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A red-emitting fluorescent probe with large Stokes shift for real-time tracking of cysteine over glutathione and homocysteine in living cells
摘要： Fluorescent probes with high quality for highly selective detection of cysteine (Cys) are still urgently in demand because of the indispensable roles Cys plays in the biological systems. Herein, a red-emitting fluorescent probe CP was developed for the highly selective detection of Cys over glutathione (GSH) and homocysteine (Hcy) by incorporating the recognition unit into the 2-(2-(4-hydroxystyryl)-6-methyl-4H-pyran-4-ylidene) malononitrile (P-OH) fluorophore which is characterized by red emission, noteworthy Stokes shift, and appreciable photostability. Basically, CP demonstrated appreciable sensing performance toward Cys including short response time of 4 min, high sensitivity with approximately 147-fold emission enhancement, low detection limit of 41.696 nM, and good selectivity both in the solution and living cells, indicating its promising potential of visualizing Cys in biological systems.
关键词： Large Stokes shift,Fluorescence imaging,Cysteine detection,Fluorescent probe
更新于2025-11-19 16:56:35
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A Glucose Oxidase-Instructed Fluorescence Amplification Strategy for Intracellular Glucose Detection
摘要： The accurate detection of glucose in the cellular level remains a big challenge. In this study, a signal amplification strategy mediated by silver nanocube (AgNC), glucose oxidase (GOx) and silver ion fluorescence probe (denoted as AgNC-GOx/Ag+-FP) is proposed for amplified intracellular glucose detection. The AgNC is oxidized into Ag+ by H2O2 generated from the GOx-catalyzed glucose oxidation reaction, and Ag+ remarkably enhances the red fluorescence of Ag+-FP. Our results show that the AgNC-GOx/Ag+-FP is highly sensitive and specific to glucose and H2O2. Afterwards, the feasibility of using AgNC-GOx/Ag+-FP to detect intracellular glucose is verified in five different cell lines. In summary, a sensitive and specific fluorescence amplification strategy has been developed for intracellular glucose detection.
关键词： intracellular glucose,silver nanocube,fluorescence probe,glucose oxidase,signal amplification
更新于2025-11-19 16:56:35
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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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Synthesis and photophysics of a series of lipophilic phosphazene-based fluorescent indicators
摘要： This work explores the 7‐amino‐4‐(trifluoromethyl)coumarin backbone for designing lipophilic fluorescent pH indicators. Four novel phosphazene bases with an advantageous combination of properties—high lipophilicity of both neutral and charged forms, lack of localized charges in the cations, and prominent spectral changes upon protonation/deprotonation—were synthesized using the Staudinger reaction. The molecular structures of the synthesized compounds were confirmed using attenuated total reflectance Fourier‐transform infrared spectroscopy (ATR‐FT‐IR), nuclear magnetic resonance (NMR), and Fourier‐transform ion‐cyclotron resonance (FT‐ICR) high‐resolution mass spectrometry. The compounds were further characterized by ultraviolet‐visible (UV‐Vis) absorption and fluorescence emission spectra, lipophilicities (logP values) and pKa values in water and acetonitrile, as well as “biphasic” pKa values in the water/1‐octanol solvent system. The bases could potentially be useful as working agents in optical pH sensors and acid‐base indicators for lipophilic membranes.
关键词： partition coefficients,fluorescence,phosphazenes,fluorescent indicator,lipophilic indicators
更新于2025-11-19 16:56:35
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The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)
摘要： Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder di?raction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a ?uorescence quantum yield of 11% and superior water solubility and ?uorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the ?uorescence of the CQDs in a speci?c and sensitive manner, we developed a method for the detection of Hg2+ using this ?uorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coe?cient of determination (R2 ? 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.
关键词： mercury(II) detection,carbon quantum dots,hydrothermal synthesis,fluorescence quenching,bioimaging
更新于2025-11-19 16:46:39
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A “turn off-on” fluorescent nanoprobe consisting of CuInS2 quantum dots for determination of the activity of β-glucosidase and for inhibitor screening
摘要： A fluorescent “turn off-on” nanoprobe is described for highly sensitive and selective determination of the activity of the enzyme β-glucosidase (β-Glu). Firstly, cysteine modified CuInS2 quantum dots (Cys-CuInS2 QDs) were prepared from indium(III) and copper(II) salts and the presence of thiourea. The red fluorescence of the Cys-CuInS2 QDs, with excitation/emission maxima at 590/656 nm, is quenched by Cu(II). However, in the presence of β-Glu and the cyanogenic glycoside, enzymatic hydrolysis leads to the formation of cyanide. The latter competitively binds to Cu(II) owing to its high affinity for cyanide. This restores the fluorescence of the Cys-CuInS2 QDs. Under the optimum conditions, fluorescence increases linearly in the 0.5–700 U·L?1 β-Glu activity range. The detection limit is 0.2 U·L?1. The nanoprobe was applied to analyze spiked soil samples, and satisfactory results were obtained. The average recoveries of β-Glu were in the range of 96–103%, and the RSD was lower than 4.0%. The fluorescent probe can also be used to screen for β-Glu inhibitors as demonstrated for castanospermine as an example.
