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Scintillation Properties of Ce3+ Doped Silicon-Magnesium-Aluminum-Lithium Glass Scintillators by using Radiation Sources
摘要： Glass scintillators can be doped with different elements to improve their luminescence properties. In this study, we present 0.5 wt% Ce3+-doped (58?x)SiO2-4MgO-18Al2O3-20Li2O and (58?x)SiO2-4MgO-18Al2O3-20LiF glass scintillators. We used a pulsed laser to measure the laser-induced emission spectrum and the decay time with decreasing temperature from 300 K to 10 K. The light intensity of both glass samples increased with decreasing temperature from 300 K to 10 K. Additionally, the two glass samples exhibited a fast decay time of approximately 25 ns. In the photo-induced spectrum, an excitation peak at 312 nm and two emission peaks, at 370 nm and 700 nm, were observed in both the glass samples. The X-ray-induced emission intensity of former is approximately six times higher than that of latter, and only former glass sample exhibits a proton-induced emission spectrum.
关键词： Luminescence,Decay time,Ce3+,Glass scintillator
更新于2025-11-25 10:30:42
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Assessing retinal ganglion cell death and neuroprotective agents using real time imaging
摘要： The evaluation of retinal ganglion cell (RGC) death is a key part of retinal disease care. Previously, we used a Sytox Orange (SO)-based real-time imaging method to assess the RGCs in mice that underwent optic nerve crush. Here, we used N-methyl-D-aspartate (NMDA) injury in rats to confirm our model and assess the effect of neuroprotective agents on RGCs. The rats received NMDA injury and the intravitreal injection of SO, a cell-impermeant dyeing compound that targets nucleic acid. After ten minutes, non-invasive confocal scanning laser ophthalmoscopy visualized damaged or dying cells. Finally, the retinas were flat-mounted for histological confirmation of RGC death, with retrograde Fluorogold labeling and Alexa Fluor 488 Annexin V-conjugate (Annexin V) staining. This also revealed the time course of retinal cell death and the neuroprotective effect of SNJ-1945. Real-time imaging showed that SO-positive cells significantly increased starting 2 hours after NMDA injection and reached an approximate plateau at 3 hours. SO-positive cells were positive for Fluorogold and Annexin V in the isolated retinas. Moreover, the number of SO-positive retinal cells was significantly lower after treatment with SNJ-1945, compared to carboxymethyl cellulose. These results were confirmed in the isolated retinas. Thus, real-time imaging with SO allows the quick quantification of NMDA-induced RGC damage and death, and evaluation of neuroprotective agents. This technique may aid research into the development of new neuroprotective therapies.
关键词： retinal ganglion cell,Real-time imaging,SYTOX orange,neuroprotection
更新于2025-11-21 11:24:58
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Zwitterionic near-infrared fluorophore-conjugated epidermal growth factor for fast, real-time, and target-cell-specific cancer imaging
摘要： Epidermal growth factor receptor (EGFR) is overexpressed in many types of cancers, which is associated with metastatic potential and poor prognosis in cancer patients. Therefore, development of EGFR-targeted sensitive imaging probes has been a challenge in tumor targeting, image-guided cancer surgery, patient-selective anti-EGFR therapy, and efficient targeted therapies. Methods: We synthesized a zwitterionic near-infrared fluorophore (ATTO655)-conjugated epidermal growth factor (EGF) as a novel activatable molecular probe. Fluorescence OFF/ON property and EGFR-targeting specificity of EGF-ATTO655 as well as its utility in real-time near-infrared (NIR) fluorescence imaging of EGFR-positive cancers were evaluated using in vitro and in vivo studies. Results: When conjugated to EGF, the fluorescence of ATTO655 quenched efficiently by photo-induced electron transfer (PET) mechanism between the conjugated dyes and nearby amino acid quenchers (tryptophan/tyrosine residues), which was stably maintained at physiological pH and in the presence of serum for at least 17 h. The fluorescence of EGF-ATTO655 turned on by receptor-mediated endocytosis and subsequent disintegration of EGF in EGFR-positive A431 cancer cells, thereby enabling specific and real-time fluorescence imaging of EGFR-positive cancer cells. Consequently, EGFR-positive tumors could be clearly visualized 3 h post-injection with a significantly high tumor-to-background ratio (TBR = 6.37). Conclusion: This PET mechanism-based OFF/ON type of EGF probe showed great potential for rapid, real-time, and target-cell-specific imaging of EGFR-overexpressing cancers in vitro and in vivo.
