Journal of Fluorescence最新文献

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.

A new Chemosensor, 5-ferrocenylsalicylaldehyde-2-pyridinehydrazone (SP-Fc), was designed and synthesized by condensing 5-ferrocenylsalicylaldehyde with 2-hydrazinopyridine. Its structure was characterized by ¹H NMR, ¹³C NMR and HRMS. SP-Fc could be used to identify Al³⁺ through dual optical and electrochemical responses. Upon addition of Al³⁺, The probe exhibited a significant fluorescence enhancement attributed to CHEF and the inhibition of both PET and ESIPT processes. The probe specifically regonized Al^3 + in a wide pH range and had a well linear range (0-200 µM). Job's plot analysis revealed that the interaction of SP-Fc with Al³⁺ was 1:1 binding stoichiometry. The detection limit of probe for Al³⁺ was observed as low as 1.30 × 10^- 7 M. The response mechanism of SP-Fc to Al^3 + was confirmed through NMR titration experiment. Additionally, the electrochemical signals of SP-Fc in the presence of the Al³⁺ was shifted significantly compared with those of the other metal cations tested. Moreover, Confocal fluorescence microscopy imaging demonstrated that SP-Fc can monitor Al³⁺ in living MCF-7 cells with low cytotoxicity. This showcases SP-Fc's promise for biological system and analytical chemistry, providing a robust tool for Al^3 + detection in diverse settings.

Based on Hg²⁺-triggered deselenation-hydrolysis self-immolative reaction, a novel colorimetric and ratiometric fluorescent probe L-1 for Hg²⁺ detection was fabricated. L-1 had maximum absorption and fluorescence emission peaks at 496 nm and 648 nm respectively. Upon reaction with Hg²⁺, these peaks underwent a marked blue shift to 386 nm and 528 nm respectively. Concurrently, the solution colors of L-1 displayed a color transition: from pink to colorless under natural light, and from red to green under a 365 nm UV lamp. Notably, L-1 enabled colorimetric and ratiometric detection of Hg²⁺ via the fluorescence intensity ratio (F_{528 nm}/F_{648 nm}), featuring a large Stokes shift (152 nm), rapid response (6 min), favorable sensitivity (LOD = 0.4 µM), and excellent selectivity against other coexisting metal ions. Furthermore, L-1 was successfully employed for detecting Hg²⁺ in real water samples, such as river water, tap water and drinking water. Most importantly, by integrating the concentration-dependent color gradient of Hg²⁺ with a smartphone application for red-green-blue (RGB) analysis, we established an instrument-free platform for rapid on-site Hg²⁺ detection.

MicroRNA-183-5p is a clinically relevant biomarker, yet its detection is hindered by short sequence length, high homology, and low abundance in complex biological fluids. We report a hydrothermally synthesized nickel chloride-decorated graphitic carbon nitride (NiCl₂@g-C₃N₄) with intrinsic peroxidase-like and fluorescence activities for label-free dual-mode detection. Characterized by multiple spectroscopic and microscopic techniques, the nanocomposite enables quantitative analysis via π-π stacking and van der Waals interactions between the probe and target, eliminating the need for enzymes or fluorescent labels. Under optimal conditions, using the formula LOD = 3Sb/b, the detection limit was calculated as 0.69. This material with broad linear ranges, excellent selectivity, month-long stability, and recovery rates of 97.7-101.6% in spiked serum. This facile and cost-effective platform offers a promising tool for sensitive miRNA quantification in clinical diagnostics.

The temperature-dependent photophysical behavior of Coumarins 6 (C6), 7 (C7), and 30 (C30) was systematically investigated in non-polar alkane solvents (n-heptane, cyclohexane and n-hexadecane) across 303-343 K. Using steady-state absorption and photoluminescence together with time-resolved fluorescence (TCSPC), we quantified emission maxima shifts, quantum yields (Φ), fluorescence lifetimes (τ) and derived first-order rate constants (k_f, k_nr) with propagated uncertainties. Small blue shifts in absorption and emission with heating indicate reduced solute-solvent stabilization. C6 in n-hexadecane showed increased radiative contribution at higher temperature, C7 exhibited high thermal robustness with minimal k_nr activation, and C30 was most sensitive to thermal activation in cyclohexane. Arrhenius analysis of lnk_nr versus 1/T yields activation energies in the range 0.3-5.7 kJ·mol⁻¹ (reported with standard errors). All Φ values were corrected for temperature-dependent refractive index (n(T)) and Förster-Hoffmann analysis lnk_nr vs. ln(η/T) confirms viscosity as a primary control parameter. These quantitative results clarify how solvent viscosity and molecular structure modulate LE-ICT balance and inform the design of thermally stable coumarin fluorophores for sensing and optoelectronic applications.

Synozol Navy Blue poses severe ecological risks, necessitating advanced treatment approaches. Ni-Ag co-doped ZnO (Ni-Ag@ZnO) catalyst was synthesized via the sol-gel method and characterized using XRD, SEM-EDX, BET, UV-Vis, PL, and XPS. In contrast to previous research primarily focused on simple model dyes, this study demonstrates the effective degradation of Synozol Navy Blue, a highly resistant azo dye, utilizing Ni-Ag co-doped ZnO under visible light. Comprehensive characterization, including XPS analysis, offered valuable insights into the oxidation states and successful incorporation of Ni and Ag. Furthermore, scavenger studies, mineralization tests, and pH-dependent performance evaluations elucidated the mechanistic pathways and conditions that optimize photocatalytic activity. Ni-Ag doping reduced crystallite size from 35.4 to 29 nm and increased surface area from 1.89 to 2.54 m²/g, while narrowing the band gap from 3.42 to 3.28 eV. Photoluminescence confirmed reduced electron-hole recombination. Under optimized conditions of 75 mg/L dye concentration, 0.03 g/50 mL catalyst dosage, pH 2-, and 50-min contact time 10% Ni-Ag@ZnO doping ratio achieved 81% degradation efficiency under solar light irradiation, significantly outperforming pure ZnO. The process followed pseudo-first-order kinetics (k = 2 × 10⁻² min⁻¹) and attained 80% mineralization (TOC removal) in 60 min. Scavenging tests identified hydroxyl and superoxide radicals as the dominant reactive species, with IPA and BQ enhancing charge separation. These results establish 10% Ni-Ag@ZnO as a promising eco-friendly photocatalyst for wastewater remediation.