Immobilization of leucine on polypyrrole for biosensor applications: A density functional theory study

Adsorption based immobilization of amino acids leucine on the surface of undoped polypyrrole (Ppy) is investigated. Calculations are done based on density functional theory using Gaussian03 software and applying GGA exchange-correlation model of PBE (Perdew, Burke, Ernzerhof) with 6–31G(d) basis set. The energy of the Ppy doped with amino acids are minimized with respect to the orientation and distance of the amino acids to the Ppy. Neutral leucine carboxyl shows greater binding energy as compared to that other glycine configurations. It has adsorption energy of 0.25 eV at optimum distance of 2.2 Å from the surface of Ppy.