As a technique for investigating the intracellular location of low molecular weight compounds, an imaging method using a fluorescence microscope accompanied with introduction of a fluorescence group to molecules is well known. Due to the relatively large size of the fluorescence group, this tends to reduce the activity of the compound in many cases. For this reason, we tried using Raman microscopy for overcoming this problem.

A Raman microscope directly detects and analyzes the molecules in a sample based on Raman scattering light reflecting the vibrating state of molecules. Alkynes show characteristic and strong Raman scattering light that is not shown by intracellular molecules, despite being very small entities. Therefore, we investigated the use of alkynes as tags for imaging under a Raman microscope.

We paid attention to Edu(5-ethynyl-2'-deoxyuridine） as a molecule, which contains an alkyne. It is known that EdU is a mimic molecule of dT（deoxythymidine）, which is a DNA component, and is incorporated in DNAs being present in a nucleus. Accordingly, by means of an EdU treated cell, we succeeded in the detection of Raman scattering derived from the vibration of the alkyne by Raman microscope, and were able to observe the state of the time-course incorporation of EdU in a live cell. These observed facts suggest that live cell imaging by means of a Raman microscope is promising. We now aim at establishing a new imaging technique by improving both the Raman microscope and tag molecules.