fluorescence detection of mercury ions by cysteine-functionalized carbon quantum dots as a nanosensing probe

Mercury is one of the most hazardous chemical elements that affect human health and the environment. mercury is so toxic that even exposure to low levels of it can cause serious health problems such as cardiovascular and neurological diseases. therefore, it’s essential to develop a sensor to detect mercury toxicity. a one-step hydrothermal approach was used to synthesize cysteine-functionalized carbon quantum dots (cys-cqds). the obtained cys-cqds displayed a strong emission peak at 520 nm. fourier transform infrared (ft-ir), fluorescence spectroscopy, and, dynamic light scattering (dls) were used to characterize the synthesized cys-cqds. the synthesized cys-cqds were used as a novel platform for highly selective measurement of hg(ii) in an aqueous solution based on the fluorescence “turn-off” response with a limit of detection of 0.05 ppm and a linear range of 2.5–17.5 ppm. furthermore, cys-cqds were used effectively to determine the precise amounts of hg(ii) in a millipore water sample. more significantly, combining such an effective sensor with point-of-care technology can offer portable, user-friendly, and quick-sensing devices for improved biological and clinical applications.