| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 609885 | Journal of Colloid and Interface Science | 2010 | 8 Pages |
The dynamics of the exchange of the moderately hydrophobic neutral dye Coumarine 152 between the aqueous phase and the phase formed by neutral Triton X-100 micelles is studied by Fluorescence Correlation Spectroscopy. The changes in the photophysical properties of the dye in presence of the micelles are discussed. The low quantum yield, the low saturation threshold and the necessary high energetic excitation of this dye requires a careful selection of the experimental conditions in order to obtain dynamic and diffusional properties with reasonable precision. It is shown that the contrast between the brightness of free and bound dye has a strong influence on the sensitivity of the FCS experiment. The entry rate constant of the dye to the micelles, k+ = (0.8 ± 0.3) × 1010 M−1 s−1, is very near to the diffusion controlled limit. The high association equilibrium constant of K = (129 ± 3) × 103 M−1 is mainly determined by the low exit rate constant, k− = (0.6 ± 0.2) × 105 s−1.
Graphical abstractFlickering of the fluorescence intensity reveals the fast exchange dynamics of a hydrophobic dye between micelles and the surrounding aqueous solution. Fluorescence Correlation Spectroscopy yields the entry and exit rate constants.Figure optionsDownload full-size imageDownload high-quality image (207 K)Download as PowerPoint slide
