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MPA-CdTe quantum dots as a??on-off-ona?? sensitive fluorescence probe to detect ascorbic acid via redox reaction
摘要： Mercaptopropionic acid (MPA) capped CdTe quantum dots (MPA-CdTe QDs) were synthesized in aqueous medium by hydrothermal method, which modified by Fe3+ could be used as a fluorescent probe to detect ascorbic acid (AA). MPA-CdTe QDs fluorescence probe could be used as successive sensor for metal ions and AA with "on-off-on" process. The fluorescence of QDs was quenched after adding Fe3+ to MPA-CdTe QDs. Then, the fluorescence of the Fe3+@MPA-CdTe QDs can be sensitively turned on by AA to give an "on–off–on" fluorescence response according to the oxidation–reduction between Fe3+ and AA. There was a linear relationship between fluorescence intensity quenching value and the concentration of Fe3+ in the range of 2–10 μM since Fe3+ sensitively reacted with CdTe QDs. The linear detection range for AA was 0.1–1 μM with a limit of detection of 6.6 nM. The principle is proved by fluorescence emission spectroscopy, nuclear magnetic resonance spectroscopy. The proposed method is successfully used to detect the AA in human plasma sample.
关键词： CdTe quantum dots,Redox reaction,Fluorescent probe,Ascorbic acid
更新于2025-09-23 15:19:57
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Peroral cholangioscopya??guided probe-based confocal laser endomicroscopy for preoperative diagnosis of pancreatic cancer in a patient with surgically altered anatomy
摘要： A 79-year-old man was referred to our hospital because of jaundice. He had previously undergone Billroth-II gastrectomy for gastric cancer. Contrast CT showed a mass lesion in the pancreatic head with contrast effects and invasion of the distal bile ducts. Additionally, ERCP was performed to obtain more detail. Because of the patient’s prior gastrectomy, ERCP was performed with a short-type single-balloon enteroscope, SIF-H290S (Olympus Medical Systems, Tokyo, Japan) with a working length of 152 cm and channel diameter of 3.2 mm. Cholangiography showed a defect in the distal bile duct. The procedure was then completed with fluoroscopy-guided biopsy of the bile duct. However, the size of the biopsy sample was insufficient to enable a conclusive diagnosis. ERCP was performed again 2 weeks later. With the aim of improving diagnostic ability, a CF-H260AI colonoscope (Olympus Medical Systems Corporation, Tokyo, Japan) with a working length of 133 cm and channel diameter of 3.7 mm was used to perform peroral cholangioscopy (POCS) guided by SpyGlass DS (Boston Scientific Corp, Marlborough, Mass, USA) fluorescein-dripping laser endomicroscopy (pCLE) probe-based confocal (CholangioFlex, Cellvizio; Mauna Kea Technologies, Inc, Paris, France) and POCS-guided biopsy. When the papilla was reached, it was possible to insert the cholangioscope inside the bile duct. Both findings suggested cancer, with POCS showing an irregular, hemorrhagic, papillary protrusion lesion, and pCLE showing a dark ductal structure with irregular margins. POCS confirmed that the bile ducts at nonlesion sites had normal mucosa, and pCLE showed a reticular network of thin, dark, branching bands, considered to be normal. POCS-guided biopsies were performed at both lesion and nonlesion sites. In contrast to the initial fluoroscopy-guided biopsy performed with ERCP, a sample of sufficient size was collected by the POCS-guided biopsy. The biopsy samples contained atypical cells with hyperchromatic nuclei and eosinophilic cytoplasm. Similarly to the pCLE findings, these formed a ductal structure with irregular margins. The nuclei showed marked variations in size, irregular morphology, and irregular arrangement, indicating adenocarcinoma. Biopsy specimens from normal bile ducts showed no malignancy. Therefore, a preoperative diagnosis of pancreatic cancer was made, and pancreatoduodenectomy was performed. The histopathologic findings from the surgical samples were similar to those from the POCS biopsy tissue samples, and irregular, invasive proliferation by atypical bile ducts with eosinophilic cytoplasm was found, confirming pancreatic cancer.
