New methods used for the detection of DNA hybridisation process, including electrochemical, optical scattering, surface plasmon resonance, nanogravimetric, and fluorimetric are described and their application in assays assessing DNA damage is discussed in this book. The analyses of damage and alterations for the DNA in solution as well as for the DNA immobilised on core-shell gold nanoparticles and solid electrodes are presented. These methods enable evaluating the degree of DNA damage caused by toxicants and can be applied to studies of the interactions of atrazine and other herbicides and pesticides with DNA.