The covalent methods previously discussed for fullerene modification using cycloaddition reactions also can be applied to carbon nanotubes. This strategy results in chemically link- ing molecules to the graphene rings on the outer surface of the cylinder, resulting in stable conjugates that can be designed to include hydrophilic groups for water solubilization. Georgakilas et al. (2002) describe the Cyclic voltammograms of the electrode pretreatment and PB-glucose sensor construction.