Lipidated gemini peptide amphiphiles with enhanced loading capacity and cell membrane affinity for drug delivery

Lipidated peptide amphiphiles exhibit high affinity for plasma cell membranes, good cell internalization and improved stability against degradation, which make them attractive as a drug delivery system. However, low drug loading capacity limits their application for drug delivery. Herein, we developed a gemini peptide amphiphile with enhanced membrane activity and endosomal escape, containing dodecanoic acid hydrophobic tails at the N-terminus, rhodamine on the pendant chain and an active targeting peptide sequence (GRGDS). The presence of rhodamine not only provides high drug loading capability due to the π-π stacking interaction between camptothecin (CPT) and rhodamine, but also promotes peptide amphiphiles to form compact spherical micelles, as well as allows for fluorescence imaging. Single-molecule total internal reflection fluorescence microscopy investigation reveals gemini peptide amphiphile has higher affinity for plasma cell membranes than single-tail peptide amphiphile. Meanwhile, better cell internalization of gemini peptide amphiphile was confirmed by flow cytometry and confocal laser scanning microscopy. Moreover, CPT-loaded gemini peptide amphiphile induced enhanced cytotoxicity in cancer cells when compared to free CPT, indicating that lipidated peptide amphiphile with π-conjugates on the pendant chain and two hydrophobic tails can serve as a highly efficient drug delivery vehicle.