Temperature-responsive drug delivery systems based on polyaspartamides with isopropylamine pendant groups

To develop poly(amino acid)s with temperature-sensitivity, a series of polyaspartamides with isopropylamide and hydroxyalkylamide pendant groups were synthesized by a successive aminolysis reaction of polysuccinimide. The structure of the resulting polymers was examined by 1H NMR and FT-IR. The polyaspartamide derivatives self-assembled into nanoparticles in water and showed sharp temperature-responsive phase transition behaviour. The phase transition temperature (Tp) could be modulated by the hydrophilic–hydrophobic balance of the copolymer controlled by altering the composition of both pendants. Besides, an antitumor agent, doxorubicin, was successfully loaded into the polymeric nanoparticles via a dialyzing method. The drug release profile was temperature-dependent accelerating significantly above the Tp and decelerating below the Tp. This easily prepared polymeric nanoparticle with excellent biocompatibility and tunable temperature responsiveness has significant potential for controlled drug release applications.