Fabrication of a Modified Electrode Based on Fe3O4-Graphene Oxide Hybrid Composite: Applying to Simultaneous Determination of Adenine and Guanine in DNA

A Fe 3 O 4 -graphene oxide hybrid composite (Fe 3 O 4  GO) was synthesized and used to construct a novel electrochemical sensor for the simultaneous detection of adenine and guanine. The Fe 3 O 4  GO based electrochemical sensor exhibits linear ranges of 0.05–25 μM and 0.05–25 μM with detection limits of 4 nM and 3 nM for adenine and guanine, respectively. This method was applied in the determination of guanine and adenine in many samples with satisfying results. The value of (G+C)/(A+T) in DNA was calculated to be 0.7536. The sensor exhibits some advantages, such as rapidity, good reproducibility and long-term stability.