A study of surfactant micelles with a fluorescent probe

Abstract

The fluorescence probe technique has been used to study micelles of anionic, cationic and non-ionic surfactants. The solute was pyrene. The formation of a fluorescent excited dimer (excimer) by pyrene means that this probe can be used not only to explore intramicellar kinetics, but also to monitor the manner in which micelles change their size. The change in size of ionic surfactants with electrolyte concentration and of non-ionic surfactants with temperature is explored. We have developed a simple method involving the effect of oxygen (in air) on the fluorescence spectrum for detecting statistical distribution effects in the solubilization of pyrene in micelles. The combination of fluorescence spectra with time-dependent fluorescence intensity (fluorescence 'decay') allows a full analysis.

Photophysical Studies of Pyrene Incorporated in Nafion Membranes*

“…At low probe concentrations, confinement of the chromophore into restricted volumes prevents excimer formation during the lifetime of the monomer excited state. Such effects are frequently observed in micellar solutions (Khuanga et al, 1976) and were also observed in water swollen Nafion (Lee and Meisel, 1980). No excimer formation could be observed in water swollen Nafion even at the pyrene saturation limit of the membrane (Fig.…”

Temperature jump as a new technique to study the kinetics of fast transport of protons across membranes

“…This would correspond to a vesicle concentration of about 0.9 pM if we assume an average vesicle to have -3000 phospholipid molecules (Watts et al, 1978). The distribution of gramicidin dimers among the vesicles can then be calculated from the Poisson equation (Forster & Selinger, 1964;Khuanga et al, 1976) P ( x ) = e-@pX/ All the values of JH+loH-were normalized to the total amplitude corresponding to that of trace d in Figure 4A. The tl12 values were in the range of 0.4-1 s. Other experimental conditions were the same as in Figure 1A.…”

Unique hydrophobic interactions of pyrene in aqueous solution as effected by polyelectrolytes and surfactants

“…The addition of sodium methyl sulfate, a salt with the same counterion as (l), had almost no effect on these absorption and fluorescence spectra. If the aliphatic group attached to the sulfate anion is lengthened from one carbon to 12, as in sodium dodecyl sulfate, surfactant (8), profound changes occur in the absorption and fluorescence spectra of (1). These changes are illustrated in Figures 2 and 3, respectively.…”

“…* The molecules with pyrene fluorophores come in pairs, with one positively charged and one negatively charged example for each structural classification. Cationic and anionic polyelectrolytes (6,7) and surfactants (8,9), but without pendant pyrene substituents, were also used in our experiments:…”