Shear Alignment of Bola-Amphiphilic Arginine-Coated Peptide Nanotubes

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• 作者：Ian W. HamleySamuel Burholt ; Jessica Hutchinson ; Valeria Castelletto ; Emerson Rodrigo da Silva ; Wendel Alves ; Philipp GutfreundLionel Porcar ; Rajeev Dattani ; Daniel Hermida-Merino ; Gemma Newby ; Mehedi Reza ; Janne Ruokolainen ; Joanna Stasiak
• 刊名：Biomacromolecules
• 出版年：2017
• 出版时间：January 9, 2017
• 年：2017
• 卷：18
• 期：1
• 页码：141-149
• 全文大小：675K
• ISSN：1526-4602

文摘

The bola-amphiphilic arginine-capped peptide RFL₄RF self-assembles into nanotubes in aqueous solution. The nanostructure and rheology are probed by in situ simultaneous rheology/small-angle scattering experiments including rheo-SAXS, rheo-SANS, and rheo-GISANS (SAXS: small-angle X-ray scattering, SANS: small-angle neutron scattering, GISANS: grazing incidence small-angle neutron scattering). Nematic alignment of peptide nanotubes under shear is observed at sufficiently high shear rates under steady shear in either Couette or cone-and-plate geometry. The extent of alignment increases with shear rate. A shear plateau is observed in a flow curve measured in the Couette geometry, indicating the presence of shear banding above the shear rate at which significant orientation is observed (0.1–1 s^–1). The orientation under shear is transient and is lost as soon as shear is stopped. GISANS shows that alignment at the surface of a cone-and-plate cell develops at sufficiently high shear rates, very similar to that observed in the bulk using the Couette geometry. A small isotope effect (comparing H₂O/D₂O solvents) is noted in the CD spectra indicating increased interpeptide hydrogen bonding in D₂O, although this does not influence nanotube self-assembly. These results provide new insights into the controlled alignment of peptide nanotubes for future applications.