Journal of Fluorescence最新文献

The current study describes the synthesis and characterization of AgNPs stabilized with a diester-based cationic gemini surfactant (C₁₂-E2O2-C₁₂), and their interaction behavior with protein. The main aim of the study was to explore how the surfactant-coated nanoparticle surface controls the binding and structural response of porcine serum albumin (PSA), acting here as the model protein. Synthesized C₁₂-E2O2-C₁₂-AgNPs were characterized by a spherical morphology, average size of 12.57 nm, and positive surface potential of + 19.50 ± 8.55 mV, confirming their stable dispersion. UV-Vis and fluorescence spectroscopic analyses revealed spontaneous and moderate binding of PSA to the nanoparticles, with the binding constants of 3.44 × 10⁴ M⁻¹ and 7.40 × 10⁴ M⁻¹, respectively. The interaction was mainly driven by electrostatic and hydrophobic forces, leading to changes in the secondary structure of PSA, as supported by FTIR and deconvolution of the amide I band. Surface tension studies further confirmed PSA-induced modulation of the interfacial property of the C₁₂-E2O2-C₁₂-AgNPst system, with a decrease in CMC and rise in molecular area (A_min), suggesting protein-mediated reorganization at the interface. Overall, these results offer new insights into the role of gemini surfactant-coated AgNPs in modulating protein-nanoparticles interactions relevant for biomedical and biosensing applications.

Compared to monomeric counterparts, excimer probes exhibit significantly red-shifted spectra, broadened emission profiles, and enhanced Stokes shifts, exhibiting distinctive advantages in bioimaging applications. In this work, we developed an excimer-forming membrane-targeting fluorogenic probe (DIPP) through covalent conjugation between two triphenylimidazole moieties via a 1,5-bis(pyridin-1-yl)pentane linker. In various organic solvents, DIPP demonstrated exclusive excimer fluorescence, except in DMSO where monomer-excimer dual emission was observed, whereas its monomeric counterpart (MIPP) exhibits predominant monomer fluorescence, demonstrating that dimerization enhances excimer formation. Notably, DIPP displays negligible fluorescence in aqueous solution but exhibits significantly enhanced excimer emission intensity upon incorporation into SDS micelles. Leveraging the environmental sensitivity of excimer emission, DIPP was employed as a membrane-targeting fluorescent probe demonstrating multiple advantages: bright red emission (> 610 nm), a large Stokes shift (Δλ > 210 nm), low cytotoxicity, rapid cellular internalization (~ 5 min), and wash-free imaging capability.

Fluorescent conjugated polymers, recognized for their environmental stability, biocompatibility, tunable conductivity, and facile processability, have been extensively employed in the fabrication of multifunctional materials. In this study, three novel fluorescent conjugated polymers-PF-SO10 (blue), PF-SO10-BT1 (green), and PF-SO10-DTBT1 (red)-were synthesized and characterized, and subsequently applied for the enhancement of latent and visible blood fingerprints via powder dusting. Under 365 nm irradiation, the developed fingerprints displayed strong fluorescence, enabling clear visualization across six non-porous substrates and revealing third-level fingerprint details. The prominent photoluminescence property of the conjugated polymers provides a basis for the visualization of blood fingerprints. In a comparative evaluation with conventional reagents, including Amido Black 10B (AB) and 3,3',5,5'-Tetramethylbenzidine (TMB), demonstrated the superior performance of this method. To address the potential subjectivity of visual inspection, a Python-based quantitative evaluation framework was further introduced, incorporating metrics such as global contrast, average gradient sharpness, local contrast, and ridge orientation consistency. Collectively, the findings highlight the advantages of this strategy, including low cost, high contrast, strong selectivity, and minimal background interference, thereby offering a promising approach for reliable detection and visualization of blood fingerprints in forensic applications.

