Journal of Fluorescence最新文献

In this study, a series of Ba₂La_1- xSbO₆:xEu³⁺ (x = 0, 5, 10, 15, 20, 25 mol%) phosphors and graphitic carbon nitride (g-C₃N₄) powders were synthesized via a high-temperature solid-phase method. Their structural and luminescent properties are characterized by X-ray diffraction, scanning electron microscopy, and photoluminescence spectra. Upon excitation at 273 nm, Ba₂LaSO₆:Eu³⁺ exhibits pronounced red emission, demonstrating anti-thermal quenching behavior within the temperature range of 313-453 K. At 453 K, its emission intensity reaches 131.3% of its initial intensity measured at 313 K. In contrast, g-C₃N₄ shows rapid thermal quenching, with emission intensity dropping to 12.0% at 573 K compared to that at 313 K. A mixed material, composed of Ba₂LaSO₆:10 mol%Eu³⁺ and g-C₃N₄, demonstrates dual-mode thermometric performance. Using fluorescence intensity ratio (FIR), the maximum absolute sensitivity (S_a) and relative sensitivity (S_r) are determined to be 1.34% K^-1 (522 K) and 1.53% K^-1 (368 K), respectively. Temperature characterization using color coordinate (CIE) shifts achieves maximum S_a and S_r values of 0.16% K^-1 (313 K) and 0.63% K^-1 (313 K), respectively. Additionally, the mixed material exhibits excellent repeatability, achieving a repeatability parameter (R) of 98.8% for FIR and 98.9% for CIE measurements across five temperature cycles. These results underscore the potential of the mixed material for self-calibrating optical thermometers.

A novel Schiff base compound, 3-hydroxy-(2-hydroxy-3,5-dichlorobenzylidene)-2-naphthohydrazide (HDN), was successfully synthesized through the condensation of 3-hydroxy-2-naphthoylhydrazide with 3,5-dichlorosalicylaldehyde. The molecular structure was comprehensively characterized using NMR, HR-MS, and FT-IR analysis. Spectroscopic investigations revealed that HDN demonstrates a selective "turn-off" fluorescent response towards Co²⁺ ions in a PBS: DMF (4:6, v/v) medium with minimal interference from competing metal ions. Mechanistic investigations, including Job's plot analysis and ¹H NMR titration, confirmed a 1:1 binding stoichiometry between HDN and Co²⁺. Density functional theory (DFT) calculations suggested that fluorescence quenching is due to enhanced self-absorption effects upon complex formation. A linear calibration curve was established between fluorescence intensity and Co²⁺ concentration within the range of 0.1-10 µM, with a detection limit of 5.57 × 10^-8 mol/L. Additionally, HDN exhibited significant viscosity-sensitive emission behavior during chitosan cross-linking processes. These findings establish HDN as a dual-functional probe for both environmental Co²⁺ monitoring and real-time viscosity detection in polymer matrix systems.

Orthorhombic-phase silver tungstate (Ag₂WO₄), a polymorphic ternary oxide, was synthesized through hydrothermal methods and thoroughly examined for its crystallographic accuracy, quantum optical behavior, and photonic applications. The gradual adjustment of synthesis time led to morphological phase changes from disordered anisotropic rods to well-defined polyhedral grains, as confirmed by XRD and FESEM. The elemental composition and stoichiometry were validated using EDX and hyperspectral color mapping, which demonstrated atomic-level uniformity. UV-Vis. spectroscopy revealed significant ligand-to-metal charge transfer (LMCT) transitions (O 2p → W 5d/Ag 4d), enhanced by defect-induced intra-bandgap states and localized surface plasmon resonances (LSPR), resulting in a tunable optical bandgap (1.38-2.89 eV). Urbach tail analysis illustrated disorder-induced band edge smearing and electronic localization. Time-resolved and steady-state photoluminescence studies showed biexponential and trap-assisted recombination kinetics, with W1 achieving the highest quantum yield (Φ = 0.693) and ultrafast lifetime decay (τ = 2.1 ns), indicating low non-radiative losses. CIE, NCS, and TM-30-18 vector analyses provided insights into precise chromaticity engineering, revealing high spectral fidelity (R_f = 86.4), an optimized color gamut (R_g = 98), and perceptual hue shifts across the emission spectrum. SPD and ΔE_ab assessments demonstrated spectral coherence, minimal chromatic aberration, and excellent color rendering. Notably, the material's defect-tunable, dye-free photoluminescence facilitated multispectral latent fingerprint detection with sub-micron resolution, linking quantum materials science with forensic biophotonics. These results establish Ag₂WO₄ as a promising plasmonic-semiconducting hybrid for cutting-edge optoelectronic systems, biometric sensing, and high-index photonic coatings.

