Sequence-specific detection of DNA using functionalized graphene as an additive

We developed a simple and sensitive method for sequence-specific DNA detection using functionalized graphene (FG) and methylene blue (MB). Target DNA with a specific sequence was identified by differential-pulse voltammetry, which produces a change in the redox currents of the incorporated MB. FG played a critical role in enhancing the sensitivity of DNA detection and reduced the concentration of MB substantially near the electrodes when the sequence of the target DNA was not complementary to that of the probe by adsorbing the single-stranded DNA with the bound MB, and sinking. Our system could detect even single base-pair mismatches between the target and probe. Fabricating this system does not involve a laborious probe-immobilization process and is considerably simpler than fabricating graphene-electrode-based DNA sensors.