Ultrasensitive detection of methamphetamine in environmental water bodies by an Au@carbon dots/chitosan nanocomposite...

The robust analytical methods for methamphetamine (METH), the second most widely used illicit drug globally, in aqueous environments are essential for on-site detection of regional drug abuse and pollution, and then timely control its threat to ecological environment and public health.

A simple and label-free electrochemical aptasensor based on aptamer/Au@carbon dots/chitosan nanocomposite modified gold electrode (Apt/Au@CDs/CS/AuE) was firstly developed for measuring trace METH in environmental water bodies. The aptamer was immobilized on Au nanoparticles through Au-N bond, where carbon dots provided large surface area for good dispersion of nanomaterials. Under optimal conditions, the aptasensor could detect METH from 10^-3-10³ ng L^-1 with a detection limit of 0.87 pg L^-1 and present satisfactory reproducibility, stability and specificity. The developed aptasensor was applicable to common pH and wide temperature and ionic strength range, free from the interference of organic matters, such as humic acid, polysaccharides-like and protein-like substances, whereas suspended particle was a significant influencing factor during METH detection. The aptasensor showed feasibility for METH detection in four kinds of real waters (drinking water, river water, lake water and untreated wastewater) with recoveries of 92.4-104.6 %.

The developed aptasensor provides a promising sensing platform for quick testing of illicit drug in aqueous environments. The water quality indicators are crucial influencing elements to be considered in the design and application of the electrochemical biosensors for trace pollutants detection in environmental water bodies.