In this study, a DNA biosensor was constructed and used for the determination of phenazopyridine and D-penicillamine. This biosensor made of pretreated pencil graphite electrode (PGE) modified with multiwall carbon nanotubes (MWCNTs) and chitosan (CHIT) decorated with ds-DNA.

The interaction of phenazopyridine hydrochloride with ds-DNA based on the decreasing of the oxidation signal of guanine and adenine was studied electrochemically at a pencil graphite electrode (PGE) using differential pulse voltammetry. The difference between adenine and guanine signals of the ds-DNA after and before interaction with phenazopyridine hydrochloride was directly proportional to phenazopyridine hydrochloride concentration, which used for quantitative inspections. Under the optimum conditions, a linear dependence of the guanine and adenine oxidation signals was observed for the phenazopyridine hydrochloride concentration in the range of 0.01–50 µg mL⁻¹ with a detection limit of 0.003 µgmL⁻¹. This method is successfully applied for the determination of phenazopyridine hydrochloride in real samples.

The second part, assessment of DNA damage caused by D-penicillamine in the presence of iron(ІІІ). using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, a linear dependence of the guanine and adenine oxidation signals was observed for the phenazopyridine hydrochloride concentration in the range of 0.05–150 µg mL⁻¹ with a detection limit of 0.005 µgmL⁻¹.

Keywords

Phenazopyridine hydrochloride, D-penicillamine, DNA biosensor, differential pulse voltammetry, Electrochemical impedance spectroscopy.