Copper(II) nanosensor based on a gold cysteamine self-assembled monolayer functionalized with salicylaldehyde

Fabrication and electrochemical characterization of a novel nanosensor for determination of Cu2+ in subnanomolar concentrations is described. The sensor is based on gold cysteamine self-assembled monolayer functionalized with salicylaldehyde by means of Schiff's base formation. Cyclic voltammetry, Electrochemical impedance spectroscopy (EIS), and electrochemical quartz crystal microbalance were used to probe the fabrication and characterization of the modified electrode. The sensor was used for quantitative determination of Cu2+ by the EIS in the presence of parabenzoquinone in comparison with stripping Osteryoung square wave voltammetry (OSWV). The attractive ability of the sensor to efficiently preconcentrate trace amounts of Cu2+ allowed a simple and reproducible method for copper determination. A wide range linear calibration curve was observed, 5.0 x 10(-11)-5.0 x 10(-6) and 5.0 x 10(-10)-5.0 x 10(-6) M Cu2+, by using the EIS and OSWV, respectively. Moreover, the sensor presented excellent stability with lower than 10% change in the response, as tested for more than three months daily experiments, and a high repeatability with relative standard deviations of 6.1 and 4.6% obtained for a series of eight successive measurements in 5.0 x 10(-7) M Cu2+ solution, by the EIS and OSWV, respectively.