Studies on the Electrochemical Behavior of Chlorogenic Acid and Its Interaction with DNA at a Graphene Modified Electrode

Graphene was used to modify the glassy carbon electrode surface using drop-casting method and the graphene modified electrode (Gr-GME) was prepared. The electrochemical behavior of chlorogenic acid (CGA) was studied. A new method to provide a rapid measure of CGA was established. A sensitive quasi-reversible redox peak was obtained from-0.4V to1.4V in pH=3.0 phosphate buffered saline (PBS) by cyclic voltammetry (CV). Compared with the unmodified glassy carbon electrode (GCE), the Gr-GME was observed to greatly increase the reaction rate of CGA, showing strong signal enhancement effects. The peak current of oxidation was proportional to the concentration of CGA and the linear range was from 3.20x 10(-7) to 4.50x 10(-5)mol. The detection limit was 8.00x 10(-9) mol L-1. The relative standard deviation (RSD) for six replicate measurements was 1.5%. The interaction of CGA with DNA at a Gr-GME was also studied by CV. As a result, the peak current decreased and the peak potential shifted to the positive side after adding DNA into the solution containing CGA. We deduced that the interaction of CGA with DNA mainly is intercalation. Hyperchromicity and small red shifts were observed in its Ultraviolet-Visible (UV-Vis) spectra upon addition of DNA. It can be concluded that there existed intercalation and electrostatic interactions.