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Two-step Kinetic Model as Self-assembling Mechanism for Diphenylalanine Micro/Nanotubes Formation

Abstract

Peptides nanostructures compose a new class of material that has gained attention due to their interesting properties. Among them, nanotube of diphenylalanine (FF) and its analogues have been one of the most studied structures in the last years. Their importance originates from the need to better understand the formation of β-amyloids fibrils which is associated to Alzheimer’s disease. In this work, FF self-assembly process was probed by time-resolved Raman microscopy. The changes of the Raman spectra are followed in time after injecting water in a FF-film until micro/nanotubes (MNT) are formed. Specific features in the Raman spectra clearly suggest that FF-molecules after water injection form an intermediate species before forming the FF-MNT. The broad Raman bands observed for the intermediate species suggests the presence of very heterogeneous structures based on FF. The FF-MNT appears almost instantaneously (detected via the rise of the typical Raman bands of FF-MNT at 761, 1249 and 1426 cm-1) after the intermediate structures are formed. This delayed formation of FF-MNT supports a nucleation process. The formation via a nucleation of FF-MNT is further corroborated by a simulation of Raman spectra based on a 2-step kinetic model and respective vibrational Raman modes are identified by Density Functional Theory vibrational calculation. Our results indicate that the driving force for the FF-MNT patterning process is the electric dipole re-orientation originated from the FF dipeptide units connectivity along the time.

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Publication details

The article was received on 27 Sep 2017, accepted on 13 Nov 2017 and first published on 13 Nov 2017


Article type: Paper
DOI: 10.1039/C7CP06611B
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Two-step Kinetic Model as Self-assembling Mechanism for Diphenylalanine Micro/Nanotubes Formation

    M. Ishikawa, C. Busch, M. Motzkus, H. Martinho and T. Buckup, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP06611B

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