An aldehyde-containing fulleropyrrolidine derivative, 2-(4-formylphenyl)-5-(1-hydroxyethyl)- fulleropyrrolidine (C₆₀-CHO), was synthesized by the reaction of C₆₀ with L-threonine and terephthalaldehyde in refluxing toluene under a nitrogen atmosphere. To fabricate a novel DNA biosensor, the C₆₀-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 (DR_et) before and after hybridization showed good linear relationship with logarithm of the target-sequence concentrations in the range from 1.0×10⁻¹³ to 1.0×10⁻⁹ mol/L with the regression equation of DR_et/(10³ Ω)＝3.471 lg (C_S2/mol/L)＋50.425. The detection limit of 1.5×10⁻¹⁴ 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.

Key words: DNA biosensor, fulleropyrrolidine derivative, electrochemical impedance spectroscopy