G-quartet biomolecular nanowires

Abstract

We present a first-principle investigation of quadruple helix nanowires, consisting of stacked planar hydrogen-bonded guanine tetramers. Our results show that long wires form and are stable in potassium-rich conditions. We present their electronic bandstructure and discuss the interpretation in terms of effective wide-bandgap semiconductors. The microscopic structural and electronic properties of the guanine quadruple helices make them suitable candidates for molecular nanoelectronics.

Electron Channels in Biomolecular Nanowires

“…Two special k-points in the irreducible wedge were employed for Brillouin Zone (BZ) sums in the case of the G4-wire. The infinite helix was simulated by repeated supercell containing three stacked G4 tetrads, 27 employing periodic boundary conditions in the three spatial direction a thick vacuum layer (∼ 16 A) in the directions perpendicular to the helical axis prevented spurious interactions between adjacent replicas of the wire. For the isolated G-quartet, the same vacuum thickness was employed also in the third direction perperdicular to the plane of the tetrad, and only the Γ point was used in the BZ sampling.…”

“…From the theoretical point of view, quantum chemistry and molecular dynamics studies focused on the energetics and on the geometry of isolated G-quartets or finite clusters of stacked G4's, 26 whereas the electronic properties of these materials were so far investigated to a much lesser extent. 27 In the following, we present a first-principle investigation of the electronic and conduction properties of periodically repeated G4-wires. Recently, 27 we described the structure and the energetics, as well as some basic features of the electronic structure, of an infinite G4-wire with and without the presence of K + ions in the inner cavity.…”

“…27 In the following, we present a first-principle investigation of the electronic and conduction properties of periodically repeated G4-wires. Recently, 27 we described the structure and the energetics, as well as some basic features of the electronic structure, of an infinite G4-wire with and without the presence of K + ions in the inner cavity. In this paper, we focus entirely on the electronic properties of the same system and present a complete and thorough analysis of the guanine-guanine and metal-guanine interactions, discussing the effects on the conduction properties of the tubular system.…”

Comparative Electrostatic Force Microscopy of Tetra‐ and Intra‐Molecular G4‐DNA

“…the tetrad unit and the tetrad-tetrad stacking. By comparing adjacent molecules of both types, co-adsorbed on the same mica surface, we circumvent the problem of phase calibration, showing that the EFM signal is twice as strong in the parallel configuration as compared with the anti-parallel G4-DNA, possibly because of greater charge mobility in tetra-molecular G4-DNA, thus making tetra-molecular G4-DNA a better candidate for conductivity measurements.Theoretical [7,8] and experimental [4,9] studies showed that out of the four natural bases, guanine may form a π-stacking with the greatest chance of providing a conducting bridge between bases, due to its lowest oxidation potential. [9] Moreover, the robust quadruple helix, in which each tetrad (Figure 1a) is formed by eight hydrogen bonds rather than by two or three as in dsDNA, is more rigid than the duplex dsDNA helix and may withstand surface deformations in solid-state molecular devices.…”

“…Theoretical [7,8] and experimental [4,9] studies showed that out of the four natural bases, guanine may form a π-stacking with the greatest chance of providing a conducting bridge between bases, due to its lowest oxidation potential. [9] Moreover, the robust quadruple helix, in which each tetrad (Figure 1a) is formed by eight hydrogen bonds rather than by two or three as in dsDNA, is more rigid than the duplex dsDNA helix and may withstand surface deformations in solid-state molecular devices.…”