pH-sensitive polymeric micelles assembled by stereocomplexation between PLLA-b-PLys and PDLA-b-mPEG for drug delivery

pH-responsive stereocomplexed micelles based on poly(l-lactic acid)-b-polylysine/poly(d-lactic acid)-b-methoxy poly(ethylene glycol) (PLLA-b-PLys/PDLA-b-mPEG) were fabricated by stereocomplexation between enantiomeric PLA segments. The morphology, critical micelle concentration, formation of stereocomplexation and pH sensitivity of the stereocomplexed micelles were investigated by TEM, DLS, fluorescence spectra, DSC, XRD, and the acid-base titration method. Interestingly, it was observed that compared to PLLA-b-PLys micelles, the stereocomplexed micelles showed lower critical micelle concentration. Anticancer drug doxorubicin (DOX) was encapsulated in the stereocomplexed micelles and then they were incubated with Hela cells to study the in vitro anti-tumor effect. The results showed that the DOX-loaded stereocomplexed micelles exhibited a slower drug release behavior and a weaker efficacy of intracellular proliferation inhibition than PLLA-b-PLys micelles. Stereocomplexation would provide a favorable platform to construct stable micelles for cancer therapy.