Fluorescence Quenching Studies of the Interaction of a Pyrene-Labeled Polyelectrolyte with Quencher-Carrying Oppositely Charged Micelles

Abstract

The interaction between poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) labeled with 1 mol % pyrene (PyPAMPS) and mixed micelles of hexaethylene glycol n-dodecyl monoether (C12E6) and n-hexadecyltrimethylammonium chloride (CTAC), in which N,N-dimethylaniline (DMA) was solubilized, was studied by steady-state and time-dependent fluorescence quenching by varying the mole fraction of CTAC (Y) in the mixed micelle. At Y < 0.05, fluorescence quenching is essentially dynamic, arising from collisional encounters of the pyrene sites and DMA-carrying mixed micelles. Strong quenching begins to occur at Y ≅ 0.05, corresponding to the onset of polyelectrolyte−micelle interactions. In the region 0.05 < Y < 0.09, the quenching was shown to occur via transient complex formation between PyPAMPS and the mixed micelle. Changes in the vibrational structures of fluorescence spectra of pyrene in PyPAMPS indicate that pyrene groups are inserted in the hexa(oxyethylene) phase of the mixed micelle when the polymer−micelle complex is formed. The extent of quenching reaches a limiting value at Y > 0.11 in excess micelle solution, corresponding to the state in which all pyrene groups are micelle-bound.

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

“…Fluorescence techniques offer, in principle, considerable insight into such questions. 26,27 Although fluorescence probes have been frequently used to study polymersurfactant interactions, 28 the goal of such investigations has been the determination of the aggregation number of bound (i.e., versus free) micelles. A different application of fluorescence to polyelectrolyte-colloid interactions was presented in our investigation of the fluorescence behavior of a pyrene-tagged polyanion arising from its photophysical interaction with tryptophan residues in lysozyme.…”

“…The enhancement of quenching upon increase in σ or decrease in κ was investigated by steady-state and timedependent fluorescence spectroscopy to provide insight into the dynamics of polyelectrolyte-micelle association. 26, 27 The behavior of fluorescence-labeled polyelectrolytes may be perturbed by the physicochemical properties of the label. Thus, turbidimetric, light scattering, and fluorescence studies revealed that the interaction of pyrene-labeled poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) (PAMPS) with mixed micelles of n-dodecyl hexa(oxyethylene) glycol monoether (C 12 E 6 ) and cetyltrimethylammonium chloride (CTAC), although predominantly driven by electrostatic forces, occurred preferentially with pyrene sites.…”

“…26 Thus, we observed a conjoint effect of hydrophobic and electrostatic interactions on the polyion-micelle interaction. 26,27 One aspect of the present work is the resolution of electrostatic and hydrophobic contributions to the binding of micelles to polyelectrolytes. As noted, fluorescence-quenching studies can yield substantial insight into the thermodynamics and kinetics of polyelectrolyte-micelle association.…”

Steady-State and Time-Dependent Fluorescence Quenching Studies of the Binding of Anionic Micelles to Polycation

“…[33][34][35][36] Among these methods, fluorescence techniques are expected to provide a powerful tool to gain insight into the dynamics of polyelectrolyte-micelle interactions. Recently, we used a pyrene-labeled polyanion in conjunction with quencher-carrying mixed micelles to characterize the microscopic polyelectrolytemicelle phase transition.…”

“…Recently, we used a pyrene-labeled polyanion in conjunction with quencher-carrying mixed micelles to characterize the microscopic polyelectrolytemicelle phase transition. [33][34][35][36] The intensity of the polyelectro- † Part of the special issue "Noboru Mataga Festschrift". ‡ Current address: Shiseido Basic Research Center, 2-2-1 Hayabuchi, Tsuzuki, Yokohama 224-8558, Japan…”