- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Accidental contamination of substrates and polymer films by organic quantum emitters
摘要： We report the observation of ubiquitous contamination of dielectric substrates and polymethylmethacrylate matrices by organic molecules with optical activity in the visible spectral range. Contamination sites of individual solvent-related fluorophores in thin films of polymethylmethacrylate constitute fluorescence hotspots with quantum emission statistics and quantum yields approaching 30% at cryogenic temperatures. Our findings not only resolve prevalent puzzles in the assignment of spectral features to various nanoemitters on bare dielectric substrates or in polymer matrices, they also identify means for simple and cost-efficient realization of single-photon sources in the visible spectral range.
关键词： contamination of substrate and polymer matrix,organic fluorophores,single photon emitters,single molecule spectroscopy,Photoluminescence and fluorescence spectroscopy
更新于2025-11-25 10:30:42
-
Single-cell redox states analyzed by fluorescence lifetime metrics and tryptophan FRET interaction with NAD(P)H
摘要： Redox changes in live HeLa cervical cancer cells after doxorubicin treatment can either be analyzed by a novel fluorescence lifetime microscopy (FLIM)-based redox ratio NAD(P)H-a2%/FAD-a1%, called fluorescence lifetime redox ratio or one of its components (NAD(P)H-a2%), which is actually driving that ratio and offering a simpler and alternative metric and are both compared. Auto-fluorescent NAD(P)H, FAD lifetime is acquired by 2- photon excitation and Tryptophan by 3-photon, at 4 time points after treatment up to 60 min demonstrating early drug response to doxorubicin. Identical Fields-of-view (FoV) at each interval allows single-cell analysis, showing heterogeneous responses to treatment, largely based on their initial control redox state. Based on a discrete ROI selection method, mitochondrial OXPHOS and cytosolic glycolysis are discriminated. Furthermore, putative FRET interaction and energy transfer between tryptophan residue carrying enzymes and NAD(P)H correlate with NAD(P)H-a2%, as does the NADPH/NADH ratio, highlighting a multi-parametric assay to track metabolic changes in live specimens.
关键词： Fluorescence Lifetime Imaging Microscopy (FLIM),single-cell analysis,NADPH/NADH ratio,NAD(P)H,redox,FAD,fluorescence lifetime redox ratio (FLIRR),NAD(P)H-a2%
更新于2025-11-21 11:24:58
-
Spectroscopy Used as a Tool to Evaluate Hair Damage and Protection
摘要： OBJECTIVE: Methods that can be used to analyze hair damage and to support a claim of hair protection are important for the cosmetic industry. There are many approaches available, but they are usually laborious and expensive. The researchers propose a simple fluorescence method that is based upon the emissive properties of damaged hair. METHODS: Hair fluorescence was observed when using both fluorimetry and microscopic procedures. The method was developed by comparing native hair with hair that was damaged by UVA and visible light. RESULTS: Spectroscopic properties (absorption and emission) of hair in the visible range are presented. The changes in the emissive properties of hair during irradiation were characterized and they were correlated with photobleaching, which is due to the generation of singlet oxygen. Emissions were also obtained in the hair shafts that had been previously treated with chamomile extract and this treatment was able to avoid hair bleaching. CONCLUSION: The emissive properties of hair in the visible range can be used as a tool for the evaluation of hair damage and protection. This method can be useful as a tool in order to claim
关键词： Hair treatment,singlet oxygen,spectroscopy,claim substantiation,fluorescence,visible
更新于2025-11-21 11:24:58
-
Deep learning enables cross-modality super-resolution in fluorescence microscopy
摘要： We present deep-learning-enabled super-resolution across different fluorescence microscopy modalities. This data-driven approach does not require numerical modeling of the imaging process or the estimation of a point-spread-function, and is based on training a generative adversarial network (GAN) to transform diffraction-limited input images into super-resolved ones. Using this framework, we improve the resolution of wide-field images acquired with low-numerical-aperture objectives, matching the resolution that is acquired using high-numerical-aperture objectives. We also demonstrate cross-modality super-resolution, transforming confocal microscopy images to match the resolution acquired with a stimulated emission depletion (STED) microscope. We further demonstrate that total internal reflection fluorescence (TIRF) microscopy images of subcellular structures within cells and tissues can be transformed to match the results obtained with a TIRF-based structured illumination microscope. The deep network rapidly outputs these super-resolved images, without any iterations or parameter search, and could serve to democratize super-resolution imaging.