关键词： photo-induced electron transfer,Epidermal growth factor,real-time cancer imaging,tumor-specific targeting
更新于2025-11-21 11:24:58
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On the Blue Emitting Phosphor Na <sub/>3</sub> RbMg <sub/>7</sub> (PO <sub/>4</sub> ) <sub/>6</sub> :Eu <sup>2+</sup> Showing Ultra High Thermal Stability
摘要： This work concerns a novel blue emitting LED phosphor activated by Eu2+. It turned out that this luminescent material can be efficiently pumped by near UV or UV-A radiation sources while it exhibits a high quantum yield for a doping level between 0.3 and 3.0%. More impressively, the material has a very high quenching temperature T1/2 and will thus be applicable on-chip in high power phosphor converted LEDs or even in laser diodes. The emission and thermal stability is almost identical to that of BAM:Eu2+ while the absorption band is broader and reaches into the near UV range. Therefore, Na3RbMg7(PO4)6:Eu2+ is a promising candidate as a blue emitter in high CRI full conversion LEDs. To investigate the site preference of Eu2+, DFT and Ligand Field Theory based calculations were performed to successfully predict the emission spectrum. An unusual decay behavior was observed at low temperatures and the underlying mechanism involving spin-forbidden transitions of Eu2+ is discussed.
关键词： high thermal stability,solid state lighting,Eu2+ luminescence,near UV LED,high CRI,decay time,Blue photoluminescence
更新于2025-11-21 11:18:25
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Peptic Fluorescent “Signal-On” and “Signal-Off” Sensors Utilized for the Detection Protein Post-Translational Modifications
摘要： Protein post-translational modifications (PTMs) are typically enzyme-catalyzed events generating functional diversi?cation of proteome; thus, multiple PTM enzymes have been validated as potential drug targets. We have previously introduced energy-transfer-based signal-modulation method called quenching resonance energy transfer (QRET), and utilize it to monitor PTM addition or removal using the developed peptide-break technology. Now we have reinvented the QRET technology, and as a model, we introduced the tunable ?uorescent “signal-on” and “signal-o?” detection scheme in the peptide-break PTM detection. Taking the advantage of time-resolved ?uorescence-based single-label detection technology, we were able to select the signal direction upon PTM addition or removal by simply introducing di?erent soluble Eu3+-signal-modulating molecule. This enables the selection of positive signal change upon measurable event, without any additional labeling steps, changes in assay condition or Eu3+-reporter. The concept functionality was demonstrated with four Eu3+-signal modulators in a high-throughput compatible kinase and phosphatase assays using signal-on and signal-o? readout at 615 nm or time-resolved Fo?rster resonance energy transfer at 665 nm. Our data suggest that the introduced signal modulation methodology provides a transitional ?uorescence-based single-label detection concept not limited only to PTM detection.
关键词： time-resolved fluorescence,signal-off,high-throughput screening,peptide-break technology,protein post-translational modifications,FRET,signal-on
更新于2025-11-19 16:56:35
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Black phosphorous sensitized TiO <sub/>2</sub> mesocrystals photocatalyst for hydrogen evolution with visible and near-infrared light irradiation
摘要： Wide absorption from ultraviolet (UV) to near-infrared (NIR) region and enhanced charge separation are two main requirements for promising semiconductor photocatalysts. Here, we studied visible-NIR driven photocatalytic hydrogen evolution over black phosphorus nanosheets/TiO2 mesocrystals loaded with Pt heterostructure (BP NS/ Pt (3 wt%)/TMC TMC). BP NS/Pt (3 wt%)/TMC can harvest photons from UV to NIR and simultaneously has enhanced charge separation to increase the generation of electrons for photocatalytic reduction of water. BP NS/Pt (3 wt%)/TMC exhibited photocatalytic H2 evolution rates of 1.9 and 0.41 μmol h-1 under visible (λ> 420 nm (420-1800 nm)) and NIR (λ> 780 nm (780-1800 nm) irradiation, respectively, compared with 0.3 and 0.10 μmol h-1 for BP NS/Pt (3 wt%)/P25. Moreover, a comparative study was made to examine the effect of thickness of BP NS on the photocatalytic H2 evolution. Femtosecond time-resolved diffused reflectance spectroscopy (fs-TRDRS) was integrated together with photoelectrochemical measurement to shed the light on the importance of charge transfer and separation, confirming that decreasing the thickness of BP NS enhances electron injection from BP NS to TMC to increase the photocatalytic activity.
关键词： hydrogen evolution,Black phosphorus,visible-light photocatalyst,charge carriers dynamics,TiO2 mesocrystals,femtosecond time-resolved diffuse reflectance
更新于2025-11-19 16:51:07
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Phosphorimetric determination of 4-nitrophenol using mesoporous molecular imprinting polymers containing manganese(II)-doped ZnS quantum dots
摘要： Mesoporous molecularly imprinted polymers (MIPs) containing mangnanese-doped ZnS quantum dots (Mn-ZnS QDs) were prepared for specific recognition and detection of 4-nitrophenol (4-NP). The Mn-ZnS QDs display orange room-temperature phosphorescence with excitation/emission peaks at 295/590 nm and a decay time of 2.0 ms. In the presence of 4-NP, the orange phosphorescence is strongly reduced. Phosphorescence drops linearly in the 0.1–100 μM 4-NP concentration range, and the detection limit is 60 nM. The detection limit is far lower than the maximally allowed 4-NP concentrations in surface water and drinking water as specified by the U.S. Environmental Protection Agency. The intraday (n = 5) and interday (n = 6) spiked recovery rates were 96.0–104.5% and 97.9–107.9%, respectively, with relative standard deviations of 0.7–4.8% and 1.8–7.5% respectively. These MIPs integrated the characteristic features of phosphorimetry and molecular imprinting. Potential interference by competitive substances, background fluorescence or scattered light are widely reduced.
