Liposomal cargo unloading induced by pH‐sensitive peptides

Amphiphilic peptides designed to have a pH-dependent conformational change and membrane activity are described. At physiologic pH, the peptides would exist in a random coil conformation, but at endosomal pH values they would switch to amphiphilic alpha-helices, disrupt membranes, and release liposomal contents. A series of peptides have been investigated that contain a high percentage of Glu residues for the pH-induced conformational switch, and Leu residues for optimal lipid binding. Circular dichroism (CD) results in aqueous and liposomal environments were performed and demonstrate a pH-dependent shift to helicity upon acidification. Liposomal release data at neutral and acidic pH, also document the success of this design strategy.