Luminescence最新文献

Cyclic adenosine monophosphate (cAMP) is required for turning chemical signals into electrical impulses in the olfactory system, and low levels in people with olfactory deficits result in olfactory dysfunction. A micellar-based spectrofluorimetric approach has been developed to quantify cAMP in human nasal secretions, offering an efficient tool for assessing cAMP. The proposed method is based on enhancing the native fluorescence intensity of cAMP by leveraging an optimized micellar system, where hydrogen bonds form between cAMP's hydroxyl and amine groups and the sulfate groups of sodium dodecyl sulfate, resulting in a significant rise in fluorescence emission at 342 nm upon excitation at 255 nm. The method was validated and demonstrated sensitive linearity and precision within the concentration range of 10–200 ng/mL, with a lower limit of quantification at 1 ng/mL. The method was used to compare cAMP levels in the nasal secretions of healthy people and patients with olfactory dysfunction, revealing significantly lower cAMP concentrations in the latter group. This finding highlights the significant role of cAMP in the olfactory process and how dysregulation contributes to olfactory dysfunctions. Because of its simplicity, sensitivity, and selectivity, the technique can be used in clinical research diagnostic applications to explore olfactory disorders.

The development of rare-earth-doped oxide nanomaterials has garnered significant interest due to their potential applications in display and biomedical imaging technologies. Among them, MoO₃, with its favourable optical properties, emerges as a promising host material for nanophosphors. In this work, the hydrothermal method was employed to synthesise MoO₃: Tb³⁺ nanobelts by varying the terbium concentration. Structural, optical, morphological and photoluminescence characteristics were systematically examined. FESEM and TEM revealed nanobelt morphology. XPS verified the successful incorporation of Tb³⁺ ions. A thorough study of the photoluminescence mechanism, including concentration quenching and lifetime measurements, was carried out, as these aspects are still not well studied for this material. Under 260 nm excitation, blue-green emission was observed with optimal photoluminescence intensity at 2 mol% Tb³⁺ doping. The optimised sample was annealed at 500°C for 12 h, resulting in greenish-white emission. Emission colour coordinates were determined using the CIE chromaticity diagram, and a dipole–dipole interaction mechanism with a critical distance of 17 Å was identified as the cause of quenching. The average photoluminescence lifetime of the annealed sample was ~1.1 μs. These results demonstrate the potential of MoO₃: Tb³⁺ nanobelts as efficient phosphor materials for next-generation display and bioimaging applications.

A green, simple, sustainable, and robust synthetic approach has been employed to construct zinc oxide nanoparticles (ZnO NPs) for the first time by using an extract of the leaves of the plant Dypsis lutescens as a reducing and capping agent. Several analytical techniques have been used to characterize the synthesized ZnO NPs, including UV–visible spectroscopy, SEM, EDX, FTIR, and XRD. The findings indicated that the ZnO nanoparticles exhibited a spherical morphology, averaging 13 nm in size, and demonstrated a crystallinity of 66%. The ZnO NPs showed exceptional photocatalytic potential for degradation of an anionic Red Me4BL dye, with 71.17% degradation under sunlight and 63% degradation under tungsten lamp irradiation. Using the Langmuir–Hinshelwood integrated rate law, the kinetic studies showed that this reaction followed zero order. This work illustrated the potential of eco-friendly ZnO NPs for the degradation of various organic pollutants through photocatalysis.

This study presents a sustainable analytical methodology for the simultaneous quantification of the antiemetic drug meclizine (MCZ) and its potentially teratogenic impurity 4-chlorobenzophenone (BZP) using first derivative synchronous fluorescence spectroscopy (FDSFS). The method employs a Δλ of 40 nm followed by first derivatization, enabling the selective determination of MCZ at 275 nm and BZP at 311 nm. Given the clinical importance of MCZ in managing nausea and vomiting during pregnancy (affecting 70%–80% of expectant mothers) and the documented reproductive toxicity of the BZP impurity (capable of crossing the placenta and disrupting fetal development), this method addresses a critical safety concern in pharmaceutical quality control. BZP has been linked to adverse reproductive outcomes, hormonal disruption, and developmental toxicity in animal and human studies, making its detection alongside the parent drug imperative for maternal–fetal safety. The practicality and sustainability were quantitatively assessed using the Blue Applicability Grade Index (BAGI), achieving a remarkable score of 80/100, confirming its superior applicability in routine pharmaceutical analysis. This eco-friendly, sensitive, and selective analytical approach represents a significant advancement in the impurity profiling of meclizine used during pregnancy, offering a sustainable tool for pharmaceutical quality assurance with direct implications for maternal and fetal health protection.

