The Application of DNA-Biosensors and Differential Scanning Calorimetry to the Study of the DNA-Binding Agent Berenil

The in situ DNA-damaging capacity of berenil (1) has been investigated using an electrochemical approach employing double stranded (ds) DNA-modified glassy carbon electrode biosensors. Electrochemical voltammetric sensing of damage caused by 1 to dsDNA was monitored by the appearance of peaks diagnostic of the oxidation of guanine and adenine. When 1 was incorporated directly onto the biosensor surface, DNA damage could be observed at concentrations of additive as low as 10 μM. In contrast, when the dsDNA-modified biosensor was exposed to 1, in acetate buffer solution, the method was much less sensitive and DNA damage could be detected only in the presence of 100 μM berenil. When mixed solutions of 1 and single stranded (ss) DNA, polyguanylic acid or polyadenylic acid were submitted to voltammetric study, the oxidation signals of the respective bases decreased in a concentration-dependent manner and the major variation of the adenine current peak indicated preferential binding of 1 to adenine. The electrochemical results were in close agreement with those deriving from a differential scanning calorimetric study of the DNA-berenil complex.