Self-assembled micelles of a multi-functional amphiphilic fusion (MFAF) peptide for targeted cancer therapy

A new multi-functional amphiphilic fusion (MFAF) peptide comprised of a multi-functional fusion peptide sequence (GFLGR8GDS) and a hydrophobic polycaprolactone (PCL) tail was designed and prepared. In aqueous solution, through the strong hydrophobic interaction among the PCL tails, this MFAF peptide can self-assemble into core–shell micelles at a low concentration with the anti-tumor drug doxorubicin (DOX) loaded in the core and the multi-functional fusion peptide sequence located on the shell. When incubating the DOX-loaded micelles with tumor and normal cells, the micelles can use the RGD and membrane-penetrating peptide (eight continuous arginine residues, R8) sequences to target tumor cells and penetrate cell membranes. Subsequently, cathepsin B, an enzyme over-expressed in late endosomes and lysosomes of tumor cells that can specifically hydrolyze the GFLG sequence, can break the micellar structure and lead to a rapid release and escape of loaded DOX from endosomes, resulting in the apoptosis of tumor cells. The MFAF peptide presents great potential as a new drug delivery platform for targeted cancer chemotherapy.