Monitoring of DNA oxidative damage with piezoelectric quartz crystal method

Abstract The piezoelectric quartz crystal (PQC) sensor was used to detect the whole process of DNA damage oxidized by H 2 O 2 system containing Cu 2+ or Zn 2+ based on the density–viscosity change of the detected solution. The PQC impedance method has been applied to further investigate the damage process of DNA oxidized by H 2 O 2 system containing Cu 2+ . It was found that the ratio of Δ R 1 to Δ f 0 or Δ L 1 coincided well with that calculated from Martin's equations reflecting the solution density–viscosity effect, suggesting that the continuing change in liquid loading on to the PQC surface caused the significant variation of Δ f 0 , Δ R 1 and Δ L 1 . It has also been found that the H 2 O 2 system containing Cu 2+ could oxidize DNA more completely than that containing Zn 2+ , and a trace Cu 2+ in the system could cause DNA damage. However, no significant breakage in the DNA backbone was observed if the system contained only H 2 O 2 . The DNA concentration was linearly related to Δ f 0s , which is the different between the initial frequency and the frequency after a reaction time of 45 min, in the range of 50–1000 μg ml −1 . The effect of H 2 O 2 or Cu 2+ concentration of was also investigated. The above-mentioned results that the H 2 O 2 system containing Cu 2+ or Zn 2+ could break the DNA backbone were also supported by the agarose gel electrophoresis technique.