Modeling and ab initio study of the adsorption of histidine on a graphene sheet

S. J. RODRÍGUEZ; L. MAKINISTIAN; E.A. ALBANESI

La Plata

Workshop; VI Workshop on Novel Methods for Electronic Structure Calculation; 2015

The graphene is a bidimensional crystal with unique physical and chemical properties: high carriers mobility, it is flexible, transparent, foldable, and with one atom of thickness, among others. These properties make it promising for biomedical, bioelectronics and biosensor applications. In comparison to other materials used for the construction of biosensors, graphene has great advantages; it is a sensitive, selective, biocompatible, in addition to being an intrinsically low-noise material. In this work we present the results of modeling, from first principles, the adsorption of histidine on a graphene sheet. The calculations were implemented in the context of the density functional theory (DFT) within a pseudopotentials approach. The study was carried out for two systems: the histidine molecule with carboxyl (-COOH) and amino groups (-NH2) and the imidazole ring alone (i.e., the histidine without its carboxyl and amino groups), with the aim to evaluate the relevance of including the carboxyl and amino groups in the adsorption process onto the graphene sheet. We report the total energy vs. final mean distance of the molecule, adsorption distances, adsorption energies, electronic properties of each system, densities of states before and after the adsorption, equilibrium geometries and charge transfer from the graphene to the histidine molecule. Furthermore, we discuss some results from three approaches to the exchange-correlation approximation: local LDA, generalized gradient GGA-PBE, and one including van der Waals forces (DFT-D2). This work would contribute to the evaluation of graphene as a sensor for biomolecules, providing initials tools for functionalization and characterization of new devices. Finally, we also comment some ongoing preliminary calculations of electronic transport in the system under a bias voltage.