Nitrogen- and Sulfur-Codoped Carbon Dots for Highly Selective and Sensitive Fluorescent Detection of Hg²⁺ Ions and Sulfide in Environmental Water Samples

Abstract

Nitrogen-and sulfur-codoped carbon dots (N,S-CDs) with a fluorescence quantum yield of 16.1% and good photoluminescent properties were synthesized by a simple hydrothermal method. Cytotoxicity of the N,S-CDs was evaluated by the MTT assay, and human hepatoma HepG2 cells were chosen as the target. The cell viability was more than 85% after 24 h of incubation when its concentration was up to 300 μg/mL, suggesting low cytotoxicity and good biocompatibility of the N,S-CDs. The fluorescence spectra of the N,S-CDs are excitation-dependent in the excitation-wavelength range of 295−400 nm, and it emits bright blue fluorescence centered at 435 nm. Its selective fluorescence recognition for Hg 2+ ions was found. When Hg 2+ ions were added to the N,S-CDs solution, its bright blue fluorescence was obviously quenched and could be recovered by the addition of sulfide. Accordingly, a new strategy based on N,S-CDs−Hg 2+ system as a highly selective and ultrasensitive "turn off−on" fluorescence sensing for the detection of sulfide was fabricated. The limits of detection (S/N = 3) are 83 nM for Hg 2+ ions and 11 nM for sulfide. Almost no statistically significant interference for Hg 2+ -ion and sulfide detection was observed among possible coexisting substances in the water samples, including 17 common metal ions and 11 anions. This probe was successfully applied for the cellular imaging of Hg 2+ ions in HepG2 cells by fluorescence microscopy.

Direct and sensitive detection of sulfide ions based on one-step synthesis of ionic liquid functionalized fluorescent carbon nanoribbons

“…hydroxyl and oxygen radicals) when a high oxidation voltage is applied. Secondly, the oxidation of the edge planes opens up the edge sheets and leads to the expansion of the graphite anode, facilitating intercalation by PF 6 À between the graphene layers. Thirdly, the oxidative cleavage of the expanded graphene sheets generates CNRs.…”

“…via reduction of sulfate ions by microbes or anaerobic processes of S-containing enzymes). [4][5][6] As the S 2À ion can stimulate the mucosa and has an extreme effect on the nervous system, exposure to S 2À ions leads to unconsciousness and respiratory paralysis and is closely related to various diseases including Alzheimer's disease, Down's syndrome and cirrhosis of the liver. [7][8][9][10] Therefore, simple, rapid and sensitive detection of S 2À is of great importance.…”

A Multi-Catalytic Sensing for Hydrogen Peroxide, Glucose, and Organophosphorus Pesticides Based on Carbon Dots

“…In general, photoluminescent CDs can be prepared by using N, S, or other heteroatom-containing organic compounds as reactants (Jiang et al, 2014;Chang et al, 2016;Deng et al, 2018;Hou et al, 2018;Meng et al, 2018;Prekodravac et al, 2019;Wu and Tong, 2019;Yao et al, 2019;Zheng et al, 2019;Hallaj et al, 2020;Ji et al, 2021). Natural amino acids containing N, O, or S heteroatoms, as building blocks of proteins, can show some favorable merits, such as being biocompatible, plentiful, and low cost, which makes them ideal precursors for synthesizing CDs.…”

The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)

“…The fluorescence method is more widely applied, and it has avoidably complicated sample preparation, using expensive instrumentations and professional skills. In this regard, some works have been reported for mercury (II) detection [14–17], such as Yue et al [16] who used apple juice as the carbon source. CQDs with good water solubilities and high stabilities were hydrothermally prepared and used for the highly sensitive and selective detection of mercury (II).…”

“…CQDs with good water solubilities and high stabilities were hydrothermally prepared and used for the highly sensitive and selective detection of mercury (II). Nitrogen and sulfur codoped carbon dots were synthesized by hydrothermal method, and this probe was applied for analysis of mercury (II) in environmental water samples [17]. The CQDS has a significant important function because it determines the selectivity and sensitivity.…”