Novel poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) based copolymers modified with RGD ligands on PEO and pendent functional groups on PCL,GRGDS-PEO-b-poly(α-benzylcarboxylate-ε-caprolactone) (GRGDS-PEO-b-PBCL) and
GRGDS-PEO-b-poly(α-carboxyl-ε-caprolactone)(GRGDS-PEO-b-PCCL), were synthesized. Chemical conjugation of doxorubicin (DOX) to PCCL core produced GRGDS-PEO-b-P(CL-DOX) micellar conjugates, while GRGDS-PEO-b-PBCL were used to physically encapsulate DOX. For both systems, micellar core degradation, drug release,intracellular drug uptake/disposition, and cytotoxicity against B16F10 metastatic cells were investigated. The PBCL and P(CL-DOX) cores were found resistant to degradation in pH 7.2, but showed10% and 40% loss in core molecular weight in pH 5.0 within 144 h, respectively. Preferential release ofDOX and DOX derivatives from PBCL and P(CL-DOX) cores was noted in pH 5.0, respectively. TheGRGDS-modified micelles showed enhanced cellular internalization through endocytosis, increased intracellular DOX release, nuclear localization, and improved cytotoxicity against metastatic B16F10 cells compared to their unmodified counterparts. The results clearly suggest a promise for the development of multifunctional polymeric micelles with RGD ligand decorated shell and endosomal pH-triggered degradable core for selective DOX delivery to metastatic cancer cells.