Highly Sensitive Electrochemical Aptasensor for Determination of Mercury Ion Based on Graphene-Chitosan

Mercury is one of the most harmful pollutants. It is very dangerous for human health and environment even in very low concentration. The maximum allowable concentrations of mercury ions reported by the United States Environmental Protection Agency and world health organization are 10 and 30 nM, respectively. So, an ultra- sensitive method is required for mercury level measurement. Traditional methods such as chromatography and spectroscopy, despite of being practical, pose well-known problems. These methods are expensive and time-consuming. So, finding the new methods for determination of mercury ion is one of the most challenges for fabrication of sensitive mercury sensors. In the present work, very sensitive electrochemical aptasensor was fabricated for determination of mercury (II) ion. For this propose graphene oxide was synthesis by the modified hummer method and chitosan-reduced graphene oxide nanocomposite(Chit-rGO) were used for immobilization of mercury aptamer molecules on the surface of modified electrode.Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy were used for characterization of synthesized materials and investigation of aptasensor. Under optimal conditions, very sensitive aptasensor with detection limit of 0.94 nM and linear range of 0.5-250 nM was fabricated. Results show that fabricated aptasensor can be used for determination of mercury ion in real sample