Journal of Fluorescence最新文献

A green-synthesized europium-based metal-organic framework (Eu-ATPA@3RhB) was developed for ratiometric fluorescence sensing of Cu²⁺. Under 245 nm excitation, Eu-ATPA@3RhB exhibits dual emission peaks at 435 nm and 588 nm. When Cu²⁺ is added, the fluorescence at 435 nm is quenched while that at 588 nm remains constant, enabling ratiometric detection based on the I₄₃₅/I₅₈₈ ratio. The method shows a linear range of 1-25 µM (R²=0.99) with a detection limit of 0.25 µM, outperforming drinking water standards. Density functional theory (DFT) calculations elucidate the interaction mechanism between Cu²⁺ and Eu-ATPA@3RhB. The Eu-ATPA@3RhB developed in this study showcases the advantages of green synthesis, simplicity, and swiftness, affirming its potential for Cu²⁺ detection in diverse environmental water samples.

The present work reports the synthesis of novel D-π-A chromophores based on the molecular architecture of triphenylamine (donor group), thiophene (conjugated bridge) and aryl-methanimine (acceptor group). The synthetic route for the target chromophores involved the condensation of 2-formyl-5-(4-(diphenylamino)styryl)thiophene (5) with the appropriate acceptor, either 4-cyanoaniline or 4-nitroaniline (TPAT-CN and TPAT-NO₂), respectively. The newly synthesized chromophores were characterized by absorption and fluorescence spectroscopy, as well as other spectral data. The absorption and emission spectra of the chromophores were recorded in DMSO and presented a good Stokes' shift ([Formula: see text] = 5505-5593 cm^-1). The FMOs patterns and energies, obtained from DFT calculations, for the solvated ground (S_o) and excited states (S₁) have been compared. Moreover, the in vitro cytotoxic activity of the chromophores has been examined against three human cancer cell lines and a human fibroblast line (WI38), using Sorafenib as a reference. The TPAT-CN chromophore displayed strong cytotoxic effectiveness towards HCT-116 and HepG2 cells (IC₅₀ = 6.25 ± 0.36 and 9.44 ± 0.05 µM), while the TPAT-NO₂ analogue exhibited moderate effectiveness across the investigated cancer cells. In addition, the VEGFR-2 kinase inhibition efficacy revealed that both chromophores effectively inhibited VEGFR-2 enzymatic activity in the sub-micromolar range, where TPAT-CN IC₅₀ = 0.53 ± 0.26 µM and TPAT-NO₂ IC₅₀ = 0.62 ± 0.11 µM. Finally, the molecular docking study was conducted against the VEGFR-2 receptor (PDB: 3WZE) and revealed promising binding affinity, superior Sorafenib.

A noble highly selective, sensitive and SmA mesogenic dipeptide-based Schiff base ligand (HL) was synthesized and characterized using various instrumental and analytical techniques. The Schiff base ligand functions as a potent fluorescent chemosensor for the dual detection of Cd²⁺ and Zn²⁺ metal ions with the detection limits of 2.02 nM and 2.68 nM, respectively. Job's plot analysis revealed 2:1 stoichiometric ratio between the probe and the metal ions, with binding constant value of 3.25 × 10⁶ M^- 1 for Zn²⁺ and 5.20 × 10⁶ M^- 1 for Cd²⁺. The probe showed reversibility nature over four cycles through alternate addition of Zn²⁺/ Cd²⁺ and EDTA, exhibiting distinct off-on-off fluorescence, enabling construction of three molecular logic gates. The probe effectively detected Zn²⁺ and Cd²⁺ in real water samples over a broad pH range. The DFT study of the Schiff base and its complexes with Zn²⁺ and Cd²⁺ were performed using LanL2DZ and 6-31G(d, p) basis set with the hybrid correlation B3LYP to ascertain the optimized geometry.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a selective, low-volatility, systemic herbicide. It is used to control broadleaf weeds in certain crops, such as rice, corn, and wheat. The use of 2,4-D has become widespread in both the agricultural and industrial sectors, with the serious drawback that 2,4-D residues can contaminate food, soil, and groundwater sources. It has been classified as a group 2B carcinogen by the International Agency for Research on Cancer. This paper proposes the development of a new alternative methodology to traditional techniques for the control and monitoring of 2,4-D in natural water samples from agricultural areas surrounding the Quinto River in the province of San Luis. The herbicide was quantified directly, in the presence of the anionic surfactant SDS, the systems were filtered through blue band filter paper as a solid support, prior to determination by solid surface fluorescence (SSF) (λ_exc = 555 nm; λ_em = 580 nm). Under optimal working conditions, a detection limit and a quantification limit of 0.33 and 0.90 ng L^- 1, respectively, with a linearity range of 0.90 to 1.13 × 10³ ng L^- 1. The proposed methodology was applied to natural water samples from agricultural areas, adjacent to the Quinto River in the province of San Luis, representing an innovative alternative to conventional methods for 2,4-D monitoring. The concentrations found were near to 3 ng L^- 1. Additionally, among the advantages of the new method, it is important to highlight the generation of low volumes of waste, preserving the environment and thus contributing to some principles of green chemistry.

