DNA is a kind of genetic material that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. DNA damage occurs frequently in organisms. Some endogenous and exogenous chemicals have been found to induce structural damages to nuclear DNA by base oxidation or modification. If unrepaired, these damaged DNA may lead to gene mutation and even tumor generation. Due to their short response time, high sensitivity, low cost and ease of miniaturization, electrochemical DNA sensors are well qualified for the rapid screening of industrial and environmental chemicals for their potential geno-toxicity. This review article first introduces briefly the types and working mechanisms of current electrochemical DNA sensors. Then it describes in more detail the work on electrochemical and photoelectrochemical sensors for the detection of DNA damage, based largely on the work of our own laboratory, including general type sensors for the rapid screening of industrial and environmental chemicals with potential geno-toxicity, as well as specific type sensors for the identification and quantification of DNA damage products such as 8-oxodGuo and methylated DNA bases. In the end, the existing problems and future research directions of the DNA damage electrochemical sensors are discussed.

Contents
1 Introduction
2 Types of DNA electrochemical sensors
3 Electrochemical sensors for DNA damage detection
4 Photoelectrochemical sensors for DNA damage detection
4.1 Photoelectrochemical detection method
4.2 Sensing mechanisms for DNA damage detection
4.3 General-type sensors
4.4 Specific-type sensors
4.5 Investigation of chemical-induced DNA damage
5 Conclusions and perspectives