Surface immobilization of carbon nanotubes by beta-cyclodextrins and their inclusion ability

The surface immobilization of beta-cyclodextrins on the surface of multiwalled carbon nanotubes (MWNTs) in an aqueous medium was achieved by covalent-binding of diamino-functionalized beta-cyclodextrin with carboxylic acid-functionalized MWNTs via amide linkages using a water-soluble condensation agent at room temperature. The obtained product denoted as beta-cyclodextrin-modified MWNTs was highly dispersible in an aqueous medium. The covalent surface functionalization of MWNTs by beta-cyclodextrin was characterized by FTIR, TGA, EDS and TEM. The thermogravimetric analyses indicated that -70 wt% beta-cyclodextrin was attached on the surface of MWNTs. Furthermore, the fluorometric analysis for adsorption of rhodamine 6G dye suggested that the formation of beta-cyclodextrin-dye inclusion conjugate takes place prior to the adsorption of dyes on MWNTs and uniform dispersion of MWNTs after surface immobilization allows superior fluorescence quenching than the pristine and oxidized MWNTs.