Electrochemical DNA Biosensor Based on the Immobilization of Probe DNA on a Fulleropyrrolidine Derivative Modified Glassy Carbon Electrode

An aldehyde-containing fulleropyrrolidine derivative, 2-(4-formylphenyl)-5-(1-hydroxyethyl)fulleropyrrolidine (C-60-CHO), was synthesized by the reaction of C-60 with L-threonine and terephthalaldehyde in refluxing toluene under a nitrogen atmosphere. To fabricate a novel DNA biosensor, the C-60-CHO was cast on the surface of a glassy carbon electrode and grafted with 5'-amino modified probe DNA through a facile amine-aldehyde condensation reaction. When the oligonucleotides related to CaMV35S promoter fragment were determined with the developed biosensor via electrochemical impedance spectroscopy using [Fe(CN)(6)](3-/4-) as indicating probe, the difference values of the electron transfer resistance (Delta R-et) before and after hybridization showed good linear relationship with logarithm of the target-sequence concentrations in the range from 1.0 x 10(-13) to 1.0 x 10(-9) mol/L with the regression equation of Delta R-et/(10(3) Omega)=3.471 lg (C-S2/mol/L)+50.425. The detection limit of 1.5 x 10(-14) mol/L was also obtained. In addition, the hybridization specificity experiments showed that the sensing system can accurately discriminate the complementary sequence from the mismatched and the noncomplementary sequences.