Fluorescence anisotropy (FA) of anionic dyes bound to ionic and zwitterionic micelles
Year: 2025
Type: article
Abstract: • Fluorescence Anisotropy (FA) of fluorescein and POH in micelles were determined. • Flourescein emits three lines from three forms and POH emits two each from two forms. • A new methodology distinguishes and determines FA of individual forms of the same dye. • FA varies with chemical form of the same dye. • Different interfacial locations for the different forms consistent with FA values are proposed. Anionic fluorescein and 8-hydroxy-1,3,6-pyrenetrisulfonate (POH), bind to cationic and zwitterionic micelles, experience hindered rotation and exhibit fluorescence anisotropy (FA). Fluorescein emits three lines from its dianion, carboxylate, and phenolate forms. POH emissions are from excited POH* and its deprotonated form, PO − . Fluorescence was excited by vertically polarized (V) light. Spectra recorded with vertical (IVV) and horizontal (IVH) polarizers in the emitted beam were corrected for instrument response and polarization bias. Corrected line shapes were fit to Gaussians availing the computationally derived second harmonic for better fit precision. FA of the individual forms of the same dye was calculated from the IVV and IVH intensities of each component line. For fluorescein, FA phenolate > carboxylate > dianion and FA PO − > POH*. Micelle-bound dye conformations, consistent with this order, are presented. Distinguishing between FA of different forms is novel and significant to elucidation of dye-host interactions.
Authors: Radha Ranganathan, Jack Franklin, Taeboem Oh, Miroslav Peric
Institution: California State University, Northridge
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,470
OpenAlex ID: W4408634552