This study aimed to establish and validate a novel detection method that combines padlock probe technology with fluorescence quantitative PCR (qPCR) for the rapid and specific detection of the SARS-CoV-2 Omicron S371L mutation in the spike protein. Padlock probes and amplification primers were designed and synthesized based on the Omicron S371L mutation site. The probe was designed to anneal with high specificity to the mutation, allowing ligase-mediated circularization only in the presence of the target sequence. The circularized probe then served as a template for qPCR amplification. Assay optimization included probe concentration, ligation temperature, ligase concentration, and ligation time. Analytical sensitivity, specificity, and recovery performance were systematically evaluated. Finally, the method was validated using 30 clinical samples, with results compared to Sanger sequencing. The optimal assay conditions were identified as a padlock probe concentration of 10 nM, ligase at 0.2 U/µL, ligation carried out at 65 °C for 30 min, and 10 µL of the ligated product used for subsequent qPCR amplification. Under these parameters, the assay achieved a limit of detection of 5.78 fM and demonstrated strong linearity (R² = 0.9669). Specificity testing showed clear differentiation between the mutant template and single-, double-, or triple-base mismatches. In performance evaluations, recovery rates ranged from 89.7% to 108.0% in both PBS and urine samples. For clinical validation, the method showed complete agreement with Sanger sequencing results, yielding positive and negative predictive values of 100%. In summary, the padlock probe-based qPCR assay developed in this study offers a fast and reliable approach for detecting the Omicron S371L mutation in SARS-CoV-2. Because the method bypasses the reverse transcription step that is typically required for RNA targets, it simplifies the workflow without compromising accuracy. These features suggest that the assay could be well suited for broader clinical application, particularly in large-scale screening of emerging SARS-CoV-2 variants.

In automated recycling systems, accurately sorting mixed-material waste remains a significant challenge, particularly when materials such as wood, metals, and polymers exhibit similar visual appearances. White polyamide polymer is widely used in industrial components due to its durability and chemical resistance, yet its recovery from waste streams is often hindered by optical similarities to light-colored wood and oxidized or coated metals. This study presents a dual imaging approach that combines laser-induced fluorescence (LIF) using ultraviolet excitation with hyperspectral imaging (HSI) of diffuse reflectance under broadband illumination (400-1000 nm). The fluorescence experiments revealed that the white polyamide polymer exhibited a strong significant wavelength at approximately 740 nm, distinctly separating it from wood and metal, alongside a less prominent secondary response at 443 nm. However, in the visible range from about 480 to 630 nm, the fluorescence responses of wood and polymer substantially overlapped, underscoring the importance of targeting the near-infrared (NIR) emission for effective polymer discrimination. Complementary diffuse reflectance HSI data analyzed through histogram techniques identified optimal wavelengths near 480 nm and 840 nm that enhanced contrast between the polymer, wood, and metal, guiding the design of simplified multispectral systems. This dual-modality imaging strategy integrates molecular fluorescence sensitivity with detailed reflectance profiling to achieve improved material discrimination, paving the way for practical, automated sorting solutions. The insights gained also support the future development of conventional aerial camera systems equipped with optimized filters and illumination sources to monitor and manage polymer waste accumulation on larger environmental scales.

