Nanothin films of tubular oligopeptides: monolayers and Langmuir-Blodgett films of β 4.4-helices with surface-pressure-dependent orientation

• Published in: Thin solid films Vol. 238; no. 2; pp. 285 - 289
• Main Authors: Römer, Daniel U., Lorenzi, Gian P., Weisenhorn, Albrecht L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1994
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(94)90068-X

The orientation of β 4.4 helices of a D, L-alternating pentadecavaline, Boc- D-Val-( L-Val- D-Val) 7-OMe, in monolayers at the air-water interface and in Langmuir-Blodgett films has been investigated. Compression of these helices in a Langmuir trough results in characteristic surface pressure-area curves exhibiting an initial rise, in which the surface pressure increases to 20 mN m -1 and the area decreases to 2.5 nm 2 helix -1, followed by a plateau up to 30 mN m, -1 and 1.35 nm 2 helix -1 and by a second rise. At the end of this second rise, before the fims collapses, surface pressure and area are about 60 mN m -1 and 1.1 nm 2 helix -1 respectively. These results are interpreted as indicating that, at low surface pressures, the β 4.4 helices lie flat on the water, and that they can reorient themselves to assume an upright position when the pressure becomes high enough. Ellipsometric and grazing incidence reflection absorption measurements show that similar orientations relative to the substrate (silanized or gilded silicon) are obtained in LB films when these are assembled at surface pressures of 14 mN m -1 and 45 mN m -1 respectively.