Characterization of peptide-guided polymer assembly at the air/water interface.
An organo-soluble, peptide-polymer conjugate that combines poly(n-butyl acrylate) with a beta-sheet-forming peptide is spread at the water surface to investigate peptide-guided self-assembly in a two-dimensional environment. Single layers of the conjugate are studied to gain information on the packing, orientation, and structure of the conjugate molecules using standard monolayer techniques: isotherms, grazing incidence X-ray diffraction (GIXD), and infrared reflection absorption spectroscopy (IRRAS). At all conditions studied, the stabilizing beta-sheet network consists of antiparallel beta-sheets oriented parallel to the air/water interface. The incorporation of temporary switch defects in the peptide segment enables beta-sheet assembly to be triggered at different packing densities. Stable monolayers, with low compressibilities similar to peptide monolayers, form when beta-sheet assembly occurs in monolayers that contain closely packed conjugate molecules. Langmuir-Schaefer transfer of the switched monolayer seeded with 1/1000 part stearic acid results in a transferred monolayer containing ordered domains with 7 nm wide stripes, a width in agreement with the end-to-end distance of the conjugate molecule. In this interfacial system, high packing densities and a hydrophobic seed molecule play an important role in beta-sheet network and structure formation. Both effects likely direct the highly ordered beta-sheet structure because of beta-strand prealignment. Insights gained from self-assembly in this system can be applied to peptide aggregation mechanisms in more complex interfacial environments.
Muenter
Annabel H
AH
Max Planck Institute of Colloids and Interfaces, MPI KG Golm, D-14424 Potsdam, Germany. edwardsa@denison.edu
Hentschel
Jens
J
Börner
Hans G
HG
Brezesinski
Gerald
G
D000179:Acrylates / Q000737:chemistry*; D000327:Adsorption; D000388:Air; D057927:Hydrophobic and Hydrophilic Interactions; D010455:Peptides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water; D014961:X-Ray Diffraction
D000179:Acrylates; D010455:Peptides; D011108:Polymers; C498324:poly(n-butyl acrylate); D014867:Water