A series of phosphors based on a pellyite-type BCZSO (Ba₂CaZn₂Si₆O₁₇) silicate host were synthesized via the conventional solid-state reaction method by co-doping with various combinations of metal ions (Pb²⁺, Bi³⁺) and rare-earth ions (Bi³⁺, Eu³⁺; Bi³⁺, Tb³⁺; Bi³⁺, Tb³⁺, Eu³⁺; and Pb²⁺, Eu³⁺) at different concentrations. The structural and morphological characteristics of the prepared samples were examined using powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Their photoluminescence (PL) properties were systematically investigated. The efficiency of energy transfer between sensitizer and activator ions was analyzed in the co-doped systems. Luminescence decay profiles revealed that the lifetimes of the doped ions fall within the microsecond (Pb²⁺, Eu³⁺) and millisecond (Bi³⁺, Eu³⁺; Bi³⁺, Tb³⁺, Eu³⁺) ranges. The chromatic properties of the phosphors were evaluated using CIE chromaticity coordinates, and the correlated color temperature (CCT) values indicated that Bi³⁺, Eu³⁺ co-doped samples emit in the cold white region, while Bi³⁺, Tb³⁺; Bi³⁺, Tb³⁺, Eu³⁺; and Pb²⁺, Eu³⁺ doped samples emit in the warm white region. Given their promising thermal stability and efficient near-white light emission, the BCZSO-based phosphors demonstrate potential as suitable candidates for use in phosphor-converted white light-emitting diodes (pc-WLEDs).

Strontium orthogermanate (Sr₂GeO₄) doped with Mn⁴⁺ and Cu²⁺ phosphors were prepared by high temperature solid state reaction. All the prepared phosphors were crystallized in the orthorhombic lattice with space group Pbn2₁. The surface morphology of prepared phosphors contains irregular shaped objects with considerable agglomeration. The FT-IR and Raman profiles of the compositions gave characteristic bands belonging to GeO₄^4- tetrahedra. Photoluminescence profiles of Sr₂GeO₄: Mn⁴⁺ compounds are characterized by red emission at 647 nm upon excitation at 433 nm, while Sr₂GeO₄: Cu²⁺ compositions gave orange emission at 603 nm under excitation at 403 nm. The emission mechanism of Sr₂GeO₄: Mn⁴⁺ was explained by Tanabe-Sugano energy level diagram of Mn⁴⁺ ion. The CIE chromaticity coordinates, color purity (CP) and correlated color temperature (CCT) values were deduced. Thermoluminescence profiles are characterized and trap depth parameters were evaluated. These compositions may be useful in the manufacturing of cool and warm solid state lighting sources.

The detection of ferric ions (Fe³⁺) is of crucial importance in environmental monitoring and biomedical diagnostics. However, developing highly selective, sensitive, and environmentally friendly detection methods remains an important challenge. In this study, nitrogen-doped carbon quantum dots (N-CQDs) were green-synthesized as a novel and sustainable fluorescent sensor for Fe³⁺ detection. The synthesis was achieved via a one-pot hydrothermal method using licorice powder as a renewable carbon source and p-phenylenediamine as a nitrogen dopant. The synthesized N-CQDs display bright blue fluorescence, with a maximum emission at 436 nm when excited at 320 nm. They serve as a highly selective and sensitive fluorescent probe for Fe³⁺, showing a distinct fluorescence "turn-OFF" response. The sensor offers a linear range of 0 to 50 µM for Fe³⁺ detection, with a calculated limit of detection (LOD) of 0.346 µM. A notable aspect of this work is the demonstration of an "ON-OFF-ON" sensing paradigm. The fluorescence quenched by Fe³⁺ can be effectively restored ("turn-ON") by adding ascorbic acid, which reduces Fe³⁺. This "ON-OFF-ON" behavior emphasizes the specificity of N-CQDs towards Fe³⁺ to Fe²⁺. The practical applicability of the sensor was confirmed through successful detection of Fe³⁺ in complex real-world samples, including beer and human blood serum, achieving excellent recovery percentages (97.6% - 101.7%) and low relative standard deviations (RSD, 0.9% - 1.8%). Overall, this research presents an environmentally friendly N-CQD-based fluorescent sensor with a unique reversible fluorescence response "ON-OFF-ON" for Fe³⁺, holding great potential applications in environmental monitoring and biomedical diagnostics.