关键词： pancreatic cancer,probe-based confocal laser endomicroscopy,surgically altered anatomy,peroral cholangioscopy
更新于2025-09-23 15:19:57
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High Peak Power Acousto-Optically Q-Switched Ho:Y2O3 Ceramic Laser at 2117 nm
摘要： The mystery of the asteroid (4179) Toutatis was revealed by Chang’e-2 spacecraft during a close ?yby on December 13, 2012. Optical imaging and navigation of the probe during the ?yby were performed entirely under ground-based radio tracking and default sequence built on ground. This paper establishes a set of estimation algorithms of the relative trajectory between Chang’e-2 and Toutatis based on dynamics, optical, and radio constraints that are determined by the unique ?yby mode. This study is the ?rst time to precisely reproduce the core process of Chang’e-2’s encounter with Toutatis based on several optical images. In addition to constructing a strict photogrammetric model, the shadowing effects caused by the illumination and the deviation of the center-of-mass (COM) from the center-of-?gure (COF) in optical images are also considered. The spacecraft trajec- tory with regard to the COF of the body is estimated using images taken from 120 km or less. The formal one sigma uncertainty is (67, 20, and 11 m) in the principal axes frame of the position error ellipse, and the closest approaching distance between Chang’e-2 and Toutatis’s COF is calculated as 1557 ± 11 m, which is more precise than previous results with an uncertainty of hundreds of meters. The spacecraft trajectory with regard to the COM of the body is estimated with an uncertainty of (211, 34, and 17 m), and the corresponding closest distance is estimated as 1451 ± 18 m based on the previously developed shape model of Toutatis. The algorithms and results in this study are important for evaluating the performance of this ?yby mission and are also valuable for any similar optical navigation during a close approach. In addition, our results can help in precisely determining the axis of Toutatis.
关键词： Chang’e-2 probe,optical imaging,relative trajectory,the closest approaching distance.,constraints
更新于2025-09-23 15:19:57
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Bridge between Temperature and Light: Bottom-Up Synthetic Route to Structure-Defined Graphene Quantum Dots as a Temperature Probe In Vitro and in Cells
摘要： Owing to their unique superiorities in chemical and photoluminescence (PL) stability, low toxicity, biocompatibility, and easy functionalization, graphene quantum dots (GQDs) were widely used in cell imaging, probes, and sensors. However, further development and deeper research of GQDs were restricted by their imprecise and complex structure and accompanying controversial PL mechanism. In this work, two kinds of structure defined water-soluble GQDs, with different oxidation degree, were synthesized from molecules by using bottom-up syntheses methods. After studied by a serial of characterizations, their optical properties, functional groups, molecular weight, and structural information were obtained. The optical properties of GQDs could be optimized by controlling their oxidation degree. PL mechanism of GQDs was investigated by comparing their structure and properties. Furthermore, robust, stable, and precise temperature probes were designed by using the GQDs, which exhibited an excellent wide responding range, which covered the whole physiology temperature range, from 0 ℃ to 60 ℃ in water. Moreover, the GQDs were successfully applied as temperature responsive fluorescence probe in Hela cell line. These works put forward a solid foundation for the applications of biological thermo probes and selectively temperature detectors in vitro cellular and in vivo.
关键词： structure controllable,living cell imaging,temperature probe,bottom-up synthesis,mechanism,graphene quantum dots
更新于2025-09-23 15:19:57
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Sulfur doped graphene quantum dots as a potential sensitive fluorescent probe for the detection of quercetin
摘要： In this work, a novel, selective and sensitive fluorescent probe (sulfur doped graphene quantum dots, SGQDs) was designed for real-time detection of quercetin in red wine samples. SGQDs were synthesized by pyrolyzing citric acid (CA) and 3-Mercaptopropionic acid (MPA) and characterized through advanced techniques. It was observed that fluorescence intensity of SGQDs could be substantially quenched by the addition of quercetin through inner filter effect (IFE) mechanism. Additionally, a visual color change (colorless to light yellow) was also noticed after addition of quercetin into a solution of SGQDs. The change in SGQDs fluorescence intensity with varying quercetin content revealed good linearity in the 0-50.0 μM range with regression coefficient of 0.9943 and a lowest detection limit of 0.006 μg/mL. To authenticate the real-time application of SGQDs as a potential fluorescent probe, red wine samples having different quercetin concentrations were used for quantitative analysis, after the optimization of several analytical parameters.
