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The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)
摘要： Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder di?raction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a ?uorescence quantum yield of 11% and superior water solubility and ?uorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the ?uorescence of the CQDs in a speci?c and sensitive manner, we developed a method for the detection of Hg2+ using this ?uorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coe?cient of determination (R2 ? 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.
关键词： mercury(II) detection,carbon quantum dots,hydrothermal synthesis,fluorescence quenching,bioimaging
更新于2025-11-19 16:46:39
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Fluorescent-Nitrogen-Doped Carbon Quantum Dots Derived from Citrus Lemon Juice: Green Synthesis, Mercury(II) Ion Sensing, and Live Cell Imaging
摘要： In this study, we report a green and economical hydrothermal synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using citrus lemon as a carbon source. The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield (～31%). High-resolution transmission electron microscopy (HRTEM) results show that the prepared NCQDs have a narrow size distribution (1?6 nm) with an average particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs was studied, and the result indicated that the material has high sensitivity, high precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3 nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities were determined to be greater than 88% upon the addition of NCQDs over a wide concentration range from 0 to 2 mg/mL. Based on the low cytotoxicity, good biocompatibility, and other revealed interesting merits, we also applied the prepared NCQDs as an effective fluorescent probe for multicolor live cell imaging.
关键词： mercury(II) ion sensing,citrus lemon juice,green synthesis,live cell imaging,fluorescent-nitrogen-doped carbon quantum dots
更新于2025-09-23 15:19:57
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Efficient “Ratiometric” fluorescence chemosensor for selective detection of Hg2+ ions based on phosphonates: its live cell imaging and molecular keypad lock applications
摘要： We report that the smart chemosensors (L1 and L2) can detect Hg2+ ion selectively over other metal ions was studied by various spectral techniques. Particularly, the proposed chemosensors exhibiting the notable color and spectra changes with the addition of mercury ions. Moreover, the colorimetric and fluorescence could be reversed with the addition of EDTA into the L1-Hg2+ and L2-Hg2+ solutions. Based on the admirable reversibility process, we displayed a molecular-scale sequential information processing circuit proposed the “Writing-Reading-Erasing-Reading” and “Multi-write” behaviors in the form of binary logic. Furthermore, L1 and L2 mimic as a molecular keypad lock and molecular logic gates with the successive addition of Hg2+ and EDTA. The binding ability of Hg2+ ion with L1 and L2 was further demonstrated by Density Functional Theory (DFT) studies. The biocompatibility of these chemosensors is successfully used for live cell imaging of Hg2+ in HeLa cells under the experimental conditions. Furthermore, the sensors L1 and L2 were also useful to determine the concentration of Hg2+ ion in real water samples to exhibit its practical applications.
关键词： Cell imaging,Molecular keypad lock,Chemosensors,Turn-off Fluorescence,Mercury (II),Logic gates
更新于2025-09-19 17:15:36
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Sulfur and nitrogen coa??doped graphene quantum dota??assisted chemiluminescence for sensitive detection of tryptophan and mercury (II)
摘要： A simple one-step thermal treatment to prepare strong fluorescent sulfur and nitrogen co-doped graphene quantum dots (SN-GQD) using citric acid and L-cysteine as precursors was developed. The ultra-weak chemiluminescence (CL) from the reaction of hydrogen peroxide (H2O2) and periodate (IO4?) was significantly enhanced by SN-GQD in acidic medium. The enhanced CL was induced by excited-state SN-GQD (SN-GQD*), which was produced from the transfer energy of (O2)2* and 1O2 to SN-GQD and recombination of oxidant-injected holes and electrons in SN-GQD. In the presence of tryptophan (Trp), the CL intensity of the SN-GQD–H2O2–KIO4 system was greatly diminished. This finding was used to design a novel method for determination of Trp in the linear range 0.6–20.0 μM, with a limit of detection (LOD) of 58.0 nM. Furthermore, Hg2+ was detectable in the range 0.1–9.0 μM with a LOD of 64.0 nM, based on its marked enhancement of the SN-GQD–H2O2–KIO4 CL system. The proposed method was successfully applied to detect Trp in milk and human plasma samples and Hg2+ in drinking water samples, with recoveries in the range 95.7–107.0%.
关键词： tryptophan,S,N co-doped graphene quantum dots,chemiluminescence,mercury (II)
更新于2025-09-16 10:30:52