Electrochemical sensing of guanine, adenine and 8-hydroxy-2′-deoxyguanosine at glassy carbon modified with single-walled carbon nanotubes covalently functionalized with lysine

Abstract

This work reports the synthesis and characterization of single-walled carbon nanotubes (SWCNT) covalently functionalized with l-lysine (Lys) and the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of SWCNT-Lys (GCE/SWCNT-Lys) for the highly sensitive quantification of guanine, adenine and 8-hydroxy-2′-deoxyguanosine. Detection limits of 75, 195 and 97 nM were obtained for guanine, adenine and 8-hydroxy-2′-deoxyguanosine, respectively by voltammetric adsorptive stripping with medium exchange. GCE/SWCNT-Lys was successfully used for the detection of adenine and guanine oxidation after adsorption of salmon sperm-double stranded DNA. A clear definition of 8-hydroxy-2′-deoxyguanosine oxidation signal is observed even in the presence of large excess of guanine, adenine or salmon sperm-double stranded DNA.