Glyco-Inside Micelles and Vesicles Directed by Protection-Deprotection Chemistry

Protection-deprotection of carbohydrate is often required in the preparation of glycopolymers, which causes an obvious polarity change of the polymers, but it has been neglected in the studies of self-assembly. In this paper, a new strategy for self-assembly of sugar-containing block copolymers is suggested based on the protection-deprotection chemistry. We found that deacetylation of a series of block copolymers of PS--PMan (PS, polystyrene block; PManAc, "sugar block" with acetylated α-mannopyranoside side groups) in THF resulted in glyco-inside structures of the deprotected copolymer PS--PMan, i.e., vesicles with a sugar wall and micelles with a sugar core. Besides, vesicle-to-micelle transition of the assemblies with decreasing the relative length of the sugar block was observed. These unique glyco-inside assemblies show interesting functions, such as generating homogeneous Au nanoparticles within the layer of the glyco-block from AuCl^4- without any additional reducing reagents or energy input. Control experiments prove that the polar layer of glyco-polymer inside the vesicle provides an essential reduction environment.