Luminescence最新文献

Herein, a novel spectrofluorometric sensor is proposed for the sensitive analysis of two nonfluorescent mucolytic drugs, namely, acetylcysteine (ACT) and carbocisteine (CST), utilizing the newly synthesized 2-[(2-hydroxyethyl)-(2,8,10-trimethylpyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidin-4-yl)-amino]-ethanol as a fluorescence probe (Flu. Probe). This fluorophore exhibits fluorescence emission at 445 nm upon excitation at 275 nm. The addition of increasing concentrations of each drug resulted in quantitative quenching of the Flu. Probe's fluorescence. Investigation into the quenching mechanism revealed that static quenching is the primary contributing factor for both drugs. The spectroscopic characteristics of the Flu. Probe in the presence of ACT and CST were analyzed using DFT and TD-B3LYP calculations, revealing typical π → π* transitions, attributed to stable hydrogen-bonding structures. The developed method was validated in accordance with ICH Q2(R1) guidelines. Linear responses for ACT and CST were observed over concentration ranges 0.125-2.25 and 0.125-3.0 μg/mL, respectively, with detection limits (LODs) 31.97 and 37.14 ng/mL. The proposed spectrofluorometric platform was successfully applied to the analysis of ACT and CST in pharmaceutical dosage forms and spiked urine, within concentration ranges 0.25-2.25 and 0.25-2.50 μg/mL and LODs = 80.21 and 71.48 ng/mL, respectively. Finally, the greenness of the proposed protocol was evaluated employing GAPI, hexagon, and AGREE approaches.

The reaction-based probe perylene diimide-hydroxyphenyl benzothiazole (PR) can be used for the detection and discrimination of H₂S, DTT and Cys in 20% HEPES buffer-DMSO and DMSO. The H₂S induced radical anion formation of PR in 20% HEPES buffer and thiolysis of the ether bond of PR in DMSO. However, the addition of DTT showed only a decrease in the absorbance intensity and Cys showed insignificant behaviour towards PR in DMSO. The optical, AFM and DLS studies along with isolation of the reaction product in the model reaction support the interaction of the PR with bio thiols.

Herein, highly fluorescent sulfur and nitrogen co-doped carbon dots (N, S-CDs) had been employed as a fluorescent probe to analyze Cu²⁺ in drinking water. The biogenic creatinine is known to form a stable complex with Cu²⁺; hence, it was rationally selected as a bioinspired nitrogen substrate for the first time to enhance N, S-CDs selectivity towards Cu²⁺. Moreover, the literature was surveyed to guide the selection of sulfur and carbon sources to optimize N, S-CDs quantum yield (QY), so thiourea and disodium edetate are co-carbonized with biogenic creatinine at 270°C for 40 min and characterized using different techniques. The resulting N, S-CDs have a homogeneous particle size distribution and high QY (60.5% ± 2.09%, n = 5). The produced N, S-CDs fluorescence intensity (FI) had been quantitatively quenched by Cu²⁺, achieving a detection limit reached of 0.07 μM. The developed environmentally friendly and sustainable platform, according to the results of three widely greenness assessment tools and the innovative RGB 12 model, had been successfully employed to detect Cu²⁺ in drinking water with excellent recovery. Finally, as this sensing platform is rapid and selective, it can be successfully employed to determine the Cu²⁺ in real-life applications.

Anions play a crucial role in various environmental, chemical, and biological processes. Among various anions, the production of perchlorate (ClO₄ ^-) ion is expected to rise in upcoming years, and thus, an efficient method for the detection of perchlorate ion is highly desirable. In this effort, a pyridyl-benzimidazole-based luminescent probe (RSB1) containing two N-H donor sites has been synthesized for selective detection of perchlorate ion. Different spectral techniques such as FT-IR, NMR, ESI-mass, UV-Vis, and fluorescence analyses have been used to characterize this probe. High selectivity of RSB1 for ClO₄ ^- was realized even in presence of strongly interfering species in aqueous-acetonitrile (CH₃CN-H₂O; 4:1, v/v) solution. Notably, RSB1 served as a "turn-on" perchlorate-responsive probe and exhibited an emission enhancement at 363 nm when excited at 300 nm. The detection limit (LoD) and the binding constant (K_b) values were depicted to be 0.121 μM and 2.6 × 10⁵ M^-1, respectively, while the binding mechanism for RSB1-ClO₄ ^- was validated via Job's plot, NMR, and DFT analyses. Furthermore, this probe was successfully employed to trace perchlorate in real samples such as tap water, distilled water, and soil samples with good to excellent recovery values.

