A Comparison of the Behavior of Monomolecular and Dual Molecular Probes in F127/Cyclodextrin Systems

• Published in: Macromolecular chemistry and physics 2019-03, Vol.220 (5), p.n/a
• Main Authors: Baratoiu, Rodica, Mocanu, Sorin, Matei, Iulia, Bem, Marioara, Hristea, Elena, Tecuceanu, Victorita, Ionita, Gabriela
• Format: Article
• Language: English
• Subjects: Complex systems; Cyclodextrins; dual molecular probes; electron paramagnetic resonance spectroscopy; Fluorescence; Hydrophobicity; Micelles; Phase transitions; pluronic F127; Poloxamers
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201800489

Molecular probes are often used to describe local interactions and to characterize inhomogeneities in complex systems. In this study, two series of monomolecular probes (paramagnetic or fluorescent) and a series of dual molecular probes are used to evaluate local changes and the regions targeted by these probes in three pluronic F127 systems, in the absence and in the presence of 2‐hydroxypropyl‐β‐cyclodextrin, which have been previously characterized. All molecular probes used in this study have as a common structural unit the short oligoethylene chains that link (2,2,6,6‐Tetramethylpiperidin‐1‐yl)oxyl (TEMPO) and/or pyrene moieties. Using these probes, changes in hydrophobicity inside the pluronic micelles are evidenced and the micelle‐to‐gel phase transition is characterized. Phase transition in F127/2‐hydroxypropyl‐β‐cyclodextrin systems is reported by mono and dual molecular probes bearing fluorescent and/or paramagnetic moieties attached to oligoethylene oxide chains. The probes target different regions in F127 micelles, as reported by the hyperfine coupling constant. The temperature variation of the fluorescence and paramagnetic spectral features is sensitive to the phase transition.