RGD-decorated redox-responsive d-α-tocopherol polyethylene glycol succinate-poly(lactide) nanoparticles for targeted drug delivery.

Developing multifunctional nanoparticles (NPs) to improve therapeutic efficacy is highly desirable in cancer therapy. In an attempt to respond to such a challenge, a novel copolymer, d-α-tocopherol polyethylene glycol succinate-SS-poly(lactide) (TPGS-SS-PLA) with a disulfide linkage between the TPGS and PLA units, was synthesized for paclitaxel (PTX) delivery. PTX-loaded NPs were fabricated using a nanoprecipitation method to form a particle size of ∼130 nm with good in vitro stability, which can be disassociated under intracellular reductive conditions to release PTX rapidly. The detached TPGS can further promote the drug retention and cytotoxicity through its P-glycoprotein inhibiting property. Integrin-specific targeting peptide, cyclic RGD (cRGD), was further conjugated to the surface of the NPs for targeting the drug delivery. The RGD-decorated NPs exhibited enhanced cellular uptake, PTX accumulation and cell cytotoxicity as compared to non-targeted NPs on murine melanoma B16F10 cells, PTX-sensitive human ovarian A2780 cells and PTX-resistant A2780/T cells. In vivo evaluation of the targeted NPs further showed an extended half-life, increased AUC (area under the concentration-time curve), and significant tumor growth inhibition in mouse sarcoma S180- and B16F10-tumor bearing mice, with reduced side effects as compared to Taxol® and non-targeted NPs. These results indicate that the RGD decorated redox-sensitive NPs could deliver chemotherapies specifically inside the cell via receptor-mediated endocytosis with enhanced efficacy, especially in integrin α_vβ₃/α_vβ₅-rich tumor cells. Such a targeted nanocarrier against receptor clustering prepared from a non-cytotoxic and biodegradable copolymer might have great potential in cancer treatment.