As opposed to the majority of CPP applications reported, which rely on covalent linkage of carrier and cargo, limiting their general use considerably as a new construct has to be generated as well as tested for any given nucleic acid cargo, we will focus in this article on a peptide termed MPG which forms highly stable non-covalent complexes with nucleic acids (Fig. (1) ). The peptide is a derivative of the original MPG peptide described by Morris and coworkers [47] and differs by five amino acids in the hydrophobic part. These changes result in an alteration of the overall structure of the peptide towards a higher tendency of adopting a helical conformation [69] . Accordingly, the two peptides behave penetratin (Antp 43-58 ) RQIKIWFQNRRMKWKK [203] transportan GWTLNSAGYLLGKINLKALAALAKKIL [204] TP10 AGYLLGKINLKALAALAKKIL [205] Oligoarginine (R8) RRRRRRRR [50] MAP KLALKLALKALKAALKLA [163] MPG GALFLGFLGAAGSTMGAWSQPKKKRKV [47] MPG GALFLAFLAAALSLMGLWSQPKKKRKV [69] differently with respect to their interaction with artificial lipids as well as Xenopus oocytes [70, 71] and most probably, their exact mechanism of uptake is not the same. Besides ionic interactions responsible for the initial peptide/nucleic acid complex formation, hydrophobic peptide/peptide interactions drive the maturation of large nanoparticles in a sandwich-like assembly reaction (Fig. (1B) and Fig. (2) ).