Herein, we report developing an electrochemical sensor based on a glassy carbon electrode modified by bismuth nanoparticles, graphene oxide, iron oxide, and poly-methyldopa namely Bi@Fe3O4-PMDA/GO/GCE for detecting guanine and adenine. Under optimized conditions (5 μL of Fe3O4-PMDA/GO, 0.5 mg mL−1 of Fe3O4-PMDA/GO solution, water as solvent of Fe3O4-PMDA/GO and acetate buffer (0.1 M, pH 6) as electrolytes), the electrochemical behaviors of guanine and adenine on the prepared modified electrode were investigated by cyclic voltammetry and differential pulse voltammetry. With a high specific surface area and numerous active sites, Bi@Fe3O4-PMDA/GO/GCE exhibited outstanding electrocatalytic properties enabling the determination of guanine and adenine over a wide concentration range with the low detection limit. The Bi@Fe3O4-PMDA/GO/GCE possessed the advantages of simplicity, speed, good sensitivity, and anti-interference performance. Using the DPV method, the resulting sensor exhibited an excellent response with a wide linear ranges from 0.5 to 300 μM for both analytes with LODs 0.027 and 0.032 µM for adenine and guanine, respectively. The designed electrode was satisfactorily employed for the analysis of the real sample. Therefore, Bi@Fe3O4-PMDA/GO/GCE demonstrating sufficient selectivity and sensitivity for the individual and simultaneous study could be applied in widespread fields, including biotechnology or microbiology.

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