 × 6 mm2), we observed mesh-like and filamentous structures in the arachnoid mater and wall of the cerebral ventricle, probably corresponding to the collagen fibers, cilia, and rootlet. Moreover, the THG images clearly depicted the densely packed axons in the white matter and cell nuclei at the cortex of the mouse brain slice sample and lipid-rich granules such as lipid droplets inside the nematode. The observations and conclusions drawn from this technique confirm that it can be utilized for various biological applications, including in vivo label-free imaging of living animals.. |
| 7. |
Kentaro Nishida, Hikaru Sato, Ryosuke Oketani, Kentaro Mochizuki, Kenta Temma, Yasuaki Kumamoto, Hideo Tanaka, Katsumasa Fujita, Using saturated absorption for super‐resolution laser scanning transmission microscopy, Journal of Microscopy, 10.1111/jmi.13033, 288, 2, 117-129, 2021.05. |
| 8. |
Atsushi Taguchi, Atsushi Nakayama, Ryosuke Oketani, Satoshi Kawata, Katsumasa Fujita, Multiphoton-Excited Deep-Ultraviolet Photolithography for 3D Nanofabrication, ACS Applied Nano Materials, 10.1021/acsanm.0c02519, 3, 11, 11434-11441, 2020.11, © 2020 American Chemical Society. Light-matter interactions in the deep-ultraviolet (DUV) wavelength region exhibit a variety of optical effects such as luminescence, photoisomerization, and polymerization in many materials. Despite the rich photochemistry and high spatial resolution due to the short wavelength, the notorious lack of DUV-compatible optical components and devices precludes the use of DUV light in microscopy and lithography as a routine laboratory tool. Here, we present the use of two-photon excitation with visible laser light to realize photopolymerization of molecules with an excitation energy equivalent to DUV light. Using standard optics for visible light, we polymerized methacrylate oligomers with 400 nm femtosecond pulses without any addition of photoinitiators and sensitizers. By scanning the laser focus in 3D, we created a series of fine 3D structures with the smallest resolved line-space features of 80 nm. We found that photopolymerizations induced by two-photon absorption at DUV is surprisingly efficient and requires laser intensity only on the order of 100 kW/cm2. The use of DUV absorption sites natively existing in monomers simplifies polymerization reactions without sacrificing material purities by adding initiators and facilitates applications to diverse materials. We have applied two-photon DUV polymerizations to metal-oxo clusters and the amino acid cysteine. With the variety of successful demonstrations including organic- and inorganic-material-made-structures presented, multiphoton DUV polymerization offers a distinct tool for fabrications of nanodevices in 3D.. |
| 9. |
Ryosuke Oketani, Haruka Suda, Kumiko Uegaki, Toshiki Kubo, Tomoki Matsuda, Masahito Yamanaka, Yoshiyuki Arai, Nicholas I. Smith, Takeharu Nagai, Katsumasa Fujita, Visible-wavelength two-photon excitation microscopy with multifocus scanning for volumetric live-cell imaging, Journal of Biomedical Optics, 10.1117/1.jbo.25.1.014502, 25, 01, 014502-5, 2019.11, Two-photon excitation microscopy is one of the key techniques used to observe three-dimensional (3-D) structures in biological samples. We utilized a visible-wavelength laser beam for two-photon excitation in a multifocus confocal scanning system to improve the spatial resolution and image contrast in 3-D live-cell imaging. Experimental and numerical analyses revealed that the axial resolution has improved for a wide range of