This study introduces the synthesis, characterization, and utilization of carbon quantum dots (CQDs) from sunflower seed shells for the first time, specifically as a photoluminescence (PL) sensor for cadmium ion detection. CQDs were synthesized by a hydrothermal method. The CQDs were analyzed employing various physicochemical methods, including XRD, FTIR, TEM, UV–Vis spectroscopy, and fluorescence spectroscopy. The green-source CQDs demonstrated an average nanoscale dimension of 2.1 nm and displayed PL behavior, an emission peak at 497 nm, with a quantum yield (QY) of 33.5%. The synthesized CQDs exhibited significant selectivity for Cd²⁺ ion detection, with PL intensity diminishing as Cd²⁺ concentrations increased (1–10 μM). The detection limit was established at 0.12 μM, while the limit of quantification was set at 0.38 μM. Selectivity experiments demonstrated that the CQDs displayed a robust response to Cd²⁺ ions with negligible interference from other metal ions. The results indicate that the synthesized CQDs are a viable, economical, and eco-friendly material for the detection of cadmium contamination in water. Additionally, density functional theory (DFT) measurements were employed to investigate the quenching mechanism between CQDs and Cd²⁺ ions. The findings indicated that aldehyde groups on the CQD surface demonstrate the most robust interaction with Cd²⁺ ions, elucidating the fluorescence quenching mechanism.

A sensitive spectrofluorimetric approach was developed for simultaneous measurement of duloxetine (DUL) and mirtazapine (MIR) in pharmaceutical dosage forms and human plasma as well. The method depends on first-derivative synchronous spectrofluorometric scan where DUL and MIR were measured at 272 and 336 nm, respectively using Δλ of 60 nm. Both drugs are co-administered in resistant depression. The linearity was attained over the ranges of 0.1–1.3 μg/mL and 0.1–1.5 μg/mL for DUL and MIR, respectively. The limit of detection was found to be 0.013, while the limit of quantitation was found to be 0.042 for both drugs. The method gives high percentage recoveries of 98.27%–101.29% for DUL and 99.55%–101.69% for MIR when determining both analytes in their dosage forms. The two analytes were estimated in human plasma using the described approach achieving excellent percentage recoveries ranging from 98% to 101.33%. This is so important for quality control laboratories and pharmacokinetic studies. ICH criteria were used to validate the adopted procedure. The method's sustainability is evaluated by applying different tools, namely, Analytical Green Star Area (AGSA), Multi-Color Assessment (MA) Tool, analytical eco-scale, the Analytical Greenness Calculator (AGREE), Green Analytical Procedure Index (GAPI) and Blue Applicability Grade Index (BAGI).

Carbon dots (CDs) exhibit diverse application potential in various fields due to their unique optical properties. However, CDs synthesized by conventional methods typically have complex compositions and lack efficient separation and purification techniques, limiting their performance in specific applications. In this work, we synthesized CDs via a solvothermal method and, for the first time, employed synchronous fluorescence spectroscopy (SFS) to determine the relative content of each CD type during synthesis. By leveraging SFS's high selectivity and resistance to spectral overlap, we analyzed the mixture's composition, successfully identifying blue fluorescent CDs (B-CDs), green fluorescent CDs (G-CDs), and orange fluorescent CDs (O-CDs). The optimal synthesis conditions for G-CDs were 180°C for 5 h. A sensor array was constructed using the obtained CDs as sensing elements for distinguishing and recognizing metal ions, and the sensor array has shown good recognition and discrimination ability for various metal ions. G-CDs and O-CDs were mixed with polyvinylpyrrolidone (PVP) to prepare CDs/PVP composite materials, demonstrating their potential in light emitting diode (LED) applications. SFS simplifies the synthesis and purification of CDs, providing key guidance for controlled CD synthesis, increased yield, and optimized fluorescence.