This study presents the development of a highly sensitive and selective electrochemiluminescence (ECL) sandwich-type immunosensor for the detection of alpha-fetoprotein (AFP), a critical biomarker for early-stage liver cancer diagnosis. The sensor platform integrates a Fe-Ni-based metal-organic framework (MOF) with magnetic Fe₃O₄ nanoparticles (Fe-Ni-MOF), functionalized with primary antibodies (Ab₁). Carbon quantum dots (CQDs) were conjugated with secondary antibodies (Ab₂) to serve as ECL luminophores. The immunosensor demonstrated a wide linear detection range for AFP from 0.001 to 1000 ng/mL, with a low detection limit of 0.0084 ng/mL. Structural, morphological, thermal, and optical characterizations confirmed the successful synthesis and functionalization of the composite materials. Moreover, the fabricated sensor exhibited excellent reproducibility, specificity, and stability, indicating its potential as a practical tool for early cancer diagnostics in complex biological samples.

Latent fingerprints (LFPs) hold significant forensic value for suspect identification and crime scene linkage, yet current methods on second-level characteristics are difficult for personal identification from incomplete LFPs. To address this, we developed a composite material through in-situ encapsulation of aggregation-induced emission (AIE) materials within zeolitic imidazolate framework-L (ZIF-L) via a one-step process. This unique configuration leverages ZIF-L's nanoconfinement effects and host-guest interactions to restrict AIE molecular motion, resulting in enhanced fluorescence intensity and photostability. The resulting AIE-2.5@ZIF-L demonstrated a synergy mechanism involving pressure differential gradients, electrostatic interactions, and hydrogen bonding, enabling selective binding to secretion residues on LFPs ridges. Subsequent red fluorescence emission achieved precise resolution of Level 3 LFPs features (pore distribution, ridge edge contours). This work establishes a design paradigm for AIE-functionalized MOFs and provides a scientific foundation for high-accuracy identification of partial LFPs in forensic applications.

A new series of Cd(II) macrocyclic complexes has been synthesized via template condensation of 1,13-diamino-4,7,10-trioxatridecane with tribulin and its derivatives in the presence of CdCl₂·H₂O (1:1:1 molar ratios). Structural characterization by FTIR, UV-Vis, ¹H & ¹³C NMR, XRD, mass spectrometry, and elemental analyses supports an octahedral geometry. The stability of the complexes in solution phase was validated through time-resolved UV-Visible spectroscopic analysis over 24 h, revealing no detectable signs of dissociation. Photoluminescence properties were examined in the solid state, revealing a common excitation maximum at 230 nm and distinct emission maxima at 467 nm, 395 nm, and 398 nm, respectively. These results demonstrate the significant optical response of Cd(II) macrocycles and highlights their potential for applications in luminescent devices and optical sensors. The antioxidant capacity was assessed using a DPPH-free radical scavenging experiment, which exhibited significant results. The newly synthesized complexes have also been screened for antibacterial and antifungal activities. In vitro antimicrobial screening of the complexes was evaluated against Gram-negative E. coli and Gram-positive S. aureus bacterial strains and A. niger and P. chrysogenum fungal strains. Antimicrobial evaluation demonstrates that these complexes exhibit superior antifungal efficacy compared to the standard drug ketoconazole, highlighting their promise as potent antifungal agents.

