Molecularly imprinted electrochemical sensor based on the synergic effect of nanoporous gold and copper nanoparticles for the determination of cysteine

A sensitive molecularly imprinted sensor for L-cysteine (Cys) determination was designed and fabricated by electrodeposition method. The molecularly imprinted polymer (MIP) film was prepared by electrodeposition chitosan (CS) in the presence of Cys after depositing nanoporous gold (np-Au) and copper nanoparticles (CuNPs) onto a glassy carbon electrode (GCE) surface. The morphology and composition of CuNPs/np-Au/GCE were characterized by SEM and energy dispersive spectroscopy (EDS). The MIP/CuNPs/np-Au/GCE sensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor displayed an excellent recognition to Cys upon measuring the variation of the oxidation current of Cys. The current response was linear to the logarithm concentration of the analyte in the range of 0.5 nM–10 μM, with a detection limit of 0.7 × 10−10 mol⋅L−1. The sensor showed good selectivity and reproducibility. The prepared sensor was successfully applied to the determination of Cys in bovine serum and sauce of instant noodle samples with satisfactory recoveries ranging from 93.0 to 110.0 %. The desirable performances may be attributed to the synergic catalytic effect and large surface area of CuNPs/np-Au nanocomposites.