The present study employs density functional theory to examine structural, optoelectronic, mechanical, and transport characteristics of ternary chalcopyrites semiconductors Al₂ZnCh₄ (X = Se, Te) to investigate their multifunctional potential. Structural optimization supports the materials' thermodynamic stability in the tetragonal phase. The mechanical properties, determined through elastic constants and moduli, exhibit mechanical stability and ductility, with softness rising from S to Te, rendering them suited to flexible device applications. Optical features reveal high absorption in the visible to ultraviolet range, with peak absorption shifting towards lower energies as chalcogens change from Se to Te. This feature demonstrates its potential for solar energy accumulation and UV protection applications. Thermoelectric study displays strong Seebeck coefficients (> 300 μV/K), moderate electrical conductivity, and low electronic thermal conductivity. Al₂ZnTe₄ exhibits the greatest power factor. The dimensionless figure of merit of Al₂ZnSe₄ and Al₂ZnTe₄ improves with temperature, attaining maximum values, demonstrating their potential for high-temperature thermoelectric applications.

Trivalent dysprosium (Dy³⁺)-doped Lu₃Ga₄AlO₁₂ (LuGAG) nanocrystals with varying Dy³⁺ ion concentrations have been synthesised using the Pechini sol–gel method. To investigate their properties, the samples were analyzed using X-ray diffraction (XRD), electron microscopy (SEM and TEM), Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectroscopy. XRD analysis confirmed that the samples crystallised in a garnet phase with an average crystallite size of approximately 19 nm. SEM and TEM images revealed that the particles were mostly spherical and agglomerated, with grain sizes ranging from 80 to 300 nm. When excited at 352 and 360 nm, the PL spectra displayed distinct emission peaks at 482 nm (blue), 580 nm (yellow), 671 nm (red) and 760 nm (infrared), attributed to the Dy³⁺ transitions ⁴F_9/2 → ⁶H_15/2, ⁶H_13/2, ⁶H_11/2 and ⁶H_9/2, respectively. The luminescence decay behaviour was non-exponential and could be described by the Inokuti–Hirayama model with S = 6, indicating dipole–dipole interaction-based energy transfer. The chromaticity coordinates were located in the neutral-white light region. Additionally, parameters such as colour purity, colour rendering index and correlated colour temperature were evaluated and compared with existing literature. Overall, the findings confirm that these Dy³⁺-doped LuGAG nanocrystals are promising candidates for white light emission, particularly under the 352-nm excitation.

Cigarette butts are the world's leading source of litter, disrupting water quality and the normal development of ecosystems. Tobacco use in its various forms is the leading preventable cause of death, illness, and disability worldwide. Nicotine (NCT), a natural alkaloid found in tobacco plants, is a psychoactive substance and the primary component responsible for the addictive properties of such products. Since NCT is an analyte with low native fluorescence, the use of a fluorophore that interacts with it is necessary for its quantification by molecular fluorescence. This work describes, for the first time, a method to determine NCT based on the enhancement of fluorescence of the metal–organic framework (MOF) europium terbium 2-phenylsuccinate (Eu-Tb-PSA), at λ_em = 611 nm (λ_exc = 280 nm). The experimental variables that influence the quantification of NCT were studied and optimized. Under optimal working conditions, a LOD of 12.7 ng L⁻¹ and a LOQ of 38.5 ng L⁻¹ were obtained. The calibration shows a linear behavior of three orders of magnitude for NCT concentration from 38.5 to 8.95 × 103 ng L⁻¹. The methodology was applied to determine trace amounts of NCT (ppb) in natural water samples.