Journal of Fluorescence最新文献

Stimuli-responsive materials with donor-acceptor (D-A) systems have significant potential for sensing toxic analytes in solution and solid state. In this regard, a new probe, N, N-dimethyl-4-(4-phenylquinazolin-2-yl) aniline (DAQ), was synthesized using microwave irradiation and characterized using various spectroscopic techniques. The crystal structure analysis revealed that DAQ crystallized in a monoclinic system with a P21/m space group. The probe exhibits fluorescence properties in solid state and solution, with positive solvatochromism observed as solvent polarity increased from hexane to DMF, indicating the existence of D-A structural units. The probe DAQ, exhibited reversible switching behaviour in the solution and solid state, indicating its sensitivity to volatile trifluoroacetic acid (TFA) and triethylamine (TEA) as confirmed by spectrophotometric and spectrofluorimetric studies. The binding constant of probe DAQ with TFA and TEA were studied by the Benesi Hildebrand (BH) plot using UV-Vis spectral titration. The estimated association constant was found to be 1.43 × 10⁴ M^- 1. The DAQ aggregation-enhanced emission properties have been successfully utilized to develop security ink and latent fingerprint information encryption on various substrates in their aggregated solid state. The study reveals that the sensitivity of DAQ warrants application on all forms of forensic evidence.

Investigation of the behavior of biopolymers in flow such as Deoxyribonucleic acid (DNA), is a critical challenge in engineering, polymer, and life sciences. In this study, we studied the rheological properties of DNA and flow characteristics in real-time. The velocity measurement was carried out using confocal detection incorporated with Fluorescence Correlation Spectroscopy (FCS). Optical experiments provided an understanding of the diffusion- and flow-dominated regimes for molecules treated in microfluidic channels and lab-on-chip devices in general. We found that the flow-dominated regime starts at a flow rate of 0.3 µl/min and the transitional regime falls into 0.02-0.3 µl/min flow rates. There are a few examples for the detection of DNA and different fragments in flow as such. It is therefore believed to provide valuable insights into the subject of flow dynamics of DNA.

Carbon quantum dots (CQDs), with their remarkable optical properties such as strong fluorescence and biocompatibility, are emerging as versatile tools in biosensing and food safety monitoring. This study investigates binding-induced Förster resonance energy transfer (FRET) between CQDs as donors and aflatoxin B1 (AFB1), a highly toxic mycotoxin, as the acceptor. Spherical CQDs, averaging 4.56 nm in diameter and emitting fluorescence at 455 nm, were synthesized for this purpose. Fluorescence spectroscopy, incorporating Stern-Volmer analysis and time-resolved lifetime measurements, revealed the critical role of FRET in this interaction. The estimated Förster radius (R₀) of 4.81 nm and donor-acceptor separation distance (r) of 5.12 nm corresponded to a FRET efficiency of 46%. The observed decrease in donor fluorescence lifetime further supports the FRET mechanism. Selectivity experiments confirmed the system's specificity for AFB1 detection, with a limit of detection (LOD) of 0.439 nM. These findings underscore the potential of FRET-based CQD systems for sensitive and selective AFB1 detection, highlighting their versatility in fluorescence-based sensing applications and their promise for rapid food safety monitoring.

This study explores the design and synthesis of innovative triazole-carvacrol hybrid molecules via copper-catalyzed 1,3-dipolar cycloaddition reactions. Leveraging advanced computational drug design tools, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiles of these compounds will be meticulously evaluated. Furthermore, molecular docking simulations will unravel the binding interactions and mechanisms with critical cancer therapy targets, including EGFR (PDB ID: 3POZ), BRAF V600E (PDB ID: 1UWJ), and Tubulin (PDB ID: 1SA0). By integrating cutting-edge synthesis and computational techniques, this work aims to uncover potent candidates with significant therapeutic potential in cancer treatment.

The development of nano and micromotors has revolutionized the field of nanotechnology, offering innovative solutions for applications in biomedical engineering, environmental monitoring, and chemical sensing. Among these nano/micromotors, graphene quantum dot (GQD)-based micromotors have gained significant attention due to their unique optical and electronic properties. This study presents the synthesis and characterization of novel graphene quantum dot-based gold-nickel (GQD-Au-Ni) micromotors. These micromotors were synthesized using an electrochemical template deposition process, allowing precise control over their composition and structure. The GQD-Au-Ni micromotors exhibit multifunctionality, employing fluorometric, magnetic, and electrochemical methods for the selective and sensitive detection of ferric ions (Fe³⁺), with a remarkable limit of detection (LOD). The study highlights the potential of these micromotors in environmental monitoring paving the way for future research into multifunctional micromotors for a wide range of applications. The findings underscore the promise of GQD-based systems in advancing sensor technology and addressing critical challenges in environmental and health monitoring.

