We report on the binding of cisplatin, carboplatin and oxaliplatin to double-stranded DNA in two different (phosphate and carbonate) buffers, using an electrochemical DNA-biosensor. The propensity of the electrophilic agent produced by hydrolysis to interact with DNA was measured as a function of the decrease of guanine oxidation signal of the metal-DNA adduct immobilized on a screen-printed electrode, by using square wave voltammetry. The results obtained confirm that carbonate reacts with platinum drugs to form activated carbonato complexes, which are able to react readily with DNA.