Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
J Phys Chem B. 2010 Dec 2;114(47):15506-11. doi: 10.1021/jp1068347. Epub 2010 Nov 5.
Fluorescence correlation spectroscopy (FCS) has been used to study the motion of fluorescent dyes in a giant (diameter 20 000 nm = 20 μm) catanionic vesicle comprised of the surfactant sodium dodecyl sulfate (SDS) and dodecyltrimethyl ammonium bromide (DTAB). The diffusion in the anion (SDS) rich catanionic vesicle was studied both in bulk water and in an immobilized vesicle attached to a positively charged glass surface. In the case of the immobilized vesicle, the diffusion coefficients (D(t)) of R6G (rhodamine 6G), DCM (4-dicyanomethylene-2-methyl-6-p-dimethyl aminostyryl-4H-pyran), and C343 (coumarin 343) are found to be 1.5, 2.5, and 10 μm(2)/s, respectively, which are 280, 120, and 55 times slower compared to those for the same dyes in bulk water. The magnitude of D(t) is found to vary for different vesicles. This was attributed to the difference in size and shape of the immobilized vesicles. In bulk, R6G binds completely to the vesicle and exhibits extremely slow diffusion with D(t) = 0.5 ± 0.1 μm(2)/s (∼850 and 3 times slower compared to that of R6G in bulk water and within the immobilized vesicle). This is attributed to very slow overall diffusion of the very large size vesicles (20 μm = 20 000 nm). Both of the dye molecules (DCM and C343) show two different diffusion coefficients for the vesicles in bulk. In this case, the small D(t) (0.5 ± 0.1 μm(2)/s) corresponds to the diffusion of the vesicle as a whole and the large D(t) value (300 and 550 μm(2)/s for DCM and C343, respectively) corresponds to the free dye molecules in bulk water.
荧光相关光谱（FCS）已被用于研究在由表面活性剂十二烷基硫酸钠（SDS）和十二烷基三甲基溴化铵（DTAB）组成的巨大（直径 20000nm=20μm）阳离子囊泡中的荧光染料的运动。在阴离子（SDS）丰富的阳离子囊泡中，在本体水和附着在带正电荷的玻璃表面的固定囊泡中都研究了扩散。在固定囊泡的情况下，R6G（若丹明 6G）、DCM（4-二氰基-2-甲基-6-对二甲氨基苯乙烯-4H-吡喃）和 C343（香豆素 343）的扩散系数（D(t)）分别为 1.5、2.5 和 10μm(2)/s，与相同染料在本体水中的扩散系数相比，分别慢 280、120 和 55 倍。发现 D(t)的大小因不同的囊泡而异。这归因于固定囊泡的大小和形状的差异。在本体中，R6G 完全结合到囊泡上，并表现出极其缓慢的扩散，D(t) = 0.5 ± 0.1μm(2)/s（与 R6G 在本体水和固定囊泡中的扩散相比，分别慢 850 和 3 倍）。这归因于非常大尺寸囊泡（20μm=20000nm）的整体扩散非常缓慢。两种染料分子（DCM 和 C343）在本体中对囊泡表现出两种不同的扩散系数。在这种情况下，小的 D(t)（0.5 ± 0.1μm(2)/s）对应于整个囊泡的扩散，而大的 D(t)值（分别为 DCM 和 C343 的 300 和 550μm(2)/s）对应于本体水中的游离染料分子。
