SWNTs with DNA in aqueous solution and film

Raman and luminescence spectra of SWNTs in aqueous solutions with fragmented single-stranded DNA and films prepared from these solutions have been obtained. SEM film study shows that nanotubes aggregate in bundles after film drying. In Raman spectra it leads to the enhancement of the intensity of the low-frequency component of the tangential mode (G(-)), to the shift and broadening of the high-frequency component of this mode (G(+)). It was shown that the ratio of areas of the high-frequency component of the G mode to the low-frequency component (S(G)+/S(G)-) can serve as an indicator of nanotube aggregation into bundles for SWNTs suspended in solution. The film yields luminescence which indicates the presence of individual tubes or small bundles in the films. The luminescence bands of SWNTs in the film become wider and are attributed to the interaction of DNA with the nanotube surface in the solid state.