The effects of water molecules on the electronic and structural properties of peptide nanotubes

Abstract

The self-assembly of short amino acid chains appears to be one of the most promising strategies for the fabrication of nanostructures. Their solubility in water and the possibility of chemical modification by targeting the amino or carboxyl terminus give peptide-based nanostructures several advantages over carbon nanotube nanostructures. However, because these systems are synthesized in aqueous solution, a deeper understanding is needed on the effects of water especially with respect to the electronic, structural and transport properties. In this work, the electronic properties of L-diphenylalanine nanotubes (FF-NTs) have been studied using the Self-Consistent Charge Density-Functional-based Tight-Binding method augmented with dispersion interaction. The presence of water molecules in the central hydrophilic channel and their interaction with the nanostructures are addressed. We demonstrate that the presence of water leads to significant changes in the electronic properties of these systems decreasing the band gap which can lead to an increase in the hopping probability and the conductivity.

Self-Assembly of Phenylalanine-Based Molecules

“…Especially, the values are slightly larger 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 for FF4 than for FF6, indicating lower stability for this form. Following previous studies 12 Note that the phenylalanine with the symmetry of four has a pore size too small (less than 5 AA) to fit water molecules inside. Compared to the electron di↵raction data 4.6 +/-0.06Å tube axis length by 11.63 +/-0.27Å width 15 our results show a slightly wider pore but with a more compact width.…”

“…Much of our analysis is limited to the inner two layers of our systems in order to minimize finite-size e↵ects. Following earlier work, 12 …”

A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

“…However, the spatial organization of peptides at a molecular level has been shown to closely relate to electronic properties. 26,27 We have previously reported that a crystalline symmetry drives the hydrophobicity of the peptide interface for FF-based assemblies. 15 Our samples were prepared using water or aniline vapor.…”

Hybrid Proton and Electron Transport in Peptide Fibrils

“…Our results, hence, clearly indicate hybrid electron and proton conduction at the low humidity range. It should be noted that both type of conduction mechanisms can contribute to the sub-exponential dependence below 60% relative humidity crossover point; on the one hand, dielectric theories predict some dependence of electron transport on humidity, [ 11c , 11d , 31 ] , [ 33 ] while on the other hand the more gradual increase in the conductance at the lower humidity range can be attributed to dominance of H 3 O + and not H + on protonic conductance. [ 19a , 20a ] The relative contribution of each type of charge carrier to the conductance at the entire relative humidity range should be further investigated.…”