BACKGROUNDA tumor-targeted and pH-responsive drug release system based on poly(ethylene glycol) (PEG) and dodecylamine (DDA)-modified poly itaconic acid (PIA) with doxorubicin (DOX) and quantum dots (QDs) (PIA-PEG-DDA-DOX@QDs) has been constructed successfully. These nanocomposites with outstanding capabilities were further designed to target liver cancer cells with vascular endothelial growth factor receptor (VEGFR) overexpressed. RESULTSThe nanoparticles constructed were spherical and monodispersed with very small diameter. The cumulative release rates of DOX conjugates were studied at pH 5.5 and pH 7.4, and the release behavior at pH 5.5 fit the first-order kinetics model, Q=46.5991 -45.2394e(-0.24355t) for PIA-PEG-DDA-DOX and Q=46.7094-38.5588e(-0.20123t) for PIA-PEG-DDA-DOX@QDs. The nanoparticles show low cytotoxicity at pH 7.4 and high cytotoxicity at pH 5.5 in cell viability studies. In the intracellular localization observation, the targeting molecule anti-VEGF conjugated NPs exhibited efficient receptor-mediated endocytosis in anti-VEGF receptor-overexpressing cancer cells, compared with nontargeted nanoparticles. CONCLUSIONSThe targeting imaging and pH-responsive drug release system could target the tumor cells and fluoresce quantum dots sensitively due to the conjugation of VEGF, and enabled pH-controlled-activation of the DOX. The water soluble conjugates have the potential of becoming a promising diagnostic tool in clinical application for cancer detection and treatment. (c) 2013 Society of Chemical Industry