Luminescence最新文献

Water-soluble fluorescent carbon quantum dots (CQDs) were synthesized via a single-step, eco-friendly hydrothermal process using Robinia hispida L. flowers as a novel carbon source. Advanced characterization techniques (HRTEM, XRD, XPS, FTIR, UV–vis, and fluorescence spectroscopy) revealed spherical CQDs with an average size of 3.96 ± 0.83 nm and a quantum yield of 5.13%. Under 365 nm UV light, the CQDs emitted blue fluorescence. Fluorescence quenching studies with various metal ions showed a significant 93.5% reduction in FL intensity with 500 μM Au³⁺ ions. At pH 7.0, a linear detection range of 0.5–3.5 μM was achieved, with limits of detection (LOD) and quantification (LOQ) of 0.4 and 1.2 μM, respectively. The non-functionalized CQDs effectively detected Au³⁺ ions in tap, drinking, and river water, acidic mine drainage (sludge), and a standard reference material (CRMSA-C Sandy Soil C), achieving spike recoveries of 96.06%–101.71% with variability below 4.13%.

Solid-state reaction method is employed to prepare K₂Ba₃(P₂O₇)₂:VO²⁺ nanopowder and studied by using powder x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, optical absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and photoluminescence (PL) spectroscopy. XRD studies revealed VO²⁺ ion doped K₂Ba₃(P₂O₇)₂ nanopowder have 21 nm crystallite size, orthorhombic phase, and Pmn2₁ space group. From Williamson–Hall analysis, crystallite size is found as 24 nm. SEM morphology recorded the presence of irregular-sized and round-shaped agglomerates. FT-IR and Raman spectra reveal characteristic bands of phosphate groups. Three characteristic peaks are observed at 848, 695, and 452 nm in optical absorption spectrum. Also, crystal and tetragonal field parameters are calculated as Dq = 1439, Ds = −2789, and Dt = 3422 cm⁻¹. In addition, bandgap energy is found as 3.97 eV. Optical and EPR analyses led to understand the incorporation of vanadyl ions into host lattice. Spin Hamiltonian parameters are evaluated. Basing PL spectrum, Commission Internationale de l'Éclairage's (CIE) chromaticity coordinates are calculated, which are present in reddish-orange region with good color correlated temperature (CCT) and color rendering index (CRI) values facilitating the use in lighting applications and LEDs.

Copper ions (Cu²⁺) play a crucial role in biological processes; however, excessive intake can result in severe health problems. Current methods for detecting copper ions are both expensive and complex. Therefore, there is a need for efficient and straightforward visual detection methods. In this study, novel nitrogen-doped carbon dots (N-CDs) were synthesized via a microchannel method using diethylenetriamine and citric acid as precursors and were characterized by TEM, XRD, and IR, among others. The N-CDs demonstrated high selectivity and strong fluorescence, showing a linear quenching response to copper ions with a detection limit of 46 nM, whereas other common metal ions, such as Ca²⁺ and Mg²⁺, exhibited negligible interference even at higher concentrations. These N-CDs were subsequently applied to test paper, allowing for on-site visual and quantitative detection of copper ions via a colorimetric method. This approach provides a novel solution for the rapid detection of copper ions, with significant potential in environmental monitoring, public health, and industrial applications.

A novel fluorescence-based sensor has been developed for the sensitive detection of malathion, an organophosphorus pesticide, using sulfur-doped quantum dots (SQDs) embedded within graphitic carbon nitride (g-C₃N₄) nanosheets. The SQDs were synthesized through a hydrothermal method, whereas the g-C₃N₄ nanosheets were produced via an exfoliation process. The resulting SQDs@g-C₃N₄ nanocomposite demonstrated outstanding performance for malathion detection in food samples, exhibiting a wide linear detection range of 10–120 μM and an exceptionally low detection limit of 0.02 μM. This sensitivity allows for accurate and rapid pesticide monitoring at trace levels. The sensor's performance was optimized by varying experimental conditions, ensuring that it provided high sensitivity, excellent stability, and impressive selectivity toward malathion, even in complex food matrices.

7-Aminoactinomycin D (7AAMD) is the fluorescent analogue of the anticancer drug actinomycin D (AMD). In order to overcome toxic side effects and enhanced bioavailability of 7AAMD, micellar drug carrier systems could be useful. We have used cationic (hexadecetyltrimethylammonium bromide [CTAB]), anionic (sodium dodecyl sulphate [SDS]) and non-ionic (t-octylphenoxypolyoxyethanol, Triton-X100 [TX 100]) surfactants to prepare micelle. We have explored the mechanism of the interaction of 7AAMD with micelles using steady-state and time-resolved fluorescence spectroscopy. Our results revealed that the Stokes' shift values of 7AAMD were decreased in all three micellar medium compared to that in the absence of any micelle. Thus, 7AAMD is localized in less polar microenvironment of micelles than bulk water. In addition, from the time-resolved fluorescence study of 7AAMD, we found that the relative contribution of the conformers of 7AAMD depended on the surfactant head group. Furthermore, acrylamide induced fluorescence quenching study shows differential accessibility of the quencher molecules towards 7AAMD depending on the ionic nature of the surfactant head group. In the presence of acrylamide, 7AAMD was expelled out from the non-ionic TX 100 micelle but not in CTAB and SDS micelle. Thus, our results are valuable to design new drug delivery system for AMD-like antitumor agents.

