scholarly journals Design of functionalized β-ketoenole derivatives as efficient fluorescent dyes for detection of amyloid fibrils

2018 ◽  
Vol 42 (16) ◽  
pp. 13308-13318 ◽  
Author(s):  
Vladyslava Kovalska ◽  
Svitlana Chernii ◽  
Mykhaylo Losytskyy ◽  
Iryna Tretyakova ◽  
Yan Dovbii ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Fluorescent Dyes ◽  
Fluorescence Sensing ◽  
Strong Emission

Functionalized β-ketoenoles for efficient fluorescence sensing of protein amyloid fibrils giving strong emission increase up to 0.5 QY are designed.

Tuning the photophysical properties of carboranyl luminophores by closo- to nido-carborane conversion and application to OFF–ON fluoride sensing

2018 ◽  
Vol 47 (48) ◽  
pp. 17441-17449 ◽  
Author(s):  
Nguyen Van Nghia ◽  
Jihun Oh ◽  
Surendran Sujith ◽  
Jaehoon Jung ◽  
Min Hyung Lee
Keyword(s):  
Photophysical Properties ◽  
Fluorescence Sensing ◽  
Strong Emission ◽  
Fluoride Sensing

Conversion of poorly emissive closo-carboranyl luminophores to nido-derivatives gave rise to strong emission, allowing the selective OFF–ON fluorescence sensing of fluoride.

scholarly journals Europium-Doped Ceria Nanocrystals as Nanozyme Fluorescent Probes for Biosensing

2021 ◽  
Vol 5 (1) ◽  
pp. 53
Author(s):  
Ali Othman ◽  
Akhtar Hayat ◽  
Silvana Andreescu
Keyword(s):  
Fluorescent Dyes ◽  
Aqueous Media ◽  
Doped Ceria ◽  
New Wave ◽  
Lactate Oxidase ◽  
Fluorescence Sensing ◽  
Combined Use ◽  
Direct Fluorescence ◽  
Average Size

Molecular nanoprobes with intrinsic enzyme-like activity represent a new wave of technology for rapid and sensitive detection of molecular targets. This work reports synthesis and characterization of novel and well-dispersed europium-doped ceria nanocrystals (EuCe NCs) with self-integrated catalytic and fluorescence sensing functions. The NCs have an average size of ∼5 nm and exhibit bright and stable fluorescence for more than 6 months in aqueous media. Their dual cooperative function as both a catalyst and fluorescent probe was explored to develop a universally applicable fluorescence-based biosensing method to monitor enzyme reactions and quantitatively measure clinically relevant molecules. Sensing capabilities are demonstrated for detection of H2O2, glucose/glucose oxidase, lactate/lactate oxidase, phosphatase activity, and the catecholamine neurotransmitter, dopamine. Results indicate that EuCe NCs not only provide high enzyme-mimetic activity, but also impart direct fluorescence sensing ability enabling all-in-one recognition, catalytic amplification, and the detection of biomolecular targets. The EuCe nanozyme offers a stable alternative to the more complex systems based on the combined use of natural enzymes and fluorescent dyes. The high stability and fluorescence detection capabilities demonstrate that EuCe NCs have the potential to be used as a generic platform in chemical and biological sensing and bioimaging applications.

Fluorescence sensing of glucose using glucose oxidase incorporated into a fluorophore-containing PNIPAM hydrogel

2016 ◽  
Vol 7 (10) ◽  
pp. 1907-1912 ◽  
Author(s):  
Yongkyun Kim ◽  
Geunseok Jang ◽  
Daigeun Kim ◽  
Jongho Kim ◽  
Taek Seung Lee
Keyword(s):  
Composite Material ◽  
Glucose Oxidase ◽  
Fluorescent Dyes ◽  
Ph Sensitive ◽  
Fluorescence Sensing

We present a new composite material composed of pH sensitive fluorescent dyes in a poly(N-isopropylacrylamide)-based hydrogel and incorporating glucose oxidase (GOx), which provides a platform for fluorescence sensing of glucose.

scholarly journals Three-Step Resonance Energy Transfer in Insulin Amyloid Fibrils

2019 ◽  
Keyword(s):  
Energy Transfer ◽  
Electrostatic Interactions ◽  
Near Infrared ◽  
Amyloid Fibrils ◽  
Fluorescent Dyes ◽  
Stokes Shift ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Detection Sensitivity ◽  
Excitation Wavelength

