Journal of Fluorescence最新文献

Herein, synthesizes of fluorenone azine-based Schiff fluorescence probes: (E)-2-(((9H-fluoren-9-ylidene)hydrazineylidene)methyl)-5-(diethylamino)phenol (3a), (E)-9-(((9H-fluoren-9-ylidene)hydrazineylidene) methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol (3b), and (E)-1-(((9H-fluoren-9-ylidene)hydrazineylidene)methyl) naphthalen-2-ol (3c). The probes were structurally characterized using Fourier-transform infrared spectroscopy (FTIR), ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS) analysis. The probes exhibit hydrogen bonding between phenolic -OH and imine nitrogen, enabling excited state intramolecular proton transfer (ESIPT) and free rotation in the azine (> C = N-N = C <) functional, facilitating twisted intramolecular charge transfer (TICT), and a positive solvatochromism in solvent-dependent emission studies. Further, density functional theory (DFT) based calculations accounted for the observed photophysical TICT and ESIPT processes, revealing a non-covalent interaction between phenolic -OH and imine nitrogen. Furthermore, the fluorescence intensity (log I) showed good linearity (R² = 0.999) with the viscosity (log η) with Förster-Hoffmann coefficient (X) values of 2.238, 1.405 and 3.121 for 3a, 3b and 3c, respectively. The study established the probes toxicity and fluorescence imaging in the Caenorhabditis elegans model. Probe 3a, the first azine-based probe for micro viscosity detection, demonstrated exceptional efficacy in detecting intercellular viscosity and facilitating bioimaging applications.

Sulfur dioxide (SO₂) is widely used in food processing to extend the shelf life of food. However, excessive intake of SO₂ and its derivatives (HSO₃^- and SO₃^2-) can cause oxidative damage to the body, and result in several diseases. How to construct probes for rapid real-time detection of HSO₃^- in the field is beneficial to the developmental needs of practical applications, but it is also very challenging. Here we report a dual-mode fluorescent probe Rh-QL for ultrafast detection of HSO₃^-, which undergoes a specific 1,4-Michael addition reaction with HSO₃^- to achieve near-infrared fluorescence turn-on. Probe Rh-QL can rapidly (< 5 s) respond to HSO₃^- with a color change from purple to green and a strong fluorescence emission at 725 nm. The probe Rh-QL has been used for the detection of HSO₃^- in real sugar samples and can be prepared as a portable sensing kit for the detection of HSO₃^- in the environment due to its high efficiency, rapidity and accuracy. In addition, the probe Rh-QL is able to target label Gram-negative bacteria after reacting with HSO₃^-, which has the potential to identify the type of pathogenic bacteria.

Ce-based nanomaterials have been widely studied as catalyst for their unique electronic structure, but there are few reports on the combination of cerium catalytic activity and photoluminescence performance. In this paper, by adjusting the molar ratio of Ce/P, CeO₂/CePO₄ nanocrystal were synthesized in one-step, which integrated the enzyme activities of CeO₂ and CePO₄, as well as the optical property of CePO₄ together. Taking H₂O₂ as analyte model, utilizing the catalase oxidization activity of CeO₂/CePO₄, TMB molecule can be oxidized, leading to the increased absorption intensity of 652 nm, realizing the colorimetric assay of H₂O₂. On the other hand, using the fluorescence of CeO₂/CePO₄ at 338 nm as output signal, which can be quenched by H₂O₂ since Ce³⁺ ions were oxidized into Ce⁴⁺, realizing H₂O₂ fluorescence detection. Compared with the single-signal probe, CeO₂/CePO₄ provides two sensing modes of fluorescence and colorimetry for H₂O₂ discrimination to obtain different test results, which can be mutually verified and effectively improve the detection accuracy.

