iRGD-mediated reduction-responsive DSPE-PEG/LA-PLGA-TPGS mixed micelles used in the targeted delivery and triggered release of docetaxel in cancer

Reduction-sensitive micelles with crosslinked cores were developed to load the lipophilic chemotherapeutic drug docetaxel (DTX) in order to overcome the issues of toxicity, water insolubility, and rapid metabolism of DTX. These DTX-loaded micelles (MM(DTX/Crosslink)) provide efficient incorporation and sustained release of DTX. Using independently synthesized LA-PLGA-TPGS and DSPE-PEG polymers as vehicles, MM(DTX/Crosslink) was found to be reduction-responsive, and possessed desirable drug entrapment efficiency (84.17 +/- 1.15%) and drug loading efficiency (6.21 +/- 0.07%). The MM(DTX/Crosslink) quickly dissociated under reduction conditions that mimicked the reductive intracellular environment, suggesting that it can rapidly release the encapsulated DTX in vitro. Furthermore, to target MM(DTX/Crosslink) to tumors for cancer therapy, iRGD was conjugated to the surface of MM(DTX/Crosslink). The iRGD-MM(DTX/Crosslink) micelles significantly increased the cellular uptake of DTX and inhibited cell proliferation, compared to the micelles without iRGD modification. Moreover, the iRGD-MM(DTX/Crosslink) micelles presented enhanced antitumor effects based on the analyses of apoptosis and cell cycle arrest. The micelles developed in this work may constitute a stable, efficient, and powerful system to deliver DTX into cancer cells.