pH/enzyme/light triple‐responsive vesicles from lysine‐based amphiphilic diblock copolymers

Abstract

We report the synthesis of pH‐ and enzyme‐responsive amphiphilic diblock copolymers through reversible addition‐fragmentation chain transfer polymerization of a lysine‐derived methacrylate monomer comprising p‐nitrobenzyl carbamate (pNBC) functionality using a poly(ethylene glycol)‐modified macro‐chain transfer agent. Depending on the hydrophobic block length, the diblock copolymers self‐assemble to form spherical micelles, wormlike micelles, and bilayered vesicles in the aqueous solution. The responsive behaviors of the polymeric vesicles to pH, enzyme, and light are investigated in detail. As the pH lowers to pH 5.0, the polymeric vesicles undergo a morphological transition from vesicles to spherical micelles. In the presence of nitroreductase and a cofactor NADH, the decomposition of pNBC releases the ε‐NH2 of the lysine moiety and hence induces the generation of the vesicles with crosslinked membranes at pH 7.4. Moreover, owing to the degradation of pNBC moiety under UV irradiation, the polymeric vesicles also demonstrate a photo‐responsive feature. As the irradiation time prolongs, it is observed a light‐triggered morphological transition from vesicles to wormlike micelles with network‐like structures.

Recent advances in permeable polymersomes: fabrication, responsiveness, and applications

“…Polymersomes with stimuli-responsiveness are of great importance because their chemical and physical features such as size, morphology adaption, surface characteristics, and assembly-disassembly transition can be well-regulated and controlled in response to environmental changes or external stimuli. 56,57 This allows them to be used effectively in a variety of applications such as controlled drug release, imaging, diagnostics, smart actuators, self-healing materials, and recyclable catalysis. 58,59 A specic research approach to the construction of polymersomes with permeability regulation is the introduction of stimuli-responsive building blocks to polymersomes, which has become the most intensively investigated route toward permeable polymersomes.…”