Effects of polydispersity on fluorescence quenching in micelles

Abstract

The effects of polydispersity on fluorescence quenching in micelle systems are discussed theoretically. Predictions are tested on computer generated fluorescence decay data for quenching in polydisperse micelle systems. It is shown that the estimated parameters, i.e, aggregation numbers and rate constants, are highly dependent on the micelle size distribution, and on the dynamic properties of the solubilizate–micelle system. Two extreme cases are considered: a static one, where no size changes of the micelles occur during the residence time, and a dynamic one where very large size variations take place. In the static case, the estimated aggregation number will decrease with quencher concentration from the weight average aggregation number in the limit of zero quencher concentration. In the dynamic case, the number average aggregation number is obtained, independent of quencher concentration. The initial decay constant contains information about the aggregation numbers, and in the generated data, this could be used to indicate the presence of polydispersity. Data from a number of experiments with the single photon counting technique are presented and analyzed according to the presented theory.

Aggregation Behavior of Sugar Surfactants in Aqueous Solutions: Effects of Temperature and the Addition of Nonionic Polymers

“…If such is the case, the theory predicts that the average aggregation number determined by TRFQ should be independent of the quencher concentration (33,34). This expectation is borne out by the results in Table 1, which show that the aggregation number of DM micelles remains constant as the TCNPCl concentration is increased.…”

“…The pyrene concentration was adjusted to be about 1% to 2% of the micelle molar concentration, [M], whereas the quencher molar concentration, [Q], was close to [M] (i.e., an average of one quencher per micelle). In some experiments, this ratio was varied to evaluate the polydispersity of the system (33,34). Prior to each experiment, the investigated solutions were deaerated by three successive freeze-pump-thaw cycles.…”

Analysis of Polydispersity of Mixed Micelles of TX-100/SDS and C12E8/SDS by Capillary Electrophoresis

“…1, for a two-component system tional heterogeneity, which, for ionic systems, goes hand in with a bulk mole fraction of component 1 (Y), a composihand with a distribution of micelle charge. The polydispertional distribution may appear in addition to a size distribusity of micelle size and aggregation number has been the tion; namely, the mole fraction of component 1 in the misubject of several theoretical studies (1)(2)(3)(4)(5). Mukerjee (1,2) celles (y) may be distributed around the mean value, Y, which for example described polydispersity in terms of weight and corresponds to the bulk, or stoichiometric mole fraction of number average degrees of aggregation.…”

The role of polymer flexibility on the interaction with surfactant micelles: poly(vinyl alcohol) and sodium dodecyl sulphate aqueous micelle interactions studied by dynamic fluorescence quenching

“…[2] should be treated as uencher-averaged aggregation numbers, (a) ¶ (45)(46)(47). The (aq is an apparent property, de endent on Q,.…”

“…The (aq is an apparent property, de endent on Q,. The weight-averaged aggregation number, Pa) , is obtained by extrapolation to zero quencher concentration (45,46) according to:…”