Open AccessNanosheet Formation by an Anionic Surfactant-like Peptide and Modulation of Self-Assembly through Ionic Complexation
Author(s) -
Ian W. Hamley,
Jessica Hutchinson,
Steven Kirkham,
Valeria Castelletto,
Amanpreet Kaur,
Mehedi Reza,
Janne Ruokolainen
Publication year - 2016
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.6b02180
Subject(s) - nanosheet , hexamethylenediamine , self assembly , circular dichroism , nanostructure , paracrystalline , pulmonary surfactant , diamine , aqueous solution , peptide , nanomaterials , materials science , ionic bonding , chemistry , chemical engineering , crystallography , polymer chemistry , nanotechnology , organic chemistry , ion , biochemistry , polyamide , engineering
The surfactant-like peptide (Ala) 6 -(Asp) (A 6 D) is shown to self-assemble into ultrathin (3 nm thick) nanosheets in aqueous solution above a critical aggregation concentration. A combination of circular dichroism and FTIR spectroscopy and X-ray diffraction shows that the nanosheets comprise interdigitated bilayers of the peptide with β-sheet conformation. The self-assembly can be modulated by addition of hexamethylenediamine which is expected to interact with the anionic C terminus (and C-terminal D residue) of the peptide. Multiple ordered nanostructures can be accessed depending on the amount of added diamine. Nanosheet and bicontinuous network structures were observed using cryogenic-TEM and small-angle X-ray scattering. Addition of hexamethylenediamine at a sufficiently large molar ratio leads to disruption of the ordered nanostructure and the formation of a solution of A 6 D-diamine molecular complexes with highly charged end groups. The multiple acid-functionalized nanostructures that are accessible in this system are expected to have many applications in the fabrication of new nanomaterials.