Journal of Fluorescence最新文献

Two new Cu(II)-based coordination polymers, [Cu(bib)₀.₅(2,6-ndc)]ₙ (CP1) and [Cu₂(bib)₁.₅(1,4-ndc)₂(H₂O)]ₙ (CP2), were synthesized via a mixed-ligand solvothermal method. Both exhibit stable 3D frameworks, high thermal stability, and strong fluorescence. Their emissions are selectively quenched by Fe³⁺ ions with detection limits of 2.02 × 10⁻⁶ M for CP1 and 3.66 × 10⁻⁶ M for CP2, showing excellent linearity (R² > 0.998), sensitivity, and selectivity. The materials maintain fluorescence stability across pH and time, and PXRD confirms structural integrity after sensing. UV-Vis studies reveal distinct quenching mechanisms: excitation-energy competitive absorption for CP1 and energy transfer for CP2. These results highlight CP1 and CP2 as robust and efficient fluorescent sensors for Fe³⁺ detection.

This work examines bifenthrin (BIF) and resmethrin (RES), two pyrethroid insecticides used in the agricultural area of Niayes, focusing on their analysis in spiked surface and groundwater. Both pesticides have an optimal pH of 7 and an optimal MeOH concentration of 20% in water. Comparing fluorescence intensities across different solvents shows that it is higher in H₂O-MeOH for both BIF and RES. Calibration curves ranging from 0.15 to 7.5 µg mL^- 1 were established in different solvents, and their linearity was confirmed through variance analysis. The method measurement is highly sensitive, with LOD values ranging from 0.12 to 1.76 ng mL^- 1 and LOQ values ranging from 0.35 to 5.82 ng mL^- 1, depending on the medium and pesticide. The interday precision values range from 1.8 to 4.3%, attesting to the intermediate precision of the results. The mean recovery results for the determination of the two pesticides in spiked natural water were satisfactory, ranging from 96.2 to 103.7%, with an intraday precision value less than 5% attesting to the repeatability of the results. Moreover, the interference study shows the robustness of the method.

DNA aptamer sequences were selected in silico with assistance from artificial intelligence (AI) using the new Xelari.com platform against three known immunogenic surface proteins of Treponema pallidum designated Tpp17, Tpp47 and Tp0751. The in silico aptamers were synthesized with 5' Alexa Fluor 647 labels and shown to bind live Treponema pallidum by fluorescence microscopy and spectrofluorometry. While AI-predicted K_d values differed somewhat from measured K_d values, it is clear that the aptamers bound the T. pallidum surface which is consistent with the molecular docking models for each aptamer with each cognate target protein all of which are thought to be largely accessible for binding (i.e., not predominately embedded in the outer membrane or cell wall). All three aptamers also demonstrated good specificity in cross-reactivity binding studies.

Herein, multifunctional fluorescent N-doped carbon dots (N-CDs) are synthesized from O-phenylenediamine and 4-aminobenzoic acid. Hydrothermal synthesis and nitrogen doping make the N-CDs possess good physical and chemical properties with bright emission at 567 nm (QY = 32%) and present obvious excitation dependence. Among common metal ions, only Cr(VI) strongly and linearly decrease the yellow fluorescence of N-CDs in wide concentration ranges of 20.0-180 µM and 180-350 µM. Thus, N-CDs are constructed as efficient fluorescence probe for Cr(VI) with detection limit of 1.94 µM. The mechanism of quenching is indicated as the inner filter effect (IFE). The proposed sensor has been successfully applied in two kinds of water samples. In addition, the CDs are tried to apply for cell imaging. Above experiments prove that N-CDs based sensors are efficient strategies for sensitive Cr(VI) detection and cell imaging.

Intracellular microviscosity is a key physicochemical parameter that influences molecular diffusion, signal transduction, and organelle function. However, fluorescence probes capable of selectively visualizing viscosity dynamics with high sensitivity and biological compatibility remain limited. Here, we report a dihydroxanthene-based viscosity-responsive fluorescent probe, ZKW, constructed with a D-π-A push-pull architecture and an o-bromophenyl molecular rotor. ZKW displays a pronounced viscosity-dependent fluorescence enhancement at 580 nm upon 550 nm excitation, originating from restricted intramolecular rotation and suppressed TICT processes. The probe exhibits good selectivity toward viscosity with negligible interference from polarity, pH, reactive species, metal ions, amino acids, or proteins, along with acceptable photostability and low cytotoxicity. Colocalization studies revealed preferential mitochondrial accumulation with partial lysosomal distribution, enabling simultaneous visualization of viscosity variations in these organelles. Using multiple cellular stress models-including LPS stimulation, oleic-acid treatment, nystatin exposure, and erastin-induced ferroptosis-ZKW effectively reported viscosity elevations at the subcellular level. These results establish ZKW as a robust and versatile tool for probing microviscosity heterogeneity in living cells and for facilitating studies of viscosity-associated physiological and pathological processes.