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Methods and Applications in Fluorescence

Bryan Donaphon, Linda B Bloom, Marcia Levitus
Rhodamine dyes in aqueous solution form non-fluorescent dimers with a plane-to-plane stacking geometry (H-dimers). The self-quenching properties of these dimers have been exploited to probe the conformation and dynamics of proteins using a variety of fluorescence approaches that require the interpretation of fluorescence intensities, lifetimes and fluctuations. Here, we report on a systematic study of the photophysical properties of three rhodamine dyes (tetramethylrhodamine, Alexa 488 and Alexa 546) covalently bound to the E...
July 9, 2018: Methods and Applications in Fluorescence
Liisa M Hirvonen, Susan Cox
Superresolution microscopy based on localisation is usually performed in a buffer containing enzymatic oxygen scavenger, which facilitates reversible photoswitching of the dye molecules. This makes correlative fluorescence localisation and atomic force microscopy (AFM) challenging, because enzymatic oxygen scavenging interferes with the AFM cantilevers. Here we report on the blinking kinetics of a new red cyanine dye, iFluor-647, which is similar to the Alexa-647 dye commonly used for superresolution microscopy, but with brightness and blinking properties which are superior to Alexa-647 in a buffer without enzymatic oxygen scavenger...
June 29, 2018: Methods and Applications in Fluorescence
Iryna Lysova, Coralie Spiegelhalter, Eleonore Réal, Sarwat Zgheib, Halina Anton, Yves Mely
Visualization of viruses in the host cell during the course of infection by correlative light-electron microscopy (CLEM) requires a specific labelling of the viral structures in order to recognize the nanometric viral cores in the intracellular environment. For Human immunodeficiency virus type 1 (HIV-1), the labelling approaches developed for fluorescence microscopy are generally not suited for transmission electron microscopy (TEM), so that imaging of HIV-1 particles in infected cells by CLEM is not straightforward...
June 25, 2018: Methods and Applications in Fluorescence
Ben Allan Russell, Ashley Garton, Abeer Saeed Alshammari, David J S Birch, Yu Chen
Fluorescent protein-encapsulated gold nanoclusters (AuNCs) offer a non-toxic means of sensing and imaging biological phenomena on the nanoscale. However, the biofunctionality of proteins encapsulating AuNCs has not been fully elucidated to date. Here we studied the biofunctionality of the second major drug binding site (Sudlow II) of Human Serum Albumin (HSA) encapsulated AuNCs after AuNC synthesis. L-Dopa, a fluorescent drug molecule associated with the clinical treatment of Parkinson's disease, which commonly binds to the Sudlow II site, was used to study the availability of the site before and after AuNC synthesis through changes to its fluorescence characteristics...
June 20, 2018: Methods and Applications in Fluorescence
Zhiqian Zhang, Changli Zhong, Taixian Yuan, Xiaoyan Zhou, Min Zhao, Husun Qian, Wei Cheng, Tingmei Chen
A hybridized chain reaction (HCR)-based biosensing method has been developed for the imaging detection of intracellular telomerase activity. The telomerase-targeting responder-transmitter DNA complex (HPT) consisting of telomerase primer sequence (HP) and a HCR initiator (trigger) is transfected into cell plasma. In the presence of telomerase, HPT can be recognized and extended, producing plenty of triggers which initiates HCR amplification reaction. Finally, a long nicked dsDNA with a lot of outstretched single chains was formed by hybridizing with Q of the reporter complex, generating an enhanced fluorescence signal...
June 20, 2018: Methods and Applications in Fluorescence
Aleš Holoubek, Petr Herman, Jan Sýkora, Barbora Brodská, Jana Humpolíčková, Markéta Kráčmarová, Dana Gášková, Martin Hof, Kateřina Kuželová
Oligomerization plays a crucial role in the function of nucleophosmin (NPM), an abundant nucleolar phosphoprotein. Two dual-color methods based on modern fluorescence confocal microscopy are applied for tracking NPM aggregates in live cells: cross-correlation Number and Brightness analysis (ccN&B) combined with pulsed interleaved excitation (PIE) and fluorescence-lifetime imaging microscopy (FLIM) utilizing resonance energy transfer (FRET). HEK-293T cells were transfected with mixture of plasmids designed for tagging with fluorescent proteins so that the cells express mixed population of NPM labeled either with eGFP or mRFP1...
