Luminescence最新文献

Heavy metal contamination has emerged as a significant global environmental concern. The contamination of Ni²⁺ and Zn²⁺ has attracted increasing attention, not only because of the pollution it causes but also because of the potential risks it poses to human health. It is of great importance to explore sensitive and rapid analytical methods for the accurate detection of Ni²⁺ and Zn²⁺. This paper presents the design and synthesis of a peptide fluorescent probe, TPE-HN (TPE-Pro-Trp-His-Glu-Phe-Gln-NH₂), coupled with a peptide to tetraphenylethylene (TPE). The aggregation-induced emission (AIE) effect has been employed to construct a rapid ‘turn-on’ assay for Ni²⁺and Zn²⁺ peptide fluorescent probes. The probe is capable of qualitatively detecting Ni²⁺ and Zn²⁺ in different buffer systems and can be distinguished by changes in buffer systems. The limit of detection for Ni²⁺ and Zn²⁺ in a 15% buffer solution was 9.613 mM (R² = 0.9924), whereas the limit of detection for Ni²⁺ in a 20% buffer solution was 1.215 mM (R² = 0.9922). The probe exhibits high sensitivity, high cell permeability and low biotoxicity, rendering it suitable for live-cell imaging under biological conditions. This demonstrates that TPE-HN is capable of detecting Ni²⁺ and Zn²⁺ in biological environments.

During unexpected accidents involving ionizing radiation, quick assessments of doses to public exposed to hazard conditions are crucial. For this purpose, selected household materials can be used as radiation detectors by combining them with a portable reading device. Potassium dietary supplements based on potassium chloride in combination with a portable luminescence reader can be a promising dosimetry tool in such emergency situations. In the paper, results of unknown dose reconstruction based on tablets and pills with granules using optically stimulated luminescence (OSL) method are presented. Some OSL properties were examined: reproducibility of OSL as standard deviation of the OSL or sensitization of samples. Reconstructed doses were compared with dose delivered to BeO detectors. The results obtained for tablets were similar to BeO doses, while pill doses were differential, up to 37%. Overall reconstructed doses were on the same order of magnitude as BeO ones. The measurements were conducted using portable Helios reader due to its ability to measure samples of various shapes and sizes, which is not possible in other OSL reader. The development of mobile readers for emergency use is important because they enable rapid dose assessment on-site without the need for lengthy and expensive laboratory procedures.

We report an eco-friendly, cost-effective, one-pot microwave-assisted synthesis of nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) using citric acid and thiourea in formamide without surface passivation. The N,S-CQDs were characterized by HRTEM, FE-SEM, XRD, EDX, FTIR, Raman, and XPS, confirming monodispersed spherical particles of 4.8 nm with an amorphous carbon phase containing oxygen, nitrogen, and sulfur. The comprehensive photophysical studies of N,S-CQD employed by steady state and different time-resolved spectroscopic techniques (TCSPC, Ultrafast Time-Resolved Fluorescence Up-Conversion and Femtosecond Transient Absorption techniques). These N,S-CQDs show broad UV–visible to near-infrared absorption with peaks near 300 and 400 nm and emit strong blue photoluminescence at 360 nm excitation, with a quantum yield of ~8.4%. Time-resolved spectroscopy (TCSPC, fluorescence up-conversion, transient absorption) reveals multiexponential carrier relaxation with time constants from 0.5 ps to > 500 ps, including a 360 ps rise component and three distinct decay components, indicating complex fluorescence driven by surface defects. Ultrafast decay components correspond to thermal cooling of hot excitons, while later decays relate to carrier trapping at surface states. The tunable optical properties and carrier dynamics make N,S-CQDs promising for optoelectronic applications such as LEDs, sensors, and photodetectors, with further enhancement possible through surface engineering and defect control.

A multifunctional surface-enhanced Raman scattering substrate Fe₃O₄@AgNPs@MIL-101 was prepared. Rapid SERS detection of pesticide residues was realized by direct pre-enrichment and separation on the peel surface. MIL-101 has an ortho-octahedral framework and large pore size, which endowed Fe₃O₄@AgNPs@MIL-101 with the ability to rapidly adsorb and separate positively charged targets. The introduction of tannic acid realized the in situ growth of AgNPs on the backbone, to modulate the electromagnetic enhancement. Pesticide molecules were adsorbed onto the surface of AgNPs mediated by central S atoms, accompanied by the interaction between pesticide molecules and AgNPs, the corresponding SERS signals of different pesticides were observed. Together with the introduction of magnetic coating Fe₃O₄, the molecules were enriched in the hotspot and separated to further enhance the SERS performance. Magnet instead of centrifugation was used to simultaneously perform surface extraction and sample separation for a noninvasive, rapid, immediate, and portable assay. The method was accomplished in measurement of thiram and thiabendazole on apple and tangerine epidermis, and the limits of detection (LODs) were 20 ng/cm² and 4 μg/cm², respectively. The recovery was reasonable, and it showed that the procedure is valuable for the rapid and nondestructive surface analysis of residual chemicals.

This study investigates the development and characterization of liposomes as carriers for a novel herbal contrast agent for magnetic resonance imaging (MRI). Liposomes were synthesized using phosphatidylcholine and cholesterol for the lipid bilayer membrane and a polar fraction isolated from the “Suaeda” plant for the aqueous phase. The encapsulation efficiency, size, zeta potential, stability, and morphology of the liposomes were evaluated using various techniques. Additionally, by cytotoxicity assays, we contrasted the toxicity of the encapsulated contrast agent to the nonencapsulated form. Finally, relaxivity computations were performed to assess the suitability of the liposomal agent for MRI applications. The liposomal contrast agent had suitable physical properties (stable mean size of 163 nm and zeta potential of −60 mV) and better biochemical characteristics than nonencapsulated media. The liposomal agent demonstrated increased relaxivity and acceptable cytotoxicity with a contrast-making concentration. Therefore, the encapsulated herbal contrast agent can be useful for biological applications.

