Journal of Fluorescence最新文献

In this work, two chain aromatic hydrocarbon derivatives 1-2, which are constructed by linking two 3 H-imidazo[4,5-b]pyridine moieties through phenyls and oxygen bridges, were designed and synthesized. The aggregation and disaggregation behavior of these sensors could be modulated by pH, as evidenced by H¹ NMR, fluorescence spectrum and DLS, attributable to the altered deprotonation of the 3 H-imidazo[4,5-b]pyridine cores. An increase in the sensor concentration leads to the reemergence of aggregation, correspondingly diminishing the fluorescence intensity. Polyaromatic aromatic hydrocarbons (PAHs), known for their luminescent characteristics, demonstrate sustained luminescence even at high concentrations of 10^- 3 M. Notably, the fluorescence of PAHs are effectively quenched upon mixed with 7 × 10^- 5 M aggregated sensor 1 or 10^- 4 M aggregated sensor 2. Aggregation is identified as the predominant mechanism for fluorescence quenching, the finding corroborated by fluorescence spectroscopy and DLS measurements. Based on computational studies and mechanistic evaluations, sensors 1 and 2 emerge as promising candidates for serving as efficient fluorescence quenchers for polycyclic aromatic hydrocarbons.

Particularly in the numerous biomedical application sectors, the special advantages of an absorbing group of fluorescence carbon dots (CDs), such as their low toxicity, physicochemical stability, photostability, and remarkable biocompatibility, are currently garnering a lot of study focus. Because imbalance of Fe³⁺ and Fe²⁺ ions are more hazardous than other ions, they are crucial for maintaining human health. CDs were used as a fluorescent probe to detect these metal ions, Fe³⁺/ Fe²⁺. However, there are a number of problems and disadvantages with conventional sensors that are used to identify metal ions. Carbon-based CDs sensors are more successful at detecting Fe³⁺/Fe²⁺ metal ions than other methods. This article discusses the most recent advancements in CDs, involving sensor uses for the detection of Fe³⁺/Fe²⁺ metal ions. Additionally, It provides a comparison based on parameters such as linear concentration range, detection limit, quantum yield, sensing techniques, selectivity, and sensitivity. Selected research article on carbon dots-based sensors for measuring Fe³⁺/Fe²⁺ ions from 2012 to 2024 is compiled and tabulated.

A series of newly synthesized red-emitting phosphors, La₃Ga₅SnO₁₄:Eu³⁺, were produced through high-temperature solid-state synthesis methods. The phase purity, particle morphology and optical properties were systematically investigated in this work. The prepared fluorescent material has high phase purity. La₃Ga₅SnO₁₄:Eu³⁺ has a strong red emission peak at 612 nm at the excitation at 268 nm, which is caused by the radiative transitions of electrons (⁵D₀→⁷F₂). The optimal doping concentration of Eu³⁺ was observed to be 30 mol% in this series of La₃Ga₅SnO₁₄:Eu³⁺. The mechanism of concentration quenching was determined to be dipole-quadrupole interaction. The chromaticity coordinates of La₃Ga₅SnO₁₄:30 mol%Eu³⁺ were (0.648, 0.352) with a corresponding high color purity of 100%. The thermal stability of the phosphor was also characterized. The luminous intensity could be sustained at 54% at 480 K. The quantum efficiency of the La₃Ga₅SnO₁₄:30 mol%Eu³⁺ phosphor is 64.4%. The exhaustive findings from this study form the basis for advocating the application of these phosphors in light-emitting devices.

Rapid detection of respiratory diseases using a noninvasive bind-and-detect breath test could shift the future of rapid diagnostics. Commercially available biotinylated anti-SARS-CoV-2 spike (S) protein antibody was conjugated to streptavidin-coated quantum dots, purified, and adsorbed onto magnetic-graphene oxide (M-GO) flakes to quench the conjugate. When inactivated SARS-CoV-2 was added at increasing levels, the antibody-quantum dot conjugates desorbed from the M-GO as a function of virus concentration with an apparent limit of detection ~ 9,600 inactivated virus particles within 2-5 min in phosphate-buffered saline (PBS) plus 10 mM Mg²⁺ assessed by a spectrofluorometer. A similar fluorescence response was obtained using a published biotinylated DNA aptamer sequence designated MSA52 and inactivated SARS-CoV-2 in PBS plus 5 mM Mg²⁺. Concentrations of Mg²⁺ greater than 5 mM diminished the aptamer magnetic-graphene oxide desorption (M-GOD) assay performance, perhaps by altering the aptamer's 3-dimensional conformation and ability to bind the virus. As reported previously, the MSA52 aptamer assay demonstrated reasonable specificity for variants of SARS-CoV-2 and significantly less intense detection of inactivated Influenza A and Respiratory Syncytial Virus (RSV) in the M-GOD assay format. This rapid and sensitive detection of inactivated SARS-CoV-2 in clear PBS buffer bodes well for the ultimate goal of rapid homogeneous bind-and-detect detection of COVID and other viral respiratory pathogens in human breath condensates and other easily accessible body fluids.

In this study, an approach to design new fluorescent organic polymers based on benzodithiophene (BDT) chromophores are presented by utilizing machine learning (ML) techniques. For this, the BDT chromophores, from the literature, along with their corresponding λ_e. by using Rapid Discovery Kit (RDKit), their molecular descriptors are designed to employ ML models for predicting their λ_max and λ_e properties. Among the evaluated models, Linear Regression, Random Forest and Decision Tree models demonstrate the best performance, achieving R² values between 0.96 and 0.98. Their analysis of SHapley Additive exPlanations (SHAP) values reveals that the Labute Accessible Surface Area (ASA) and the number of Rotatable Bonds can be the most influential features to impact their performance. Leveraging these insights, their 5,000 new polymers are designed with their predicted λ_e extending up to 987 nm. Their highest Synthetic Accessibility Likelihood Index (SALI) scores for the top 1,000 polymers reaches up to 3.21 to indicate their accessibility for synthesis. This work not only advances the understanding of BDT -based materials but can also provide a framework for designing of new fluorescent polymers.