关键词： Sulfur doped graphene quantum dots,inner filter effect,pharmaceutical assay,fluorescent probe,quenching,quercetin
更新于2025-09-23 15:19:57
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Coumarin-Modified Graphene Quantum Dots as a Sensing Platform for Multicomponent Detection and Its Applications in Fruits and Living Cells
摘要： In this work, coumarin derivatives (C) are used to enhance the ?uorescence of graphene quantum dots (GQDs) by covalently linking the carboxyl groups on the edge of the GQD sheet. The as-synthesized coumarin-modi?ed graphene quantum dots (C-GQDs) have a uniform particle size with an average diameter of 3.6 nm. Simultaneously, the C-GQDs have strong ?uorescence emission, excellent photostability, and high ?uorescence quantum yield. C-GQDs and CN? can form a C-GQDs+CN? system due to deprotonation and/or intermolecular interactions. The introduced hydroquinone (HQ) is oxidized to benzoquinone (BQ), and the interaction between BQ and the C-GQDs+CN? system could lead to ?uorescence enhancement of C-GQDs. Meanwhile, the redox reaction between BQ and ascorbic acid (AA) can be used for quantitative detection of AA with CN? and HQ being used as substrates. Based on the above mechanism, C-GQDs are developed as a multicomponent detection and sensing platform, and the detection limits for CN?, HQ, and AA were 4.7, 2.2, and 2.2 nM, respectively. More importantly, satisfactory results were obtained when the platform was used to detect CN?, HQ, and AA in living cells and fresh fruits.
关键词： multicomponent detection,CN?,fluorescent probe,HQ,coumarin-modi?ed graphene quantum dots,AA
更新于2025-09-23 15:19:57
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Metal-labeled Aptamers as Novel nanoprobes for Imaging Mass Cytometry Analysis
摘要： Imaging mass cytometry (IMC) is an emerging imaging technology that exploits the multiplexed analysis capabilities of the CyTOF mass cytometer to make spatially resolved measurements for tissue sections. In a comprehensive view of tissue composition and marker distribution, recent developments of IMC require highly sensitive, multiplexed assays. Approaching the sensitivity of the IMC technique, we designed a novel type of biocompatible metal-labeled aptamer nanoprobe (MAP), named 167Er-A10-3.2. The small molecular probe was synthesized by conjugating 167Er-polymeric pentetic acid (167Er-DTPA) with an RNA aptamer A10-3.2. For demonstration, 167Er-A10-3.2 was applied for observing protein spatial distribution on prostatic epithelium cell of paraffin embedded Prostatic adenocarcinoma (PaC) tissue sections by IMC technology. The 167Er-A10-3.2 capitalizes on the ability of aptamer to specifically bind target cancer cells, as well as the small size of 167Er-A10-3.2 can accommodate multiple aptamer binding antigen labeled at high density. The detection signal of 167Er-A10-3.2 probe was 3-fold higher than that of PSMA antibody probe for a targeted cell under lower temperature epitope retrieval (37°C) of PaC tissue. Furthermore, we successfully demonstrated the simultaneously staining ability of aptamer probes in IMC analysis. The successful imaging acquisition using aptamers probes in IMC technology may offer opportunity for the diagnosis of malignancies in the future.
