Nanopartículas de ouro funcionalizadas com flavina adenina dinucleotídeo para detecção eletroquímica de dopamina

Abstract

Dopamine (DA) is a neurotransmitter with multiple roles in the central nervous system, and alterations in its level in the organism result in Parkinson’s and schizophrenia diseases. Therefore, DA levels monitoring in the body is of medical interest. Hence, a novel electrochemical biosensor was designed on a gold substrate with a self-assembled 11-Mua monolayer, a cationic polyelectrolyte (PEI) layer, and a layer of gold nanoparticles stabilized with glutathione and functionalized with flavin adenine dinucleotide (FAD). FAD, a cofactor found in the active site of monoamine oxidase enzymes, was added to this biosensor to make it selective. The developed biosensor was characterized by UV-Visible spectroscopy, FTIR, atomic force microscopy (AFM), and cyclic voltammetry (CV), confirming a successful development process. Differential pulse voltammetry (DPV) data for detection assays using 0.1 mol L-1 (pH 7.4) PBS buffer demonstrated no interference of uric acid, ascorbic acid, serotonin, and urea. The biosensor was stable for 20 days, presenting a linear detection ranging from de 0.8 to 8.0 µmol L-1, 1.25 µA/µmol L-1 cm-2 of sensitivity, and 0.525 µmol L-1 and 1.75 µmol L-1 for calculated limits of detection and quantification, respectively. Human urine was used as a real sample, and the values of recovery ranged from 85 to 90%. In summary, the developed biosensor demonstrated perspectives for being applied in complex sample analyses.