Dye-sensitized solar cells (DSSCs) are a type of high-efficiency solar cells that can absorb sunlight using a dye sensitizer positioned on top of a titanium dioxide layer. The sensitizer is the core component in DSSCs, and the photo-to-electric conversion efficiency of DSSCs can be significantly improved by optimizing the dye sensitizer structure and properties. In this paper, a set of D-A-π-A sensitizer (SHY1 ∼ 4) were designed by modifying different donor groups and analyzed their charge transfer and photophysical properties. We compared the geometric structure, frontier molecular orbitals, Uv-vis, charge density difference, transition density matrix, photovoltaic and quantum chemical parameters of several molecules by means of density-functional theory (DFT) and time-dependent density-functional theory (TD-DFT). The results showed that SHY-2 with 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline as the donor group possessed the most outstanding photophysical and photochemical properties, including the smallest frontier molecular orbitals energy gap, the wider UV-Vis spectral range, the most appropriate open-circuit voltage value and so on, which provided a theoretical basis for the subsequent design and synthesis of molecules.

Aflatoxin B₁ (AFB₁) is a potent carcinogen which threatens human health, therefore, rapid and efficient detection of AFB₁ is highly needed. Herein, a novel turn-on ratiometric fluorescent nanoprobe (RhB@NH₂-MIL-53(Al)) was fabricated via a facial grinding for sensing AFB₁. With increasing AFB₁ concentration, the fluorescence of Al-MOFs was enhanced due to molecular clamp action and electron transport, while the fluorescence of RhB remained almost unchanged, thus obtaining limit of detection (LOD) of 4.16 nM in the range of 0.005-2.56 µM. The sensor demonstrated excellent anti-interference capabilities and gave reasonable results when used to measure AFB₁ in grains. In addition, a paper-based portable sensor for AFB₁ detection was developed with a LOD of 29.89 nM in the range of 0.04-12.8 µM, while the colour changes from light pink to blue upon UV light exposure, making it a straightforward and effective technique for the on-site determination of AFB₁.

A chemosensor (CNS) built on a naphthalene fluorophore was developed, featuring a disulfide-bridged dimer structure. The probe CNS was completely characterized by the usual spectral analysis methods like ¹H NMR, ¹³C NMR, and HR-MS. The CNS probe selectively detects Cu²⁺ ions and subsequently recognizes the amino acid tryptophan in a semi-aqueous medium of DMF:H₂O solution. The detection of Cu²⁺ ions occur via three distinct mechanisms: suppression of the photoinduced electron-transfer process (PET), arrested rotation of diuryl groups leading to conformational change, and a blue-shifted fluorescence enhancement through intramolecular charge-transfer (ICT). With a 1:1 complexation ratio and a detection limit of 2.14 x 10^-4 M, the CNS probe has been successfully applied in various practical scenarios, including real water sample analysis, glyphosate detection, smartphone-based color detection, and Cu²⁺ ion testing using a cotton-swab method.

Carbon dots (CDs) are extensively utilized in biomedicine, optical devices, and sensing due to their low toxicity, excellent optical properties, and ease of synthesis. Nonetheless, there is ongoing discussion over the comprehensive investigation of CDs photoluminescence (PL) process because of their intricate architectures and surface functions. Carbon dots (CDs) and CD/PVP composites were one step synthesized in a hydrothermal process using citric acid and NaOH as precursors. Due to surface defects of CDs after incorporating into Polyvinylpyrrolidone (PVP) both shift in color as well as change in emission is observed. It shows the enhancement of the luminescence property of CDs/PVP and the application of CD/PVP composite in the field of optical emission. Further for practical application, emission of white light emitting diodes (WLEDs) was demonstrated by coating a 370 nm UV-LED with CD/PVP composite. The WLED shows significant CRI, good S/P ratio, the color gamut score Rg and color fidelity score Rf which are essential features for a good light source. Our research offers a valuable reference for CD/PVP composites in a facile, low temperature and low-cost hydrothermal process and developing WLED with UV-LED and metal free phosphors.

In this paper, electronic absorbance and fluorescence spectra of 4-Pentylphenyl 4-n-benzoate derivatives have been measured in 29 solvents, which are non-polar, polar protic and polar aprotic solvents, and electronic transitions that vary depending on the solvent are identified. As the solvent polarity increases, the forbidden energy difference between the frontier orbitals decreases. The statistical models in order to describe the solvent effect were derived using different solvent parameters. Quite complex and multiple absorbance transitions were observed in different solvent environments. Local fluorescence transition and intramolecular charge transfer occurred in the fluorescence spectra. Absorbance transitions are global transitions, and π*←π is the absorbance electronic transition. The frontier molecular orbitals and electrostatic potential surface were founded using quantum chemical calculations. Refractive indices were found with five different methods and forbidden energy gaps were found with the Tauc method. The forbidden energy ranges were found around 4.1 and 4.5, and the forbidden energy gap decreased as the alkyl chain became longer. All compounds can be defined as insulation materials according to the forbidden energy range. Refractive index values close to the E7 liquid crystal mixture used in liquid crystal display panels were found in the investigated liquid crystals.