Viscosity plays a pivotal role in regulating diffusion, a process central to various biological functions. Its detection is crucial in diagnostics, disease detection, and food freshness identification. To probe such micro-viscosity changes in live cells, fluorescent molecular rotors (FMRs) are commonly employed. The study developed two benzothiazole-based fluorescent molecular rotors, BCN1 and BCN2, designed for viscosity sensing via the TICT mechanism. Both probes were structurally characterized by various techniques such as NMR, FTIR, HRMS, SCXRD and exhibited high sensitivity of 1.18 cP (BCN1) and 1.94 cP (BCN2) in methanol-glycerol mixtures. Photophysical studies revealed strong emission, large Stokes shifts, pH resilience, and minimal aggregation. Biocompatibility was confirmed through cytotoxicity assays, enabling successful application in live-cell imaging and food spoilage detection. Solid-state fluorescence probes enabled high-resolution latent fingerprint visualization across various substrates, revealing nine different features of three different levels of fingerprint analysis. DFT calculations supported their electronic properties. Collectively, BCN1 and BCN2 emerge as multifunctional probes with broad utility in biological, environmental, and forensic applications.

Oral squamous cell carcinoma (OSCC) remains a challenging malignancy due to poor drug efficacy and adverse effects. Resveratrol (RV) shows anti-OSCC potential but suffers from low solubility and bioavailability. To address this, a multifunctional polymer hybrid nanoparticle-poly(lactic-co-glycolic acid) (PLGA) modified with compound 1 and 4-(trimethoxysilyl)butanoic acid (TMSBA), and co-loaded with compound 2 and resveratrol (RV) (1-PLGA-TMSBA@2@RV)-was developed for fluorescence-responsive ferroptosis-associated therapy and pathological ion detection. The material exhibited high fluorescence selectivity toward OSCC-related GSH⁻ and Fe³⁺ ions, with quenching efficiencies of 98% and 92.9%, and a GSH⁻ detection range of 10⁻⁷-10⁻² M (R² = 0.9944) and Fe³⁺ detection limit of 10⁻⁶ M. CCK-8 assays showed RV-NPs significantly inhibited CAL-27 cell proliferation, outperforming free RV (53.8%), with blank carriers demonstrating good biocompatibility. qRT-PCR revealed RV-NPs downregulated ferroptosis regulator SLC7A11 by 71.2%, suggesting a ferroptosis-mediated antitumor mechanism. This nanoplatform offers an integrated approach for enhanced OSCC therapy and real-time pathological ion detection.

The existence of microplastics in the environment is currently a significant worldwide concern. Microbeads found in personal care and cosmetic products (PCCPs) are one of the primary sources of microplastics, which pose a threat to human health and the environment. This study was designed to detect microplastics in a popular PCCP (facial scrub and face wash). Twenty products (10 facial scrubs and 10 face washes) were analyzed using Rhodamine B staining prepared in ethanol, distilled water, and acetone, followed by fluorescence microscopy. All samples tested positive for the presence of microplastics. The observed microplastics displayed orange, red, and green fluorescence and varied in shape, with most appearing irregular and fragmented. One- way ANOVA (F = 31.87, p = 0.0001) demonstrated that there was statistical difference between these solvents and ethanol (11.40 ± 5.03) provided the most effective staining results. FTIR analysis further confirmed that polystyrene and polyurethane as the most common polymers in facial scrubs, while ethylene-propylene copolymer and polystyrene were predominant in face washes. Additional polymers, including polyvinyl chloride, polypropylene, and polyethylene terephthalate, were also detected in some samples. This research highlights the occurrence of microplastics in facial scrubs and face washes and emphasizes the need for increased awareness and stronger regulatory measures to limit their use in cosmetic formulations.