We are innovating new imaging technologies by using organic chemistry. For making advanced medicinal technology, in vivo optical imaging is needed. So, we have been developing luciferin analogues suitable for deep in vivo optical imaging.

It is very difficult for deep in vivo optical imaging to be absorbed and scattered light in living tissue. But, it is well known that the light in the near infrared region (NIR) has high permeability for the living tissue. It is a challenge to visualize in vivo deep optical imaging by developing an imaging material that has NIR emission. We have got structure-activity relationship data on the firefly luciferin luciferase reaction. According to the structure-activity relationship data on luciferin analogues reacted with Ppy luciferase, we have designed and marked NIR probe “TokeOni, (SIGMA-ALDRICHⓇ)”. TokeOni gives a higher brightness compared with the natural firefly luciferin because of high permeability TokeOni in tissue (Kuchimaru, T. et al. Nat. Commun. 2016, 7, 11856.).

Based on the TokeOni structure, new luciferin analogues have designed and synthesized three types.

We made the substances of three new luciferin analogues. One of these emits in the NIR and has high water-solubility in PBS, that is named “seMpai”

We will apply new probe to the animal for conforming practical ability and discuss these new luciferin analogues for in vivo imaging technology.