June 29, 2018: Methods and Applications in Fluorescence
Bingyan Han, Tingting Peng, Ying Li, Mingbo Yu, Xixi Hu, Gaohong He
Water-soluble and ultra-stable L-proline-protected copper nanoclusters (Cu NCs) are reported, which overcome the bottleneck that Cu NCs are easily oxidized. The average size of Cu NCs is found to be 1.88 ± 0.17 nm. The as-prepared Cu NCs exhibit an excellent stability over the physiologically relevant pH range, long storage time, high ionic strength, high concentration of hydrogen peroxide and various common metal ions. The fluorescence intensity of Cu NCs maintains no change after 5 months stored in the refrigerator...
June 28, 2018: Methods and Applications in Fluorescence
A K Choudhary, S K Singh, A Dwivedi, A Bahadur, S B Rai
There are two key factors to design an efficient green upconversion (UC) emission based optical sensor for temperature. The primary need is to develop a thermally stable and economical material, for a stable sensor, and the second essence is to get an efficient green UC emission, for high sensitivity of the sensor. The proof of this concept is demonstrated on a model system CaAl2 O4 : Er3+ , co-doped with Yb3+ and Zn2+ . UC emission of Er3+ ion is enhanced, primarily, through co-operative energy transfer from Yb3+ to Er3+ ions...
June 21, 2018: Methods and Applications in Fluorescence
Bahareh Babamiri, Rahman Hallaj, Abdollah Salimi
In the present study, we constructed an ultrasensitive solid surface fluorescence-immunosensor based on highly luminescent CdTe@CdS-PAMAM structures as nanoprobe for determination of HBsAg by monitoring fluorescence intensity. This strategy was achieved by using PAMAM as a signal amplifier; the PAMAM dendrimer with the many functional amine groups can amplify the fluorescence signal of QDs by covalent attachment of CdTe@CdS on PAMAM and hence, improve the sensitivity of the proposed method significantly. A sandwich type immunosensor was formed after the addition of HBsAg and the PAMAM-QD-Ab2 , respectively...
June 20, 2018: Methods and Applications in Fluorescence
Alizé Proust, Julie-Christine Lévesque, Corinne Barat, Sachiko Sato, Michel J Tremblay
Extracellular traps ejected by various immune cells (neutrophils, macrophages, eosinophils and mast cells) have several immune functions, either protective against pathogens or deleterious in some autoimmune or inflammatory disorders. Since their first description in 2004, the mechanisms of extracellular traps formation have been extensively investigated though still not fully understood. We describe here a new tool for the detection of extracellular traps by fluorescence microscopy in a single-step staining protocol, which does not require any wash...
May 29, 2018: Methods and Applications in Fluorescence
Rukiye Ayranci, Fatma Ozturk Kirbay, Dilek Odaci Demirkol, Metin Ak, Suna Timur
A simple, rapid and effective fluorescence sensing platform has been fabricated using a fluorescent conducting polymer surface. For this purpose, a rhodamine based electroactive monomer (RDC) and a functional group containing monomer (SNS) have been copolymerized to develop a conducting polymer based sensor platform having a fluorescence and enzyme-binding surface on ITO electrode. The proposed fluorescence sensing mechanism for detection of glucose is related to the consumption of dissolved oxygen at the double layer of the electrode which is fluorescence quenching agent by glucose-GOx reaction...
May 29, 2018: Methods and Applications in Fluorescence
Linlin Zhong, Kyusik Yun
A novel fluorescence 'Switch on' for the detection of heparin based on the RhB-COL/GO system was achieved. A strong fluorescence dye, Rhodamine B, was modified by chitosan oligosaccharide lactate (COL), which plays a major role in the formation of a positively charged RhB-COL complex. RhB-COL was soluble and stable in solution, which was characterized by using Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. GO sheets quenched the fluorescence intensity of RhB-COL due to electron transfer from RhB to the GO surface...
May 29, 2018: Methods and Applications in Fluorescence
James D Manton, Yao Xiao, Robert D Turner, Graham Christie, Eric J Rees
It is often necessary to precisely quantify the size of specimens in biological studies. When measuring feature size in fluorescence microscopy, significant biases can arise due to blurring of its edges if the feature is smaller than the diffraction limit of resolution. This problem is avoided if an equation describing the feature's entire image is fitted to its image data. In this paper we present open-source software, ELM, which uses this approach to measure the size of spheroidal or cylindrical fluorescent shells with a precision of around 10 nm...
May 16, 2018: Methods and Applications in Fluorescence
Nicholas Nunn, Marta d'Amora, Neeraj Prabhakar, Alexander M Panich, Natalya Froumin, Marco D Torelli, Igor Vlasov, Philipp Reineck, Brant Gibson, Jessica M Rosenholm, Silvia Giordani, Olga Shenderova
Detonation nanodiamonds (DNDs) have emerged as promising candidates for a variety of biomedical applications, thanks to different physicochemical and biological properties, such as small size and reactive surfaces. In this study, we propose carbon dot decorated single digit (4-5 nm diameter) primary particles of detonation nanodiamond as promising fluorescent probes. Due to their intrinsic fluorescence originating from tiny (1-2 atomic layer thickness) carbonaceous structures on their surfaces, they exhibit brightness suitable for in vitro imaging...
