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Katsumasa FUJITA

Professor, Ph. D.
Department of Applied Physics, Osaka University
2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
office: P2-300, Suita Campus, Osaka University
phone: +81-6-6879-7847

Symposium: BRI 2019

We organized a symposium: Biomedical Raman Imaging 2019 on 24 - 26 Nove, 2019 in Osaka. There were 129 participants from many different countries!

A report in Spectroscopy, 35 (4), 43–46 (2020).

Research Topics

HeLa cell stained with AttoR6G phalloidin

Super-resolution fluorescence microscopy : SAX microscopy
We are developing optical microscopy techniques which can resolve fine structures of samples with the spatial resolution beyond the diffraction limit of light. By using saturated excitation (SAX) of fluorescence molecules, we induce nonlinear fluorescence emission that contribute to produce super-resolution images. The SAX miroscope can be realized by simply modulating laser intensity and demodulating fluorescence signal in a typical confocal microscope.

The figure shows the fluorescence images of a HeLa cell stained with AttoR6G phalloidin (xz cross-section). SAX microscopy can image fine structures that can not be resolved by conventional confocal microscopy.

Temma et al., Opt. Express (2022).
Nawa et al., APL Photonics (2018).
Oketani et al., Opt. Lett. (2017).
Yonemaru et al., Phys. Rev. Applied (2015).
Chu et al., Phys. Rev. Lett. (2014).
Yamanaka et al., J. Biomed. Opt. (2013).
Fujita et al., Phys. Rev. Lett. (2007)

753 cm-1 : Cytochrome
1686 cm-1 : Protein
2852 cm-1 : Lipid

Movie by Raman
Cell division: cytokinesis
Cell division: mitosis
Raman microscopy for imaging of biological samples
We are developing Raman microscopes to image and analyze biomolecules in living cells. Raman scattering spectra show molecular vibrations in a sample, that contain rich information about species, conditions and environments of molecules. We have developed a slit-scanning Raman microscope and applied it to imaging of biomolecule dynamics in a living cell. We are also developing a higher-sensitive Raman detection technique for cellular imaging by using surface-enhanced Raman scattering and Raman tags to image small molecules.

The figure shows a Raman image of living HeLa cells. Molecular vibrations detected by Raman spectra produce the distribution of proteins and lipids in the cells.

Bando et al., Biomed. Opt. Express. (2022).
SPIE Newroom (2016).
Wanatabe et al., Nat. Commun. (2015).
Palonpon et al, Nat. Protoc. (2013).
Okada et al., PNAS (2012).
Ando et al., Nano Lett. (2011).
Hamada et al., J. Biomed. Opt. (2008).

Alkyne (EdU), Cytochrome , Lipid

Raman tag imaging
Raman tag imaging is a new technique to observe small molecules in living cells and tissues. Small molecules are too "small" to be labeled by fluorescent dyes and could not be observed in the physiological conditions. We have demonstrated the use of Raman tag to visualize small molecules. Raman tag, such as an alkyne, shows a Raman band district from intracellular molecules and allows us to observe small molecules labeled by Raman tags with Raman microscopy. The Raman tag also realizes multiplexed imaging of many different molecules via the extremely narrow emission band of Raman scattering. We are also working on the application of the Raman tag technique for pharmaceutical researches.

Dodo et al, JACS (2022). Koike et al, ACS Nano (2020).
Ando et al, JACS (2016).
Ando et al, PNAS (2015).
Yamakoshi et al, Bioorg. Med. Chem. Lett. (2015).
Yamakoshi et al, Chem Commun. (2014).
Palonpon et al, Nat. Protoc. (2013).
Yamakoshi et al., JACS (2011).