Alendronate sodium (ALN) is used to treat osteoporosis in men and women who experienced menopause. A new, sensitive, environmentally friendly, selective, and reasonably priced spectrofluorimetric technique was devised for ALN determination utilizing the reaction of the drug with ninhydrin and phenylacetaldehyde in the presence of Teorell–Stenhagen buffer (pH 7). The interaction yielded a highly luminescent diaryl pyrrolone product with strong emission at 464 nm following excitation at 390 nm. Optimization of various method parameters was performed, and a calibration curve was constructed. Linear regression statistical analysis shows a highly strong correlation (r = 0.9995). The method could determine ALN in the linear concentration range of 0.5–4.0 μg mL⁻¹. Adopting ICH guidelines criteria, method validation was done, and the results confirmed the acceptable accuracy and precision. The LOD and LOQ values were computed as 0.13 and 0.41 μg mL⁻¹, respectively. Application of the method for the analysis of oral tablets containing ALN alone or combined with vitamin D3 was successfully performed with no interferences from vitamin D3 or other coformulated excipients, proving excellent selectivity. Moreover, the method was evaluated for environmental greenness via three different tools confirming its acceptable greenness. Hence, the method can be successfully utilized in quality control laboratories.

The environmental impact of chemicals used in aquaculture, particularly nitrofurantoin, has raised global concern. Nitrofurantoin, a broad-spectrum antimicrobial, is commonly used in aquaculture despite safety risks. Determination of nitrofurantoin in water samples of fish ponds is necessary to ensure the safety and quality of seafood. Herein, a new spectrofluorometric method was created for the determination of nitrofurantoin in water samples from fish ponds. Carbon quantum dots were functionalized with nitrofurantoin tetra phenyl borate modifying their surface to be selective for nitrofurantoin quantification. When nitrofurantoin is present, the functionalized carbon quantum dots show concentration-dependent fluorescence quenching, allowing estimation of the drug. The method was validated and demonstrated accepted linearity in the range of 5–150 ng/mL, with a limit of detection at 1.251 ng/mL. The method offers a broader and more sensitive detection range compared with a previous UHPLC method. Additionally, the environmental friendliness of the described method was conducted and compared with the reported UHPLC method using the analytical eco-scale and the analytical greenness metric. The results demonstrate that the current method exhibits higher levels of sustainability compared with the previously reported method.

Sensitive and precise assay of prednisolone, a steroid hormone, has received great attention due to its significant role in the treatment of a series of diseases. In this study, we have developed a simple, quick, and accurate technique in this part to measure prednisolone. Cobalt 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (CoTPyP) as a mimic peroxidase catalyzes the chemiluminescence (CL) reaction of lucigenin for the first time. CoTPyP has a great impact on the CL signal. Furthermore, the CL system has been successfully used for the prednisolone flow-injection test. The findings showed that the UV irradiation of prednisolone led to an unimolecular photochemical reaction that could enhance yield of high-energy intermediate and cause higher CL emission. Under ideal experimental circumstances, CL intensity was shown to be proportionate to prednisolone concentration in the range of 0.1–170 μg mL⁻¹ (r = 0.9925, n = 4). A detection limit of 0.072 μg mL⁻¹ was observed. Compared with the HPLC approach, our proposed method provides a sensitive, fast, and efficient analysis of prednisolone in pharmaceutical formulations and biological fluids.

The fused heterocycle 1-(imidazo[5,1-a]isoquinolin-3-yl)naphthalen-2-ol (LH) has been synthesized and characterized by spectroscopic methods. Probe LH upon irradiation with λ_ex = 336 nm exhibited strong fluorescence with λ_em = 437 nm in MeOH/HEPES buffer (5 mM, pH = 7.4, 2:8, v/v). Upon adding several metal ions, the fluorescence intensity was quenched only by Cu²⁺ and Pd²⁺ ions. This fluorescence turn-off response by Cu²⁺ and Pd²⁺ ions was observed even in the coexistence of other metal ions and anions. From the Job's plot and mass spectra analysis, a 2:1 ratio of LH:M²⁺ was obtained, and the composition [Cu(L)₂H₂O] and [Pd(L)₂] has been assigned. The detection limit for Cu²⁺ and Pd²⁺ ions was determined to be 0.24 and 0.35 μM, respectively, and workable pH window to be 4–10. The binding of LH to Cu²⁺ and Pd²⁺ resulted in red-shift in the UV–visible spectrum, which was supported by DFT/TDDFT calculations.

The influence of Eu³⁺ concentration on the crystal structure and photoluminescence (PL) properties of Ca_3-x(PO₄)₂:xEu³⁺ (0.06 ≤ x ≤ 0.10) phosphors is systematically investigated using X-ray diffraction (XRD) Rietveld refinement, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, UV-visible spectroscopy, and PL spectroscopy. The prepared phosphors exhibit a single rhombohedral phase with the space group R3c. The constituent ions occupy various crystallographic sites, including Ca(1–5), Eu(1–3), P(1–3), and O(1–10) sites. Under 397-nm excitation, the emission spectra show distinct emission peaks between 525 and 725 nm, corresponding to the ⁵D₁ → ⁷F_j (j = 1 and 2) and ⁵D₀ → ⁷F_j (j = 1, 2, 3, and 4) transitions of Eu³⁺ ions. The concentration quenching observed in the phosphors is attributed to electric multipolar interactions. Among the prepared phosphors, Ca_2.92(PO₄)₂:0.08Eu³⁺ phosphor shows the highest emission efficiency and excellent color performance. These results demonstrate that Ca_3-x(PO₄)₂:xEu³⁺ phosphors have significant potential as red-emitting materials for white light–emitting diode (WLED) applications.