Solvent effects on the stability and the electronic properties of histidine/Pd-doped single-walled carbon nanotube biosensor

Abstract

The nanobiosensors physical and chemical properties are affected by the nature and the interactions with the solvent molecules. To develop a new biosensing concept for the detection of biological agents in both in vivo and in vitro, identifying the non-specific influence of the solvent on the chemical reactivity and the stability of the nanobiosensors is crucial. In this paper, the self-consistent reaction field theory (SCRF) was used to investigate the solvent effects on the structure and electronic properties of the hybride of Pd doped single-walled carbon nanotube (Pd/SWCNT) and histidine amino acid as a new generation of nanobiosensors. These effects will be investigated in three polar mediums using density functional theory (DFT) calculations in the combination with the polarizable continuum model (PCM). The emphasis will be on the results of the Quantum Theory Atoms in Molecule (QTAIM), Natural bond orbital (NBO) and the Frontier Molecular Orbital (FMO) analysis. The conceptual DFT based reactivity and stability descriptors, chemical potential, hardness and electrophilicity index were calculated in different solvents in ground state to study how the structure and electronic properties will be affected by solvents. Molecular electrostatic potential map was performed by DFT method. The value of the electrostatic potential is largely responsible for the binding of a substrate to active sites of biosensor. The presence of heterocyclic organic compound and electronegative atoms in the biological receptor of the His/Pd/SWCNT nanobiosensor will result in strong solvent-solute interactions. With increasing the electric permittivity of solvents, the stabilization energies of various conformations of nanobiosensor shifts to lower value because of the additional attractive interactions between the nanobiosensor and the solvent. The His/Pd/SWCNT presents high stability with considerable values of stabilization energies, charge transfer and sensible energy bond gap in polar medium which confirm both in vitro and in vivo biosensing application.