Sensitive and selective real-time electrochemical monitoring of DNA repair.

Unrepaired DNA damage can lead to mutation, cancer, and death of cells or organisms. However, due to the subtlety of DNA damage, it is difficult to sense the presence of damage repair with high selectivity and sensitivity. We have shown sensitive and selective electrochemical sensing of 8-oxoguanine and uracil repair glycosylase activity within DNA monolayers on gold by multiplexed analysis with silicon chips and low-cost electrospun nanofibers. Our approach compared the electrochemical signal of electroactive, probe-modified DNA monolayers containing a base defect versus the rational control of defect-free monolayers. We found damage-specific sensitivity thresholds on the order of femtomoles of proteins and dynamic ranges of over two orders of magnitude for each target. Temperature-dependent kinetics were extracted, showing exponential signal loss with time constants of seconds. Damage specific detection in a mixture of enzymes and in response to environmental oxidative damage was also demonstrated. Nanofibers were shown to behave similarly to conventional gold-on-silicon devices, showing the potential of these low-cost devices for sensing applications. This device approach achieves a sensitive, selective, and rapid assay of repair protein activity, enabling a biological interrogation of DNA damage repair.