L-Glutathione modified graphitic carbon nitride quantum dots: An ultrasensitive fluorescent sensor for detection of Pb2+ in water

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2023-09, Vol.443, p.114819, Article 114819
• Main Authors: Pattnayak, Samarjit, Sahoo, Ugrabadi, Choudhury, Shubhalaxmi, Aparajita, Pragnyashree, Hota, Garudadhwaj
• Format: Article
• Language: English
• Subjects: Graphitic carbon nitride quantum dots (g-C3N4 QDs); L-Glutathione (GSH); Limit of detection (LOD); Pb2+ ions; Quantum yield
• ISSN: 1010-6030
• DOI: 10.1016/j.jphotochem.2023.114819

[Display omitted] •GSH@g-C3N4 QDs were fabricated by an EDC/NHS carbodiimide coupling reaction.•The QDs presented a rapid, sensitive, and selective detection of toxic Pb2+ ions.•The sensing performance was attributed to the quenching of fluorescence intensity.•A static quenching mechanism was proposed by the TCSPC experiment.•The sensor system was employed in real water samples with substantial results. A facile, sensitive, and selective fluorescence detection method for Pb2+ ions is designed using L-Glutathione (GSH) modified graphitic carbon nitride quantum dots (GSH@g-C3N4 QDs). A carbodiimide-activated coupling reaction is used to bind GSH onto g-C3N4 QDs. When excited at 340 nm, the as-obtained passivated quantum dots exhibit strong blue emissions at 420 nm. With a relative quantum yield of 27%, the system demonstrates exceptional stability against ionic strength and photobleaching. Additionally, it is discovered that the fluorescence emission of the sensor is selectively quenched in the presence of Pb2+ ions. The limit of detection (LOD) for Pb2+ is measured to be 0.025 µM in a linear range of 0.01 µM-0.1 µM. The average lifetime calculations from the lifetime decay experiment along with UV–vis. absorption studies suggest that the quenching pattern follows a static quenching mechanism. Finally, the system is used in real water samples to detect Pb2+ with a substantial recovery percentage greater than 90%.