Monitoring of DNA oxidative damage with piezoelectric quartz crystal method

The piezoelectric quartz crystal (PQC) sensor was used to detect the whole process of DNA damage oxidized by H2O2 system containing Cu2+ or Zn2+ 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 H2O2 system containing Cu2+. It was found that the ratio of ΔR1 to Δf0 or ΔL1 coincided well with that calculated from Martinʹs 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 Δf0, ΔR1 and ΔL1. It has also been found that the H2O2 system containing Cu2+ could oxidize DNA more completely than that containing Zn2+, and a trace Cu2+ in the system could cause DNA damage. However, no significant breakage in the DNA backbone was observed if the system contained only H2O2. The DNA concentration was linearly related to Δf0s, 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 H2O2 or Cu2+ concentration of was also investigated. The above-mentioned results that the H2O2 system containing Cu2+ or Zn2+ could break the DNA backbone were also supported by the agarose gel electrophoresis technique.