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https://www.readbyqxmd.com/read/28213258/p-aminothiophenol-coated-cdse-zns-quantum-dots-as-a-turn-on-fluorescent-probe-for-ph-detection-in-aqueous-media
#1
Dong Li, Hu Xu, Dan Li, Yuhong Wang
Since controlling hydrogen ion concentration (i.e. pH) is fairly important in various fields, developing a facile pH detection method is highly desired. Owing to the superior optical properties, semiconductor quantum dots (QDs) have been developed as a promising alternative for organic fluorophores in fluorescence analysis. In this study, a hydrophilic p-aminothiophenol (pATP) capped CdSe/ZnS QDs (denoted as pATP-QDs) as a selective "turn-on" fluorescence probe for pH in aqueous media is reported. The pATP-QDs probe easily obtained via ligand exchange are characterized by various analytic techniques including ultraviolet-visible, fourier transform infrared, fluorescence, time-resolved fluorescence spectroscopies, and transmission electron microscope etc...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28211922/applying-phasor-approach-analysis-of-multiphoton-flim-measurements-to-probe-the-metabolic-activity-of-three-dimensional-in-vitro-cell-culture-models
#2
Pirmin H Lakner, Michael G Monaghan, Yvonne Möller, Monilola A Olayioye, Katja Schenke-Layland
Fluorescence lifetime imaging microscopy (FLIM) can measure and discriminate endogenous fluorophores present in biological samples. This study seeks to identify FLIM as a suitable method to non-invasively detect a shift in cellular metabolic activity towards glycolysis or oxidative phosphorylation in 3D Caco-2 models of colorectal carcinoma. These models were treated with potassium cyanide or hydrogen peroxide as controls, and epidermal growth factor (EGF) as a physiologically-relevant influencer of cell metabolic behaviour...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28209913/rapid-imaging-of-tumor-cell-death-in-vivo-using-the-c2a-domain-of-synaptotagmin-i
#3
André A Neves, Bangwen Xie, Sarah Fawcett, Israt S Alam, Timothy H Witney, Maaike M de Backer, Julia Summers, William Hughes, Sarah McGuire, Dmitry Soloviev, Jodie Miller, William J Howat, De-En Hu, Tiago B Rodrigues, David Y Lewis, Kevin M Brindle
Cell death is an important target for imaging the early response of tumors to treatment. We describe here validation of a phosphatidylserine-binding agent for detecting tumor cell death in vivo based on the C2A domain of Synaptotagmin-I. Methods: The capability of near infrared fluorophore-labeled and 99mTechnetium- and (111)Indium-labeled derivatives of C2Am for imaging tumor cell death, using planar near infrared fluorescence (NIRF) imaging and single photon computed tomography (SPECT) respectively, was evaluated in implanted and genetically engineered mouse models of lymphoma and in a human colorectal xenograft...
February 16, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28208666/the-mechanisms-and-biomedical-applications-of-an-nir-bodipy-based-switchable-fluorescent-probe
#4
Bingbing Cheng, Venugopal Bandi, Shuai Yu, Francis D'Souza, Kytai T Nguyen, Yi Hong, Liping Tang, Baohong Yuan
Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)₂, were conducted...