关键词： GAN,cross-modality,super-resolution,fluorescence microscopy,deep learning
更新于2025-11-21 11:24:58
-
Targeting fluorescent nanodiamonds to vascular endothelial growth factor receptors in tumor
摘要： The increased expression of vascular endothelial growth factor (VEGF) and its receptors is associated with angiogenesis in a growing tumor, presenting potential targets for tumor-selective imaging by way of targeted tracers. Though fluorescent tracers are used for targeted in vivo imaging, the lack of photostability and biocompatibility of many current fluorophores hinder their use in several applications involving long-term, continuous imaging. To address these problems, fluorescent nanodiamonds (FNDs), which exhibit infinite photostability and excellent biocompatibility, were explored as fluorophores in tracers for targeting VEGF receptors in growing tumors. To explore FND utility for imaging tumor VEGF receptors, we used click-chemistry to conjugate multiple copies of an engineered single-chain version of VEGF site-specifically derivatized with trans-cyclooctene (scVEGF-TCO) to 140 nm FND. The resulting targeting conjugates, FND-scVEGF, were then tested for functional activity of the scVEGF moieties through biochemical and tissue culture experiments and for selective tumor uptake in Balb/c mice with induced 4T1 carcinoma. We found that FND-scVEGF conjugates retain high affinity to VEGF receptors in cell culture experiments and observed preferential accumulation of FND-scVEGF in tumors relative to untargeted FND. Microspectroscopy provided unambiguous determination of FND within tissue by way of the unique spectral shape of nitrogen-vacancy induced fluorescence. These results validate and invite the use of targeted FND for diagnostic imaging and encourage further optimization of FND for fluorescence brightness.
关键词： Vascular Endothelial Growth Factor,Oncology,Targeted Fluorescence Imaging,Nanodiamond,Angiogenesis
更新于2025-11-21 11:24:58
-
Pyrophosphate Prompted Aggregation-Induced Emission: Chemosensor Studies, Cell Imaging, Cytotoxicity, and Hydrolysis of the Phosphoester Bond with Alkaline Phosphatase
摘要： Two zinc complexes [(Zn)2(L2)2Cl2(DMSO)2] (R1) and [Zn(L2)2(NO3)2(H2O)2] (R2) were synthesized and characterized with various spectroscopic data. The single X-ray structure determination reveals that complex R1 is dinuclear and tetrahedral in geometry, while complex R2 is mononuclear and octahedral in geometry. Further, both zinc complexes were investigated for pyrophosphate sensing in an aqueous medium. Complex R1 is found to be selective towards pyrophosphate; it leads to 5.5-fold enhancement in the emission intensity due to aggregation-induced emission. However, complex R2 has shown binding with all, ATP, AMP, ADP, and pyrophosphate, which is attributed to the chelate effect. Consequently, complex R1 was utilized for the intracellular detection of pyrophosphate in HeLa cells. Furthermore, the PPi based zinc complex R1 is also used as a bio-analytical tool to construct a real-time fluorescence assay for the enzymatic activity of alkaline phosphatases (ALP).
关键词： Intracellular detection,Sensors,Fluorescence,Zinc,ALP activity,Pyrophosphate
更新于2025-11-21 11:24:58
-
A sensitive and selective fluorescence probe for detection of hypochlorite (OCl?) and its bioimaging in live cells
摘要： A novel indolium-based fluorescent probe (probe 1) for the recognition and detection of hypochlorite (OCl?) has been explored via a double oxidation reaction mechanism. Probe 1 exhibited excellent selectivity and sensitivity for OCl? over other analytes, and with a detection limit of 0.11 μM. Meanwhile, probe 1 showed fast response towards OCl? in less than 3 min with obvious changes in color, which could be observed by naked eye. Moreover, fluorescence imaging experiments by using Eca109 cells were performed utilizing the new probe, demonstrating its practical applications in living cells.
