Here, we report on such a combined approach that involves, first, modeling to determine the stability criteria for CNT-DNA hybrid binding and, second, scanning tunneling microscopy (STM) for simultaneous structural and electronic characterization of hybrid structure and electronic properties with subnanometer Inhibitors,research,lifescience,medical resolution. We present the observed topographic images of the CNT-DNA hybrids with highly

resolved morphological details. The STM images reveal very stable hybrid structures where DNA is wrapped around the CNT with a well-defined wrapping angle of 63.4° and a coiling period of 3.3nm. Our previous studies [18, 31] of the helical nature of the charge density distribution in the nanotubes have demonstrated a strong correlation Inhibitors,research,lifescience,medical between CNT chirality and DNA wrapping geometry. In the current work, we further investigate this correlation and describe the dependence of the DNA-CNT binding energy on the chemical structure and wrapping geometry of a single strand DNA (ssDNA) around the (6,5) CNT. This information allows quantitative characterization of the stability of the hybrid structure with an optimal π-stacking between ssDNA bases and the nanotube

Inhibitors,research,lifescience,medical surface. Our simulations clearly show the find more existence of a very stable DNA binding geometry for the (6,5) CNT which is determined by a strong dependence of the binding energy on angular detuning of DNA strand from the nanotube chiral vector. Finally, we provide the additional evidence that the stable binding geometry of DNA nucleotides and CNTs arises from the π-stacking interactions, which tend to align the molecular plane of Inhibitors,research,lifescience,medical nucleotide parallel to the tube surface. 2. Experimental Details We used surfactant-based nanotube suspensions that were prepared by 2.5 hours of sonication of purified single-walled CNT (SWCNT) powder obtained from SES Inhibitors,research,lifescience,medical Research in 1% by weight of Triton X-100 in water. The final concentration of SWCNTs was ~0.1mg/ml.

To form DNA-based Histone demethylase nanotube suspensions, a 20-mer DNA sequence of 5′NH2(C-6) GAGAAGAGAGCAGAAGGAGA-3′ was diluted to approximately 5mg/ml in phosphate buffer solution with pH 7.4 (PBS 7.4). One mg of SWCNT was dissolved in approximately 250 microliters of the DNA solution and then diluted to approximately 0.75ml with PBS 7.4. The resulting mixture was sonicated at 0°C for at least 90min and then centrifuged at 14000rpm for 90min. 0.5ml of the DNA/SWCNT solution was decanted and purified over a NAP-10 column using deionized water as the buffer, with only first 1/2 of the eluted volume being collected. The filtered solution was finally passed again through the NAP-10 column with deionized water as eluent.