Electrochemical sensor using poly-(l-cysteine) functionalized CuO nanoneedles/N-doped reduced graphene oxide for detection of lead ions.

A highly sensitive and selective electrochemical sensor modified with poly-(l-cysteine)/CuO nanoneedles/N-doped reduced graphene oxide (l-Cys/NN-CuO/N-rGO) has been prepared for the testing of trace Pb. The electrochemical performance of this proposed sensor was investigated using electrochemical impedance spectroscopy (EIS). Based on the excellent electrochemical properties of NN-CuO/N-rGO as well as the specific complexation of natural substance l-cysteine with Pb, the l-Cys/NN-CuO/N-rGO was applied as a voltammetric biosensor for the determination of trace Pb at pH 5.0. Under the optimum experimental conditions, the voltammetric peak current was linear with the Pb concentration over the range from 0.001 to 5.0 nM and 5.0 to 1000 nM, respectively, with a low detection limit for Pb concentration on the biosensor of 8.0 × 10 nM (S/N = 3). The significant sensitivity, selectivity, and electron conductivity of this l-Cys/NN-CuO/N-rGO modified electrode have also been studied. The specific detection of Pb in water samples was also carried out.