- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
On-off-on relay fluorescence recognition of ferric and fluoride ions based on indicator displacement in living cells
摘要： A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential “on-off-on”-type relay fluorescence probe for Fe3+ ions and F? ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe3+ to IOP boronic acid (IOPBA) formed an Fe3+-IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe3+ ion in the Fe3+-IOPBA complex was coordinated to two phenyl groups to form a p-complex. Upon addition of F? to the Fe3+-IOPBA complex, the original fluorescence was recovered due to formation of [FeF6]3?, resulting in “on-off-on”-type sensor behavior. IOPBA showed high selectivity towards Fe3+ among other cations. Moreover, the Fe3+-IOPBA complex showed specific selectivity towards F?, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 106 and 4.49 × 106 mol–1 L for Fe3+ with IOPBA and F? with Fe3+-IOPBA, respectively. The limits of detection for Fe3+ and F? were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe3+ and F? in living HeLa cells.
关键词： Fluorescence imaging,On-off-on sensor,Probe for Fe3+ ions and F? ions,Living HeLa cells,Boronic acid derivative
更新于2025-11-21 11:08:12
-
Enzyme-free “on-off-on” photoelectrochemical biosensor based on cascaded quadratic amplification strategy for miRNA 141 detection
摘要： MicroRNAs (miRNAs) assay is of great significance for early diagnosis of diseases, so an enzyme-free “on-off-on” PEC biosensor has been developed for sensitive miRNA 141 determination. Manganese-doped cadmium sulfide coupled with zinc sulfide quantum dots (Mn:CdS@ZnS QDs) and manganese porphyrin (MnPP) have been used as photoelectric material and photosensitizer, respectively. And a high photocurrent of approximately 70.0 μA has been obtained. Cascaded quadratic amplification strategy has been applied in the system. Mn:CdS@ZnS QDs was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). Photoelectrochemical and electrochemical technologies were used to monitor the fabrication process of the biosensor. The sensing platform exhibits recommendable stability and good selectivity, miRNA 141 can be accurately quantified with a linear range of 1.00 × 10-14 to 1.00 × 10-8 mol·L-1 and the detection limit of 3.30 fmol·L-1. This method provides promising potential to explore sensitive detection models for various biological molecules.
关键词： Hybridization chain reaction,Catalytic hairpin assembly,Manganese-doped cadmium sulfide coupled with zinc sulfide quantum dots,MiRNA 141,Photoelectrochemistry,On-off-on
更新于2025-11-14 17:03:37
-
A pH-insensitive near-infrared fluorescent probe for wash-free lysosome-specific tracking with long time during physiological and pathological processes
摘要： A novel dicyanomethylene-4H-pyran based lysosome-specific near-infrared (NIR) probe, DCM-ML, is reported. It exhibits very weak fluorescence (Ф=0.007) in aqueous solution due to the energy relaxation from intramolecular rotation; but a large "off-on" NIR emission (20-folds) after specifically labeling lysosomes due to the local high viscosity instead of the local pH by both one- and two-photon excitation microscopy. Therefore, the imaging ability of DCM-ML will not confront the problems suffered by the currently used and reported pH-dependent lysosome probes (e.g., once lysosomal pH increases, their fluorescence gets quenched); The pH-independent feature of DCM-ML is further demonstrated to be a great advantage for tracing lysosomes’ movements in a relatively long time, even during cellular processes when lysosomes are suffered from external stimulations that induce pH increase and apoptosis. In addition to the characteristics of pH-insensitivity and "off-on" NIR emission, DCM-ML also possesses characteristics of excellent membrane permeability, high selectivity, low cytotoxicity, good photostability and large Stokes shift (> 200 nm), which qualify it as a superior wash-free NIR probe for tracking dynamic changes of lysosomes under both physiological and toxicological conditions. Hence, we believe DCM-ML may find a great potential of application in the future.
关键词： pH-insensitivity,Long-term tracking,Wash-free,"Off-on",Lysosome-specific imaging,Near-infrared
更新于2025-09-23 15:22:29
-
Construction of a novel far-red fluorescence light-up probe for visualizing intracellular peroxynitrite
摘要： Peroxynitrite (ONOO-) is an important reactive oxygen species (ROS), which can react with a variety of biologically active species and cause many diseases, such as cancer, neurodegenerative disorders. Herein, we develop a novel far-red fluorescent probe DCM-KA, which is equipping with α-ketoamide moiety caged DCM-NH2. The probe exhibits fluorescence off-on response to ONOO- over other biological interfering analytes by ONOO--induced α-ketoamide deprotection reaction. More importantly, the probe is biocompatible and has been successfully utilized to visualize endogenous ONOO- production in macrophage cell line J774A.1.
关键词： Fluorescence off-on,Far-red,Naked-eyes detection,Imaging endogenous peroxynitrite.,Dicyanomethylene benzopyran derivative
更新于2025-09-23 15:22:29
-
A novel 1,8-naphthalimide as highly selective naked-eye and ratiometric fluorescent sensor for detection of Hg2+ ions
摘要： A novel colorimetric and ratiometric fluorescent chemosensor, 2-(2-mercaptophenyl)-1H-benzo[de]isoquinoline-1,3-(2H)-dione (L3) is reported for Hg2+ ions. The selective binding of Hg2+ to L3 afforded new absorbance and fluorescence peaks at 438 nm and 480 nm, in addition to the existing bands of L3 at 332 nm and 376 nm. It also showed apparent colour change from colourless to yellowish green and weak fluorescent to bright yellowish green strong fluorescent due to selective binding of Hg2+ ion. The sensor forms a 1:1 stoichiometry with high binding constants (3.89 × 10^4 mol^-1 L) and limit of detection 1.74 × 10^-8 M with high selectivity and sensitivity towards Hg2+ in the presence of other interfering metal ions. More importantly, it has good practicability in environmental water sample. The outcome of photo-physical experiment has also been in good accordance with the time-resolved fluorescence life decays and the density functional theory (DFT) estimations. Moreover, the L3-Hg2+ solution displayed high colorimetric and fluorimetric reversibility via the addition of KI. This reversibility in fluorescence showed potential applicability of chemosensor L3 as 'on–off–on' naked eye sensor.
