First-principles study of physisorption of nucleic acid bases on small-diameter carbon nanotubes

We report the results of our first-principles study based on density functional theory on the interaction of the nucleic acid base molecules adenine ( A), cytosine ( C), guanine ( G), thymine ( T), and uracil ( U), with a single-walled carbon nanotube (CNT). Specifically, the focus is on the physisorption of base molecules on the outer wall of a ( 5, 0) metallic CNT possessing one of the smallest diameters possible. Compared to the case for CNTs with large diameters, the physisorption energy is found to be reduced in the high-curvature case. The base molecules exhibit significantly different interaction strengths and the calculated binding energies follow the hierarchy G > A > T > C > U, which appears to be independent of the tube curvature. The stabilizing factor in the interaction between the base molecule and CNT is dominated by the molecular polarizability that allows a weakly attractive dispersion force to be induced between them. The present study provides an improved understanding of the role of the base sequence in deoxyribonucleic acid ( DNA) or ribonucleic acid ( RNA) in their interactions with carbon nanotubes of varying diameters.