Tetrachlorobisphenol A (TCBPA) is a kind of fire retardant extensively used in our life, but it can accumulate in organisms and potentially have toxic effects. Transferrin (TF) is a glycoprotein predominantly present in the blood plasma, serving as an essential mediator for the transportation of iron and other small molecules. In our study, various techniques including multi-spectroscopic and molecular docking were employed to examine the interaction between TCBPA and TF. The TF-TCBPA complex was formed with the binding constant (K_a) in 2.181 ± 0.035 × 10⁴ M^-1 at 298 K. ΔH and ΔS were all negative, which means dominant driving forces were van der Waals forces and H-bonds. The secondary structure of TF was changed by TCBPA, resulting in a decline in the α-helix structure, and a corresponding increase in the β-sheet structure. The molecular docking revealed that TCBPA was positioned within a pocket of TF, and it engaged in interactions with some amino acid residues through different forces. Importantly, the interaction between Tyr426/Asp392/His585 and TCBPA implies that TCBPA potentially interferes with the transportation of iron ions in vivo. All of above results indicated the adverse effects of TCBPA on the TF structure and activity should be more attention.

Bioluminescence inhibition (BLI) measurements in bioluminescent bacteria (BB) is perceived as a potential qualitative and quantitative indicator of hazardous materials. Acute but minor fluctuations in osmolarity and pH do not affect the living systems significantly. However, significant BLI is observed from marine BB due to acute osmolarity or pH changes that may affect the bioassay sensitivity. Often, real samples have low pH and osmolarity, interfering with the hazard assessment based on the principles of BLI. This anomaly in BLI measurements may lead to false positives. Therefore, modifications in existing analytical methods to overcome such practical constraints are envisaged. In the present research, a marine BB was utilized to study the luminescence reversal effect when exposed to stressful environments such as hypotonic (deionized water), acidic (50 μM to 50 mM HCl), and 0.1-100 ppm of Hg(II) for 0-30 min. Postincubation, the calcium alginate immobilized bioluminescent bacteria (biophotonic beads) were transferred to Boss media to observe any luminescence enhancement. The results showed that osmotic shock and low-strength acidic environments (50 μM to 0.5 mM HCl) at specified incubation times were not detrimental to the biophonic beads regarding luminescence response.

The present study introduces the idea of a novel fluorescence-based imaging technique combined with a microfluidic platform that enables a precise control of dark transient state populations of fluorescent probes flowing over a uniform, top flat supergaussian excitation field with a constant flow rate. To demonstrate the imaging capability of the proposed detection method, numerical simulations have been performed by considering laser, microscope and flow parameters of experimental setup together with photophysical model and electronic transition rates of fluorescent dyes. As an output data to be assessed, fluorescence image data is simulated numerically for bromine-free carboxyfluorescein and its brominated derivatives having different numbers of bromine atoms. Based on the magnitudes of applied excitation irradiances and flow rates, which can be manually controlled by user during experiments, the presence of dark state populations can appear as broadening, shifts and decays in normalized fluorescence intensity signals that are computed from simulated fluorescence images. As such changes in signals become more pronounced upon an increase in the degree of bromination, it is elicited that heavy atom effect can be resolved by properly tuning excitation powers of laser and flow rates. Proposed imaging method has potential to provide invaluable means to conventional fluorescence methods and can open up new perspectives in biomedical research.

Bioluminescence is a functional property used by many marine organisms for multilateral communications. In the Arabian Sea, the dinoflagellate Noctiluca scintillans (Macartney) Kofoid and Swezy, 1921, contributes gradually to the bioluminescent potential (BP) of the phytoplankton community. Experiments, field sampling, and remote sensing were employed, to estimate the seasonal variation of the BP and the abundance of cells in the northwestern Arabian Sea. An experimental setup for BP measurements integrated a "Chelsea Instruments" GlowTracka sensor, which required ~5 N. scintillans cells to obtain a statistically robust signal. Plankton were sampled with 200-μm mesh size nets, in the upper mixed layer. Also, N. scintillans cells were counted in Niskin bottle samples collected from the deep chlorophyll maximum. The remotely sensed chlorophyll-a concentration was analyzed, for the period from 2000 to 2022. A positive linear relationship between the abundance of N. scintillans cells in experiments and their BP was elucidated. Peaks of BP in experiments fit the Northeast and Southwest Monsoon periods and so did the N. scintillans abundance peaks in situ. These findings showed that BP may serve as an indicator of N. scintillans abundance and biomass in the northwestern Arabian Sea.

Mercury ions (Hg²⁺) seriously harm the central nervous system of humans, leading to brain damage and even heart failure and death. Therefore, effective detection of Hg²⁺ in water quality has become an urgent research field. It is very important to develop economically efficient fluorescent sensors to achieve rapid and sensitive detection of Hg²⁺. Therefore, the high fluorescence quantum yield fluorescent carbon dots (CDs) with amide group were prepared. The process of preparing CDs was regulated by multiple key factors (carbon source, proportion, time), and the CDs with the best fluorescence performance were selected. It was comprehensively characterized, including fluorescence performance, surface structure, phase, and morphological characteristics. The amide group endows CDs with the ability to act as both donors and acceptors for hydrogen bonding, forming complexes with metal ions, thus making them suitable for the detection of Hg²⁺. It is worth noting that CDs can quickly detect Hg²⁺ within 1 min, and there is a good linear relationship within the ranges of 0.001-200 μM and 200-500 μM. The detection limit of UC-CDs is 8.2 nM. This study provides a fluorescent sensor with fast reaction, excellent sensitivity, and selectivity for the efficient detection of Hg²⁺ in water.