An electrochemical sensor based on single-stranded DNA–poly(sulfosalicylic acid) composite film for simultaneous determination of adenine, guanine, and thymine

Poly(sulfosalicylic acid) and single-stranded DNA composite (PSSA–ssDNA)-modified glassy carbon electrode (GCE) was prepared by electropolymerization and then successfully used to simultaneously determine adenine (A), guanine (G), and thymine (T). The characterization of electrochemically synthesized PSSA–ssDNA film was investigated by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The modified electrode exhibited enhanced electrocatalytic behavior and good stability for the simultaneous determination of A, G, and T in 0.1 M phosphate buffer solution (PBS, pH 7.0). Well-separated voltammetric peaks were obtained among A, G, and T presented in the analyte mixture. Under the optimal conditions, the peak currents for A, G, and T increased linearly with the increase of analyte mixture concentration in the ranges of 6.5 × 10−8 to 1.1 × 10−6, 6.5 × 10−8 to 1.1 × 10−6, and 4.1 × 10−6 to 2.7 × 10−5 M, respectively. The detection limits (signal/noise = 3) for A, G, and T were 2.2 × 10–8, 2.2 × 10–8, and 1.4 × 10–6 M, respectively.