Development of silicon-substituted xanthene dyes and their application to fluorescent probes

Fluorescence imaging is one of the most powerful techniques for visualization of the temporal and spatial biological events in living cells. Many fluorescent probes have been developed so far and contributed greatly to biological and medical researches. For biological applications, xanthene dyes have many favorable characteristics, such as high water solubility and high fluorescence quantum yield, and have been utilized as the fluorescent core for a large number of fluorescent probes. In this manuscript, we introduce a novel red fluorescein analogue, TokyoMagenta (TM), in which the O atom at the 10 position of the xanthene moiety is replaced with a Si atom, and the absorption and emission wavelengths of TM are about 90 nm longer than those of fluorescein. These silicon-substituted xanthene dyes would be useful for multicolor imaging. Nowadays, we think these xanthene dyes have been becoming one of practical fluorophores for biological researches.