May 9, 2018: Methods and Applications in Fluorescence
Xiao-Hui Wang, Hong-Shang Peng, Kun Cheng, Xiao-Ming Liu, Yuan-An Liu, Wei Yang
Ratiometric fluorescent nanoparticles (NPs) under two-photon excitation are successfully developed for sensing dissolved oxygen. The NPs comprise the oxygen probe Pt(II)-porphyrins (PtTFPP) and fluorescent organic semiconducting polymer (PFO). PFO polymer acts as both a two-photon antenna and a reference dye, while PtTFPP absorbs the photonic energy transferred by the PFO under two-photon excitation at 740 nm to sense oxygen. The red fluorescence of PtTFPP is sensitive to oxygen with a quenching response of 88% from nitrogen saturation to oxygen saturation, and PFO gives oxygen-insensitive referenced blue fluorescence...
April 27, 2018: Methods and Applications in Fluorescence
Anita R Warrier, R Gandhimathi
In this article, we report on enhancement in photoluminescence and Raman line intensity of SnS quantum dots embedded in a mesh of Sn nanostructures. SnS nanoparticles synthesized by homogenous precipitation method show strong quantum confinement with a band gap of ∼2.7 eV (blue shift of ∼1 eV compared to bulk SnS particles). The optical band gap of SnS quantum dots is controlled by varying the pH (∼0 to 2.25), ageing time (24 to 144 h) and molarity (0 to 2 M) of the precursors. These SnS nanoparticles are embedded in a mesh of Sn nanostructures which are synthesized from tin chloride by using sodium borohydride as reducing agent...
April 27, 2018: Methods and Applications in Fluorescence
Ying Lian, Long-Jiang Ding, Wei Zhang, Xiao-Ai Zhang, Ying-Lu Zhang, Zhen-Zhen Lin, Xu-Dong Wang
Cyanine dyes are widely used in biological labeling and imaging because of their narrow near infrared emission, good brightness and high flexibility in functionalization, which not only enables multiplex analysis and multi-color imaging, but also greatly reduces autofluorescence from biological matter and increases signal-to-noise ratio. Unfortunately, their poor chemical- and photo-stability strongly limits their applications. The incorporation of cyanine dyes in silica nanoparticles provides a solution to the problem...
April 27, 2018: Methods and Applications in Fluorescence
Kirti Kumari Sharma, Gavash Harsha Kannikanti, Tulsidas Ramachandra Rao Baggi, Jayathirtha Rao Vaidya
Present work is conducted to demonstrate the use of pyrene for the development of latent fingermarks. Pyrene formulation with binders can be efficiently used for developing latent fingermarks on porous, non-porous and semi-porous surfaces. The effectiveness of pyrene formulation for the detection of latent fingermarks present on a large variety of objects was systematically and comparatively carried out. To optimize the working formulation, studies were carried out using different pyrene concentrations followed by various substrate study, time dependent study, temperature study, depleted fingermark development and the stability of the proposed formulation...
April 25, 2018: Methods and Applications in Fluorescence
Ming Jun Cen, Tao Chang, Yao Bing Yin, Xiao Liang Li, Yong Wu He
A novel ratiometric fluorescent probe BCB was reported for the first time for the sensitive and selective analysis of Ag+ based on two Boradiazaindacene (BODIPY) as both the reference fluorophore and recognition part. Upon the addition of Ag+ ions, a strong fluorescence emission at 570 nm from recognition BODIPY would be appeared, whereas the fluorescence of the other BODIPY at 535 nm would be a constant reference fluorescence signal. As a result, the ratio of fluorescence intensity (λ570/λ535) was changed from 0...
April 25, 2018: Methods and Applications in Fluorescence
R K Ratnesh, M S Mehata
We have prepared stable colloidal CdTe and CdTe/ZnS core-shell quantum dots (QDs) using hot injection chemical route. The developed CdTe QDs emit tunable single and dual photoluminescence (PL) bands, originating from the direct band edge and the surface state of QDs, as evident by the steady-state and time-resolved spectroscopy. The developed CdTe and CdTe/ZnS QDs act as optical sensors for the detection of metal ions (e.g., Fe2+ and Pb2+ ) in the feed water. The PL quenching in the presence of analytes has been examined by both the steady-state and time-resolved PL spectroscopy...
April 25, 2018: Methods and Applications in Fluorescence
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