Analytical Sciences

Fluorescence Resonance Energy Transfer-based Biosensor Composed of Nitrogen-doped Carbon Dots and Gold Nanoparticles for the Highly Sensitive Detection of Organophosphorus Pesticides

Nian Chun GONG, Yan Le LI, Xi JIANG, Xiao Fang ZHENG, Ya Ya WANG, and Shuang Yan HUAN

State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemistry Engineer, Hunan University, Changsha, 410082, China

The present article reports a novel biosensor for organophosphorus pesticides based on fluorescence resonance energy transfer (FRET) between nitrogen-doped carbon dots (NC-dots) and gold nanoparticles (AuNPs). The effective NC-dots/AuNPs assembly through the Au–N interaction results in good fluorescence quenching. Active acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylthiocholine into –SH containing thiocholine to replace the NC-dots and trigger the aggregation of AuNPs. In the presence of paraoxon, the activity of AChE is inhibited, and thus preventing the generation of thiocholine, causing fewer NC-dots to be replaced. As a consequence, the fluorescence intensity gradually decreases with increasing amount of paraoxon. This biosensor does not require any complex synthesis or modification, and the results show a wide detection range of from 10⁻⁴ to 10⁻⁹ g/L with a detection limit of 1.0 × 10⁻⁹ g/L (3.6 × 10⁻¹² mol/L). Two linear response regions have been reported with a turning point at about 10⁻⁶ g/L and three different factors that would influence the response behavior. These phenomena discussed in detail so as to explain the special response mechanism.

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