On–off switchable drug release from multi-responsive degradable poly(ether urethane) nanoparticles

A novel on–off switchable drug-release system was developed based on a series of multi-responsive degradable poly(ether urethane)s. The multi-segmented poly(ether urethane)s were synthesized through a simple one-pot condensation polymerization of poly(ethylene glycol), 2,2′-dithiodiethanol, N-methyldiethanolamine and hexamethylene diisocyanate. The obtained amphiphilic copolymers could self-assemble into nanoparticles in aqueous solution, which were responsive to temperature, pH and redox potential with tailored phase-transition temperature. The whole process for the responsive behaviours of the poly(ether urethane) nanoparticles was confirmed by light transmission, dynamic light scattering, nuclear magnetic resonance and transmission electron microscopy. The nanoparticles could encapsulate hydrophobic drugs and showed a temperature-triggered accelerated and complete drug-release profile. The mechanism of the temperature-triggered multi-responsive accelerated drug release was also elucidated. These results presented the polymeric nanoparticles as an effective multi-responsive degradable nanocarrier to achieve on–off drug release.