Micellar structure of hydrophobically modified polysaccharides in aqueous solution

This article reviews previous studies on micellar structures formed by hydrophobically modified polysaccharides in aqueous solutions by static and dynamic light scattering, small angle X-ray and neutron scattering, and fluorescence from pyrene solubilized in polymer solution. The experimental results are consistently explained by the full or loose flower necklace model for pullulan bearing octenyl groups and amylose bearing dodecyl groups and by the randomly branched polymer model, which is often called a "nanogel", for pullulan bearing cholesteryl groups. We discuss the micellar structures of hydrophobically modified polysaccharides as well as of an amphiphilic alternating vinyl polymer bearing dodecyl groups in regard to the degree of substitution as well as the chemical structures of the hydrophobic moiety and backbone chain. Hydrophobically modified polysaccharides have attracted considerable attention in the biomedical field because of their biocompatibility, biodegradability, and nontoxicity. This article reviews previous studies on micellar structures formed by hydrophobically modified polysaccharides (pullulan and amylose) in aqueous solutions by static and dynamic light scattering, small angle X-ray and neutron scattering, and fluorescence from pyrene solubilized in the polymer solution. Depending on the degree of substitution, the hydrophobically modified polysaccharides exist in aqueous solution as full or loose flower necklaces or as nanogels made up of randomly branched polymers.