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Nematic and Columnar Ordering of a PEG-Peptide Conjugate in Aqueous Solution

DOI: 10.1002/chem.200800817 DOI Help
PMID: 18618539 PMID Help

Authors: M. J. Krysmann (University of Reading) , Valeria Castelletto (University of Reading) , A. Kelarakis (University of Athens) , R.a. Hule (University of Delaware) , D.j. Pochan (University of Delaware.) , Ian Hamley (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry - A European Journal , VOL 14 (36) , PAGES 11369-11374

State: Published (Approved)
Published: December 2008

Abstract: 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 ?-peptide, A?(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 ?-sheet self-assembled structure with a radial arrangement of ? 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.

Journal Keywords: Amphiphiles; Liquid; Crystals; Peptides; Polymer Peptide Conjugates; Self Assembly

Subject Areas: Chemistry, Materials

Instruments: NONE-No attached Diamond beamline

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