关键词： Cys-CuInS2 QDs,Cu(II),Cyanide,Competitively binds,Cyanogenic glycoside,Soil,Enzyme activity,Fluorescence,Amygdalin,Castanospermine
更新于2025-11-19 16:46:39
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A novel fluorescent probe for H2O2 detection based on CdSe@ZnS quantum dots/Ag nanocluster hybrid
摘要： The selective and quantitative detection of H2O2 is important for its employment in physiological, environmental and industrial applications. In this paper, a sensitive and selective strategy for H2O2 detection was established based on the fluorescence quenching of CdSe@ZnS quantum dots (QDs) by H2O2-mediated etching process of Ag nanoclusters (AgNCs). In this strategy, dihydrolipoic acid (DHLA) modified AgNCs were applied as H2O2 response group, the existence of H2O2 could initiate the oxidation of AgNCs and the production of Ag+, which could give rise to the effective fluorescence quenching of CdSe@ZnS QDs. Based on this strategy, the present fluorescent assay could realize the quantificational detection of H2O2 and the limit of detection is calculated to be 0.3 mM under the optimum conditions. Furthermore, CdSe@ZnS/AgNCs hybrid-based probe was applied to detecting H2O2 in milk samples and showed a good recoveries results ranged from 95.8% to 112.0%, meaning the potential applicability of this strategy.
关键词： H2O2 detection,Ag nanoclusters,Fluorescence quenching,CdSe@ZnS quantum dots
更新于2025-11-19 16:46:39
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Broad-Spectrum Tunable Photoluminescent Material Based on Cascade Fluorescence Resonance Energy Transfer between Three Fluorophores Encapsulated within the Self-Assembled Surfactant Systems
摘要： A broad spectrum tunable photoluminescent material with dual encryption based on a two-step Fluorescence Resonance Energy Transfer (FRET) between Pyrene (Py), Coumarin480 (Cou480) and Rhodamine6G (R6G) in micelles of SDS and bmimDS is presented. The phenomenon is achievable due to the encapsulation of the fluorophores within these micelles. The transfer of energy as FRET between the pair Py and Cou480 showed ON at 336 nm and OFF at 402 nm in contrast to the FRET observed between the pair Cou480 and R6G that showed ON at 402nm and OFF at 336 nm. However, the transfer of energy as FRET occurs from Py to R6G in the presence of Cou480 when excited at 336 nm, thereby making it a chain of three fluorophores with Cou480 acting as a relay fluorophore receiving energy from Py and transferring it to R6G. The different FRET scenarios between the three fluorophores in micelles provide a window for the generation of a matrix of colors, which occupies a significant 2D area in the chromaticity diagram, having potential applications in security printing. The different fluorophoric ratios generate different colors based on their individual photonic emissions and the FRET processes taking place between them. Writing tests were carried out using varied ratios of the fluorophores in the micellar systems producing different colored outputs under the UV light with insignificant visibility under the white light. We envision that this as-discovered three fluorophoric FRET system could form the basis for the future development of multi-FRET light-harvesting devices and anti-counterfeiting security inks based on much simpler non-covalent interaction aided encapsulation of the fluorophores within the self-assembled soft systems.
关键词： micelles,security printing,Rhodamine6G (R6G),SDS,Pyrene (Py),Coumarin480 (Cou480),bmimDS,Fluorescence Resonance Energy Transfer (FRET),photoluminescent material
更新于2025-11-19 16:46:39
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Homogeneous immunoassay for alpha-fetoprotein based on the quenching of the fluorescence of quantum dots by antibody labelled with complexed copper ion tags
摘要： A homogeneous fluorescent immunoassay is described for the determination of alpha fetoprotein (AFP) relying on the interaction between copper ion complex and quantum dots (QDs). The copper ion complex-labelled antibody can be employed as a quencher of fluorescence of QDs and capture probe of AFP in homogeneous solution. The labelled antibody is mixed with QDs to form the immune ensemble probe. Upon the addition of AFP, the labelled antibody is stripped away from QDs by antigen-antibody combination leading to the increase in the fluorescence signal. Thus, the determination of AFP can be realized by fluorometry (best measured at excitation/emission wavelengths of 360/520 nm). The fluorescence intensity shows a good linear relationship with the AFP concentration ranging from 40 to 640 ng mL?1, and the LOD is 26 ng mL?1. The proposed method provides a new approach to incorporate metal complexes into QD-based biomolecule sensing.
关键词： Stern-Volmer plot,Metal complex,DTPAA,Copper ion complex-labelled antibody,Fluorescence quenching
更新于2025-11-19 16:46:39
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Facile synthesis of extended TPA-quinazolinone derivatives and the nonlinear optical properties
摘要： In this work, four new quinazolinone(QZ)-based compounds containing triphenylamine (TPA) moiety have been synthesized, defined as QZC, QZC-1, QZC-2, QZC-3, for the application of third-order nonlinear optical (NLO) responses. A new design of two-step synthesis has been put forward, the first step is Ullmann reaction with QZ, and the second is connecting QZ and the substituted triphenylamines (TPAs) through a Suzuki cross-coupling reaction to afford the target products. Electrochemical measurement data indicated that the tuning of the HOMO and LUMO energy levels can be easily achieved by introducing and modifying the donor moiety. The NLO properties were evaluated by the Z-scan technique which showed that introduction of a benzene ring as a π bridge could reduce the transmission energy of electrons from a ground state to an excited state, and the added methoxy in TPA moiety could promote the ICT, and improve the third-order NLO properties of molecules. Theoretical calculations matched well with the electrochemical information and NLO information. The results suggest that the materials based on QZ have potential applications in integrated NLO devices.
关键词： Fluorescence,photophysical property,Extended Quinazolinone derivative,third-order NLO material,Z-scan technology
更新于2025-11-19 16:46:39