Water-soluble fluorescent carbon quantum dots (CQDs) were synthesized via a single-step, eco-friendly hydrothermal process using Robinia hispida L. flowers as a novel carbon source. Advanced characterization techniques (HRTEM, XRD, XPS, FTIR, UV–vis, and fluorescence spectroscopy) revealed spherical CQDs with an average size of 3.96 ± 0.83 nm and a quantum yield of 5.13%. Under 365 nm UV light, the CQDs emitted blue fluorescence. Fluorescence quenching studies with various metal ions showed a significant 93.5% reduction in FL intensity with 500 μM Au³⁺ ions. At pH 7.0, a linear detection range of 0.5–3.5 μM was achieved, with limits of detection (LOD) and quantification (LOQ) of 0.4 and 1.2 μM, respectively. The non-functionalized CQDs effectively detected Au³⁺ ions in tap, drinking, and river water, acidic mine drainage (sludge), and a standard reference material (CRMSA-C Sandy Soil C), achieving spike recoveries of 96.06%–101.71% with variability below 4.13%.

Solid-state reaction method is employed to prepare K₂Ba₃(P₂O₇)₂:VO²⁺ nanopowder and studied by using powder x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, optical absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and photoluminescence (PL) spectroscopy. XRD studies revealed VO²⁺ ion doped K₂Ba₃(P₂O₇)₂ nanopowder have 21 nm crystallite size, orthorhombic phase, and Pmn2₁ space group. From Williamson–Hall analysis, crystallite size is found as 24 nm. SEM morphology recorded the presence of irregular-sized and round-shaped agglomerates. FT-IR and Raman spectra reveal characteristic bands of phosphate groups. Three characteristic peaks are observed at 848, 695, and 452 nm in optical absorption spectrum. Also, crystal and tetragonal field parameters are calculated as Dq = 1439, Ds = −2789, and Dt = 3422 cm⁻¹. In addition, bandgap energy is found as 3.97 eV. Optical and EPR analyses led to understand the incorporation of vanadyl ions into host lattice. Spin Hamiltonian parameters are evaluated. Basing PL spectrum, Commission Internationale de l'Éclairage's (CIE) chromaticity coordinates are calculated, which are present in reddish-orange region with good color correlated temperature (CCT) and color rendering index (CRI) values facilitating the use in lighting applications and LEDs.

Copper ions (Cu²⁺) play a crucial role in biological processes; however, excessive intake can result in severe health problems. Current methods for detecting copper ions are both expensive and complex. Therefore, there is a need for efficient and straightforward visual detection methods. In this study, novel nitrogen-doped carbon dots (N-CDs) were synthesized via a microchannel method using diethylenetriamine and citric acid as precursors and were characterized by TEM, XRD, and IR, among others. The N-CDs demonstrated high selectivity and strong fluorescence, showing a linear quenching response to copper ions with a detection limit of 46 nM, whereas other common metal ions, such as Ca²⁺ and Mg²⁺, exhibited negligible interference even at higher concentrations. These N-CDs were subsequently applied to test paper, allowing for on-site visual and quantitative detection of copper ions via a colorimetric method. This approach provides a novel solution for the rapid detection of copper ions, with significant potential in environmental monitoring, public health, and industrial applications.

A novel fluorescence-based sensor has been developed for the sensitive detection of malathion, an organophosphorus pesticide, using sulfur-doped quantum dots (SQDs) embedded within graphitic carbon nitride (g-C₃N₄) nanosheets. The SQDs were synthesized through a hydrothermal method, whereas the g-C₃N₄ nanosheets were produced via an exfoliation process. The resulting SQDs@g-C₃N₄ nanocomposite demonstrated outstanding performance for malathion detection in food samples, exhibiting a wide linear detection range of 10–120 μM and an exceptionally low detection limit of 0.02 μM. This sensitivity allows for accurate and rapid pesticide monitoring at trace levels. The sensor's performance was optimized by varying experimental conditions, ensuring that it provided high sensitivity, excellent stability, and impressive selectivity toward malathion, even in complex food matrices.

7-Aminoactinomycin D (7AAMD) is the fluorescent analogue of the anticancer drug actinomycin D (AMD). In order to overcome toxic side effects and enhanced bioavailability of 7AAMD, micellar drug carrier systems could be useful. We have used cationic (hexadecetyltrimethylammonium bromide [CTAB]), anionic (sodium dodecyl sulphate [SDS]) and non-ionic (t-octylphenoxypolyoxyethanol, Triton-X100 [TX 100]) surfactants to prepare micelle. We have explored the mechanism of the interaction of 7AAMD with micelles using steady-state and time-resolved fluorescence spectroscopy. Our results revealed that the Stokes' shift values of 7AAMD were decreased in all three micellar medium compared to that in the absence of any micelle. Thus, 7AAMD is localized in less polar microenvironment of micelles than bulk water. In addition, from the time-resolved fluorescence study of 7AAMD, we found that the relative contribution of the conformers of 7AAMD depended on the surfactant head group. Furthermore, acrylamide induced fluorescence quenching study shows differential accessibility of the quencher molecules towards 7AAMD depending on the ionic nature of the surfactant head group. In the presence of acrylamide, 7AAMD was expelled out from the non-ionic TX 100 micelle but not in CTAB and SDS micelle. Thus, our results are valuable to design new drug delivery system for AMD-like antitumor agents.