Krieg M, Srichai M B, Redmond R W
Pediatrics Department, MACC Fund Research Center, Medical College of Wisconsin, Milwaukee 53226.
Biochim Biophys Acta. 1993 Sep 19;1151(2):168-74. doi: 10.1016/0005-2736(93)90101-5.
All symmetrical dialkylthiacarbocyanine dyes, with the exception of the diethyl derivatives, are incorporated into liposomes. Absorption and fluorescence data indicate a solubilization site close to the bilayer surface with the alkyl chains penetrating into the lipid bilayer. Incorporation into organized assemblies affects the photophysical parameters of these dyes. Photoisomerization occurring from the first excited state becomes more difficult as the restrictive effect of the solubilization site increases. As a consequence, competing deactivation processes, such as fluorescence and triplet formation, become more efficient with the result that fluorescence quantum yields, triplet yields and singlet oxygen quantum yields are larger in liposomes than in homogeneous solution. Dihexylthiacarbocyanine iodide has a fluorescence quantum yield of 0.27 and 0.10 (25 degrees C) in dimyristoylphosphatidyl-choline liposomes and ethanol, respectively, and the singlet oxygen yield increases by a factor three to 0.006 on going from ethanol to liposomes. The effect of a highly organized environment is even more pronounced in thin polymer films. In these systems, photoisomerization is completely inhibited and only triplet formation is observed in the transient absorption spectrum.
除二乙基衍生物外，所有对称二烷基硫代碳菁染料都能掺入脂质体中。吸收和荧光数据表明，其增溶位点靠近双层表面，烷基链插入脂质双层中。掺入有序组装体中会影响这些染料的光物理参数。随着增溶位点限制效应的增加，从第一激发态发生的光异构化变得更加困难。因此，诸如荧光和三重态形成等竞争性失活过程变得更加有效，结果是脂质体中的荧光量子产率、三重态产率和单线态氧量子产率比在均相溶液中更大。二己基硫代碳菁碘化物在二肉豆蔻酰磷脂酰胆碱脂质体和乙醇中的荧光量子产率分别为0.27和0.10（25℃），从乙醇到脂质体，单线态氧产率增加三倍，达到0.006。在聚合物薄膜中，高度有序环境的影响更为明显。在这些体系中，光异构化被完全抑制，在瞬态吸收光谱中仅观察到三重态的形成。