February 11, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28208302/real-time-monitoring-atp-in-mitochondrion-of-living-cells-a-specific-fluorescent-probe-for-atp-by-dual-recognition-sites
#5
Kai-Yue Tan, Chun-Yan Li, Yong-Fei Li, Junjie Fei, Bin Yang, Ya-Jun Fu, Fang Li
Adenosine triphosphate (ATP) is mainly produced in the mitochondrion and used as a universal energy source for various cellular events. Various fluorescent probes for ATP have been established successfully, but most of them are not appropriate for monitoring the fluctuation of the mitochondrial ATP level. Herein, a fluorescent probe named Mito-Rh is first synthesized and used to recognize ATP in mitochondrion. In the probe, rhodamine, diethylenetriamine, and triphenylphosphonium are selected as fluorophore, reaction site, and mitochondrion-targeting group, respectively...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28208244/fluorescein-based-chromogenic-and-ratiometric-fluorescence-probe-for-highly-selective-detection-of-cysteine-and-its-application-in-bioimaging
#6
Zhen-Hai Fu, Xiao Han, Yongliang Shao, Jianguo Fang, Zhi-Hong Zhang, Ya-Wen Wang, Yu Peng
A dual mode fluorescent probe, which is based on an integration of fluorescein and coumarin fluorophores, was developed for the discrimination of Cys from Hcy and GSH. This probe (2) shows the advantage of quick reaction (5 min) with Cys, resulting in a strong fluorescence turn-on response when excited at 450 nm. Notably, it also demonstrates the ratiometric fluorescence property while excited by a shorter wavelength (332 nm). All of results suggest probe 2 has a high selectivity toward Cys even in the presence of other amino acids, cations and anions...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28207759/investigations-on-therapeutic-glucocerebrosidases-through-paired-detection-with-fluorescent-activity-based-probes
#7
Wouter W Kallemeijn, Saskia Scheij, Sascha Hoogendoorn, Martin D Witte, Daniela Herrera Moro Chao, Cindy P A A van Roomen, Roelof Ottenhoff, Herman S Overkleeft, Rolf G Boot, Johannes M F G Aerts
Deficiency of glucocerebrosidase (GBA) causes Gaucher disease (GD). In the common non-neuronopathic GD type I variant, glucosylceramide accumulates primarily in the lysosomes of visceral macrophages. Supplementing storage cells with lacking enzyme is accomplished via chronic intravenous administration of recombinant GBA containing mannose-terminated N-linked glycans, mediating the selective uptake by macrophages expressing mannose-binding lectin(s). Two recombinant GBA preparations with distinct N-linked glycans are registered in Europe for treatment of type I GD: imiglucerase (Genzyme), contains predominantly Man(3) glycans, and velaglucerase (Shire PLC) Man(9) glycans...
2017: PloS One
https://www.readbyqxmd.com/read/28207199/bisphosphonate-functionalized-imaging-agents-anti-tumor-agents-and-nanocarriers-for-treatment-of-bone-cancer
#8
REVIEW
Robin A Nadar, Nicola Margiotta, Michele Iafisco, Jeroen J J P van den Beucken, Otto C Boerman, Sander C G Leeuwenburgh
Bone metastases result from the invasion of primary tumors to bone. Current treatment modalities include local treatments such as surgery and radiotherapy, while systemic treatments include chemotherapy and (palliative) treatment of skeletal metastases. Nevertheless, once bone metastases have been established they remain incurable leading to morbidity and mortality. Bisphosphonates are a well-established class of drugs, which are increasingly applied in the treatment of bone cancers owing to their effective inhibition of tumor cells and suppression of bone metastases...
February 16, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28207001/genome-editing-using-facs-enrichment-of-nuclease-expressing-cells-and-indel-detection-by-amplicon-analysis
#9
Lindsey A Lonowski, Yoshiki Narimatsu, Anjum Riaz, Catherine E Delay, Zhang Yang, Francesco Niola, Katarzyna Duda, Elke A Ober, Henrik Clausen, Hans H Wandall, Steen H Hansen, Eric P Bennett, Morten Frödin
This protocol describes methods for increasing and evaluating the efficiency of genome editing based on the CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated 9) system, transcription activator-like effector nucleases (TALENs) or zinc-finger nucleases (ZFNs). First, Indel Detection by Amplicon Analysis (IDAA) determines the size and frequency of insertions and deletions elicited by nucleases in cells, tissues or embryos through analysis of fluorophore-labeled PCR amplicons covering the nuclease target site by capillary electrophoresis in a sequenator...
