A dual stimuli-responsive amphiphilic polymer: reversible self-assembly and rate-controlled drug release

Abstract

We report the dual stimuli-responsive self-assembly and rate-controlled drug release of a novel functionalized PEG amphiphilic polymer (FcC 11 AzoPEG) in aqueous solution. The novel FcC 11 AzoPEG amphiphilic polymer was synthesized by the esterification reaction of poly (ethylene glycol) methyl ether (PEG) and 4-(4′-(11-ferrocenyl-undecanoxy)) azobenzoic acid. The azobenzene (Azo) and ferrocene (Fc) moieties respectively afford the polymer a slow photo-response and a fast redox-response. Upon exposure to different stimuli (light irradiation, redox reaction, and a combination of light irradiation and redox reaction), FcC 11 AzoPEG in aqueous solution can reversibly self-assemble into various nanostructures and also disassemble either slowly by light irradiation or fast by redox reaction in an appropriate concentration range. Moreover, the drug release from the drug-loaded micelles can be precisely controlled by different stimuli: a slow release rate and a small amount of release for UV irradiation, a fast rate and a medium amount of release for oxidation by Fe2(SO4)3, and a large amount of release for the combined stimulation of UV irradiation and oxidation by Fe2(SO4)3. This work not only demonstrates the effect of stimuli-induced amphiphilicity change of functional groups on the solution aggregation behavior of functionalized PEG amphiphilic polymers but also provides a useful smart system with great potential application in drug delivery.