Density functional calculations on adsorption of methionine amino acid onto functionalized carbon nanotubes

Chemical modification of carbon nanotube by covalent functionalization can change thesurface properties [1,2]. Chemical functionalization enhances the solubility of nanotubes invarious solvents and their separation into semiconducting and metallic ones.Functionalization of nanotube sidewalls, end caps or tips [3] either by covalent ornoncovalent methods expands the potential applicability of carbon nanotubes in the severalareas such as catalysis, hydrogen storage, biosensors and nanobiotechnology [4]. Thedistribution of SWNT can be achieved by the adsorption of amino acid molecules.Methionine amino acid is required for growth and tissue repair. A sulfur-containingmethionine improves the tone and pliability of skin, hair, and strengthens nails. Involved inmany detoxifying processes, sulfur provided by methionine protects cells from pollutants,slows cell aging.