  We investigate the adsorption of the nucleic acid bases, adenine (A), guanine
(G), cytosine (C), thymine (T) and uracil (U) on the outer wall of a high
curvature semiconducting single-walled boron nitride nanotube (BNNT) by first
principles density functional theory calculations. The calculated binding
energy shows the order: G>A\approxC\approxT\approxU implying that the
interaction strength of the (high-curvature) BNNT with the nucleobases, G being
an exception, is nearly the same. A higher binding energy for the G-BNNT
conjugate appears to result from a stronger hybridization of the molecular
orbitals of G and BNNT, since the charge transfer involved in the physisorption
process is insignificant. A smaller energy gap predicted for the G-BNNT
conjugate relative to that of the pristine BNNT may be useful in application of
this class of biofunctional materials to the design of the next generation
sensing devices.
