Morphology and mechanical stability of amyloid-like peptide fibrils.
Synthetic, amyloid-like peptide fibrils have recently attracted interest as a novel, potentially biocompatible material for applications in biotechnology and tissue-engineering. In this paper, we report atomic force microscopy (AFM) studies of the morphology and mechanical stability of fibrils self-assembled in vitro from the short peptide TTR(105-115), which serves as a model system for amyloid fibrils. It forms predominantly straight rods of approximately 1 microm in length and of diameters between 7 nm and 12 nm. We found polymorphism, with some fibrils exhibiting an unstructured morphology and others showing a regular, longitudinal surface pattern of 90 nm periodicity. Contact mode AFM-imaging in air was utilised to perform mechanical tests of individual fibrils on the nanometer scale with a defined, vertical force in the nN-range applied by the AFM-tip. Above 100 nN, all fibrils showed a permanent, mechanical deformation whereas below 40 nN, fibrils remained unaffected. Tapping-mode AFM-imaging in water led to fibril decomposition within 1.5 h whereas tapping-mode imaging in air left fibrils intact. Additional investigations by circular-dichroism spectroscopy showed that dispersed fibrils were structurally stable in aqueous solution between pH 3 and pH 8, and in sodium phosphate buffer of concentration between 50 mM and 1 M.
Mesquida
Patrick
P
London Centre for Nanotechnology, Department of Medicine, University College London, 5 University Street, London, WC1E 6JJ, UK. patrick.mesquida@kcl.ac.uk
Riener
Christian K
CK
MacPhee
Cait E
CE
McKendry
Rachel A
RA
D000682:Amyloid / Q000737:chemistry* / Q000648:ultrastructure*; D004355:Drug Stability; D004548:Elasticity; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D019563:Mechanics; D018625:Microscopy, Atomic Force / Q000379:methods*; D011228:Prealbumin / Q000737:chemistry* / Q000648:ultrastructure*; D011487:Protein Conformation; D011489:Protein Denaturation; D013314:Stress, Mechanical; D013718:Tensile Strength
D000682:Amyloid; D011228:Prealbumin; C076571:transthyretin-related amyloid fibril protein, human