关键词： Oxidize,Fluorescence probe,Bioimaging,Hypochlorite
更新于2025-11-21 11:24:58
-
Fluorophore Labeling, Nanodisc Reconstitution and Single-molecule Observation of a G Protein-coupled Receptor
摘要： Activation of G protein-coupled receptors (GPCRs) by agonist ligands is mediated by a transition from an inactive to active receptor conformation. We describe a novel single-molecule assay that monitors activation-linked conformational transitions in individual GPCR molecules in real-time. The receptor is site-specifically labeled with a Cy3 fluorescence probe at the end of trans-membrane helix 6 and reconstituted in phospholipid nanodiscs tethered to a microscope slide. Individual receptor molecules are then monitored over time by single-molecule total internal reflection fluorescence microscopy, revealing spontaneous transitions between inactive and active-like conformations. The assay provides information on the equilibrium distribution of inactive and active receptor conformations and the rate constants for conformational exchange. The experiments can be performed in the absence of ligands, revealing the spontaneous conformational transitions responsible for basal signaling activity, or in the presence of agonist or inverse agonist ligands, revealing how the ligands alter the dynamics of the receptor to either stimulate or repress signaling activity. The resulting mechanistic information is useful for the design of improved GPCR-targeting drugs. The single-molecule assay is described in the context of the β2 adrenergic receptor, but can be extended to a variety of GPCRs.
关键词： Phospholipid nanodiscs,G-protein coupled receptors,Conformational dynamics,β2 adrenergic receptor,Single-molecule fluorescence
更新于2025-11-21 11:24:58
-
A Double-Hybridization Approach for the Transcription- and Amplification-Free Detection of Specific mRNA on a Microarray
摘要： A double-hybridization approach was developed for the enzyme-free detection of specific mRNA of a housekeeping gene. Targeted mRNA was immobilized by hybridization to complementary DNA capture probes spotted onto a microarray. A second hybridization step of Cy5-conjugated label DNA to another section of the mRNA enabled specific labeling of the target. Thus, enzymatic artifacts could be avoided by omitting transcription and amplification steps. This manuscript describes the development of capture probe molecules used in the transcription- and amplification-free analysis of RPLP0 mRNA in isolated total RNA. An increase in specific signal was found with increasing length of the target-specific section of capture probes. Unspecific signal comprising spot autofluorescence and unspecific label binding did not correlate with the capture length. An additional spacer between the specific part of the capture probe and the substrate attachment site increased the signal significantly only on a short capture probe of approximately 30 nt length.
关键词： gene expression,enzyme-free,fluorescence microscopy,mRNA detection,microarray
更新于2025-11-21 11:24:58
-
Fluorescence microscope light source stability
摘要： The process of fluorescence starts with the efficient generation of light that is required for the excitation of fluorophores. As such, light sources are a crucial component of a fluorescence microscope. Choosing the right illumination tool can not only improve the quality of experimental results, but also the microscope’s economic and environmental footprint. While arc lamps have historically proven to be a reliable light source for widefield fluorescence microscopy, solid-state light-emitting diodes (LEDs) have become the light source of choice for new fluorescence microscopy systems. In this paper, we demonstrate that LEDs have superior light stability on all timescales tested and use less electrical power than traditional light sources when used at lower power outputs. They can be readily switched on and off electronically, have a longer lifetime and they do not contain mercury, and thus are better for the environment. We demonstrate that it is important to measure light source power output during warm-up and switching, as a light source’s responsiveness (in terms of power) can be quite variable. Several general protocols for testing light source stability are presented. A detailed life cycle analysis shows that an LED light source can have a fourfold lower environmental impact when compared to a metal halide source.
关键词： Light source,Fluorescence,Solid state,LED,Stability,Microscopy
更新于2025-11-21 11:24:58