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Nematic and Columnar Ordering of a PEG–Peptide Conjugate in Aqueous Solution
Author(s) -
Hamley Ian W.,
Krysmann Marta J.,
Kelarakis Antonios,
Castelletto Valeria,
Noirez Laurence,
Hule Rohan A.,
Pochan Darrin J.
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200800817
Subject(s) - conjugate , peg ratio , aqueous solution , peptide , materials science , liquid crystal , crystallography , chemistry , mathematics , organic chemistry , biochemistry , business , mathematical analysis , optoelectronics , finance
The self‐assembly in aqueous solution of a PEG–peptide conjugate is studied by spectroscopy, electron microscopy, rheology and small‐angle X‐ray and neutron scattering (SAXS and SANS). The peptide fragment, FFKLVFF is based on fragment KLVFF of the amyloid β‐peptide, Aβ(16–20), extended by two hydrophobic phenylalanine units. This is conjugated to PEG which confers water solubility and leads to distinct self‐assembled structures. Small‐angle scattering reveals the formation of cylindrical fibrils comprising a peptide core and PEG corona. This constrained structure leads to a model parallel β‐sheet self‐assembled structure with a radial arrangement of β sheets. On increasing concentration, successively nematic and hexagonal columnar phases are formed. The flow‐induced alignment of both structures was studied in situ by SANS using a Couette cell. Shear‐induced alignment is responsible for the shear thinning behaviour observed by dynamic shear rheometry. Incomplete recovery of moduli after cessation of shear is consistent with the observation from SANS of retained orientation in the sample.