Reactive oxygen species (ROS) are highly overproduced in cancerous tissues, and thus oxidation-responsive nanoparticles (NPs) have emerged as a promising drug carrier for cancer-targeted drug delivery. In this study, we successfully synthesized poly(vanillyl alcohol- co-oxalate) (PVAX) polymer with an excellent ROS-responsive capacity. A well-established emulsion-solvent evaporation method was used to fabricate PVAX-based curcumin (CUR)-loaded NPs (PVAX-NPs) and their counterparts (poly(lactic- co-glycolic acid)-based CUR-loaded NPs, PLGA-NPs). It was found that these NPs had a hydrodynamic particle size of approximately 245 nm, narrow size distribution (polydispersity index less than 0.1), negative zeta potential (around -18 mV), smooth surface appearance, and high drug encapsulation efficiency. Moreover, we found that the CUR release rate of PVAX-NPs was greatly increased in the presence of a hydrogen peroxide-rich environment due to the cleavage of polyoxalate ester bonds in PVAX polymer, resulting in the evenly distribution of CUR within the whole cancer cells. More importantly, PVAX-NPs exhibited much stronger anticancer activities and pro-apoptotic capacities than PLGA-NPs both in vitro and in vivo. These results clearly demonstrate that these ROS-responsive PVAX-NPs can be exploited as a robust anticancer drug delivery platform in chemotherapy.
Keywords: chemotherapy; drug delivery; nanoparticle; reactive oxygen species; stimuli-responsive polymer.