Fossil fuels like oil and natural gas continue to be the primary sources of global energy. Enhancing hydrocarbon recovery from exploited reservoirs has been a major scientific concern in the petroleum industry. Following extended exploitation, the reservoir's oil-water dynamics become intricate, thereby complicating petroleum and natural gas extraction. Pore-scale analysis of microscopic remaining oil (micro-remaining oil) offers theoretical underpinning for enhancing production from high-water-cut oil reservoirs. Fluorescence thin-section analysis allows for the direct evaluation of reservoir oil-bearing properties using oil-containing samples, providing insights into the occurrence and distribution patterns of micro-remaining oil without requiring time-consuming core displacement experiments. The high resolution of fluorescence images further establishes this technique as a representative method for studying micro-remaining oil. However, conventional fluorescence image analysis methods are often subjective and labor-intensive. To address this limitation, we trained four deep learning networks-U-Net, ResU-Net, ScSEU-Net, and Unet++-and applied them innovatively to automate fluorescence image segmentation. Evaluation of network performance via statistical metrics and visual observation indicated that all four networks achieved high segmentation accuracy, particularly ResU-Net, which showed robustness against over-segmentation, under-segmentation, and image noise. Finally, leveraging optimal segmentation results, we conducted quantitative analyses of oil saturation, micro-remaining oil patterns, and pore occupancy. The study demonstrated that ternary composite agents substantially decreased the presence of cluster, film, and adsorbed oils by reducing the oil-water mobility ratio and lowering oil-water interfacial tension. Primarily, these agents displaced crude oil from pores larger than 60 micrometers in an equivalent radius, leading to a significant reduction in their content. Nevertheless, substantial quantities of micro-remaining oil are still confined in pores smaller than 50 micrometers in an equivalent radius, emphasizing the need for attention during subsequent development adjustments. Our research has notably improved the efficiency and accuracy of fluorescence image analysis, effectively supporting the enhancement of recovery in high-water-cut oil reservoirs.

The abdominal aortic aneurysm (AAA) is a dilation of the lower part of the body aorta. AAA has no obvious symptoms in the early stages until the aortic wall ruptures suddenly, resulting in massive blood loss and flow into the abdominal cavity. Currently, there is no effective drug treatment for AAA, and the development of effective drugs is crucial. In this study, a novel approach utilizing chitosan/genipin/zinc oxide (CH/G-ZnO) composite nanoparticles as a drug delivery system is proposed. Compound 1 was loaded onto these nanoparticles to form CH/G-ZnO@1 composite. The composite material exhibited light-triggered and rapid gelation properties, and its structure and performance were comprehensively characterized. Subsequently, by treating vascular smooth muscle cells (VSMCs), we found that CH/G-ZnO@1 was able to significantly reduce metalloproteinase (MMP) and increase the expression of COL4A1, thereby increasing the proliferative activity of VSMCs.

To fully utilize the wastes of the traditional Chinese herbs, a highly functionalized fluorescent carbon nano dots (CDs) based ferric ion sensor was prepared from forsythia residue via a one-step hydrothermal method. Under transmission electron microscope (TEM), the CDs were observed to be spherical with the diameter in the range of 5-20 nm. Comprehensive analyses documented the CDs' favorable morphology, diverse functional groups, high water solubility, remarkable optical properties, and exceptional stability under various environmental conditions. Moreover, the CDs exhibited good optical properties with vivid green photoluminescence (PL) when they were exposed to ultraviolet (UV) light. Furthermore, the prepared CDs demonstrated selective fluorescence quenching behavior towards ferric ions with satisfactory sensitivity and a low limit of detection (LOD) of 4.3 µM. Additionally, the CDs displayed good selectivity towards Fe³⁺ and the least interference with several other metal ions. Consequently, this strategy could be effectively applied to real water samples, demonstrating its potential for broader applications.

Vibegron is a novel selective beta-3 adrenergic receptor agonist molecule, recently approved by US Food and Drug Administration (FDA) in tablet pharmaceutical formulation for treating overactive bladder syndrome. Such formulation necessitates the development of a simple, fast and cost-effective methodology capable of assaying the drug in various real samples with high sensitivity. Herein, a facile and robust spectrofluorimetric method was introduced, for the first time, for vibegron quantification based on analytical quality-by-design approach. The method involves drug reaction with dansyl chloride at pH 9.8, as a smart approach to overcome the non-fluorescent nature of vibegron, giving a highly fluorescent yellow derivative measured at 514 nm after being excited at 345 nm. Plausible reaction scheme between the drug and dansyl chloride was elucidated through studying the differences in their infrared (IR) spectra. Variables affecting fluorescence intensities were carefully screened and rationally optimized via preliminary scouting studies and central composite design for accurate and robust results. Full International Council for Harmonisation (ICH) validation protocol was followed where linearity was achieved in range of 20.0-400.0 ng/mL with minimum detectability of 3.6 ng/mL. The proposed method expressed good capability in assaying the marketed dosage forms with no excipient inference. Finally, the high sensitivity of such method paved the way for extending its application to quantify vibegron in spiked human plasma at concentrations around its real human plasma concentrations for further bioavailability studies.

