Efficient oral administration of anticancer agents requires a nanocarrier to long survive in the stomach, effectively penetrate across the small intestine, tightly retain the drug during bloodstream and quickly release drug in tumor cells. Herein a kind of dual pH-sensitive polyelectrolyte complex nanoparticles (CNPs) was developed by employing electrostatic interaction between positively charged chitosan (CS) and negative poly (L-glutamic acid) grafted polyethylene glycol-doxorubicin conjugate nanoparticles (PG-g-PEG-hyd-DOX NPs) with acid-labile hydrazone linkages. The obtained NPs and CNPs were characterized for their morphology, particle size, ζ-potential, pH-sensitivity under the simulated physiological conditions, drug release, as well as in vivo antitumor activity and biodistribution. The results indicated that CNPs can remain intact structure in pH range from 3.0 to 6.5. After detaching CS layer due to the pH-induced deprotonation with increasing pH to 7.4 in the mucus layer of the small intestine, the inner NPs would be released and effectively absorbed into blood circulation via opening the tight junctions by CS. PG-g-PEG-hyd-DOX NPs with demonstrated long-circulating properties can be accumulated in the tumor via EPR effect and dump the drug within tumor cells by acid-cleavage of hydrazone bonds between PG-g-PEG and DOX, achieving high therapeutic efficacy and low systemic toxicity. These results suggest that the design presented here, combining the functions of the gastrointestinal pH-sensitive electrostatic complex and intracellular acid-sensitive macromolecular prodrugs NPs, can sequentially overcome the biological barriers of oral anticancer drug delivery, which thus provides a promising nanomedicine platform for oral chemotherapy.
Keywords: Chitosan; Doxorubicin; Macromolecular prodrugs; Oral chemotherapy; Polyelectrolyte complex nanoparticles; pH-sensitive.
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