关键词： Room-temperature phosphorescence,Mesoporous molecularly imprinted polymers,Photoinduced electron-transfer,4-Nitrophenol,Decay time
更新于2025-11-14 17:04:02
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Graphene quantum dots enhanced ToF-SIMS for single-cell imaging
摘要： Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has shown promising applications in single-cell analysis owing to its high spatial resolution molecular imaging capability. One of the main drawbacks hindering progress in this field is the relatively low ionization efficiency for biological systems. The complex chemical micro-environment in single cells typically causes severe matrix effects, leading to significant signal suppression of biomolecules. In this work, we investigated the signal enhancement effect of graphene quantum dots (GE QDs) in ToF-SIMS analysis. A × 160 magnification of ToF-SIMS signal for amiodarone casted on glass slide was observed by adding amino-functionalized GE QDs (amino-GE QDs), which was significantly higher than adding previously reported signal enhancement materials and hydroxyl group-functionalized GE QDs (hydroxyl-GE QDs). A possible mechanism for GE QD-induced signal enhancement was proposed. Further, effects of amino-GE QDs and hydroxyl-GE QDs on amiodarone-treated breast cancer cells were compared. A significant signal improvement for lipids and amiodarone was achieved using both types of GE QDs, especially for amino-GE QDs. In addition, ToF-SIMS chemical mapping of single cells with better quality was obtained after signal enhancement. Our strategy for effective ToF-SIMS signal enhancement holds great potential for further investigation of drug metabolism pathways and the interactions between the cell and micro-environment.
关键词： Signal enhancement,Single-cell analysis,Graphene quantum dots,Time-of-flight secondary ion mass spectrometry
更新于2025-11-14 15:32:45
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Photo-physical properties of substituted 2,3-distyryl indoles: Spectroscopic, computational and biological insights
摘要： The structural dependence of the photo-physical properties of substituted 2,3-distyryl (23DSI) indoles were studied using several spectroscopic techniques including steady-state UV-VIS spectroscopy, steady-state fluorescence spectroscopy, steady-state excitation spectroscopy, time correlated single photon counting (TCSPC) spectroscopy, and time-resolved fluorescence upconversion spectroscopy (TRFLS). Each of 23DSI derivatives investigated showed distinct fluorescence emission and UV-VIS spectra, indicating strong structural dependence of the emission and the excitation. The UV-VIS spectra of the 23DSI derivatives showed three main identical absorption bands with minor deviations in the absorbance caused by substituent groups on the distyryl rings. The time-resolved fluorescence up-conversion studies indicated that the fluorescence undergoes a mono-exponential decay whereas the calculated fluorescence lifetime showed relatively short fluorescence lifetimes of approximately 1 ns. All of the 23DSI derivatives showed two-photon absorption upon direct excitation of 1.6 W laser pulses at 800 nm. These studies suggest that the substituents, attached to distyryl core, are capable of boosting or hindering fluorescence intensities by distorting the π-conjugation of the 23DSI molecule. Our studies showed that 23DSI (p-F) has the highest fluorescence emission quantum yield. Theoretical calculations for the ground state of 23DSI derivatives confirmed differences in electron densities in 23DSI derivatives in the presence of different substituent attachments. The excellent fluorescence emission, high fluorescence quantum yield and two-photon absorption properties of these 23DSI molecules make them attractive candidates for potential applications in the fields of biological imaging, biomedicine, fluorescent probes, and photodynamic inactivation (PDI). B. subtilis samples, treated with micro molar solutions of 23DSI (p-OCH3) and 23DSI (p-CH3), showed very effective photodynamic inactivation (PDI) upon irradiation with white light.
关键词： Two photon absorption,Time-resolved fluorescence upconversion laser spectroscopy,Photodynamic inactivation,Gaussian calculations,Photo-physical properties,Light-activation
更新于2025-11-14 15:26:12
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Dynamics of infrared excitations in boron doped diamond
摘要： We report on the investigation of relaxation dynamics of optical excitations in IIb high pressure high temperature (HPHT) diamond doped by natural boron and isotopically enriched 11boron. The measurements were performed with a pump-probe technique using short pump pulses from a wavelength-tunable infrared free electron laser. Lifetimes of excited boron states ranging from a few picoseconds to a few hundred picoseconds, have been derived from the obtained data. The relaxation rates depend on the pumped states, the pump intensity and the diamond lattice temperature. We discuss possible contributions to the optical and nonradiative intracenter relaxation rates observed in these experiments. Theoretical simulations support ultrafast relaxation by multiple phonon emission, for the electronic states with the energy gap exceeding the energy of optical phonon.
关键词： time-resolved spectroscopy,boron-doped diamond,diamond
更新于2025-11-14 15:14:40