Thermoresponsive Structure and Dye Encapsulation of Micelles Comprising Bolaamphiphilic Quercetin Polyglycoside

A bolaamphiphile is a special member of amphiphilic molecules, which contains a hydrophobic skeleton and two water-soluble groups on both ends. Bolaamphiphiles form thermally stable associates in water under lower concentration than those of typical monoheaded amphiphiles, indicating the potential usefulness of bolaamphiphiles as the component of nanomaterials. However, the structural diversity of bolaamphiphiles is limited at this moment. We recently developed the synthesis of quercetin-3-O-polyglycoside (QP) as a new entry of bolaamphiphiles via a one-pot polymerization using sugar-based cyclic sulfite initiated by quercetin skeleton. Herein, we show the bolaamphiphilic properties of QP in detail. The micellization behaviors of QP are systematically investigated through comparison with those of quercetin (Que) and isoquercitrin (IQ) to evaluate the roles of glycone on the micellization of quercetin derivatives. The morphology of the micelles bearing QP is observed by cryo-transmission electron microscopy (cryo-TEM), suggesting the formation of bolaamphiphile-specific giant ribbon-like micelles in addition to spherical micelles. The thermoresponsive micellization behaviors are also discussed through the critical micelle concentration (CMC) values, the dynamic light scattering analyses at various temperatures, and thermal hysteresis of the micellizations. It is indicated that the polysaccharide chains integrated on the surface of micelles would serve as a steric protecting group to endow the micelles with kinetic stability. These results will shed light on natural glycoside skeletons to design a new class of micelles for advanced health applications in near future.