Amino acids interacting with defected carbon nanotubes: ab initio calculations

Document Type: Original Article

Author

Department of Nanochemistry, Faculty of Pharmaceutical Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran - Iran (IAUPS)

Abstract

The adsorption of a number of amino acids on a defected single-walled carbon nanotube (SWCNT) is
investigated by using the density-functional theory (DFT) calculations. The adsorption energies and
equilibrium distances are calculated for various configurations such as amino acid attaching to defect
sites heptagon, pentagon and hexagon in defective tube and also for several molecular orientations
with respect to the nanotube surface. The results showed that amino acids prefer to be physisorbed on
the outer surface of the defected nanotube with different interaction strength following the hierarchy
histidine > glycine > phenylalanine > cysteine. Comparing these findings with those obtained for
perfect SWCNTs reveals that the adsorption energy of the amino acids increase for adsorption onto
defected CNTs. The adsorption nature has also been evaluated by means of electronics structures
analysis within the Mulliken population and DOS spectra for the interacting entities

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