Original Papers
  • K. M. Helal, H. Cahyadi, J. N. Taylor, A. Okajima, K. Tabata, Y. Kumamoto, K. Mochizuki, Y. Itoh, T. Takamatsu, H. Tanaka, K. Fujita, T. Komatsuzaki, Y. Harada, "Raman imaging of rat non-alcoholic fatty liver tissues reveals distinct biomolecular states," FEBS Lett. (accepted).
  • K. Mochizuki, Y. Kumamoto, S. Maeda, M. Tanuma, A. Kasai, M. Takemura, Y. Harada, H. Hashimoto, H. Tanaka, N. I. Smith, and K. Fujita, "High-throughput line-illumination Raman microscopy with multislit detection," Biomed. Opt. Express., 14 (3), 1015-1026 (2023).
  • M. Hayakawa, J. N. Taylor, R. Nakao, K. Mochizuki, Y. Sawai, K. Hashimoto, K. Tabata, Y. Kumamoto, K. Fujita, E. Konishi, S. Hirano, H. Tanaka, and T. Komatsuzaki, "Lipid Droplet Accumulation and Adipophilin Expression in Follicular Thyroid Carcinoma," Biochem. Biophys. Res. Commun., 640, 192-201 (2023).
  • M. Li, Y. Nawa, S. Ishida, Y. Kanda, S. Fujita, and K. Fujita, "Label-free chemical imaging of cytochrome P450 activity by Raman microscopy," Commun Biol., 5, 778 (2022)
  • M. Li, H.-X. Liao, K. Bando, Y. Nawa, S. Fujita, and K. Fujita, "Label-free monitoring of drug-induced cytotoxicity and its molecular fingerprint by live-cell Raman and autofluorescence imaging," Anal. Chem., 94 (28) 10019–10026 (2022).
  • A. Nakayama, Y. Kumamoto M. Minoshima, K. Kikuchi, A. Taguchi, and K. Fujita, "Photoinitiator-free two-photon polymerization of biocompatible materials for 3D micro/nanofabrication,”Adv. Opt. Mater., 2200474 (2022).
  • K. Bando, S. Yabuuchi, M. Li, T. Kubo, R. Oketani, N. I. Smith, and K. Fujita, "Bessel-beam illumination Raman microscopy,” Biomed. Opt. Express. 13 (6) 3161-3170 (2022).
  • K. Temma, R. Oketani, R. Lachmann, T. Kubo, N. I. Smith, R. Heintzmann, and K. Fujita, "Saturated-excitation image scanning microscopy," Opt. Express. 30 (8) 13825-13838 (2022).
  • K. Koike, N. I. Smith, and K. Fujita, “Spectral focusing in picosecond pulsed stimulated Raman scattering microscopy,” Biomed. Opt. Express., 13 (2), 995-1004 (2022).
  • K. Nishida, H. Sato, R. Oketani, K. Mochizuki, K. Temma, Y. Kumamoto, H. Tanaka, K. Fujita*, "Using saturated absorption for super‐resolution laser scanning transmission microscopy," J. Microsc. 288 (2), 117-129 (2022).
  • S. A. Hussain, T. Kubo, N. Hall, D. Gala, K. Hampson, R. Parton, M. A. Phillips, M. Wincott, K. Fujita, I. Davis, I. Dobbie, M. J. Booth, "Wavefront‐sensorless adaptive optics with a laser‐free spinning disk confocal microscope," J. Microsc., 288 (2), 106-116 (2022).
  • H. Lee, H. Yoo, G. Moon, K.-A. Toh, K. Mochizuki, K. Fujita, and D. Kim, "Super-resolved Raman microscopy using random structured light illumination: concept and feasibility," J. Chem. Phys. 155, 144202 (2021).
  • T. Kubo, K. Temma, K. Sugiura, H. Shinoda, K. Lu, N. I. Smith, T. Matsuda, T. Nagai, K. Fujita, "Visible-wavelength multiphoton activation confocal microscopy," ACS Photonics, 8 (9) 2666–2673 (2021).
  • T. Ichimura, T. Kakizuka, K. Horikawa, K. Seiriki, A. Kasai, H. Hashimoto, K. Fujita, T. M. Watanabe, T. Nagai, “Exploring rare cellular activity in more than one million cells by a trans-scale scope,” Sci. Rep., 11, 16539 (2021).
  • H. Kawagoe, J. Ando, M. Asanuma, K. Dodo, T. Miyano, H. Ueda, M. Sodeoka, K. Fujita, “Multiwell Raman plate reader for high-throughput biochemical screening,” Sci. Rep., 11, 15742 (2021).
  • J. Ando, H. Kawagoe, A. Nakamura, R. Iino and K. Fujita, "Label-free monitoring of crystalline chitin hydrolysis by chitinase based on Raman spectroscopy," Analyst, 146, 4087-4094 (2021).
  • F. Tai, K. Koike, H. Kawagoe, J. Ando, Y. Kumamoto, N. I. Smith, M. Sodeoka, K. Fujita, "Detecting nitrile-containing small molecules by infrared photothermal microscopy," Analyst, 146, 2307-2312 (2021).
  • T. Kubo, K. Temma, N. I. Smith, K. Lu, T. Matsuda, T. Nagai, and K. Fujita, "Hyperspectral two-photon excitation microscopy using visible wavelength," Opt. Lett., 46 (1) 37–40 (2021).

