The formation of micellar aggregate composed of peptide-based surfactant containing side-chain ligands

Amphiphilic polypeptide of poly (peptide-co-ethylene glycol) containing lig ands (pyridine moiety) in the side chains of the polypeptide, P(2 PLG(17)/M LG(13))-PEG, was prepared. The amphiphile was soluble in water to form sphe rical aggregates. The critical micelle concentration (CMC) of the amphiphil e in aqueous solution was estimated to be 1.6x10(-6) M by observing the cha nges in intensity ratio, I-339/I-334, of pyrene, which was used as a fluore scent probe. In the aggregate, the polypeptide segment is in the alpha -hel ix structure. From atomic force microscope (AFM) observation, the aggregate s were spheres 20 similar to 30 nm in diameter. In addition, the formation of aggregates under the addition of Cu2+ and the complex formation behavior between the side-chain pyridyl ligand and Cu2+ in the aggregate were exami ned. The formation of a novel micellar aggregate was confirmed, in which th e complex formation with Cu2+ is possible. Also, the CMC of the amphiphile was affected by Cu2+ concentration.