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This work describes the immobilization of purine and pyrimidine bases and immobilization/hybridization of synthetic oligonucleotides on graphite electrodes modified with poly(4-methoxyphenethylamine) produced in acid medium. The immobilization of adenine, guanine, cytosine and thymine on these modified electrodes was efficient, producing characteristic peaks. Another relevant observation is that, according to the literature, pyrimidine bases, cytosine and thymine are more difficult to detect. However, when immobilized onto the poly(4-methoxyphenethylamine), a significant increase in the magnitude of the current was obtained. The observation of the hybridization between the poly(GA) probe and its complementary, poly(CT) target, was possible by monitoring the guanosine and adenosine peaks or through methylene blue indicator, using differential pulse voltammetry. Hybridization results in a decrease of the peak current of guanosine and adenosine or the signal of methylene blue accumulated on the modified electrode surface. The hybridization with the complementary target was also investigated by electrochemical impedance spectroscopy. The results showed a significant modification in the Nyquist plot, after addition of the complementary target, with increase of the charge transference resistance.

It was observed the formation of polymeric films derived from 4‐aminophenol on the graphite electrode in aqueous medium (pH 0.5, 8.0 and 12.0). The electrochemical behavior of formed films was studied by voltammetry cyclic and impedance. These analyses indicate that the preparation in acid medium favors the charge transfer rate of the polymer. Polymers formed at pH 8.0 present higher coverage of the electrode surface and impedance increase. Scanning electron microscopy showed that the formed polymer present globular morphology.