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Ferric ion (Fe3+) serves as an essential and indispensable inorganic element in various biological process. Excess Fe3+ is harmful for biological systems and human health. Herein, highly sensitive carbon quantum dots (Fe-CQDs) for ferric ions were synthesized by a high-efficiency, one-step hydrothermal route utilizing L-arginine and citric acid. The prepared Fe-CQDs exhibited good water solubility, high photostability, and bright blue florescence with relatively high quantum yields (QYs) over 21.33% and a Stokes shift exceeding 100 nm. The functionalized Fe-CQDs offer rapid, sensitive, and selective recognition of Fe3+ with a linear relationship from 0.6 to 80 μM and a low detection limit of 0.2 μM. Moreover, the synthesized Fe-CQDs illustrated strong anti-interference properties in samples and buffer solutions. The developed sensor demonstrated high biocompatibility and was successfully applied for intracellular Fe3+ determination in SHSY5Y and HT22 cells, illustrating excellent imaging application. The present work provides a promising platform for the early clinical diagnosis of Fe3+-associated diseases. [ABSTRACT FROM AUTHOR]

This research centers on the development and synthesis of a longwave fluorescence probe, labeled as 60T, designed for the simultaneous detection of hydrogen sulfide, cysteine/homocysteine, and glutathione. The probe showcases a swift response, good linearity range, and heightened sensitivity, boasting that the detection limits of the probe for Cys, Hcy, GSH and H2S were 0.140, 0.202, 0.259 and 0.396 μM, respectively. Notably, its efficacy in monitoring thiol status changes in live MCF-7 cells is underscored by a substantial decrease in fluorescence intensity upon exposure to the thiol trapping reagent, N-ethyl maleimide (NEM). With an impressive red emission signal at 630 nm and a substantial Stokes shift of 80 nm, this probe exhibits remarkable sensitivity and selectivity for biothiols and H2S, indicating promising applications in the diagnosis and surgical navigation of relevant cancers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A phenothiazine coumarin based fluorescent probe (WX-Lyso) for the detection of ClO– was synthesized. • WX-Lyso displayed a low LOD (0.99 µm) and rapid responsive time to ClO– (<5 s). • WX-Lyso was proved successfully has good lysosomal-targeting and imaging abilities to ClO– in Hela cells. A new phenothiazine coumarin based probe WX-Lyso for detection of ClO– was developed. The probe showed obvious aggregation-induced emission (AIE) characteristic and exhibited a highly selective and sensitive turn-on fluorescence signal at 544 nm for ClO– with a large Stokes shift of 144 nm. The limit of detection (LOD) of ClO– was measured as low as 0.99 μM and a good line equation was obtained in the 0–50 μM concentration range. The detection mechanism was elucidated FT-IR, ESI-MS analysis and DFT. Furthermore, the probe had been demonstrated successfully has good lysosomal-targeting and high-contrast imaging abilities, which has the potential to become a new chemical tool and provide help for detecting ClO– in living systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ratiometric peptide-based fluorescent probe DWPH was developed. • DWPH showed highly selective ratiometric response to Hg2+ and S2− in 100 % aqueous solutions. • Low detection limits for Hg2+ (24.6 nM) and S2− (23.3 nM) were obtained. • DWPH were successfully used to determine Hg2+ and S2− in living cells and zebrafish. • Smartphone-assisted detection platform could achieve visual assay of different Hg2+ and S2− concentrations. A new ratiometric peptide-based fluorescent probe DWPH was designed and synthesized, comprising dansyl fluorophore as a fluorescent dye, and tripeptide backbone (Trp-Pro-His-NH 2) as a recognition group. The addition of Hg2+ caused the maximum emission peak of DWPH to blue shift from 560 nm to 510 nm. DWPH exhibited large Stokes shift (230 nm), satisfactory water solubility (100 % aqueous medium), good selectivity (only Hg2+), high sensitivity (24.6 nM), rapid response (within 50 s) and strong anti-interference ability for Hg2+ detection over a wide pH range (7–11). Additionally, the complex DWPH -Hg2+ as a relay response probe could also be applied to S2− according to displacement approach. Notably, the detection limit for S2− was calculated as 23.3 nM, exhibiting that DWPH showed great potential for environmental monitoring and bioimaging. In addition, DWPH were successfully used to determine Hg2+ and S2− in living cells and zebrafish based on excellent permeability and low cytotoxicity. What's more, the gradient concentration color changes of Hg2+ and S2− were combined with the smartphone APP to obtain red–green–blue (RGB) values, thus enabling rapid semi-quantitative detection of Hg2+ and S2− without expensive instruments. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe EDPH specializes in the detection of H 2 S with high selectivity, high sensitivity and good detection limits. • The probe EDPH has been shown to have applications in intracellular fluorescence imaging. • Purine-based fluorescent probes for the detection of H 2 S are a new direction. Hydrogen sulfide (H 2 S) is a gas with a toxic odor that plays an irreplaceable role in physiological activities within the mammalian body. Therefore, it is important to do the distribution and quantitative detection of H 2 S in mammalian cells. In this paper, a fluorescence probe (EDPH) based on purine scaffold was designed and synthesized with high sensitivity and good selectivity. H 2 S induced ether bond breakage in EDPH , resulting in a significant redshift of the absorption band (from 370 nm to 500 nm) with a Stokes shift of 130 nm. After the addition of H 2 S, the fluorescence intensity of EDPH showed a good linear correlation with the concentration of H 2 S, which enabled the quantitative detection of H 2 S with a low limit of detection (41 nM). Finally, the EDPH was applied to the cellular Hele, and the probe has good cellularity imaging capability for the detection of H 2 S in living systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • An "off–on" long-wavelength fluorescent probe is synthesized for Cys detection. • The probe has a large Stokes shift (211 nm) and reacted with Cys specifically. • The probe can monitor Cys fluctuations caused by redox imbalance in HepG2 cells. • The probe can be used for fluorescence imaging in cells and mice. In this research, an "off–on" long-wavelength fluorescent probe (DCMN-Cl) based on (E)-2-(3-(2-(6-hydroxynaphthalen-2-yl)vinyl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (DCMN) is designed and synthesized for cysteine (Cys) detection. DCMN-Cl exhibits a large Stokes shift (211 nm) and shows rapid response and high specificity to Cys. The fluorescence initensity at 635 nm reveals a good linear relationship with Cys concentration in the 0 to 50 μM range, and the detection limit is as low as 159 nM. The probe is also used for fluorescence imaging of Cys in cells and mice. Moreover, the probe provided visual evidence of Cu2+ and curcumin-induced intracellular Cys fluctuations. [ABSTRACT FROM AUTHOR]