关键词： imaging mass cytometry,prostate specific membrane antigen,molecular probe,metal labeled aptamer
更新于2025-09-23 15:19:57
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Coherent Exciton Dynamics in Ensembles of Size-Dispersed CdSe Quantum Dot Dimers Probed via Ultrafast Spectroscopy: A Quantum Computational Study
摘要： Interdot coherent excitonic dynamics in nanometric colloidal CdSe quantum dots (QD) dimers lead to interdot charge migration and energy transfer. We show by electronic quantum dynamical simulations that the interdot coherent response to ultrashort fs laser pulses can be characterized by pump-probe transient absorption spectroscopy in spite of the inevitable inherent size dispersion of colloidal QDs. The latter, leading to a broadening of the excitonic bands, induce accidental resonances that actually increase the efficiency of the interdot coupling. The optical electronic response is computed by solving the time-dependent Schrodinger equation including the interaction with the oscillating electric field of the pulses for an ensemble of dimers that differ by their size. The excitonic Hamiltonian of each dimer is parameterized by the QD size and interdot distance, using an effective mass approximation. Local and charge transfer excitons are included in the dimer basis set. By tailoring the QD size, the excitonic bands can be tuned to overlap and thus favor interdot coupling. Computed pump-probe transient absorption maps averaged over the ensemble show that the coherence of excitons in QD dimers that lead to interdot charge migration can survive size disorder and could be observed in fs pump-probe, four-wave mixing, or covariance spectroscopy.
关键词： coherent electronic dynamics,pump-probe transient absorption spectroscopy,CdSe quantum dots dimers,exciton dynamics,size dispersion effects
更新于2025-09-23 15:19:57
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<p>A Lysosome-Targetable Fluorescence Probe Based on L-Cysteine-Polyamine-Morpholine-Modified Quantum Dots for Imaging in Living Cells</p>
摘要： Quantum dots (QDs) are used as fluorescent probes due to their high fluorescence intensity, longevity of fluorescence, strong light-resistant bleaching ability and high light stability. Therefore, we explore a more precise probe that can target an organelle. Methods: In the current study, a new class of fluorescence probes were developed using QDs capped with 4 different L-cysteine-polyamine-morpholine linked by mercapto groups. Ligands were characterised by Electrospray ionization mass spectrometry (ESI-MS), H-Nuclear Magnetic Resonance (1H NMR) spectroscopy, and 13C NMR spectroscopy. Modified QDs were characterized by Transmission Electron Microscope (TEM), Ultraviolet and visible spectrophotometry (UV–Vis), and fluorescence microscopy. And the biological activity of modified QDs was explored by using MTT assay with HeLa, SMMC-7721 and HepG2 cells. The fluorescence imaging of modified QDs was obtained by confocal laser scanning fluorescence microscopy (CLSM). Results: Synthesized QDs ranged between 4 to 5 nm and had strong optical emission properties. UV–Vis and fluorescence spectra demonstrated that the cysteine-polyamine-morpholine were successfully incorporated into QD nanoparticles. The MTT results demonstrated that modified QDs had lesser cytotoxicity when compared to unmodified QDs. In addition, modified QDs had strong fluorescence intensity in HeLa cells and targeted lysosomes of HeLa cells. Conclusion: This study demonstrates the modified QDs efficiently entered cells and could be used as a potential lysosome-targeting fluorescent probe.
关键词： lysosome-targetable,cells imaging,quantum dots,fluorescence probe
更新于2025-09-23 15:19:57
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Nonequilibrium Green’s function method: Büttiker probes for carrier generation and recombination
摘要： The non-equilibrium Green function (NEGF) method is capable of nanodevice performance predictions including coherent and incoherent effects. To treat incoherent scattering, carrier generation and recombination is computationally very expensive. In this work, the numerically efficient B¨uttiker-probe model is expanded to cover recombination and generation effects in addition to various incoherent scattering processes. The capability of the new method to predict nanodevices is exemplified with quantum well III-N light-emitting diodes and anti-ambipolar 2D material heterojunctions.
关键词： B¨uttiker-probe model,non-equilibrium Green function,carrier generation,nanodevices,recombination
更新于2025-09-23 15:19:57