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

Abstract

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 <b>PS-</b><i><b>b</b></i><b>-PMan</b><i><b>Ac</b></i> (PS, polystyrene block; PMan<i>Ac</i>, "sugar block" with acetylated α-mannopyranoside side groups) in THF resulted in <i>glyco-inside</i> structures of the deprotected copolymer <b>PS-</b><i><b>b</b></i><b>-PMan</b>, 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 <i>glyco-inside</i> 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.