화학공학소재연구정보센터
Langmuir, Vol.21, No.18, 8123-8130, 2005
Effect of the addition of a nonionic surfactant on the complex poly(asparagine)-cationic surfactant
Poly(asparagine) (pAsn) at 0.1wt% in the presence of dodecyltrimethylammonium bromide (DTAB) and pentaoxyethylene octyl ether (CepsilonE5) at 1: 1 molar ratio leads to the formation of mixed DTAB/C8E5 micelle-like aggregates onto the polypeptide as a total surfactant critical association concentration (cac) is reached, as revealed by surface tension. measurements and NMR chemical shifts. Two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY) capable of revealing spatial relationships among proximal protons has been performed on the pAsn-DTAB-C8E5-water system to study structural details of the surfactant-polypeptide aggregates. NOESY cross-peaks at sample temperature of 298.15 K indicate that the polypeptide interacts with the DTAB/C8E5 Micelle-like aggregates. The NOE intermolecular effects also show direct interactions between surfactant and polypeptide in the pAsn-DTAB-water system, whereas no interaction has been revealed in the pAsn-C8E5-water system. Furthermore, the experimental evidence suggest that the DTAB-polypeptide complex is mainly driven by the polar attraction between the two molecules.