In recent years, various types of molecular imaging technologies have been developed, but many of them require probes
and may have some influence on the distribution of the target molecules. In contrast, Raman microscopic analysis is
effective for molecular identification of materials, and molecular imaging methods employing Raman scattering light can
be applied to living organisms without use of any exogenous probes. Unfortunately, Raman microscopic imaging is
rarely used in the biomedical field due to the weakness of Raman signals. When the conventional Raman microscopes
are used, the acquisition of an image of a cell usually takes several hours. Recently, a slit-scanning confocal Raman
microscope has been developed. It can acquire images of living cells and tissues with faster scanning speed. In this study,
we used the slit-scanning confocal Raman microscope (RAMAN-11) to image the distribution of a drug in living cells.
We could acquire images of the distribution of an anticancer reagent in living cells within several minutes. Since the
wavelength of Raman scattering light is determined by the frequency of molecular vibration, the in situ mapping of the
intracellular drugs without use of a probe is possible, suggesting that laser Raman imaging is a useful method for a
variety of pharmacokinetic studies.
We develop a compact scanning head for use in laser confocal fluorescence microscopy for in situ fluorescence imaging of organs. The head, cylindrical in shape, has 3.5 mm diameter and 30 mm length, and is thus small enough to operate in a living rat heart. The lateral and axial resolutions, defined as full widths at half maximum (FWHM) of a point spread function (PSF), measures 1.0 and 5.0 µm, respectively, for 488-nm excitation and 1.0 and 5.4 µm, respectively, for 543-nm excitation. The chromatic aberration between 488- and 543-nm laser beams is well suppressed. We perform Ca2+ imaging in cardiomyocytes through the right ventricular chamber of a perfused rat heart in line-scan mode with 2.9-ms time resolution. We also carried out two-color imaging of a fixed mouse heart and liver with subcellular resolution. The compact head of the microscope equipped with a line-scan imaging mode and two-color imaging mode is useful for in situ imaging in living organs with subcellular resolution and can advantageously be applied to in vivo research.