Folate-conjugated and pH-triggered doxorubicin and paclitaxel co-delivery micellar system for targeted anticancer drug delivery

A folate-conjugated and pH-sensitive polymeric micellar system for the co-delivery of DOX and PTX was studied. A doxorubicin conjugated prodrug was synthesized via Schiff's base reaction. Subsequently, folate was grafted onto the prodrug and PTX was encapsulated. Sustained drug release of both DOX and PTX from the polymeric micelles was observed and the release rate could be accelerated by decreasing the media pH. A cellular uptake assay revealed that the polymeric micelles were internalized in the cytoplasm via endocytosis by SW1353 cells, and the cellular uptake was enhanced for the folate-conjugated micelles due to an active FR-mediated endocytosis pathway, showing stronger red fluorescence compared to that of non-folate micelles. The in vitro anticancer efficiency of the polymeric micellar system was evaluated using a cytotoxicity assay by incubating different drug formulations with the SW1353 cells. Both free drugs and micellar formulations displayed inhibition of cell growth at different levels, while the folate-conjugated dual-drug loaded polymeric micelles (Folate-Oxd-DOX/PTX) displayed a much lower IC50 value than other drug formulations, indicating a desirable in vitro anticancer efficiency due to the synergistic effect of co-delivery and active targeting. Thus, the polymeric micellar system is a promising platform for targeted cancer chemotherapy.