This investigation devised an eco-friendly spectrofluorometric Pb(II) ion measurement approach. To determine Pb(II) ions, a polymeric fluorescence sensor membrane with excellent selectivity has been developed. It contains photoinitiators, functional monomers that can be cured under UV radiation, and cross-linking agents. After the characterization of the membrane, the most suitable parameters for the measurement of Pb(II) ions were determined. The measurement was performed in a short time-roughly 40 s-at emission and excitation wavelengths of 488 nm and 277 nm, respectively, at pH 6.0. The developed method's detection limit was calculated as 1.42 × 10^- 9 mol L^- 1, and its calibration range was recorded as 4.83 × 10^- 9 to 9.66 × 10^- 8 mol L^- 1. Recovery studies and the sensor's stability, lifetime, and repeatability have been evaluated. Real sample applications have been implemented using wastewater samples. The suggested approach may be used to quickly and accurately determine Pb(II) ions at low concentrations with good selectivity and sensitivity.

Yttrium vanadate (YVO₄) is a non-toxic ceramic matrix that, when doped with lanthanides, can be used as a photoluminescent biosensor. In this study, we meticulously synthesized upconversion nanoparticles (UCNPs) of YVO₄ via chemical coprecipitation, using Er³⁺ and Yb³⁺ ions for codoping. The light emission achieved through upconversion mechanisms enables the excitation of nanoparticles with infrared light rather than ultraviolet light, enhancing the potential of current bioimaging techniques. The light emission intensity of our YVO₄: Er, Yb UCNPs, a key factor in their effectiveness, depended on various easily adjustable factors during the synthesis, such as the dopant concentration, the heat treatment, and the cleaning process. The UCNPs were characterized using a range of advanced techniques, including X-ray diffraction (XRD) and Rietveld refinements, as well as Raman, photoluminescence (PL), and ultraviolet-visible (UV-vis) spectroscopies, and high-resolution transmission electron microscopy (HRTEM). We found the most convenient stoichiometry to obtain the YVO₄: Er, Yb UCNPs and showed that a rigorous thermal treatment was necessary to achieve light emission through upconversion mechanisms. We also discovered that some porosity characteristics can be promoted in the YVO₄: Er, Yb UCNPs during the cleaning process, depending on the solvent employed. The porosity and morphology of the nanoparticles could be predicted using the microstrain values obtained from the refinement of the crystalline structures. All these meticulous steps in our research have enabled us to develop an efficient synthesis pathway to produce YVO₄: Er, Yb UCNPs with high photoluminescent intensity.

A new Ni (II) metal-organic frameworks with the formula [Ni₂(HL)₂(H₂O)₄]∙3H₂O (1) and a novel phenoxo-O bridged rare-earth dinuclear Schiff base complex with the formula [La₂(dbm)₄L·CH₃OH] (2), where the HL^2- is the partial deprotonated of the organic ligand H₃L, and H₂L is a bis-Schiff foundation ligand (H₃L = 4,6-dioxo-1,4,5,6-tetrahydro-1,3,5-triazine-2-carboxylic acid, H₂L = N, N'-bis (2-hydroxy-3-methoxybenzylidene) -propane-1,2-diamine, Hdbm = dibenzoylmethane), have been successfully generated under the solvothermal condition. The targeted product sample of 1 and 2 has been fully characterized by single-crystal X-ray data, elemental analysis, FT-IR, powder X-ray diffraction, and thermogravimetric analysis. Furthermore, fluorescence performance testing of the complexes revealed that in complex 1, H₃L forms a rigid chain through coordination with Ni²⁺ ions and further forms a highly rigid three-dimensional framework within the hydrogen bond network, resulting in fluorescence enhancement of up to 13.7-fold, displaying deep blue fluorescence with CIE coordinates of (0.1626, 0.1375). In contrast, complex 2 forms only discrete zero-dimensional molecules and exhibits light blue fluorescence with CIE coordinates of (0.1744, 0.2306). This demonstrates their potential as fluorescent materials.