Graphene oxide/urease nanobiosensor applied for cadmium detection in river water

The work reported an ultrasensitive cantilever nanobiosensor based on graphene oxide and urease for cadmium detection in river water. Since an efficient adsorption between sensitive layer and the analyte was achieved, the biosensor showed high sensitivity (0.0147 nm/ppt) and low detection limit (18 ppt). Nanobiosensors were applied to analyze real water samples (river) collected in periods with and without rainfall. River water samples collected are a complex matrix, presented different physical and chemical characteristics for turbidity, conductivity and sodium concentration, which is related to the amount of rain in the period. While the values of pH, color, potassium, and magnesium concentration found in the samples collected did not show any significant difference. The response of the nanobiosensor was satisfactory and the effect of the matrix can be minimized with the cadmium fortification in the samples. Different interfering species as sodium, potassium, and magnesium were tested finding a negligible effect. The nanobiosensor based on graphene nanomaterial and urease enzyme has been satisfactorily applied to the determination of cadmium in river water samples.