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 Pb2+. 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 Pb2+, the l-Cys/NN-CuO/N-rGO was applied as a voltammetric biosensor for the determination of trace Pb2+ at pH 5.0. Under the optimum experimental conditions, the voltammetric peak current was linear with the Pb2+ concentration over the range from 0.001 to 5.0 nM and 5.0 to 1000 nM, respectively, with a low detection limit for Pb2+ concentration on the biosensor of 8.0 × 10-5 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 Pb2+ in water samples was also carried out.