In this study, a new electrochemical sensor using a glassy carbon electrode modified with graphene oxide (GO) and Zn-doped magnetite Fe3O4 nanosheets is proposed for simultaneous trace determinations of Adenine (AD) and Guanine (GA). First, graphene oxide nanoparticles were synthesized by the Hammer method, and then UV-Vis, FTIR, and XRD techniques were used to characterize them. The second step involved hydrothermal preparation of Zn-doped magnetite Fe3O4 nanosheets. Different methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and energy dispersive X-ray spectroscopy (EDS) were utilized to investigate Zn-doped magnetite Fe3O4 nanosheets. The electrochemical behavior of Adenine(AD) and Guanine(GA) was investigated using different voltammetric techniques, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), chronoamperometry (CA). It was found that by combining GO with Zn-doped magnetite Fe3O4 nanosheets, the electrochemical sensitivity of the sensor can be improved, and low levels of adenine and guanine can be measured. In a differential pulse voltammetry (DPV) experiment conducted with this electrode under optimal conditions, such as buffer type, accumulation time, and PH, the electrode showed great sensitivity to both adenine and guanine. The detection limit values were 0.14 µM and 0.08 µM for AD and GA, respectively. The suggested sensor's performance was tested using human serum as a real sample, and the proposed sensor showed high recovery. As a result of the investigation, it was found that the proposed electrode displayed high sensitivity, good repeatability, and high stability.
