Journal of Fluorescence最新文献

This work focuses on the synthesis of Bentonite supported nano zero valent bimetallic nanoparticles (B/nZVCu-M NPs) to be utilized for fast and highly sensitive, reversible, fluorescent determination of dopamine (DA) in the presence of dopamine, other biomolecules and ions. The X-ray Photoelectron Spectroscopy(XPS), Powder X-Ray Diffraction(PXRD) and Scanning Electron Microscopy(SEM) revealed the formation of nanoparticles with size ranging from 15 to 20 nm. The composition was revealed by Fourier Transform Infrared(FTIR) Spectoscopy and Energy Dispersive X-Ray (EDX) Analysis. The Limits of Detection(LOD) were noted to be 5.57nM and 6.07nM. The binding of DA is noted to be reversible with respect to EDTA^2-. Furthermore, the developed sensor exhibited good repeatability, satisfactory long-term stability, and was successfully used for the selective detection of dopamine sample with desired recoveries or reversibilities. The main aim of our work is to selectively detect dopamine in presence of its major interferents and biomolecules that are normally present/ co-exist with dopamine in biological systems.

Preparing a biomass adsorbent material with high-absorption performance but low cost plays a vital role in wastewater treatment. In this study, a novel nitrogen-doped sisal fiber-based carbon dots (SF-N-CDs) composite was prepared by directly growing carbon dots (CDs) on sisal fiber (SF) using a microwave method with polyethyleneimine (PEI) as a raw material. The prepared SF-N-CDs were characterized using FTIR, XRD, Contact angle(CA), TGA, XPS, and SEM. The results revealed that the CDs were successfully grown on SF. The adsorption properties of SF-N-CDs were significantly enhanced when they adsorbed methyl blue (MeB) dye. Specifically, the adsorption of MeB by SF-N-CDs was up to 619.7 mg/g, which was about 2.6 times higher than that of raw SF. This implied that the introduction of CDs increases the adsorption site, thus enhancing the adsorption capacity. Analysis on kinetics and thermodynamics of MeB adsorption by SF-N-CDs revealed that the adsorption process followed the Langmuir isotherm model and were consistent with both kinetic models. It signifies that the adsorption involves both physical and chemical adsorption processes. Further, the SF-N-CDs maintained a removal rate of 70.9% after six adsorption-regeneration cycles, demonstrating good regeneration performance. Moreover, the SF-N-CDs could selectively separate MeB from a mixture of rhodamine B and saffron T. Consequently, the findings of this study suggest that SF-N-CDs are promising adsorbents for anionic dyes.

The rapid development of fluorescence probe technology has promoted in-depth research in fields such as environment and life medicine. Traditional single channel fluorescent probes can achieve highly sensitive detection of targets, but they appear powerless in complex environments. In addition, in today's deteriorating resource environment, implementing multi target detection with one probe can effectively save preparation resources, which is in line with the development direction of fluorescent probes. To achieve this goal, designing and preparing multi-site probes is undoubtedly the first choice, but the complexity of their preparation is daunting. Herein, we propose the concept of cascade detection for the first time. After the probe completes the first target detection, the complex between the probe and the first target is achieved based on the characteristics of the first target to achieve subsequent target detection. Based on this, a metal-organic framework was used as a basic skeleton and the concept of serial reactions was applied. First, copper ions were detected through coordination. Then, the specificity of copper for sulfur-containing amino acids was utilized to detect the three types of amino acids, and the practical applications of the three probes were studied separately.

A fixed Nd³⁺ and varied Yb³⁺ ion concentration were incorporated in a Zinc-Silicate (SZNYX) composite solution using ex-situ sol-gel solution to fabricate a novel thin film (TF) on Si (100)-substrate. The upconversion luminescence (UCL) spectra of the thin films were measured under 980 nm laser excitation, with the most optimized result for Yb³⁺ ion concentration of 1.5 mol%. Additionally, a 2-D photoluminescence (PL) confocal mapping of the SZNY15-TF material confirmed uniform PL distribution throughout the space under the same excitation wavelength. Structural characterization via XRD revealed the tetragonal Zn₂SiO₄ nano-crystalline nature of the film at three distinct annealing temperatures. Morphological characterization using the Field-emission scanning electron Microscope (FESEM) coupled with energy dispersion spectrometer (EDS) affirmed the nanoflower structure and the purity of doping purity in the samples, respectively. These findings collectively confirm the promising UCL properties of the SZNYX-TF samples, suggesting potential applications in photonic.

