Electrochemical Sensor Based on DNA Aptamers Immobilized on V2O5/rGO Nanocomposite for the Sensitive Detection of Hg(II).

We developed a sensor consisting of V2O5 nanorods and a reduced graphene oxide (rGO) nanocomposite (V2O5/rGO) with immobilized DNA aptamers (Apt-NH@V2O5/rGO) for the sensitive electrochemical detection of Hg (II). The V2O5 nanorods anchored on rGO nanosheets were synthesized using a hydrothermal method. The nanocomposite was analyzed by various powerful physical methods that include X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, the Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared spectroscopy (FTIR). The FE-SEM of V2O5 disclosed the nanorod-like structure and uniform anchoring of V2O5 on the rGO nanosheet. Moreover, the BET results showed that the V2O5/rGO nanocomposite possesses excellent porosity. Furthermore, a glassy carbon electrode (GCE) was modified with Apt-NH@V2O5/rGO and used for the electrochemical detection of Hg(II) by differential pulse voltammetry (DPV). The aptasensor exhibited excellent sensitivity and selectivity toward Hg(II) detection, with a limit of detection (LOD) of 5.57 nM, which is below the maximum permissible limit established by WHO for rivers (30 nM). The sensor also exhibited significant stability and good repeatability.