A series of
pullulan-
doxorubicin conjugates (Pu-DOXs) were investigated for effectively delivering DOX to nuclei of hepatic
carcinoma cells in subcutaneous
tumor model. These Pu-DOXs were prepared by conjugating DOX onto
pullulan molecule via pH-responsive
hydrazone bond using spacers with different
alkane chain length. The highest
drug loading content of Pu-DOXs went up to nearly 50%, and the diameter of Pu-DOX nanoparticles ranged from 50 to 170 nm, as measured by DLS and TEM. These Pu-DOX nanoparticles could rapidly release DOX in the acidic environment at pH = 5.0 while being kept relatively stable in neural conditions. The in vitro cell coculture experiments revealed that these Pu-DOX nanoparticles were selectively internalized by hepatic
carcinoma cells through receptor-mediated endocytosis via
asialoglycoprotein receptor on the hepatic
carcinoma cell surface. DOX was rapidly released from Pu-DOX nanoparticles in acidic endosome/lysosome, diffused into cell nuclei due to its strong affinity to
nucleic acid, inhibited the cell proliferation, and accelerated the cell apoptosis. In the nude mice subcutaneous hepatic
carcinoma model, Pu-DOX nanoparticles efficiently accumulated in the
tumor site through the enhanced permeation and retention effect. Then DOX was specifically internalized by hepatic
carcinoma cells and rapidly diffused into the nuclei of cells. Compared with the control group in in vivo experiments, these Pu-DOX nanoparticles effectively inhibited solid
tumor growth, prolonging the lifetime of the experimental animal. These pH sensitive nanoparticles might provide an important clinical implication for targeted hepatic
carcinoma therapy with high efficiency and low systematic toxicity.