The applicability of the three-step Förster resonance energy transfer (FRET) to detection of insulin amyloid fibrils was evaluated, using the chromophore system, containing Thioflavin T (ThT), 4-dimethylaminochalcone (DMC), and two squaraine dyes, referred to here as SQ1 and SQ4. The mediator chromophore DMC was found to enhance the fluorescence intensity of the terminal acceptor, SQ1, excited at 440 nm (at the absorption maximum of the principal donor, ThT), in fibrillar insulin compared to the system without DMC, providing the evidence for the cascade energy transfer in the chain ThT→DMC→SQ4→SQ1. Furthermore, the resulting Stokes shift in the four-chromophore system was 240 nm, as compared to 45 nm for the fibril-bound ThT, suggesting that higher signal-to-noise ratio is the advantage of amyloid fibril detection by multistep FRET. The maximum efficiencies of energy transfer in the insulin fibrils estimated from the quenching of the donor fluorescence in the presence of acceptor for the donor-acceptor pairs ThT-DMC, DMC-SQ4 and SQ4-SQ1 were 40%, 60% and 30% respectively, while negligible FRET occurred in the non-fibrillized protein. The most pronounced differences between fibrillar and non-fibrillized insulin were observed in the 3D fluorescence spectra. Specifically, two intensive spots centered at the emission wavelengths ~ 650 nm (SQ4) and ~ 685 nm (SQ1) were revealed at the excitation wavelength ~ 440 nm in the 3D patterns of insulin amyloid aggregates. In contrast, in the case of the non-fibrillized protein, the barely noticeable spots centered at the same wavelengths, as well as higher fluorescence intensities at the excitation above 550 nm were observed, suggesting the predominant impact of the direct excitation of SQ1 and SQ4 on their fluorescence responses. The inter-chromophore distances calculated from the experimental values of the energy transfer efficiency assuming the isotropic rotation of the dyes, were found to be 2.4, 4.5 and 4.3 nm for the ThT-DMC, DMC-SQ4 and SQ4-SQ1 pairs, respectively, revealing the different fibril binding sites for the examined dyes. The quantum-chemical calculations and simple docking studies provided evidence for the SQ1, SQ4 and ThT, DMC binding to the wet and dry interface of the insulin amyloid protofilament, respectively. The dye-protein complexes are likely to be stabilized by the hydrophobic, van der Waals, aromatic and electrostatic interactions. In summary, the above technique based on the multistep FRET can be employed for the identification and characterization of amyloid fibrils in vitro along with the classical ThT assay, allowing the increase of the amyloid detection sensitivity and lowering the probability of the pseudo-positive result. The applicability of the multistep FRET for amyloid visualization in vivo can be also tested by the involvement of the near-infrared fluorescent dyes to the cascade.

Detection, inhibition and disintegration of amyloid fibrils: the role of optical probes and macrocyclic receptors

2017 ◽  
Vol 53 (19) ◽  
pp. 2789-2809 ◽  
Author(s):  
Achikanath C. Bhasikuttan ◽  
Jyotirmayee Mohanty
Keyword(s):  
Early Detection ◽  
Neurodegenerative Diseases ◽  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Fluorescent Dyes ◽  
Fibril Formation ◽  
Optical Probes ◽  
Macrocyclic Receptors ◽  
Amyloid Fibril Formation

This article provides a brief account of the recent reports on the early detection of amyloid fibril formation using fluorescent dyes and inhibition and disintegration of fibrils using macrocyclic receptors, which find applications in the treatment of fibril associated neurodegenerative diseases.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Analysis of 3-d molecular distribution with the digital imaging microscope

1988 ◽  
Vol 46 ◽  
pp. 40-41
Author(s):  
W.A. Carrington ◽  
F.S. Fay ◽  
K.E. Fogarty ◽  
L. Lifshitz
Keyword(s):  
Image Restoration ◽  
Digital Imaging ◽  
Fluorescent Dyes ◽  
Optical Axis ◽  
Computer Hardware ◽  
Computer Algorithms ◽  
Low Contrast ◽  
Specific Proteins ◽  
Effective Use ◽  
Single Living Cells

Advances in digital imaging microscopy and in the synthesis of fluorescent dyes allow the determination of 3D distribution of specific proteins, ions, GNA or DNA in single living cells. Effective use of this technology requires a combination of optical and computer hardware and software for image restoration, feature extraction and computer graphics.The digital imaging microscope consists of a conventional epifluorescence microscope with computer controlled focus, excitation and emission wavelength and duration of excitation. Images are recorded with a cooled (-80°C) CCD. 3D images are obtained as a series of optical sections at .25 - .5 μm intervals.A conventional microscope has substantial blurring along its optical axis. Out of focus contributions to a single optical section cause low contrast and flare; details are poorly resolved along the optical axis. We have developed new computer algorithms for reversing these distortions. These image restoration techniques and scanning confocal microscopes yield significantly better images; the results from the two are comparable.

Liquid crystalline ordering of paired helical filaments in neurofibrillary tangles of Alzheimer's disease

1986 ◽  
Vol 44 ◽  
pp. 348-349
Author(s):  
D.F. Clapin ◽  
V.J.A. Montpetit
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Liquid Crystalline ◽  
Amyloid Fibrils ◽  
Geometric Analysis ◽  
Paired Helical Filaments ◽  
Microscopic Level ◽  
Light Microscopic Level ◽  
Regular Spacing

Alzheimer's disease is characterized by the accumulation of abnormal filamentous proteins. The most important of these are amyloid fibrils and paired helical filaments (PHF). PHF are located intraneuronally forming bundles called neurofibrillary tangles. The designation of these structures as "tangles" is appropriate at the light microscopic level. However, localized domains within individual tangles appear to demonstrate a regular spacing which may indicate a liquid crystalline phase. The purpose of this paper is to present a statistical geometric analysis of PHF packing.

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