Electrochemical ds-DNA-based biosensor decorated with chitosan modified multiwall carbon nanotubes for phenazopyridine biodetection

• A novel electrochemical sensor was introduced for the determination of phenazopyridine.
• The graphite electrode was modified with MWCNTs-chitosan decorated with ds-DNA.
• The oxidation signals of guanine and adenine were used as probe for the analyte detection.
• Phenazopyridine could be measured at 0.01–50 µg/mL with a detection limit of 0.003 µg/mL.

A simple and inexpensive method was used to develop a novel electrochemical sensor for the determination of phenazopyridine hydrochloride (PAP). Differential pulse voltammetry was used for the electrochemical investigation of the interaction of PAP with calf thymus ds-DNA at a pencil graphite electrode (PGE) based on the reduced oxidation signals of guanine and adenine. The biosensor was constructed using pretreated pencil graphite electrode (PGE) modified with multiwall carbon nanotubes (MWCNTs) and chitosan (CHIT) decorated with ds-DNA. The reductions in the intensities of guanine and adenine oxidation signals after their interaction with PAP were used as indicators for the sensitive determination of PAP. The differences observed between adenine and guanine oxidation signals (of the ds-DNA) before and after their interaction with PAP were found to be directly proportional to PAP concentration, which was used for quantitative inspections. Under optimum conditions, a linear dependency was observed between guanine and adenine oxidation signals and PAP concentration in the range of 0.01–50 µg/mL with a detection limit of 0.003 µg/mL. The method was also found to be highly selective and was successfully employed for the determination of PAP in real samples such as human plasma and urine.

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