Green synthesis of surface-passivated carbon dots from the prickly pear cactus as a fluorescent probe for the dual detection of arsenic(iii) and hypochlorite ions from drinking water.

Efforts were made to develop a simple new approach for the green synthesis of surface-passivated carbon dots from edible prickly pear cactus fruit as the carbon source by a one-pot hydrothermal route. Glutathione (GSH) was passivated on the surface of the CDs to form a sensor probe, which exhibited excellent optical properties and water solubility. The prepared sensor was successfully characterized by UV-visible spectrophotometry, fluorescence spectrophotometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The simple sensing platform developed by the GSH-CDs was highly sensitive and selective with a "turn-off" fluorescence response for the dual detection of As and ClO ions in drinking water. This sensing system exhibited effective quenching in the presence of As and ClO ions to display the formation of metal complexes and surface interaction with an oxygen functional group. The oxygen-rich GSH-CDs afforded a better selectivity for As/ClO ions over other competitive ions. The fluorescence quenching measurement quantified the concentration range as 2-12 nM and 10-90 μM with the lower detection limit of 2.3 nM and 0.016 μM for the detection of As and ClO ions, respectively. Further, we explored the potential applications of this simple, reliable, and cost-effective sensor for the detection of As/ClO ions in environmental samples for practical analysis.