Folic acid grafted and tertiary amino based pH-responsive pentablock polymeric micelles for targeting anticancer drug delivery.

Increasing target to tumor sites and reducing accumulation at normal tissue sites of anticancer drugs are essential to improve the cancer chemotherapy efficiency. In this study, we have developed a novel pentablock polymeric poly(ethylene glycol)-b-(poly(2-(diethylamino) ethyl methacrylate)-b-poly (hydroxyethyl methacrylate)-g-folic acid) [PEG-b-(PDEAEMA-b-PHEMA-g-FA)] micelles as anticancer drug nanocarrier. The carriers could target tumor cells rapidly, and response to the tumor sites pH to control drug release. The critical micelle concentration (CMC) of the intermediates copolymers was 4.37-7.08mg/L, which indicated that the self-assembled micelles had comparatively good internal circulation stability. The drug loaded micelles were prepared using dialysis method, resulting in an average particle size of below 120nm, and the drug loading content and entrapment efficiency were 21% and 48% respectively. The pH-responsiveness and in vitro drug release of the micelles were studied, and the results showed a higher doxorubicin (DOX) cumulative amount at pH5.0 (~90%) compared to pH7.4 (~20%) owing to the protonation of the tertiary amino groups. In vitro cytotoxicity and endocytosis experiments showed that the tumor-suppressing effect of drug-loaded micelles was close to those of free DOX. The loaded DOX could be delivered into the cancer cells in a short time, and about 80% of the tumor cells were killed after 48h incubation. The results indicate that the pentablock polymeric micelles have the potential to be applied for targeting anticancer drug delivery and control release.