A polyoxometalate based electrochemical sensor for efficient detection of L-cysteine

L-cysteine (L-cys), as an important sulfur-containing amino acid, plays an indispensable role in biological systems. Too low and excessively high ratio of L-cys will cause harm to the function of human organs. Therefore, it is very necessary to develop efficient methods to detect it in multifarious samples. This paper has built an electrochemical sensor by combining Keggin-type polyoxometalate (PMo9V3) and cobalt tetrasulfonate (II) phthalocyanine (CoTsPc) on indium tin oxide electrodes using the layer-level self-assembly technology for efficiently detection of L-cys. The assembly process and surface morphology of the modified electrode was characterized by ultraviolet–visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope, and atomic force microscopy. The conditions of electro-catalysed oxidation of L-cys were optimized by cyclic voltammetry, and the kinetic electrochemical parameters were also evaluated by electrochemical impedance spectra. Furthermore, the sensing performance of the modified electrode was explored using amperometry. The proposed electrochemical L-cys sensor was found to have superior sensing performance with a range of linear response of 2.5 × 10–7 to 1.7 × 10–4 mol·L−1 and 1.7 × 10−4 to 39.5 × 10−4 mol·L−1, the detection limit of 1.0 × 10–7 mol·L−1 (signal/noise = 3), and satisfactory anti-interference ability. Consequently, the fabricated sensor has the potential to be applied in laboratory practices for L-cys deterimination in commercial drinks.