Modeling sensing mechanisms in carbon nanotube biosensors

We have applied extensive ab initio density functional theory coupled with non-equilibrium Green's function (DFT/NEGF) and molecular dynamics simulations to study the details of physical interactions between carbon nanotubes and amino acids in order to understand the underlying mechanisms that contribute to changes in electronic transport of carbon nanotubes in a two-terminal configuration. It was found that Coulombic interactions with charged amino acids produced the only significant changes in IV characteristics and that those changes are bias dependent. The results show that displacements in atomic coordinates resulting from the adsorption of short peptides onto the CNT surface do not produce any significant change in conductance. The results also demonstrate that semi metallic carbon nanotubes can be used to detect charged species.