IFIMAR, Instituto de Investigaciones Físicas de Mar del Plata (CONICET-UNMDP), Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (B7602AYL) Mar del Plata, Argentina.
Departamento de Química, Universidad Nacional de Río Cuarto, CONICET, (X5804BYA) Río Cuarto, Argentina.
Photochem Photobiol Sci. 2017 Jul 1;16(7):1117-1125. doi: 10.1039/c7pp00051k. Epub 2017 May 26.
The properties and photochemical and photophysical behavior of the mycosporine-like amino acids (MAAs) shinorine and porphyra-334 were experimentally evaluated in solutions of direct ionic micelles as simple biomimicking environments. The preferential partition of the natural molecules in the aqueous phase of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC) micellar systems is confirmed. Although the proton dissociation of the carboxylic groups in the MAAs is slightly inhibited in CTAC solutions, the molecules are predicted to be in the form of zwitterions in all the explored media around physiological pH. The increase in the fluorescence quantum yield, emission lifetime and stationary anisotropy in the presence of CTAC micelles suggest electrostatic attractions of the MAAs with the surface of the cationic micelles. Consistently, the triplet-triplet absorption spectra in CTAC solutions reveal the typical environmental features of the micellar interface, while in the presence of SDS they are similar to those determined in neat water. Finally, the photostability of the MAAs increases in the micellar systems, more noticeably in the case of CTAC. It is concluded that the ability of the two MAAs to act as UV screens is susceptible to the influence of electrostatic interactions with organized microheterogeneous environments.
实验评估了作为简单仿生环境的直链离子胶束溶液中真菌胺类似氨基酸（MAAs） shinorine 和 porphyra-334 的性质以及光化学和光物理行为。证实了天然分子在十二烷基硫酸钠（SDS）或十六烷基三甲基氯化铵（CTAC）胶束系统的水相中的优先分配。尽管 MAAs 中羧酸基团的质子解离在 CTAC 溶液中略有抑制，但在所有探索的生理 pH 附近的介质中，这些分子预计都以两性离子的形式存在。在 CTAC 胶束存在下，荧光量子产率、发射寿命和稳态各向异性增加表明 MAAs 与阳离子胶束表面之间存在静电吸引。一致地，CTAC 溶液中的三重态-三重态吸收光谱显示出胶束界面的典型环境特征，而在 SDS 存在下，它们与在纯水中确定的相似。最后，MAAs 在胶束体系中的光稳定性增加，在 CTAC 的情况下更为明显。结论是，两种 MAAs 作为紫外线屏蔽剂的能力容易受到与组织微异质环境的静电相互作用的影响。