Review Articles

Invited Talks (International)
  • K. Fujita, "Raman microscopy: a new imaging modality that opens up analytical biology," SCIX2022 (Covington, 5 Oct 2022).
  • K. Fujita, "Detecting drugs in cells and tissues by Raman/SERS microscopy," SCIX2022 (Covington, 4 Oct 2022).
  • K. Fujita, "On-the-fly Raman image microscopy with guaranteeing accuracy using reinforcement learning PART II: Experiment," SCIX2022 (Covington, 4 Oct 2022).
  • K. Fujita, "Label-free imaging of cell spheroids by slit-scanning Raman microscopy," The 15th Asia Pacific Physics Congress (online, 25 Aug 2022).
  • K. Fujita, "Detecting drugs in cells and tissues by Raman/SERS microscopy," 27th International Conference on Raman Spectroscopy (ICORS) (Long Beach, 16 Aug 2022).
  • K. Fujita, "Line-illumination Raman microscopy for imaging biological samples," Conference on Lasers and Electro-optics PacificRim (CLEO-PR) 2022 (Sapporo, 4 Aug 2022).
  • K. Fujita, "Raman microscopy: a new modality to probe cell activity by listening to molecular vibrations," TSRC Workshop (Telluride, 21 Jun 2022).
  • K. Fujita and K. Koike, "Slit-scanning Raman microscopy using Bessel beam illumination" SPIE Photonics West (San Francisco, 23 January 2022).
  • K. Fujita and K. Koike, "Enhancing Raman microscopy by structured light" SPIE Photonics West (San Francisco, 22 January 2022).
  • K. Fujita, "Vibrational-tag SERS microscopy for detecting intracellular molecules and environments," Pacifichem 2021 (online, 16-21 December 2021).
  • K. Fujita, "Intracellular chemical imaging by surface enhanced Raman scattering (SERS) microscopy," International Forum of Microscopy 2021, Guilin (online, 15 Nov 2021). Keynote
  • K. Fujita, "High-speed and High-resolution Raman Imaging of Biological Molecules Using Line Illumination," Asia Communications and Photonics Conference 2021, Shanghai (online, 25 Oct 2021).
  • K. Fujita, " Raman imaging of intracellular structures with improved image contrast," The 11th International Conference on Advanced Vibrational Spectroscopy (ICAVS11) (online, 25 August 2021).
  • K. Fujita, “Photo-initiator free two-photon polymerization using nonlinear deep-UV excitation, SPIE Optics + Photonics 2021 (San Diego (hybrid), 1 August 2021).

