Colorimetric Sensing of Dopamine Based on Peroxidase-Like Activity of Gold Nanoparticles

Development of a simple and label-free colorimetric sensing assay for dopamine is urgent, because of the important roles dopamine plays in many physiological processes. Herein, a label-free colorimetric method for determination of dopamine has been proposed based on the enhancement of the peroxidase-like activity of bare gold nanoparticles (AuNPs). The assay is based on specific interactions between protonated dopamine and gold atoms through the catechol group, which induces aggregation of AuNPs and significantly enhances their peroxidase-like activity. The catalytic activity is evaluated by chromogenic reaction of 3,3',5,5'-tetramethylbenzidine with H2O2. The mechanism for enhancement of catalytic activity is discussed. The detection limit of dopamine was 25 nM by virtue of UV-Vis spectroscopy, and 0.21 μM by naked eye. The whole detection procedure can be completed in 15 min. The proposed sensor is simple, fast, cost-effective and sensitive. These advantages make this sensor a powerful tool for the determination of dopamine in water samples.