A simple, cost-effective, accurate, and sensitive spectrophotometric method has been developed for the determination of fluometuron in environmental samples. The method is based on the formation of a metal complex between fluometuron and Fe(III), exhibiting maximum absorbance at 347 nm. The calibration curve followed Beer's law in the concentration range of 0.25-5.0 µg mL^- 1, with a correlation coefficient (R²) of 0.997, indicating excellent linearity. The method demonstrated a limit of detection (LOD) of 0.0787 µg mL^- 1 and a limit of quantification (LOQ) of 0.238 µg mL^- 1. Recovery studies performed on spiked environmental matrices showed high accuracy, with percent recoveries ranging from 82.12 ± 2.95% to 97.80 ± 6.11%. The developed method was successfully applied to the analysis of fluometuron in real samples, including tap water, canal water, pond water, and soil, confirming its reliability for routine environmental monitoring.

Although oil film thickness is an important indicator for estimating the volume of oil spill pollution on the sea surface, the quantitative inversion on oil film thickness is still a challenge. This study proposes a quantitative inversion method for oil film thickness based on the three-band fluorescence index (TBFI). The fluorescence of oil film samples with different thicknesses was excited using a tripled-frequency Nd: YAG laser. The fluorescence spectra of the oil film samples with different thicknesses were measured by a high-resolution spectrometer, and the corresponding optimal band combinations were explored using the optimal band combination algorithm. The selected optimal band combinations were combined with partial least squares regression (PLSR) to establish an oil film thickness prediction model. By comparing the prediction results of four TBFI-PLSR models, TBFI3-PLSR showed the best prediction effect for oil film thickness. For gasoline and diesel in the TBFI3-PLSR model, R², RMSE, and MSRE are 0.989, 25.94, 0.80%; 0.908, 78.71, 67.45% respectively.

Detection of tumor biomarkers is critical for early cancer diagnosis and cancer therapeutic monitoring, but traditional methods often lack sufficient sensitivity and specificity, especially at low biomarker concentrations. To address this challenge, in this study a multiplex detection platform based on core-shell quantum dot-encoded silica microspheres was developed for highly sensitive, simultaneous detection of multiple tumor biomarkers in a single assay. The core-shell silica architecture provides a high surface area for bioconjugation, while embedded quantum dots (QDs) offer strong fluorescence, making them ideal labels. Carbon quantum dots (CQDs), which have low toxicity, superior biocompatibility, and high photostability, were used as reporter molecules instead of organic dyes. This choice improved detection sensitivity and reduced the detection system's environmental toxicity relative to traditional dye-based assays. After optimizing QD-silica conjugation and immunoassay conditions, the platform achieved highly sensitive multiplex detection of four tumor biomarkers (AFP, CEA, CA125, CA19-9) commonly used in early cancer screening. Results demonstrated specific detection of all four targets within a short time frame, with excellent stability and reproducibility. By enhancing sensitivity for these biomarkers and reducing assay toxicity while improving stability, this platform shows significant potential to greatly improve early cancer screening and cancer therapeutic monitoring in clinical practice.

Cysteine (Cys) plays a critical role in both physiological and food domains, with abnormal levels being closely linked to various diseases. Therefore, the development of highly selective and sensitive detection methods is essential. In this study, a "On-off" fluorescent probe, TPA-DNBS, based on a triphenylamine (TPA) derivative, was designed. Compared to traditional probes, TPA-OH offers greater rigidity, stronger conjugation, and a larger Stokes shift, demonstrating superior signal-to-noise ratio and detection stability in complex biological and environmental samples. The probe exhibits specific response to Cys via a photo-induced electron transfer (PET) mechanism: in the presence of Cys, the DNBS quencher group is cleaved, leading to a significant increase in fluorescence. The probe shows excellent detection performance, with a linear range from 1 × 10⁻³ M to 1 × 10⁻⁹ M and a detection limit as low as 1.05 nM, along with good selectivity, interference resistance, stability, and reproducibility. In practical sample analysis, the recovery rates of spiked Cys in milk and mineral water were 99.7%-106.6% and 102.1%-103.3%, respectively, with relative standard deviations below 2.5%. These results indicate the broad applicability of the probe in complex samples.