A Suggestion of Electrochemical Biosensor for Study of Platinum(II)-DNA Interactions

As a consequence of the employment of platinum based cytostatic drugs in tumor diseases treatment, it became necessary not only to detect them in biological samples but also to determine and study the Pt‐DNA adducts, which is highly important during investigation of resistance on antitumor treatment. Thus, the main objective of this work was to study the interactions between DNA and cisplatin. Primarily, we studied changes in electrochemical behavior of cisplatin in the presence of different concentrations of sodium chloride using differential pulse voltammetry. We found out that the highest signal of cisplatin was measured in 0.75 M NaCl with detection limit of 100 pM. The current accepted opinion about platinum based cytostatics mechanism of action is that the drugs induce their cytotoxic properties through binding to the nuclear DNA. That is why we followed by investigation of DNA interactions with cisplatin. For these purposes we have suggested a new biosensor, EDTA metallothionein modified hanging mercury drop electrode (EDTA MT biosensor) and used cyclic voltammetry as a comparative technique. The average concentration of the drug bound to DNA was estimated as 8.1 ng of cisplatin per 500 ng of DNA by EDTA MT biosensor. It follows from the results obtained that the suggested EDTA MT biosensor could be a new useful tool for investigation of interaction of DNA with cisplatin, because give a response only in the present of Pt(II)‐DNA adduct.