Electrochemical sensor for individual and simultaneous determination of guanine and adenine in biological fluids and in DNA based on a nano-In–ceria modified glassy carbon paste electrode

Abstract

A novel, simple and sensitive electrochemical method for individual and simultaneous determination and direct electro-oxidation behaviors of guanine (G) and adenine (A) was developed using an In doped ceria nanoparticle modified glassy carbon paste electrode (In–CeO₂/GCPE). Scanning electron microscopy (SEM) and electrochemical techniques were employed for characterization of the fabricated modified electrode. The electrochemical sensor exhibits a potent and persistent electro-oxidation behavior followed by well-separated oxidation peaks toward G and A. Electrochemical performances related to the electro-oxidation of G and A at the nano-In–CeO₂NPs/GCPE were investigated, showing that their peak currents were greatly enhanced due to the catalytic effect of In doped ceria. The prepared In–CeO₂NPs/GCPE showed high selectivity and sensitivity for G and A oxidation over uric acid (UA). A linear range of 0.07–34 μM with a detection limit of 1.19 × 10⁻⁸ M for G and 1.96–88.2 μM with a detection limit of 2.86 × 10⁻⁸ M for A were achieved. The proposed sensor was used for individual and simultaneous determination of G and A in biological fluids and in ssDNA samples. The value of (G + C)/(A + T) in DNA was calculated to be 0.75.