Dual-responsive TPGS crosslinked nanocarriers to overcome multidrug resistance.

Efficient delivery of chemotherapeutic agents into tumor cells and reversal of chemoresistance are crucially important to enhance cancer therapy. We fabricated pH/redox dual responsive nanocarriers based on cell penetrating peptides (TAT) functionalized TPGS (cTAT-TPGS) and polypeptide (PEG-b-poly(aspartic-lipoic acid), PPAL) to reduce the permanent drug release and overcome multidrug resistance. TAT was used to functionalize TPGS and shielded by pH-responsive fatty acids, and polypeptides with lipoic acid side chains (PPAL) were synthesized. Reversibly crosslinked hybrid micelles (RCMs) were fabricated based on cTAT-TPGS and PPAL. RCMs nanocarriers exhibited acid-responsive charge reversal and redox-responsive drug release. The in vitro results showed that the RCMs could be efficiently internalized by the MCF-7/ADR cells in an acidic microenvironment and inhibited the DOX efflux, causing a higher cytotoxicity than non-crosslinked nanocarriers. Furthermore, the dual-responsive structure effectively prolonged the circulation time of RCM nanocarriers and achieved a high level of accumulation in cancer cells in vivo, leading to much more effective inhibition of tumor growth. The DOX-loaded RCMs also showed excellent biosafety, especially for the myocardium tissue. This novel strategy provided an effective platform for drug target delivery and reversal of MDR.