siRNA cell delivery represent a valuable tool for treatment of cancer disease, viral infections and genetic disorders. However, classical strategies involve covalent linking of cargo molecules and CPPs, which does not provide efficient protection of siRNA molecules "in vivo"; thus results reported in literature are not consistent. Recently, non-covalent strategies have been successfully reported. Secondary amphipathic peptides based on aromatic tryptophan and arginine residues linked with lysine as spacer have been reported under the name of CADY. CADY contains a short peptide sequence of 20 amino acids, with the sequence “Ac-GLWRALWRLLRSLWRLLWRA-cysteamide."