Quadruple-Stimuli-Sensitive Polymeric Nanocarriers for Controlled Release under Combined Stimulation

Here we report a novel quadruple-stimuli-responsive block copolymer nanocarrier sensitive to pH, temperature, light, and reducing agent. The well-defined amphiphilic diblock copolymer poly­(2-nitrobenzyl methacrylate)-SS-poly­(dimethylaminoethyl methacrylate) (PNBM-SS-PDMAEMA) was synthesized via two steps of atom transfer radical polymerization (ATRP). In aqueous solution, the diblock copolymer self-assembled into nanoparticles consisting of a light-responsive hydrophobic PNBM core, a pH- and temperature-responsive hydrophilic PDMAEMA corona, and a redox-sensitive disulfide linker. The multi-stimuli-responsive behaviors of the block copolymer assemblies were revealed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The release of encapsulated molecules from the polymeric nanocarriers could be enhanced under combined stimulation. The prepared multi-stimuli-responsive nanocarriers may offer significant opportunities in diverse applications in the fields of nanotechnology and biotechnology for controlled release.