DNA-wrapped carbon nanotubes

Abstract

The stability and electronic properties of complexes of single-walled carbon nanotubes wrapped by homopolymeric single-stranded DNA molecules (CNT@DNA) are considered using a quantum mechanical density-functional tight-binding method (DFTB). A phenomenological model of the CNT@DNA formation energy depending on the nanotube radii is developed, which shows that the decoration of a CNT by a few DNA chains leads to a high water solubility of CNT@DNA. Pyrimidine-based DNAs are found to be more effective to wrap the CNTs than other DNAs. The densities of states of the CNT@DNA complexes are close to the superposition of those of the 'free' components with some additional states below the Fermi level. The band gap in a hybrid CNT@DNA system is determined by the competition between the Fermi levels of the 'free' DNA and CNT. In a few specific cases a considerable charge transfer from the DNA to the CNT was observed, combined with an additional gain in the CNT@DNA formation energy.