Journal of Fluorescence最新文献

In this study, a dual-ratiometric optical probe utilizing europium-doped carbon dots (Eu-CDs) was developed for simultaneous fluorescent and colorimetric detection of tetracycline (TC). The Eu-CDs complex was synthesized through a hydrothermal approach. Upon coordination with Eriochrome Black T (EBT), the Eu-CDs complex exhibits a distinct magenta coloration. Introduction of TC triggers a ligand displacement reaction, resulting in color transition from magenta to blue, resulting in ratiometric colorimetric visual detection. Meanwhile, the TC-bound EBT-CDs@Eu complex emits ratiometric fluorescence change. A ratiometric fluorescence detection method was established for TC based on the absorbance-energy transfer-emission (AETE) mechanism, culminating in the successful design of a dual-ratiometric optical probe. The colorimetric assay demonstrated a detection limit (LOD) of 20.5 nM for TC. Furthermore, the practical applicability of this sensor was validated through successful TC detection in aquaculture samples, highlighting its potential for real-world monitoring applications.

The current study describes the synthesis and characterization of AgNPs stabilized with a diester-based cationic gemini surfactant (C₁₂-E2O2-C₁₂), and their interaction behavior with protein. The main aim of the study was to explore how the surfactant-coated nanoparticle surface controls the binding and structural response of porcine serum albumin (PSA), acting here as the model protein. Synthesized C₁₂-E2O2-C₁₂-AgNPs were characterized by a spherical morphology, average size of 12.57 nm, and positive surface potential of + 19.50 ± 8.55 mV, confirming their stable dispersion. UV-Vis and fluorescence spectroscopic analyses revealed spontaneous and moderate binding of PSA to the nanoparticles, with the binding constants of 3.44 × 10⁴ M⁻¹ and 7.40 × 10⁴ M⁻¹, respectively. The interaction was mainly driven by electrostatic and hydrophobic forces, leading to changes in the secondary structure of PSA, as supported by FTIR and deconvolution of the amide I band. Surface tension studies further confirmed PSA-induced modulation of the interfacial property of the C₁₂-E2O2-C₁₂-AgNPst system, with a decrease in CMC and rise in molecular area (A_min), suggesting protein-mediated reorganization at the interface. Overall, these results offer new insights into the role of gemini surfactant-coated AgNPs in modulating protein-nanoparticles interactions relevant for biomedical and biosensing applications.

Compared to monomeric counterparts, excimer probes exhibit significantly red-shifted spectra, broadened emission profiles, and enhanced Stokes shifts, exhibiting distinctive advantages in bioimaging applications. In this work, we developed an excimer-forming membrane-targeting fluorogenic probe (DIPP) through covalent conjugation between two triphenylimidazole moieties via a 1,5-bis(pyridin-1-yl)pentane linker. In various organic solvents, DIPP demonstrated exclusive excimer fluorescence, except in DMSO where monomer-excimer dual emission was observed, whereas its monomeric counterpart (MIPP) exhibits predominant monomer fluorescence, demonstrating that dimerization enhances excimer formation. Notably, DIPP displays negligible fluorescence in aqueous solution but exhibits significantly enhanced excimer emission intensity upon incorporation into SDS micelles. Leveraging the environmental sensitivity of excimer emission, DIPP was employed as a membrane-targeting fluorescent probe demonstrating multiple advantages: bright red emission (> 610 nm), a large Stokes shift (Δλ > 210 nm), low cytotoxicity, rapid cellular internalization (~ 5 min), and wash-free imaging capability.

Fluorescent conjugated polymers, recognized for their environmental stability, biocompatibility, tunable conductivity, and facile processability, have been extensively employed in the fabrication of multifunctional materials. In this study, three novel fluorescent conjugated polymers-PF-SO10 (blue), PF-SO10-BT1 (green), and PF-SO10-DTBT1 (red)-were synthesized and characterized, and subsequently applied for the enhancement of latent and visible blood fingerprints via powder dusting. Under 365 nm irradiation, the developed fingerprints displayed strong fluorescence, enabling clear visualization across six non-porous substrates and revealing third-level fingerprint details. The prominent photoluminescence property of the conjugated polymers provides a basis for the visualization of blood fingerprints. In a comparative evaluation with conventional reagents, including Amido Black 10B (AB) and 3,3',5,5'-Tetramethylbenzidine (TMB), demonstrated the superior performance of this method. To address the potential subjectivity of visual inspection, a Python-based quantitative evaluation framework was further introduced, incorporating metrics such as global contrast, average gradient sharpness, local contrast, and ridge orientation consistency. Collectively, the findings highlight the advantages of this strategy, including low cost, high contrast, strong selectivity, and minimal background interference, thereby offering a promising approach for reliable detection and visualization of blood fingerprints in forensic applications.

A series of phosphors based on a pellyite-type BCZSO (Ba₂CaZn₂Si₆O₁₇) silicate host were synthesized via the conventional solid-state reaction method by co-doping with various combinations of metal ions (Pb²⁺, Bi³⁺) and rare-earth ions (Bi³⁺, Eu³⁺; Bi³⁺, Tb³⁺; Bi³⁺, Tb³⁺, Eu³⁺; and Pb²⁺, Eu³⁺) at different concentrations. The structural and morphological characteristics of the prepared samples were examined using powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Their photoluminescence (PL) properties were systematically investigated. The efficiency of energy transfer between sensitizer and activator ions was analyzed in the co-doped systems. Luminescence decay profiles revealed that the lifetimes of the doped ions fall within the microsecond (Pb²⁺, Eu³⁺) and millisecond (Bi³⁺, Eu³⁺; Bi³⁺, Tb³⁺, Eu³⁺) ranges. The chromatic properties of the phosphors were evaluated using CIE chromaticity coordinates, and the correlated color temperature (CCT) values indicated that Bi³⁺, Eu³⁺ co-doped samples emit in the cold white region, while Bi³⁺, Tb³⁺; Bi³⁺, Tb³⁺, Eu³⁺; and Pb²⁺, Eu³⁺ doped samples emit in the warm white region. Given their promising thermal stability and efficient near-white light emission, the BCZSO-based phosphors demonstrate potential as suitable candidates for use in phosphor-converted white light-emitting diodes (pc-WLEDs).