Laccase-based amperometric biosensor enhanced by Ni/Au/PPy-COOH multisegmental nanowires for selective dopamine detection

One-dimensional Ni/Au/PPy-COOH nanowires with multiple segments were synthesized in this study. Smooth surfaces and magnetic properties of nanowires were investigated by scanning transmission electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and Electron Spin Resonance (ESR) techniques. The nanowires were used to modify the screen-printed electrode surface and as a micro-environment for Trametes versicolor laccase. The ability of this enzyme biosensor to detect dopamine change in human biological samples was demonstrated by a wide linear range (0.01-50 mu M) and a low LOD (2.265 nM). In addition, the biosensor exhibited excellent selectivity allowing the detection of dopamine in the presence of ascorbic acid, uric acid, L-Cys, serotonin, and glucose, with high sensitivity of reduction currents obtained at -0.2 V (vs. Ag/AgCl). The proposed biosensor allowed the detection of dopamine in commercial serum and artificial urine with recovery values close to 100 %. It also demonstrated reproducibility, reusability, and long-term storage stability. The sensitivity, K-m(app), and I-max values of the biosensor were determined as 2.05 mu M and 1.03 mu A, respectively. The LAC-Ni/Au/PPy-COOH/NAF/SPE biosensor is a reliable design for detecting dopamine with a wide linear range.