March 2017: Nature Protocols
https://www.readbyqxmd.com/read/28205171/synthesis-and-live-cell-imaging-of-fluorescent-sterols-for-analysis-of-intracellular-cholesterol-transport
#10
Maciej Modzel, Frederik W Lund, Daniel Wüstner
Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE)...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28199055/photo-induced-click-chemistry-for-dna-surface-structuring-via-direct-laser-writing
#11
Ljiljana Fruk, Antonina Kerbs, Patrick Mueller, Michael Kaupp, Ishtiaq Ahmed, Alexander S Quick, Doris Abt, Martin Wegener, Christof M Niemeyer, Christopher Barner-Kowollik
Oligonucleotides containing photo-caged dienes were prepared and shown to react quantitatively in a light-induced Diels-Alder cycloaddition with functional maleimides in aqueous solution within minutes. Due to its high yield and fast rate, the reaction was exploited for DNA surface patterning with sub-micrometer resolution employing direct laser writing (DLW). Functional DNA arrays were written via direct laser writing (DLW) in variable patterns, which were further encoded with fluorophores and proteins through DNA directed immobilisation...
February 15, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28198876/precise-background-subtraction-in-stimulated-emission-double-depletion-nanoscopy
#12
Peng Gao, G Ulrich Nienhaus
Low-resolution background in stimulated emission depletion (STED) nanoscopy can arise from incomplete depletion or re-excitation by the STED beam. We have recently introduced stimulated emission double depletion (STEDD), a technique to efficiently suppress this background. In STEDD, the conventional, doughnut-shaped STED pulse, which depletes excited fluorophores outside the center of the focal region, is followed by a second Gaussian STED pulse, which specifically depletes the central region. The background is removed by calculating a weighted difference of photon events collected before and after the second STED pulse...
February 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28197572/three-in-one-prototropy-free-highly-stable-aadd-type-self-complementary-quadruple-hydrogen-bonded-molecular-duplexes-with-a-built-in-fluorophore
#13
Sanjeev Kheria, Suresh Rayavarapu, Amol S Kotmale, Gangadhar J Sanjayan
This communication reports an effective approach for addressing the prototropy-related problems in heterocycle-based AADD-type self-assembling systems by freezing their hydrogen-bonding codes, by utilizing intramolecular bifurcated hydrogen bonding interactions. Using this strategy, we have also developed a hydroquinone-conjugated AADD-type self-assembling system adorned with three valuable features such as prototropy-free dimerization yielding single duplexes, high duplex stability and a built-in fluorophore, which would augment its application potential...
February 15, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28196307/molecule-counts-in-localization-microscopy-with-organic-fluorophores
#14
Mike Heilemann, Franziska Fricke, Christos Karathanasis, Gerhard Hummer
Single-molecule localization microscopy (SMLM) can be used to count fluorescently labeled molecules even when they are not individually resolved. We demonstrate SMLM molecule counting for nucleic acids labeled with the organic fluorophore Alexa Fluor 647 and imaged under photoswitching conditions. From the observed distributions of the number of fluorophore blinking events, we extracted the number of fluorophores per spot using a statistical model. We validate the molecule counting method for single Alexa Fluor 647 fluorophores, and for trimers of Alexa Fluor 647 constructed on a DNA origami structure...
February 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28195691/the-gcamp-r-family-of-genetically-encoded-ratiometric-calcium-indicators
#15
Jung-Hwa Cho, Carter J Swanson, Jeannie Chen, Ang Li, Lisa G Lippert, Shannon E Boye, Kasey Rose, Sivaraj Sivaramakrishnan, Cheng-Ming Chuong, Robert H Chow
We report on GCaMP-Rs, a new family of genetically encoded ratiometric calcium indicators that extend the virtues of the GCaMP proteins to ratiometric measurements. We have engineered a tandem construct of calcium-dependent GCaMP and calcium-independent mCherry fluorescent proteins. The tandem design assures that the two proteins localize in the same cellular compartment(s) and facilitates pixelwise ratiometric measurements; however, Förster resonance energy transfer (FRET) between the fluorophores reduces brightness of the sensor by up to half (depending on the GCaMP variant)...
