Journal of Fluorescence最新文献

Mercury (Hg²⁺) contamination in water poses severe environmental and health risks due to its extreme toxicity and bioaccumulation potential. Herein, we report a sulfur doped activated carbon derived from banana stem (BS-AC (400)), synthesized via H₂SO₄ activation and low-temperature annealing under N₂, as a low-cost yet highly efficient fluorescent probe for Hg²⁺ detection. Comprehensive characterization (XPS, FTIR, XRD, HR-TEM/SAED) confirmed successful heteroatom incorporation, high porosity, and graphitic domains. BS-AC (400) exhibited intense photoluminescence with a maximum emission at 335 nm upon 230 nm excitation, which was selectively and efficiently quenched by Hg²⁺ even in the presence of 14 competing metal ions. The sensor achieved a detection limit of 9.73 µM and demonstrated excellent reproducibility, photostability, and applicability in real water samples, achieving 94-103% recovery. Comparative analysis with recent biomass-derived sensors revealed that BS-AC (400) offers competitive sensitivity and superior selectivity, attributed to strong Hg²⁺-S interactions (soft-soft binding) and enhanced surface chemistry from heteroatom doping. These results highlight BS-AC (400) as a sustainable, scalable, and versatile platform for real-time mercury monitoring in environmental water systems.

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.

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.

Derivatives of 1,2,4-triazine have emerged as versatile scaffolds with broad pharmacological and biological potential, prompting deeper exploration of their optical behavior. In this study, we investigate the photophysical properties of a novel 1,2,4-triazine dye, 4-amino-6-(4-methoxyphenyl)-1,4,6,7 tetrahydrothieno [2,3-e] [1,2,4] triazine-3(2 H)-thione (Triazine I) with a focus on its interaction with noble metal nanoparticles. The synthesized dye was structurally characterized using FTIR, ¹H-NMR, ¹³C-NMR, and mass spectrometry to confirm its purity and molecular structure. Silver (Ag-NPs) and gold (Au-NPs) nanoparticles were synthesized via a chemical reduction method and thoroughly characterized using UV-vis spectroscopy, TEM, DLS, Zeta Potential, and XRD, confirming their successful formation, stability, and crystalline nature. Spectroscopic investigations revealed solvent-dependent absorption and emission behavior of Triazine I, along with a dual fluorescence response in the presence of nanoparticles: superquenching by Ag-NPs via non-radiative decay enhancement, and fluorescence amplification by Au-NPs through radiative enhancement (MEF). These findings open promising avenues for using such systems in advanced fluorescence-based biosensing and immunoassays. Furthermore, DFT-based computational studies provided insights into molecular geometry, electronic transitions, and electrostatic potential, reinforcing experimental observations and guiding future molecular de sign. This integrated experimental-theoretical approach highlights Triazine I as a promising candidate for tunable optical applications, particularly in bioimaging and diagnostic platforms.

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.