Diabetes is a chronic metabolic disease characterized by high blood glucose (or blood sugar) levels, which harms the heart, blood vessels, eyes, kidneys, and nerves over time. So, it is crucial to regularly control glucose concentration in biological fluids to check its targets, reduce unpleasant symptoms of high and low blood sugar, and avoid long-term diabetes complications. This study developed a simple, rapid, sensitive, and cost-effective fluorescence system for glucose determination. The fluorescent Aptasensor was fabricated using cadmium telluride quantum dots (CdTe QDs) modified with thioglycolic acid and functionalized with thiol-glucose-aptamer through ligand exchange. The thiol-glucose-aptamer interacted directly with CdTe QDs, increasing fluorescence intensity. However, it decreased when the target molecules of glucose were introduced. The structural and morphological characteristics of the Aptasensor were confirmed by various analytical methods such as UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS). According to the typical Stern-Volmer equation, the relationship between fluorescent quenching and target concentration was linear with a detection limit (LOD) of 0.13 ± 1.95 × 10^-11 mol L^-1 and a relative standard deviation (RSD) of 1.05%. The Aptasensor demonstrated high specificity towards the target and stability over 28 days. Furthermore, it detected glucose in human serum and urine with a recovery rate of up to 99.74%. The results indicate that the fluorescent Aptasensor could be valuable in developing robust sensing technology for low-concentrated analytes.

Recently, a new fluorescent senor based on 3-hydroxy-2-(naphthalen-2-yl)-4 H-chromen-4-one (HFN) for selective detection of H₂S_n was obtained in the experiment (Spectrochim. Acta Part A 271(2022)120962). Based on HFN, three new compounds (HFN1, HFN2 and HFN3) are designed to explore the influences of dimethylamine (-N(CH₃)₂) and cyano (-CN) groups on the excited-state intramolecular proton transfer (ESIPT) process and luminescent features of HFN. After analyzing the mainly geometrical parameters, electron densities and infrared spectra, we discovered that the intramolecular hydrogen bonds (IHBs) in the target molecules become stronger upon photo-excitation. Introducing -CN or/and -N(CH₃)₂ groups into HFN indeed influences its ESIPT behavior and luminescent properties. The -N(CH₃)₂ group enhances IHB, reduces ESIPT barrier and caused absorption/ fluorescence (at T form) peak blue-shift, while the -CN group shows a counterproductive effect. The coincidence of -N(CH₃)₂ and -CN made the absorption/fluorescent wavelength of HFN red-shift more than single -N(CH₃)₂ or -CN group does.

To investigate the role of PbO as a former or a modifier and effect of its compositional variation on the physical, structural and optical properties, lithium lead borophosphate glasses were synthesized by melt quenching technique. For the physical properties of the prepared glasses, density was measured using the Archimedes principle, which showed an increasing trend from 3.13 to 4.51 with increasing concentrations of lead oxide. Additionally, other physical parameters were calculated based on the measured density values. The structural analysis were performed through X-ray diffraction and Fourier transform infrared spectroscopy. Lack of sharp and characteristic peaks in the XRD spectra confirmed the non crystalline nature of the prepared glasses. Structural units due to PbO, ${\text{P}}_2{\text{O}}_5$ and ${\text{B}}_2{\text{O}}_3$ were identified from the FTIR spectra. Ultraviolet-visible absorption spectroscopy was performed for optical properties and increase in the indirect band gap from 4.80 eV to 4.90 eV was observed. One glass sample was chosen for doping of erbium, neodymium, thulium and ytterbium, for study of their up-conversion properties. The UV-Vis-NIR absorption spectra of erbium, neodymium, and thulium samples were recorded, and wavelength of 980 nm was chosen for excitation. Ytterbium, acting as a sensitizer, facilitated the conversion of the excitation infrared light into visible light. Upon excitation at 980 nm, the erbium-doped sample emitted light at 520 nm, 547 nm, and 665 nm, utilizing excited state up-conversion (ESA) and energy transfer up-conversion (ETU) mechanisms. Similarly, the neodymium-doped sample emitted at 542 nm, 602 nm, and 660 nm, while the thulium-doped sample emitted at 488 nm, 521 nm, and 649 nm. The results of up-conversion indicate that rare earth-doped lithium lead borophosphate glasses are excellent hosts for up-conversion processes.

