Direct electrochemistry of dopamine on gold—Agaricus bisporus laccase enzyme electrode: Characterization and quantitative detection

Direct electrochemistry of a new laccase enzyme immobilized on gold and its application as a biosensor for dopamine (DA) are investigated by voltammetry and electrochemical impedance spectroscopy. The sensor demonstrated a redox adsorption behavior with E0′ = + 180 mV vs. Ag/AgCl for immobilized Agaricus bisporus laccase (LacAB) enzyme. The MPA platform was assembled on Au with and without utilization of ultrasounds. Excellent results were obtained by using the enzyme electrode fabricated based on MPA assembled with sonication. The LacAB immobilized in this condition showed a large electrocatalytic activity for oxidation of DA. Accordingly, a third-generation (mediator free) biosensor was constructed for DA. The DA concentration could be measured in the linear range of 0.5 to 13.0 and 47.0 to 430.0 μmol L− 1 with correlation coefficients of 0.999 and 0.989, respectively, and a detection limit of 29.0 nmol L− 1. The biosensor was successfully tested for determination of DA in human blood plasma and pharmaceutical samples.

(A) Differential pulse voltammograms obtained on the Au-MPA-LacAB SAM electrode fabricated: Without sonication of Au-MPA; (curve a) in the absence of DA and (curve b) in the presence of DA. And with sonication of Au-MPA; (curve c) in the presence of DA. The DA concentration was 4 μmol L− 1 DA, when it was present in the test solution. (B) The EIS complex plane plots obtained at E1/2 in the frequency range of 10 kHz to 100 mHz, in the same conditions as (A).Figure optionsDownload as PowerPoint slideHighlights
► A new enzymatic sensor is constructed for dopamine (DA) detection.
► It suggests direct electron transfer between Au electrode and fixed laccase enzyme.
► Excellent antifouling effect and good analytical merits are observed.
► The key point is enzyme immobilization on Au-thiol electrode assembled by sonication.
► The sensor was successfully tested for DA detection in real samples.