Electrochemical behavior of antioxidants: Part 3. Electrochemical studies of caffeic Acid–DNA interaction and DNA/carbon nanotube biosensor for DNA damage and protection

Multi-walled carbon nanotubes-modified glassy carbon electrode biosensor was used for electrochemical studies of caffeic acid–dsDNA interaction in phosphate buffer solution at pH 2.12. Caffeic acid, CAF, shows a well-defined cyclic voltammetric wave. Its anodic peak current decreases and the peak potential shifts positively on the addition of dsDNA. This behavior was ascribed to an interaction of CAF with dsDNA giving CAF–dsDNA complex by intercalative binding mode. The apparent binding constant of CAF–dsDNA complex was determined using amperometric titrations. The oxidative damage caused to DNA was detected using the biosensor. The damage caused by the reactive oxygen species, hydroxyl radical (OH) generated by the Fenton system on the DNA-biosensor was detected. It was found that CAF has the capability of scavenging the hydroxide radical and protecting the DNA immobilized on the GCE surface.