Nonlinear polarization effects in superchiral nanotube sensors of amino acids

We develop a theoretical model showing that insertion of a polar and polarizable alpha-helix in a chiral carbon nanotube, used in resonator configuration, substantially improves the enantiospecific detection of chiral molecules. The differential resonance frequency shift associated with the adsorption of the two alanine enantiomers is calculated to increase by about 50% when compared to the response of the tube alone at the linear polarization approximation, and up to 100% when nonlinear polarization effects are taken into account. (C) 2009 Elsevier B. V. All rights reserved.