One-Pot Hydrothermal Synthesis of Carbon Dots as Fluorescent Probes for the Determination of Mercuric and Hypochlorite Ions

Abstract

Nitrogen and sulfur codoped carbon dots (NSCDs) were synthesized via a one-pot hydrothermal method, and citric acid, ethylenediamine, and methyl blue were used as precursors. The obtained NSCDs were spherical with an average size of 1.86 nm. The fluorescence emission spectra of the NSCDs were excitation independent and emitted blue fluorescence at 440 nm with an excitation wavelength at 350 nm. The quantum yield of the NSCDs was calculated to be 68.0%. The NSCDs could be constructed as fluorescent probes for highly selective and sensitive sensing mercuric (Hg2+) and hypochlorite (ClO−) ions. As the addition of Hg2+ or ClO− ions to the NSCDs, the fluorescence intensity was effectively quenched due to dynamic quenching. Under the optimal conditions, the linear response of the fluorescence intensity ranged from 0.7 μM to 15 μM with a detection limit of 0.54 μM and from 0.3 μM to 5.0 μM with a limit of detection of 0.29 μM for Hg2+ and ClO− ions, respectively. Finally, the proposed method was successfully used for quantifying Hg2+ and ClO− ions in spiked tap water samples.

Carbon Dots–Based Ratiometric Fluorescence Sensor for Hippuric Acid

“…The maximum absorption at 363 nm corresponds to the n–π* transition of the C ═ O bond and the other surface functional groups. [ 22,23 ] The absorption spectrum extends up to 550 nm into the visible region of the electromagnetic spectrum and hence the CDs solution appears to be yellow in color. The broad absorption peak could be due to the different surface functional groups.…”

“…An aromatic C = C–C stretching and –C–O–C bending are found at 1453 and 666 cm −1 , respectively. [ 23,27 ]…”

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care—An Updated Review (2018–2021)

“…The resultant N/S-CDs were found to be~2 nm in size and spherical in shape, and could revel excellent luminescence stability under UV light irradiation, at high salt concentrations and broad pH range [149]. In another study, hydrothermal synthesis of N/S-CDs was carried out by employing methyl blue, ethylenediamine, and citric acid as sources, where the prepared N/S-CDs could reveal excitation independent blue fluorescence emission [150].…”

Surfactant-free synthesis of fluorescent platinum nanoclusters using HEPES buffer for hypochlorous acid sensing and imaging

“…37,38 Endogenous hypochlorite can be generated through the myeloperoxidase (MPO)-catalyzed peroxidation of chloride ions (Cl − ) using hydrogen peroxide (H 2 O 2 ), and it served as a crucial innate immune defense killing invading bacteria and pathogens. 39,40 Moreover, excessive hypochlorite can induce cellular oxidative stress and lead to the denaturation of proteins, enzymes, lipid droplets and nucleic acids through oxidation or chlorination, which directly causes tissue damage and is tightly related to neurodegenerative disorders, 41 inflammatory diseases, 42,43 liver injuries 44 and even cancer. 45 Taking into account the above scientific issues, it is essential and urgent to develop a surfactant-free NMNC-based fluorescent probe with high biocompatibility to monitor hypochlorous acid in biosystems.…”