On-Off-On Fluorometric Detection of Hg(II) and L-Cysteine Using Red Emissive Nitrogen-Doped Carbon Dots for Environmental and Clinical Sample Analysis.

This research introduces a novel fluorescence sensor 'on-off-on' employing nitrogen-doped carbon dots (N-CDs) with an 'on-off-on' mechanism for the selective and sensitive detection of Hg(II) and L-cysteine (L-Cys). N-CDs was synthesized using citric acid as the carbon precursor and urea as the nitrogen source in dimethylformamide (DMF) solvent, resulting in red emissive characteristics under UV light. Comprehensive spectroscopic analyses, including UV-Vis, fluorescence, FT-IR, XRD, XPS, Raman, and Zeta potential techniques, validated the structural and optical characteristics of the synthesized N-CDs. The maximum excitation and emission of N-CDs were observed at 548 and 622 nm, respectively. The quantum yield of N-CDs was calculated to be 16.1%. The fluorescence of N-CDs effectively quenches upon the addition of Hg(II) due to the strong coordination between Hg(II) and the surface functionalities of N-CDs. Conversely, upon the subsequent addition of L-Cys, the fluorescence of N-CDs was restored. This restoration can be attributed to the stronger affinity of the -SH group in L-Cys towards Hg(II) relative to the surface functionalities of N-CDs. This dual-mode response enabled the detection of Hg(II) and L-Cys with impressive detection limits of 15.1 nM and 8.0 nM, respectively. This sensor methodology effectively detects Hg(II) in lake water samples and L-Cys levels in human urine, with a recovery range between 99 and 101%. Furthermore, the N-CDs demonstrated excellent stability, high sensitivity, and selectivity, making them a promising fluorescence on-off-on probe for both environmental monitoring of Hg(II) and clinical diagnostics of L-Cys.

Turn-Off Fluorometric Determination of Bilirubin Using Facile Synthesized Nitrogen-Doped Carbon Dots as a Fluorescent Probe.

Bilirubin plays a significant role in human health management, particularly in the case of jaundice. Because of the need for the monitoring of bilirubin levels in jaundice patients, the development of a robust sensitive method becomes essential. Here, we describe the development of a highly sensitive and selective turn-off fluorometric detection method for bilirubin in blood serum samples using nitrogen-doped carbon dots (N-CDs). N-CDs was synthesized by the pyrolysis process, using citric acid and L-asparagine as the carbon and nitrogen sources, respectively. The prepared N-CDs solution showed highly intense blue emission with good stability. The HR-TEM image of N-CDs revealed spherical dot-like structures with an average size calculated to be 7.16 nm. Further, the surface functional groups of N-CDs were analyzed by FT-IR, Raman, XRD, and XPS techniques. Fluorescence spectra showed the maximum emission intensity at 443 nm (λex). The linear range of addition was performed from 1 to 150 µM, and the limit of detection (LOD) was determined to be 1.97 nM. The emission of N-CDs was quenched by Förster Resonance Energy Transfer (FRET) by adding bilirubin. These N-CDs showed extraordinary sensitivity and selectivity in the detection of bilirubin. Hence, this fluorescent probe has been proven successful in detecting the concentration of free bilirubin in human serum samples.

Independent hydrothermal synthesis of the undoped, nitrogen, boron and sulphur doped biogenic carbon nanodots and their potential application in the catalytic chemo-reduction of Alizarine yellow R azo dye.

This research study highlights the catalytic usage of hetero atoms doped and undoped biogenic carbon nano dots (BCNDs) in the reduction of Alizarine yellow R (AYR) dye. Hydrothermal route was followed to synthesize the eco-friendly and fluorescent undoped as well as, N, B & S doped BCNDs from Syzygium cumini (S. cumini) fruit extract. Synthesized BCNDs exhibited good fluorescent and optical properties. From the HR-TEM results, the sizes of the spherically shaped undoped, N, B & S doped BCNDs were found to be 4.75 nm, 4.31 nm, 4.07 nm & 3.96 nm respectively. XRD results highlighted their amorphous nature. Functional groups and elemental percentages were elucidated from the results of FT-IR, EDS and XPS. Graphitic texture of the BCNDs were explained from Raman spectroscopy results and SAED. Thermal stability of BCNDs was evident from the results of TGA analysis. Further, BCNDs were used as green catalyst in the reduction of Alizarine Yellow R (AYR) dye. Langmuir- Hinshelwood mechanism was applied to evaluate the catalytic influence of BCNDs on AYR dye.

Biogenic robust synthesis of silver nanoparticles using Punica granatum peel and its application as a green catalyst for the reduction of an anthropogenic pollutant 4-nitrophenol.

A robust synthesis of silver nanoparticles (AgNPs) using the peel extract of Punica granatum is reported in this article. The formation of AgNPs was confirmed by the appearance of brownish yellow color and the Surface Plasmon Resonance (SPR) peak at 432 nm. The biogenic AgNPs were found to have the size approximately 30 nm with distorted spherical shape. The high negative zeta potential values of AgNPs revealed their high stability which could be attributed to the capping of AgNPs by the phytoconstituents of the Punica granatum peel. The biogenic AgNPs were also found to function as an effective green catalyst in the reduction of anthropogenic pollutant viz., 4-nitrophenol (4-NP) by solid sodium borohydride, which was evident from the instantaneous color change of bright yellow (400 nm) to colorless (294 nm) solution, after the addition of AgNPs. The catalytic action of biogenic AgNPs in the reduction of 4-NP could be explained on the basis of Langmuir-Hinshelwood model.

Anti-inflammatory activity of roots of Ecbolium viride (Forsk) Merrill.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditionally the aqueous extracts of dried roots of the plant Ecbolium viride are used for menorrhagia, rheumatism and jaundice. AIM OF THE STUDY: The aim was to evaluate the anti-inflammatory activity of Ecbolium viride extract in an in vivo model. MATERIALS AND METHODS: The ethyl acetate fraction of Ecbolium viride root extract was prepared and administered orally to rats. The anti-inflammatory activity of Ecbolium viride was determined by carrageenan-induced paw edema and cotton pellet granuloma models. RESULTS: Oral administration of Ecbolium viride extract reduced inflammation significantly (P<0.01) in both the carageenan paw edema and the cotton pellet granuloma models. CONCLUSIONS: The results of the study supported the traditional use of Ecbolium viride in the treatment for inflammatory disease.

Dalsympathetin--a new isoflavone gentiobioside from Dalbergia sympathetica (Dennst.).

Two isoflavonoids isolated from Dalbergia sympathetica were identified as 5,4'-dihydroxy-7-methoxyisoflavone (1) (Prunetin) and Prunetin-4'-O-beta-D-gentiobioside (2) (Dalsympathetin). The natural occurrence of Dalsympathetin is reported for the first time. The position of glycosylation in Dalsympathetin at 4'-position has been confirmed by 2D-NMR spectral studies.

Monoterpenoids from the seeds of Heracleum candolleanum.

The isolation and NMR spectra of 2-exo,3-endo-camphanediol (1) and 2-pinene-4,10-diol (2) from the seeds of Heracleum candolleanum are reported.