In forensic drug analysis, detecting low concentrations of illicit drugs in samples presents a significant challenge. This paper introduces a novel approach for developing molecularly imprinted quantum dot materials (Co-AD QDs-MIPs) capable of efficiently detecting methamphetamine (METH) in artificial urine without the need for extraction or pretreatment. Using free radical polymerization, molecularly imprinted materials were coated onto the surface of quantum dots, forming a Co-AD QDs-MIPs fluorescence nanoprobe. The resulting Co-AD QDs-MIPs demonstrated enhanced specificity for METH detection and showed strong fluorescence quenching. Under optimal conditions, the method enabled selective and quantitative detection of METH. A good linear correlation was observed between the fluorescence quenching effect and increasing METH concentration in the range of 67-469 nM, with a detection limit of 23 nM. The Co-AD QDs-MIPs nanoprobe successfully detected METH in simulated human urine samples, with a recovery rate of 96.2% to 102.1%. Therefore, it is a simple, cost-effective, and selective nanoprobe for detecting low concentrations of METH.

Quinoline imidazole conjugate (PABIQO) was synthesized by one-pot condensation of benzil with 6-methoxy-2-oxo-quinoline-3-carbaldehyde and ammonium acetate in the presence of a non-toxic and inexpensive catalyst, p-toluene sulphonic acid (PTSA). It has been characterized by ¹H NMR, C¹³ NMR and HRMS and was subjected to absorption and emission studies. The photonics of the compound PABIQO showed selectivity and sensitivity towards Fe²⁺ and Hg²⁺ inCH₃CN: H₂O(1:1v/v) at pH 7.4 in PBS buffer. Fluorescence titration, Jobs Plot and Stern-Volmer analysis confirmed 2:1 binding stoichiometry for Fe²⁺ ions and 1:1for Hg²⁺ ions with a binding constant of 7.36 × 10^-3 M^-1 and 5.080 × 10^-3 M^-1 with a detection limit of 1.75 × 10^-6 M and 1.125 × 10^-6 M respectively with a dual analyte interaction. The stoichiometry ratio was confirmed by HRMS analysis. Further, the compound PABIQO was subjected to density functional studies which were in conformity with the experimental results. Additionally, cytotoxicity studies were also carried out which demonstrated the utility of PABIQO as a fluorescent probe for detecting metal ions in live cells, underscoring its potential for bioanalytical and diagnostic applications.

Herein, highly fluorescent blue-emitting carbon dots (B-CDs) were synthesized via a facile one-pot hydrothermal method using folic acid (FA) and tris(hydroxymethyl)aminomethane (Tris) as co-precursors. The synergistic effects of FA's nitrogen-rich aromatic structure and Tris's hydroxyl-rich dendritic architecture enabled controlled heteroatom doping, endowing the CDs with excellent optical properties. The B-CDs exhibited strong blue fluorescence (emission at 446 nm under 360 nm excitation), excellent water solubility, remarkable photostability, and a high quantum yield of 25.27%. Utilizing these B-CDs, we developed an "on-off-on" fluorescent nanoprobe for the dual detection of Ag⁺ and glutathione (GSH). The mechanism involves Ag⁺-induced fluorescence quenching via static quenching, followed by GSH-triggered recovery due to Ag⁺/GSH chelation. Under optimal conditions, there were great linear relationships between [I₀/I-1] and the concentration of Ag⁺, [I₂/I₁-1]and the concentration of GSH, with low detection limits of 17.45 nM and 80.95 nM, respectively. Furthermore, based on the "on-off-on" fluorescent sensing platform, Ag⁺ was effectively detected in mineral water & river water, and GSH was detected in tomato & green pepper.