Glucose is a critical energy source for human cells, and maintaining stable glucose levels is essential for normal physiological functions. Abnormal glucose levels can lead to health issues such as diabetes, obesity, and hypoglycemia, highlighting the need for precise and rapid glucose detection methods for clinical diagnostics and health management. In this study, a novel ratiometric fluorescent probe was constructed for glucose detection. Using glucose oxidase (GOx) and horseradish peroxidase (HRP) as enzymatic mediators, the probe employs orange-emitting carbon dots (oCDs) as the detection signal and red-emitting quantum dots (rQDs) as the reference signal. Glucose is oxidized by GOx to produce hydrogen peroxide (H₂O₂), which subsequently generates hydroxyl radicals (·OH) under HRP catalysis. The ·OH interacts electrostatically with oCDs, forming non-fluorescent complexes and quenching the oCDs fluorescence. Glucose concentration is quantified by monitoring the fluorescence intensity ratio (I₅₉₀/I₇₁₅) between oCDs and rQDs. The probe has a limit of detection (LOD) of 0.47 µM and a limit of quantification (LOQ) of 1.58 µM. After methodological validation, it has been successfully applied to the detection of glucose in human serum. This study provides a solid basis for accurate glucose monitoring and holds potential for the early diagnosis and treatment of metabolic diseases such as diabetes.

Carbon dots (CDs) have recently regarded as an attractive fluorescent sensor for water quality detection. However, the actual detection application of CDs is limited owing to the low fluorescence quantum yield (QY) and unclear ion detection mechanism. Here, nitrogen doped CDs (N-CDs) with abundant amide groups, which were easy to prepare using urea and citric acid under mild reaction conditions and displayed great light absorption and strong fluorescence performance with a fluorescence QY of up to 26.6%. More importantly, N-CDs could achieve selective detection of iron ion (Fe³⁺) and its concentrations as low as 0.47 µM in water. Meanwhile, N-CDs exhibited a good linear relationship within the concentration range of 0.5-500 µM of Fe³⁺. This mainly because the introduction of amide groups of N-CDs not only could serve as both donors (NH-), but also acceptors (C = O) for hydrogen bonding, which consequently increased multifunctional fluorescent recognition sites and formed coordination interactions with metal ions, and ultimately achieved fluorescence detection of ions. Therefore, the preparation of N-CDs rich in amide groups provides a promising strategy for rapid and efficient detection of Fe³⁺ ions for water quality detection applications.

In this work, a dual-emission material based on lanthanide metals was synthesized and used as a ratio fluorescence sensor to respond to Hg²⁺ and H₂O₂, respectively. Tb-BDC-NH₂ as a bimetal MOFs had double ligands and exhibited double fluorescence emission peaks at 550 nm and 450 nm. The two emission peaks of Tb-BDC-NH₂ can be quenched by Hg²⁺ and H₂O₂ respectively, forming a built-in calibration signal for ratio fluorescence detection. Based on the different detection conditions of the Hg²⁺ and H₂O₂, the simultaneous detection of the two detection substances can be achieved with simple operation. This detection system had good stability and anti-interference ability. Under optimal conditions, the detection limit for Hg²⁺ detection was 0.2 µM. Meanwhile, for the detection of H₂O₂, the detection limit was 11 µM and large linear ranges were obtained. Through actual sample testing, it had been proven that the ratio fluorescence sensor based on Tb-BDC-NH₂ had good application prospects. And the work also provided a new idea for double substances detection.

In this study, the sphere-to-rod transition in sodium dodecyl sulfate (SDS) micelles was induced by increasing the ionic strength of the medium. This transition was monitored through the fluorescence of the lipophilic probe 2-amino-N-hexadecyl-benzamide (AHBA), which has a 16-carbon hydrocarbon chain and aggregates in aqueous solution. AHBA fluorescence parameters, such as emission intensity, spectral position, lifetime, and steady-state anisotropy, were monitored to understand the probe's behavior in aqueous solution as a function of ionic strength. The results showed that the addition of NaCl induces a spectral red shift in AHBA fluorescence, suggesting a repositioning of the probe within its aggregate. Fluorescence quenching experiments were also conducted using the Co²⁺ ion as a quencher of AHBA fluorescence, both when free in aqueous solution and at different salt concentrations. The quenching results revealed the presence of two distinct AHBA populations, each with different access to Co²⁺. The Stern-Volmer plots for low Co²⁺ concentrations, where quenching primarily affects the population most exposed to Co²⁺, indicated that NaCl slightly reduces the accessibility of this population to the quencher. Finally, the sphere-to-rod transition in SDS micelles was monitored through fluorescence quenching assays. The Stern-Volmer plots showed a dependence on the ionic strength of the medium, indicating that the change in the micelle shape occurs between 0.2 M and 0.3 M NaCl. Once the rod shape is reached, the quenching constant assumes lower values, suggesting that AHBA becomes more inserted into the micelles, with reduced access to Co²⁺.