Journal of Fluorescence最新文献

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.

Trace-level nitrite detection is essential for environmental monitoring. We have developed a rapid, reagent-minimal method for the detection of trace amounts of nitrite. Our study focused on the spectral characteristics of the fluorescent probe 6-amino-1,3-naphthalenedisulfonic acid (ANDSA). We identified the fluorescence intensity at excitation and emission wavelengths of 278 nm and 465 nm, respectively, as the key indicator of nitrite quantification. This method, utilizing a 278 nm excitation wavelength, achieves high sensitivity for trace levels of nitrite. The incorporation of ultrasound assistance has reduced the detection time to 12 min. Through method optimization, only two reagents, sulfuric acid and potassium bromide, are required to form the ANDSA solution for sensitive nitrite detection. Nitrite addition reduces the fluorescence emission peak of ANDSA. In the nitrite concentration range of 0 to 3.2 µM, a strong exponential relationship exists between ANDSA's fluorescence response and nitrite concentration, conforming to the equation F₀/F = 0.94183 × e^(0.8766 C). The proposed method yields reliable results, with relative standard deviations ranging from 0.4% to 2.5% and recovery rates between 89.87% and 101.97% for real water samples. This method provides a highly sensitive solution for nitrite monitoring.

Meat adulteration poses significant challenges to public health and consumer trust, necessitating the development of effective detection methods. Isothermal nucleic acid amplification (NAA) techniques, such as loop-mediated isothermal amplification (LAMP) and polymerase spiral reaction (PSR), have emerged as rapid and cost-effective alternatives to conventional polymerase chain reaction (PCR). These techniques simplify infrastructure requirements and can enable naked-eye detection (NED) through visible color changes with specific dyes. This study highlights the potential and suitability of various dyes for the NED of IA-based meat adulteration detection. Intercalating dyes, such as SYBR Green I, bind to the amplified DNA and emit fluorescence. pH-sensitive dyes, including phenol red, neutral red, and xylenol orange, change color with pH shifts during amplification. Triphenylmethane dyes, such as crystal violet and malachite green, directly interact with DNA, showing no pH dependence. Intercalating dyes, such as SYBR Green I, achieve superior sensitivity, often reaching 10 fg of target DNA. Conversely, other dyes like Hydroxynaphthol blue and other pH-sensitive and pH-independent dyes provide slightly lesser sensitivity, typically ranging from 100 fg to 1 pg. Dye-based NED combined with IA offers advantages such as rapid results, high sensitivity and specificity, suitability for field testing, and potential integration into lab-on-chip systems. However, further research is required to optimize dye formulations, develop multiplex assays, enhance sample preparation for complex food matrices, and investigate novel isothermal methods and primer designs. Accurate standardization and validation of these techniques are crucial for their widespread adoption to ensure food safety and consumer trust in the meat industry.