A rhodamine based chemoprobe BESN was engineered and employed as a selective ''OFF-ON'' chromo-fluorogenic sensor for Al³⁺ in H₂O:MeOH (1:9, v:v). Notable changes in the absorption and emission spectra of BESN were clearly detectable upon the addition of Al³⁺. Sensitivity and binding mechanism studies demonstrated a good sensing performance of BESN with nanomolar detection limit (130 nM), and it was found to be highly selective towards interfering metal ions. Besides, the binding constant between BESN and Al³⁺ was found to be 3.19 × 10³ M^-1. Then, the validation study of BESN for Al³⁺ was performed based on significant analytical parameters and statistical tests. The binding of Al³⁺ with BESN (1:1) was probed via infrared, high-resolution mass and emission (Job's plot) spectroscopy measurements. The sensing performance of BESN could make it ideal chemosensor for real applications including vegetable, tuna fish and water samples, also for Smartphone and test-kit applications. The recovery values of the BESN to Al³⁺ were estimated within a range from 95.13% to 105.30% for water, 94.63% to 109.62% for tuna fish and 94.80% to 109.80% for vegetable samples. Additionally, the BESN has very low cytotoxicity and was triumphantly utilized for the recognition of Al³⁺ in living-cells.

A neoteric colorimetric probe based on 2-hydroxy-1-naphthaldehyde (PMB3) was designed and synthesized for the real-time as well as on-site naked-eye detection of Cu²⁺/Ni²⁺ ions. Various physicochemical methods were employed to characterize the probe, and its colorimetric response to different metal ions was meticulously investigated. The probe, PMB3, exhibited a sensitive colorimetric response to Cu²⁺/Ni²⁺ ions among other competing metal ions, culminating in a prominent colour change from colourless to yellow. The stoichiometry of the ligand metal complexes was ascertained to be in a 1:1 ratio using Job's plot analysis, which was further corroborated by ESI-MS data. With detection limits of 4.56 µM for Cu²⁺ and 2.68 µM for Ni²⁺, the method was effectively extended to real sample analysis, ensuring propitious results that closely aligned with the actual values.

Fluorescent polyurethane has been widely used as fluorescent probes and switches due to its diverse structure and properties, but most of them are solvent-based and synthesized from petroleum-based products. A new type of rosin-based anthraquinone fluorescent waterborne polyurethane (WPU-DAAQ) with good and stable fluorescence properties was synthesized by reacting rosin modified ester (RAG) as a diol and 2, 6-diaminoanthraquinone (DAAQ) as a fluorescent agent with diisocyanate. The structure of WPU-DAAQ was characterized by Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy, and hydrogen magnetic resonance spectroscopy. The fluorescence properties, water resistance, and solvent resistance of WPU-DAAQ were tested. The results showed that DAAQ was successfully grafted onto the polyurethane molecular chain. The fluorescence intensity of WPU-DAAQ increases and then decreases with increasing excitation wavelengths, and increases with the increase of solvent ether content, and is significantly enhanced compared to DAAQ. The dispersion stability was good with the increase of DAAQ. The introduction of DAAQ into polyurethane improved the thermal stability, hydrophobicity, and solvent resistance of WPU-DAAQ. Therefore, WPU-DAAQ is a new type of fluorescent waterborne polyurethane with stable dispersion properties, good fluorescent properties, heat resistance and water resistance.