Electrochemical nucleic acid biosensors for the detection of interaction between peroxynitrite and DNA

We studied the reactivity of peroxynitrite and different nucleic acid molecules using DNA electrochemical biosensors. SIN-1 (3-morpholinosydnonimine) has been used for the simultaneous generation of NO- and superoxide, i.e., as a peroxynitrite (ONOO-) donor. Double strand DNA (dsDNA), single strand DNA (ssDNA) and 15 guanine bases oligonucleotide (Oligo(dG)(15)) were immobilized on a carbon paste electrode to generate the biosensor and DPV was selected as the electroanalytical technique. Results showed that electrochemical biosensors were very sensitive for detecting interaction between ONOO- and DNA. A down/up effect was observed, i.e., at low ONOO- concentrations the guanine oxidation signal decreased while at high ONOO- concentrations the guanine oxidation current increased. Oligo(dG)15 exhibited greater interaction at low ONOO- concentrations than the other DNA molecules. The reactivity between ONOO- and DNA was also evaluated in solution phase, showing the same down/up effect. Finally, the capacity of DNA to hybridize was prevented after interaction with ONOO-.