pinhole sizes used for confocal detection. We observed the 3-D movements of the Golgi bodies in living HeLa cells with an imaging speed of 2 s per volume. We also confirmed that the time-lapse observation up to 8 min did not cause significant cell damage in two-photon excitation experiments using wavelengths in the visible light range. These results demonstrate that multifocus, two-photon excitation microscopy with the use of a visible wavelength can constitute a simple technique for 3-D visualization of living cells with high spatial resolution and image contrast.. |
| 10. |
Yu-Ting Chen, Po-Hsuan Lee, Po-Ting Shen, Jann Launer, Ryosuke Oketani, Kuan-Yu Li, Yen-Ta Huang, Kyoko Masui, Satoru Shoji, Katsumasa Fujita, Shi-Wei Chu, Study of Nonlinear Plasmonic Scattering in Metallic Nanoparticles, ACS Photonics, 10.1021/acsphotonics.6b00025, 3, 8, 1432-1439, 2016.08, Nonlinear optical effects play key roles to communication, sensing, imaging, and so on. Recently, nonlinear scattering (saturation and reverse saturation) was discovered in gold nanospheres, providing a novel approach to nonbleaching super-resolution microscopy. However, the nonlinearity was previously limited to green-orange plasmonic band. It is highly desirable to extend the applicable wavelength range. In this work, we demonstrated nonlinear scattering in near-infrared with gold nanorods and in blue-violet with silver nanospheres. Besides, the nonlinear mechanism is clarified via different material/geometry. By spectrally decoupling the contributions of plasmonic absorption/scattering and interband/intraband transitions, we have verified plasmonic absorption, and the subsequent thermal effects to be the dominating source of nonlinearity. Our work not only provides the physical mechanism of the nonlinear scattering, but also paves the way toward multicolor super-resolution imaging based on plasmonic scattering.. |
| 11. |
Hsueh-Yu Wu, Yen-Ta Huang, Po-Ting Shen, Hsuan Lee, Ryosuke Oketani, Yasuo Yonemaru, Masahito Yamanaka, Satoru Shoji, Kung-Hsuan Lin, Chih-Wei Chang, Satoshi Kawata, Katsumasa Fujita, Shi-Wei Chu, Ultrasmall all-optical plasmonic switch and its application to superresolution imaging, Scientific Reports, 10.1038/srep24293, 6, 1, 24293, 2016.07. |
| 12. |
Hsuan Lee, Kuan-Yu Li, Yen-Ta Huang, Po-Ting Shen, Gitanjal Deka, Ryosuke Oketani, Yasuo Yonemaru, Masahito Yamanaka, Katsumasa Fujita, Shi-Wei Chu, Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle, Journal of Visualized Experiments, 10.3791/53338, 107, e53338, 2016.01. |
| 13. |
Shi-Wei Chu, Tung-Yu Su, Ryosuke Oketani, Yen-Ta Huang, Hsueh-Yu Wu, Yasuo Yonemaru, Masahito Yamanaka, Hsuan Lee, Guan-Yu Zhuo, Ming-Ying Lee, Satoshi Kawata, Katsumasa Fujita, Measurement of a Saturated Emission of Optical Radiation from Gold Nanoparticles: Application to an Ultrahigh Resolution Microscope, Physical Review Letters, 10.1103/physrevlett.112.017402, 112, 1, 017402, 2014.01. |
| 14. |
Hsuan Lee, Ryosuke Oketani, Yen-Ta Huang, Kuan-Yu Li, Yasuo Yonemaru, Masahito Yamanaka, Satoshi Kawata, Katsumasa Fujita, Shi-Wei Chu, Point spread function analysis with saturable and reverse saturable scattering, Optics Express, 10.1364/oe.22.026016, 22, 21, 26016-26022, 2014.10. |
| 15. |
Shi-Wei Chu, Hsueh-Yu Wu, Yen-Ta Huang, Tung-Yu Su, Hsuan Lee, Yasuo Yonemaru, Masahito Yamanaka, Ryosuke Oketani, Satoshi Kawata, Satoru Shoji, Katsumasa Fujita, Saturation and Reverse Saturation of Scattering in a Single Plasmonic Nanoparticle, ACS Photonics, 10.1021/ph4000218, 1, 1, 32-37, 2014.01. |