关键词： Molecular logic gate,Red-shift,DFT,Off–on–off Hg2+ chemosensor,Naked eye detection,Ratiometric fluorescence
更新于2025-09-19 17:15:36
-
On-off-on fluorescent carbon dots from waste tea: Their properties, antioxidant and selective detection of CrO42?, Fe3+, ascorbic acid and L-cysteine in real samples
摘要： In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV-visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λex=365 nm), and the fluorescence could be effectively quenched by CrO4 2- and Fe3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO4 2- and Tea-CDs-Fe3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO4 2-, Fe3+, AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO4 2-, Fe3+, AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.
关键词： carbon dots,waste tea,L-cysteine,ascorbic acid,on-off-on fluorescent nano-sensor,metal ions
更新于2025-09-19 17:15:36
-
“Turn off-on” fluorescent sensor based on quantum dots and self-assembled porphyrin for rapid detection of ochratoxin A
摘要： We report herein a “turn off-on” fluorescent sensor based on ZnCdSe quantum dots (ZnCdSe QDs) and self-assembled zinc porphyrin for sensitive and rapid detection of ochratoxin A (OTA). Using environmentally friendly dodecyl dimethyl betaine as “soft template”, zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (ZnTPyP) was self-assembled into nanorods (SA-ZnTPyP) through a green process. The OTA detection process involves two steps: (1) the fluorescence of ZnCdSe QDs is significantly quenched by SA-ZnTPyP, and (2) the combination between SA-ZnTPyP and OTA releases ZnCdSe QDs from their quenchers such that the fluorescence is recovered. Under the optimized experimental conditions, the newly developed fluorescent sensor showed a linear response in concentration range 0.5–80 ng mL?1, with a detection limit of 0.33 ng mL?1. The excellent applicability of the system has been verified in milk and coffee samples, with relative recoveries between 98.33% and 103.70%. The proposed fluorescent sensor exhibits excellent selectivity and high sensitivity, and thus could be a promising tool for on-site determination of OTA in food safety control and environmental monitoring.
关键词： Turn off-on,Self-assembled zinc porphyrin,Ochratoxin A,Quantum dots
更新于2025-09-16 10:30:52
-
Fluorometric determination of hydroquinone by using blue emitting N/S/P-codoped carbon dots
摘要： N/S/P-codoped carbon dots (CDs) are shown to be a viable fluorescent probe in a turn-off-on fluorometric assay for hydroquinone (HQ). The preparation of CDs was carried out using a one-step hydrothermal reaction starting with glyoxal and isocarbophos. The method is based on the formation of ground state complexes between CD and Fe(III) which leads to quenching of blue fluorescence (with excitation/emission peaks at 363/448 nm). On addition of HQ, it will be oxidized by Fe(III) upon which fluorescence recovers. This turn-off-on system can be utilized to quantify HQ. A linear relationship exists between fluorescence recovery and HQ concentration in range between 0.56 and 375 μM. The limit of detection is 0.16 μM. The assay was successfully applied to the determination of HQ in spiked water samples and developer samples.
关键词： Developer samples,Blue emission,1,4-dihydroxybenzene,Glyoxal,Fluorescence turn-off-on system,Heteroatoms,Carbon dots,Water samples,Hydrothermal reaction,Fe(III)
更新于2025-09-09 09:28:46
-
Versatile polymeric microspheres with tumor-microenvironment bioreducible degradation, pH-activated surface charge-reversal, pH-triggered “off-on” fluorescence and drug release as theranostic nanoplatforms
摘要： Facile approach has been developed for the versatile polymeric microspheres with tumor-microenvironment bioreducible degradation, pH-activated surface charge-reversal, pH-triggered “off-on” fluorescence and drug release via emulsion copolymerization of glycidyl methacrylate (GMA), poly(ethylene glycol) methyl ether methacrylate (PEGMA), N-rhodamine 6G-ethyl-acrylamide (Rh6GEAm) with N,N-bis(acyloyl)cystamine) (BACy) as disulfide crosslinker and functionalization. The final PGMA-DMMA microspheres showed excellent cytocompatibility, pH-triggered surface charge reversal at pH 5-6, strong fluorescence only in acidic media, and bioreducible degradation with high reductant level, indicating their promising application as theranostic nanoplatforms for precise imaging-guided diagnosis and chemotherapy. The DOX-loaded PGMA-DMMA microspheres with a drug-loading capacity of 18% and particle size of about 150 nm possessed unique pH/reduction dual-responsive controlled release, with a cumulative DOX release of 60.5% within 54 h at the simulated tumor microenvironment but a premature leakage of < 8.0% under the simulated physiological condition. Enhanced inhibition efficacy against HepG2 cells was achieved than the free DOX.
关键词： tumor-microenvironment bioreducible degradation,pH-triggered “off-on” fluorescence,pH-triggered drug release,theranostic nanoplatforms,pH-activated surface charge-reversal,polymeric microspheres
更新于2025-09-09 09:28:46