    ..... and more

  • H. Yamakoshi, K. Fujita, “Spontaneous Raman and SERS microscopy for Raman tag imaging,” in Stimulate Raman Scattering Microscopy, pp. 275-287 (J.-X. Chen et al Ed, Elsevier 2021).
  • K. Fujita, "Super-Resolution Imaging in Raman Microscopy" in Label-Free Super-Resolution Microscopy, Astratov Ed. (Springer Nature, 2019).
  • K. Mochizuki, N. I. Smith, K. Fujita, "Raman microscopy," Reference Module in Chemistry, Molecular Sciences and Chemical Engineering (Elsevier)
  • J. Ando, K. Dodo, K. Fujita, M. Sodeoka, "Visualizing Bioactive Small Molecules by Alkyne Tagging and Slit-Scanning Raman Microscopy, "Visualizing bioactive small molecules by alkyne tagging and slit-scanning Raman microscopy," Systems Chemical Biology: Methods and Protocols, Methods in Molecular Biology, Vol.1888, pp. 99-114 (Springer Nature 2019).
  • K. Fujita, "Micro-Raman Spectroscopy," in Compendium of Surface and Interface Analysis, pp. 375-379 (Springer Singapore, 2018).
  • K. Fujita, K. Mochizuki, N. I. Smith, "SAX microscopy and its application to imaging of 3D cultured cells," in Super-resolution imaging in biomedicine (A. Diaspro and M. A. M. J. van Zandvoort Eds., CRC Press, October 14, 2016).
  • M. Hashimoto, T. Ichimura, K. Fujita, "CARS Microscopy: Implementation of Nonlinear Vibrational Spectroscopy for Far-Field and Near-Field Imaging," in Raman Imaging, Springer Series in Optical Sciences 168 (A. Zoubir Ed., Springer-Verlag Berlin Heidelberg 2012).
  • Yasuaki Kumamoto, Nicholas Isaac Smith, Katsumasa Fujita, Jun Ando and Satoshi Kawata, "Optical Techniques for Future Pacemaker Technology," in Modern Pacemakers - Present and Future (M. K. Da ed. InTech 2011).
  • N. I. Smith, S. Kawano, M. Yamanaka, and K. Fujita, "Nonlinear Fluorescence Imaging by Saturated Excitation," in Nanoscopy and Multidimensional Optical Fluorescence Microscopy, pp. 2-1 ~ 2-16 (A. Diaspro Ed., Chapman and Hall/CRC press, April 2010).
  • P. Verma, K. Fujita, T. Ichimura, and S. Kawata, "Raman, CARS and near-field Raman-CARS microscopy for cellular and molecular imaging," in "Nano Biophotonics - Science and Technology -," pp. 57-71 (H. Masuhara, S. Kawata, and F. Tokunaga Ed. Elservier B.V., Amsterdam, 2007).
  • K. Fujita, N. Smith, and O. Nakamura, "Nonlinear optical imaging and stimulation of living cells," in Nanophotonics -Intengrating photochemistry, Optics and Nano/Bio Materials Studies - (H. Masuhara and S. Kawata Ed. Elsevier B.V., Amsterdam, 2004).
  • K. Fujita and T. Takamatsu, "Real-time in situ calcium imaging with single and two-photon confocal microscopy," in Confocal and two-photon microscopy: Foundation, Application and Advances (A. Diaspro Ed. John Wiley & Sons, Inc., New York, 2001).

    ..... and more


  • "Technology development could bring Raman microscopy to the clinic," Optica New Release, Feburuary 6, 2023
  • “A further leap of biomedical Raman imaging,” Spectroscopy, Vol. 35, Issue 7, p.10 (2020).
  • “Technology Feature | Live-cell imaging: Deeper, faster, wider,” Science, Vol. 359, Issue 6383, pp. 1549 (2018).
  • "Raman Imaging of Live Cells," Spectroscopy, 18 Nov (2014).
  • "Harmonic Microscopy," RIKEN Research 14 Mar (2008).
  • Richard Gaughan, "Laser Technique Monitors Calcium," PHOTONICS SPECTRA, January, p.65 (2002).
  • Richard Gaughan, "Near-infrared laser generates calcium waves," Biophotonics International, March, p.54 (2002).