Photoresponsive Glycopolymer Aggregates as Controlled Release Systems

Abstract

The use of a new block copolymer made up of poly(azobenzene methacrylate) (PMAzo) and poly(3‐O‐4‐vinylbenzoyl‐ d ‐glucopyranose) (PBG) is described for the solubilization of water‐insoluble dyes such as Nile Red in aqueous solutions. This polymer, which is abbreviated as PMAzo ‐b‐ PBG, self‐assembles into spherical aggregates in water as confirmed by atomic force microscopy. UV irradiation of the aqueous polymer solution destabilizes the aggregates brought about as a result of the trans–cis isomerization of the MAzo units. Dissociated aggregates reunite to form tubular aggregates when the solution is irradiated with 450 nm light. Nile Red, which is a hydrophobic dye, can be incorporated into these aggregates and subsequently released using UV light. The encapsulation, release, and re‐encapsulation of Nile Red are studied using fluorescence spectroscopy. image