February 14, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28195410/design-of-na-selective-fluorescent-probes-a-systematic-study-of-the-na-complex-stability-and-the-na-k-selectivity-in-acetonitrile-and-water
#16
Hans-Jürgen Holdt
Overall, there is a tremendous demand for highly Na+-selective fluoroionophores to monitor the top analyte Na+ in life science. Herein, we report on a systematic route to develop highly Na+/K+ selective fluorescent probes. Thus, we synthesized a set of fluoroionophores to investigate the Na+/K+ selectivity and Na+-complex stability in CH3CN and H2O. These Na+-probes bearing different 15-crown-5 moieties to bind Na+ stronger than K+. Further, we found for the N-(o-methoxyphenyl)aza-15-crown-5 substituted fluoroionophores 2, 8 and 9 (see Scheme 1) in H2O an enhanced Na+-complex stability in the following order 8 > 2 > 9 and an increased Na+/K+ selectivity in the reverse order 9 > 2 > 8...
February 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28195278/influence-of-the-excitation-light-intensity-on-the-rate-of-fluorescence-quenching-reactions-pulsed-experiments
#17
Gonzalo Angulo, Jadwiga Milkiewicz, Daniel Kattnig, Michał Nejbauer, Yuriy Stepanenko, Jan Szczepanek, Czesław Radzewicz, Paweł Wnuk, Günter Grampp
The effect of multiple light excitation events on bimolecular photo-induced electron transfer reactions in liquid solution is studied experimentally. It is found that the decay of fluorescence can be up to 25% faster if a second photon is absorbed after a first cycle of quenching and recombination. A theoretical model is presented which ascribes this effect to the enrichment of the concentration of quenchers in the immediate vicinity of fluorophores that have been previously excited. Despite its simplicity, the model delivers a qualitative agreement with the observed experimental trends...
February 14, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28194980/cell-penetrating-peptide-spirolactam-derivative-as-a-reversible-fluorescent-ph-probe-for-live-cell-imaging
#18
Meng-Chan Xia, Lesi Cai, Sichun Zhang, Xinrong Zhang
A colorless and nonfluorescent spirolactam derivative, RhB-R12K, was synthesized by amide condensation between the carboxyl group of rhodamine B (RhB) and the amino group of cell-penetrating peptide (CPP). The fluorescence intensity of RhB-R12K sharply increased as the pH value decreased from 8.0 to 4.9, demonstrating sensitive and reversible response to intracellular pH distribution. This CPP probe was completely water soluble, had low cytotoxicity, was membrane permeable, and was suitable for pH measurement in various organelles by choosing organelle-specific CPP sequences...
January 17, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28194940/dna-duplex-engineering-for-enantioselective-fluorescent-sensor
#19
Yuehua Hu, Fan Lin, Tao Wu, Yufeng Zhou, Qiusha Li, Yong Shao, Zhiai Xu
The rapid identification of biomacromolecule structure that has a specific association with chiral enantiomers especially from natural sources will be helpful in developing enantioselective sensor and in speeding up drug exploitation. Herein, owing to its existence also in living cells, apurinic/apyrimidinic site (AP site) was first engineered into ds-DNA duplex to explore its competence in enantiomer selectivity. An AP site-specific fluorophore was utilized as an enantioselective discrimination probe to develop a straightforward chiral sensor using natural tetrahydropalmatine (L- and D-THP) as enantiomer representatives...
January 30, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28193412/lepteridine-as-a-unique-fluorescent-marker-for-the-authentication-of-manuka-honey
#20
Bin Lin, Kerry M Loomes, Gordana Prijic, Ralf Schlothauer, Jonathan M Stephens
The recent discovery of two unique manuka marker fluorescence wavelengths (MM1 and MM2) potentially offers a rapid and cost-effective approach for manuka honey authentication using spectroscopy. The fluorophore responsible for the MM1 marker has been identified as leptosperin. We investigated whether lepteridine may be responsible for the MM2 fluorescence. We quantified the lepteridine in manuka honey and manuka nectar, which ranged between 5-52mg/kg and 80-205mg/kg, respectively. Notably, the fluorescent spectrum of synthetic lepteridine matched the MM2 fluorescence signature...
June 15, 2017: Food Chemistry
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