Journal of Fluorescence最新文献

Hypochlorous acid (HOCl) is a reactive oxygen species involved in both host defense and pathological processes, making its detection in biological systems of critical importance. Herein, we report the design and synthesis of a phenazine-based fluorescent probe, PNN, incorporating an imidazoline-2-thione recognition unit for selective HOCl detection. PNN exhibits a distinct "turn-on" fluorescence at 555 nm upon reaction with HOCl, with an enhancement of approximately 108-fold, surpassing that of previously reported thione-based probes, which typically emit in the 445-505 nm range. PNN also shows high sensitivity, rapid response, and excellent selectivity over other reactive oxygen and nitrogen species. Furthermore, PNN displays negligible cytotoxicity in HeLa cells and enables concentration-dependent visualization of exogenous HOCl in living cells. These features position PNN as a robust and reliable tool for monitoring HOCl in complex biological environments, providing a versatile platform for investigating its physiological and pathological functions.

Schiff base tethered 1,2,3-triazole (TBT) having excellent optical properties were examined via fluorescence and UV-vis spectroscopy that revealed it to be a highly selective and sensitive Lead and Copper ions sensor. TBT exhibited colorimetric changes for the Cu²⁺ and Pb²⁺ ions in the solution form. The probe TBT exhibited ultra-low detection limit of 190 pM and 130 pM for the Cu²⁺ and Pb²⁺ ions respectively. The Job's plot analysis confirmed the 1:1 stoichiometry of TBT-Cu²⁺ and TBT-Pb²⁺ complexes and time dependent, pH titration, and the reversibility, mimicking INHIBIT logic gate, were also explored photo-physically. Moreover, TBT-Cu(II) and TBT-Pb(II) complexes were studied via DFT studies at the B3LYP/6-311G++(d, p)/LANL2DZ depicting their binding interactions that supplemented with their experimental FTIR and mass analysis. Furthermore, the practical utility of sensor TBT was validated in real water samples with exclusive Pb(II) and Cu(II) ions detection imminent potential in environmental and analytical applications.

The liquid-assisted grinding method synthesizes six novel europium complexes with "6-fluoro-7-piperazinyl-4-quinoline" (L) and heterocyclic ancillary ligands. This synthesis method is eco-friendly and less time-consuming. The prepared complexes were characterised by various spectroscopic techniques CHN analysis IR, UV-Vis, XRD, EDAX and SEM. IR and NMR spectroscopic techniques indicate the mode of coordination of the ligand and ancillary ligand with metal ions. UV-vis absorption and reflectance spectra of the all complexes give information about the optical properties and Urbach energy of the complexes. Photoluminescent properties in powder and solution state suggest that the complexes show ruby red emission under UV radiation. The ⁵D₀ →⁷F₂ transition is responsible for emitting ruby red color. The intensity of europium transitions increases with the introduction of an ancillary ligand along with L. Judd Ofelt parameter is also vital to define the symmetry of lanthanide coordination environment and lanthanide-ligand bond's nature in the complexes. The LUMPAC software also validates the JO parameters. Color purity and the CCT (correlated colour temperature) values indicate that the complexes with high color purity, warm red-light sources, are used in the illuminating OLEDs. The thermal stability of complexes is investigated by thermogravimetric analysis and temperature-dependent photoluminescence. The branching ratio and lasing aspect were also precisely derived. As a result of all characterisation, these complexes are used in photoluminescent and optoelectronic devices. Complexes are a strong contender for the antimicrobial and antioxidant agent because they have good biological properties.

The hydrazide functional group is known for its specific recognition of peroxynitrite. Upon incorporation into rhodamine fluorophores, the resulting fluorescent probes have been widely used for the real-time tracking of peroxynitrite in biological systems. However, the lack of in-depth research on the fundamental reaction mechanism in peroxynitrite detection has limited the optimization of these probes. In this study, we developed two hydrazide-based peroxynitrite probes by linking hydrazine moiety to rhodamine and thio-rhodamine. The responsiveness of these probes toward peroxynitrite was also systematically investigated. Theoretical calculations indicate that the key mechanism of hydrazide-based probes in peroxynitrite detection lies in the reduced Gibbs free energy difference between the ring-open and ring-closed isomers of the oxidized intermediate, which thereby facilitates the ring-opening process. Overall, this study elucidates the reaction mechanism of hydrazide-based peroxynitrite probes from the perspective of Gibbs free energy, providing valuable insights for the rational design and optimization of rhodamine ring-opening probes.

