Electrochemical detection of natural DNA damage induced by in situ peroxidase-generated reactive nitrogen species in DNA layer-by-layer films

► PDDA/DNA/{HRP/DNA}2 layer-by-layer films are used to detect DNA damage by CV. ► DNA damage is caused by NO2
- radicals produced in situ with H2O2 + NO2− solutions. ► Catalase on surface of PDDA/DNA/{HRP/DNA}2 films can protect inside DNA from damage. ► This work provides a foundation for fabricating biosensors in detecting DNA damage. ► An in vitro model to simulate the pathway of DNA damage and protection is presented.