Journal of Fluorescence最新文献

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.

Zinc phthalocyanines can be used as exceptional chemical sensors due to their outstanding stability, strong NIR absorption, and intense fluorescence emission, which facilitate accurate analyte detection. 3-Hydroxypyridine substituted zinc phthalocyanine (ZnPcPy) has been employed as a dual probe for the fluorescent determination of biliverdin and colorimetric determination of bilirubin. The fluorescence of ZnPcPy is effectively quenched by biliverdin through a static quenching mechanism facilitated by the inner filter effect. Furthermore, when ZnPcPy interacts with bilirubin, it undergoes a distinctive color shift from colorless to pinkish-red, thereby enhancing its efficacy in colorimetric detection. This newly designed dual sensor demonstrates an impressive detection limit of 8.60 × 10^- 8 M and 2.42 × 10^- 7 M for biliverdin and bilirubin, respectively, revealing superior selectivity and sensitivity against other co-existing molecules. Additionally, the methodology has been effectively employed in artificial and real samples, delivering encouraging results.

Hydrogen peroxide (H₂O₂) plays a key role in diverse physiological and pathological processes, including immune responses, cancer progression and aging. Herein, we report a novel ratiometric fluorescent probe (CBN) for H₂O₂ detection, synthesized via a one-step condensation reaction between 3-cyano-7-hydroxycoumarin and 4-(bromomethyl)benzeneboronic acid pinacol ester. The probe exhibited excellent selectivity and sensitivity toward H₂O₂ (limit of detection [LOD] = 0.71 µM) with minimal interference from competing ions. Furthermore, CBN demonstrated application in exogenous H₂O₂ detection in living HepG2 cells, highlighting its potential for biomedical research.

Recently, the fluorescent probe (E)-3-(4-(di(p-toluylamino)phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (TAPHP) was synthesized for hydrazine detection in living cells (Sensors and Actuators B 263 (2018) 229). However, the excited-state intramolecular proton transfer (ESIPT) mechanism of TAPHP has not been experimentally elucidated. In this work, we employ density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate the ESIPT process, electronic spectra, and ring aromaticity of TAPHP in detail. Furthermore, four derivatives (TAPHP-1, TAPHP-2, TAPHP-3, TAPHP-4) were designed by substituting carbon atoms with nitrogen at various positions on the benzene ring to explore the effect of nitrogen substitution on TAPHP's properties. The calculated electronic spectra show good agreement with experimental data, validating the computational approach. Our results reveal that photoexcitation strengthens intramolecular hydrogen bonds, promoting the ESIPT process. Nitrogen substitution causes red-shifts in absorption and fluorescence wavelengths, modifies the ESIPT energy barrier, and reduces both intramolecular charge transfer (ICT) and aromaticity in TAPHP. These findings provide deeper insight into the structure-property relationships governing ESIPT processes and may guide the design of improved fluorescent probes.