Interaction of fragmented double-stranded DNA with carbon nanotubes in aqueous solution

• Published in: Molecular physics 2006-10, Vol.104 (20-21), p.3193-3201
• Main Authors: Gladchenko, G. O., Karachevtsev, M. V., Leontiev, V. S., Valeev, V. A., Glamazda, A. Yu, Plokhotnichenko, A. M., Stepanian, S. G.
• Format: Article
• Language: English
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268970601061220

Aqueous suspensions of ultrasonically fragmented double-stranded (fds-) DNA and single-walled carbon nanotubes (SWNTs) have been investigated by UV- and IR-absorption, NIR-emission and Raman spectroscopy. According to gel-electrophoresis, the lengths of the polymer fragments were 100-500 base pairs. Analysis of IR and UV data indicates the presence of both double-stranded (ds) and single-stranded (ss)-regions in the fragments. SWNT complex with DNA was revealed by NIR-emission and Raman spectroscopy. It turned out that fds-DNA is less efficient in holding nanotubes in the aqueous solution than ss-DNA. From the UV-data, the character of the helix-coil transition is seen to be like that for fds-DNA off and on nanotube, however, DNA thermostability increased in this latter case. The effective charge density on the DNA sugar-phosphate backbone of the fds-DNA:SWNT hybrid was less than that of DNA alone. Spectroscopic data can be explained by a model in which the formation of hybrids starts due to the interaction between untwisted ss-regions of DNA and the nanotube: the strands wrap on the tube and thus create an 'anchor' for the whole polymer. The ds-part of the polymer is located close to the nanotube.