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Photonic Imaging Ozeki Laboratory

Photonic Imaging
Ozeki Laboratory

Development of advanced photonic imaging methods

Development and biomedical applications of stimulated Raman scattering (SRS) microscopy

We develop optical technologies to visualize living systems and understand how biomolecules work. As part of this effort, we proposed and demonstrated stimulated Raman scattering (SRS) microscopy, which uses two-color laser pulses to detect molecular vibrations in biological samples with high sensitivity. To improve the ability of SRS microscopy to distinguish different molecules, we have also developed an SRS spectroscopic imaging system using our original high-speed wavelength-tunable laser. This system allows us to acquire SRS images at various molecular vibration frequencies, and we are using it for a wide range of biological imaging experiments. We are also working on metabolic imaging, super-resolution imaging, and highly multiplexed imaging using Raman-tagged molecules (Fig. 1). These approaches help us analyze complex structures, dynamics, and interactions inside living systems.

Semiconductor measurement by stimulated Raman scattering (SRS) microscopy

Semiconductors that support our daily lives are made of crystals, in which atoms are arranged in a regular pattern. However, imperfections in the crystal structure can occur during crystal growth or semiconductor processing, and these imperfections can limit the performance and reliability of devices. We are developing SRS-based methods for measuring the inside of semiconductor materials. We are applying these methods to analyze stress distributions inside silicon (Fig. 2) and to study crystal dislocations in wide-bandgap semiconductors.

Secretion imaging

Secretion is a process in which cells release messenger molecules to transmit information to surrounding cells. We have developed “Live-cell imaging of secretion activity: LCI-S,” a technology that uses total internal reflection fluorescence microscopy to observe secretion as it occurs in living cells. For example, LCI-S can visualize the release of molecules involved in inflammation and allergic responses from activated immune cells (Fig. 3). We are advancing research to apply this technology to blood tests for monitoring the body’s condition, analyzing cellular responses to drugs, and evaluating cell-based therapies.

Figure 1. Highly multiplexed imaging of cells using four Raman-tag colors and four fluorescence colors
Figure 2. Imaging inside a silicon substrate using SRS microscopy with a long-wavelength light source
Figure 3. Live-cell imaging of IL-1β release from a dying human monocyte

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Originally, I had been interested in electronics projects and computers since I was a child. At university, I majored in electronic engineering, and after gradually shifting my research field over time, I now work on biophotonics research that makes use of laser pulses. Once you understand how electronics and optics behave, they become powerful tools that allow you to develop new research through various creative approaches. Biophotonics is also a field that advances through collaboration with researchers from a wide range of areas, including chemistry and biology. Since there is so much we do not know about each other’s fields, we carry out our research by learning from one another, starting from the basics. Every day is full of intellectual curiosity. My hobby is playing the electric guitar, and since the COVID-19 pandemic, I have had more opportunities to enjoy music.