Dual and multiple stimuli-responsive platonic micelles bearing disaccharides

Abstract

We recently identified completely monodisperse micelles whose aggregation number (Nagg) coincides with the vertex number of regular polyhedra, named Platonic micelles. The combination of both the micellar properties and controlling their structures by external stimuli could be promising for producing precisely controlled self-assembled structures. From this perspective, we newly synthesized a calix[4]arene-based amphiphile bearing disaccharides, cellobioses. The crowded and bulky structure in the hydrophilic group could provide a novel stimuli-responsiveness of disaccharides in amphiphiles. The aggregation behavior such as the morphologies and the aggregation number of the calix[4]arene-based micelle was characterized using small angle scattering techniques and analytical ultracentrifugation measurements. Owing to hydrogen bonding among the disaccharide, the head volume became smaller than expected, resulting in the formation of cylindrical ones. However, cleaving the hydrogen bond by controlling temperature or pH induced morphological transition of the micellar structure from cylindrical to spherical. The dual-stimuli (temperature and pH) generated smaller micelles with Nagg of 12. Interestingly, when the amphiphile formed spherical micelles at various conditions, the Nagg matched the Platonic number, and the change of Nagg in response to the external stimuli was non-continuous, which is consistent with the concept of Platonic micelles.