A pH‐responsive drug release system based on doxorubicin conjugated amphiphilic polymer coated quantum dots for tumor cell targeting and tracking

BACKGROUND A 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. RESULTS The 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. CONCLUSIONS The 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.