Biofunctional self-assembled nanoparticles of folate–PEG–heparin/PBLA copolymers for targeted delivery of doxorubicin

Abstract

To achieve a targeted drug delivery system for chemotherapy, we synthesized a ligand-mediated nanoparticulate drug carrier composed of folate-conjugated heparin-based copolymers. The use of a heparin-based drug delivery system is of special interest due to the attractive anticancer properties of heparin. Heparin–poly(β-benzyl-L-aspartate) (HP) and folate–poly(ethylene glycol)-conjugated HP (FPHP) amphiphilic copolymers were synthesized for delivery of doxorubicin (DOX). DOX was effectively incorporated into HP and FPHP nanoparticles at a high loading content and efficiency by a simple dialysis method. The DOX-loaded HP and FPHP nanoparticles had average diameters of 86–210 nm, depending on the drug loading content and the compositions of copolymers. Both DOX-loaded HP and FPHP nanoparticles had a sustained drug release pattern, and DOX-release from nanoparticles at pH 5.0 was much faster than that at pH 7.4. This pH-dependent DOX release property may ensure intracellular drug release due to decreases in pH values inside the endosomes and lysosomes of tumor cells. Furthermore, the DOX-loaded FPHP nanoparticles exhibited a greater extent of intracellular uptake against folate-receptor positive KB cells than DOX-loaded HP nanoparticles, indicating that the FPHP nanoparticles may serve as an effective active targeting carrier. The DOX-loaded FPHP nanoparticles also showed more potent cytotoxic effect on KB cells than on folate-receptor negative A549 cells. These results suggested that the FPHP nanoparticle is a promising candidate for targeted delivery of anticancer drugs to folate-receptor positive cells.