中文摘要：

中位醛基取代的五甲川菁染料（Cy5）与传统Cy5相比其最大吸收和发射波长稍微蓝移，斯托克斯位移增加，在水中能达到48nm；具有低的荧光量子产率，而且随溶剂极性变化较小．实验发现这种染料对环境的粘度非常敏感，随着染料分子所处环境的粘度逐渐增加，其荧光强度明显增加，而且荧光强度与溶液粘度的关系满足F6rster-Hoffmann关系式．该染料具有活细胞膜的穿透性，能跨膜进入活细胞内，使得该染料在检测活细胞内微环境粘度变化方面具有潜在的应用价值．

英文摘要：

Compared with the traditional cyanine dyes （Cy5）, both the maximum absorption and emission wavelengths of new Cy5 dyes with aldehyde group substituted at central position of the conjugated chain slightly blue shift, and the Stokes Shift is enlarged evidently to more than 28 nm, and largest up to 48 nm in water. The fluorescence quantum yield is rather low without obvious change in different solvents. It is found that the fluorescence of dye is sensitive to viscosity of the solvents, and the emission intensity of the dye can be enhanced largely by ascending of environmental viscosity with well linear relationship between lg If and lg （viscosity） （Forster-Hoffmann equation）. It is living cell membrane permeable for the dye 4 to map cellular microenvironmental viscosity, which demonstrates the potential application for dye 4 to investigate the intracellular microviscosity change.