Interaction of fragmented double-stranded DNA with carbon nanotubes in aqueous solution |
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Authors: | G O Gladchenko M V Karachevtsev V S Leontiev V A Valeev A Yu Glamazda A M Plokhotnichenko |
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Institution: | 1. B. I. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Science of Ukraine , 47 Lenin Ave, 611303, Kharkov, Ukraine gladchenko@ilt.kharkov.ua;3. B. I. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Science of Ukraine , 47 Lenin Ave, 611303, Kharkov, Ukraine |
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Abstract: | 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. |
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