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Carbon nanotubes wrapped by DNA molecules

Carbon nanotubes wrapped by DNA molecules

This video was recorded at SLONANO conference, Ljubljana 2007. Complexes of carbon nanotubes (CNTs) and nucleic acids allow fully exploit the potential of the CNTs in nanoelectronic devices, both by a size-specific matching of the two components and by the possibility to anchor also non-polar CNTs on the polar substrates such as oxides. The wrapping CNTs by the nucleic acid molecules allow also a transfer of CNTs into water solutions and a performance for their radii and lengths separation using chromatographical methods. In the present work for the first time the stability and electronic properties of the associates of the single-walled carbon nanotubes wrapped by homopolymeric single-stranded DNA molecules (CNT@DNA) are studied using a dispersion corrected modification of 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 (not single) DNA chains leads to a high water solubility of CNT@DNA. Pyrimidine-based DNAs are found to be more effective to wrap the CNTs, whereas purine-based DNAs are in wrapping more sensitive to the change of radii. 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 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 (complexes of polycytosine-DNA and a chiral metallic CNT) a considerable charge transfer from the DNA to the CNT was observed, combined with an additional gain in the CNT@DNA formation energy.

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