In this work, we report the synthesis and characterisation of holmium-doped lanthanum indium oxide as a promising luminescent material for biomedical applications. Samples were prepared via the Pechini sol-gel method and structurally confirmed to crystallise in an orthorhombic perovskite phase (Pnma), with minor In₂O₃ impurities. Morphological analysis revealed irregular micrometric agglomerates with homogeneous elemental distribution. Optical studies demonstrated efficient absorption at 890 nm (the first biological window) and emission centred at ~ 1200 nm (the second biological window), attributed to the ⁵I₆ → ⁵I₈ transition of Ho³⁺. The sample doped with 1.0 mol% Ho³⁺ exhibited the highest emission intensity. Luminescence tests confirmed detectable luminescence through up to 4 mm of blood, highlighting the material's potential for deep-tissue imaging. These results position LaInO₃:Ho³⁺ as a viable candidate for infrared bioimaging working in the first and the second biological windows simultaneously.

In this study, a Zinc oxide/Tin dioxide/Carbon quantum dots nanocomposite (ZnO/SnO₂/CQDs NCPs) was successfully synthesized and comprehensively characterized, and its application as a photoluminescence-based sensor for highly sensitive uric acid detection was explored. Individual nanoparticles of CQDs, ZnO, and SnO₂ were synthesized via a hydrothermal method, while the final composite was fabricated through a straightforward physical mixing approach. Characterization results obtained from UV-vis spectroscopy, XRD, TEM, and EDX analyses confirmed the structural integrity, morphology, and improved surface properties of the as-prepared nanocomposite. TEM images revealed that SnO₂ nanoparticles possessed an average diameter of ≈ 3 nm, ZnO nanoparticles ≈ 50 nm, and CQDs ≈ 22 nm, with ZnO, SnO₂, and CQDs randomly interconnected within the ZnO/SnO₂/CQDs nanocomposites (ZnO/SnO₂/CQDs NCPs). The sensing mechanism was governed by the "turn-on" photoluminescence phenomenon, arising from electron transfer between the excited nanocomposite and uric acid molecules. The fabricated sensor exhibited outstanding analytical performance, including an ultra-low limit of detection (LOD) of 0.085 nM, an exceptionally wide linear detection range spanning from 10^-13 M to 0.1 M, and a strong linear correlation coefficient (R² = 0.992) at the excitation wavelength of 420 nm, attributed to the synergistic interactions among the components. These findings underscore the composite's potential as a highly sensitive and reliable platform for uric acid detection. This work thus provides a simple, cost-effective, and promising strategy for clinical diagnostics and broader biomedical applications.

A dual-responsive fluorescent chemosensor based on a 1,3,4-oxadiazole-linked bis-indole scaffold (FM) was developed for the selective and sensitive detection of 2,4,6-trinitrophenol (TNP) and iron ions (Fe³⁺ and Fe²⁺) in aqueous media. The probe exhibits strong photophysical properties, including a prominent emission at 438 nm and a large Stokes shift of 79 nm. Upon interaction with TNP or iron ions, a significant fluorescence "turn-off" response and bathochromic shifts were observed, attributed to π-π stacking, hydrogen bonding, and coordination interactions. Job's plot analysis revealed a 2:3 binding stoichiometry for TNP and 1:1 for both iron species, indicating distinct recognition mechanisms. For TNP, a high Stern-Volmer quenching constant (K_sv = 113.98 × 10³ M⁻¹) and a low detection limit (LOD = 59 nM) were obtained, outperforming many previously reported sensors. The probe also demonstrated reliable detection of Fe³⁺ and Fe²⁺ ions with LOD values of 2.95 µM and 16.2 µM, respectively. The FM sensor exhibited excellent photostability, rapid response (< 30 s), and high selectivity in the presence of competing analytes. Furthermore, a paper-based detection platform was successfully fabricated, enabling rapid visual detection of TNP under UV and daylight. These results highlight FM as a promising fluorescent sensor for environmental and security-related applications involving nitroaromatic explosives and metal ions.