Consideration of end effects of DNA hybridization in selection of fluorescent dyes for development of optical biosensors

1999 ◽  
Vol 77 (12) ◽  
pp. 2083-2087 ◽  
Author(s):  
S C Jakeway ◽  
U J Krull
Keyword(s):  
Quantum Efficiency ◽  
Dna Hybridization ◽  
Fluorescent Dyes ◽  
Hydrocarbon Chain ◽  
Spectroscopic Properties ◽  
Excitation Wavelength ◽  
End Effects ◽  
High Quantum Efficiency ◽  
The Stability ◽  
Selection Of

Intercalating fluorescent dyes are in widespread use to detect the presence of double-stranded DNA. Applications include the development of biosensors that rely on the attachment ("tethering") of a dye molecule by a short hydrocarbon chain to the terminus of a strand of DNA so that dye is continuously available and the biosensor is fully reversible. Double strands of DNA have end effects that limit the stability of hybridization and dye intercalation near the termini of the duplexes. Therefore, the selection of the dye must be based on consideration of spectroscopic properties and also issues associated with tether length and the stoichiometry of the binding of the dye with double- and single-stranded DNA. Ethidium bromide (EB) has been used extensively to detect hybridization of DNA in applications such as electrophoresis, gene chips, and biosensors. A number of dyes with greater quantum efficiency than EB for detection of hybridization have been reported. Furthermore, other practical spectroscopic advantages can be gained in terms of improved S/N by use of dyes that have excitation that is red shifted relative to EB. Pyrilium iodide has been disclosed as an intercalator of high quantum efficiency and long excitation wavelength. This work investigates pyrilium iodide in comparison to EB as a candidate for preparation of a tethered dye for detection of hybridization of DNA 20-mers.Key words: biosensors, DNA, hybridization, fluorescence, end effects.

Simultaneous, non-interfering collection of optimal fluorescent and backscattered light signals on the MRC 500/600

1993 ◽  
Vol 51 ◽  
pp. 156-157
Author(s):  
JB Pawley ◽  
WB Amos ◽  
A Dixon ◽  
TC Brelje
Keyword(s):  
Optical Properties ◽  
Quantum Efficiency ◽  
Fluorescent Dyes ◽  
Living Cells ◽  
Microscopical Examination ◽  
High Quantum Efficiency ◽  
Fluorescent Signal ◽  
High Quantum ◽  
Signal Collection ◽  
Light Signals

One of the most important attributes of the confocal LM is that it can be used for imaging living cells. Unfortunately, cells that contain fluorescent dyes are far less tolerant of the intense illumination characteristic of microscopical examination than unstained cells. As a result, it early became evident that every effort should be made to extract as much information as possible from every photon striking the specimen. This implies not only utilizing detectors with high quantum efficiency but also detecting the light which is back-scattered by (BSL), or passing through, the specimen in addition to any fluorescent signal. Both transmitted light and BSL carry information about the optical properties of the specimen and it is possible to detect this information without compromising fluorescent signal collection.

Fabrication and Characterization of Silica Opals

2008 ◽  
Vol 55 ◽  
pp. 118-126 ◽  
Author(s):  
Cristina Armellini ◽  
Andrea Chiappini ◽  
A. Chiasera ◽  
Maurizio Ferrari ◽  
Yoann Jestin ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Photonic Band Gap ◽  
Sol Gel ◽  
Spectroscopic Properties ◽  
Visible Range ◽  
Core Shell ◽  
Luminescence Decay Curve ◽  
Inverse Opal ◽  
Polystyrene Spheres ◽  
High Quantum Efficiency

We present the details of the sol-gel processing used to realize inverse silica opal, where the silica was activated with 0.3 mol% of Er3+ ions. The template (direct opal) was obtained assembling polystyrene spheres of the dimensions of 260 nm by means of a vertical deposition technique. The Er3+-activated silica inverse opal was obtained infiltrating, into the void of the template, the silica sol doped with Er3+ ions and subsequently removing the polystyrene spheres by means of calcinations. Scanning electron microscope showed that the inverse opals possess an fcc structure with a air hollow of about 210 nm. A photonic band gap in the visible range was observed from reflectance measurements. Spectroscopic properties of Er3+activated silica inverse opal were investigated by photoluminescence spectroscopy. A bandwidth of 21 nm was measured for the 4I13/2 → 4I15/2 transition of Er3+ ions upon excitation at 514.5 nm. The luminescence decay curve of the 4I13/2 metastable state of the Er3+ ions presents a lifetime τ = 16.8 ± 0.1 ms giving a very high quantum efficiency of the fabricated system. Core-shell Er3+-activated silica spheres, where the core is the silica sphere and the shell is an Er2O3-SiO2 coating is proposed as a possible route for opal fabrication. For core-shell system a quantum efficiency of about 70% was estimated.

Optical and spectroscopic properties of erbium-activated modified silica glass with 1.54 μm high quantum efficiency

2005 ◽  
Author(s):  
Vincent Benoit ◽  
Shivakiran Narasimha Bantwal Bhaktha ◽  
Brigitte Boulard ◽  
Stephane Chaussedent ◽  
Andrea Chiappini ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Silica Glass ◽  
Spectroscopic Properties ◽  
Modified Silica ◽  
High Quantum Efficiency ◽  
High Quantum

scholarly journals Highly Efficient Phosphorescent Blue-Emitting [3+2+1] Coordinated Iridium (III) Complex for OLED Application

2021 ◽  
Vol 9 ◽  
Author(s):  
Zijian Liu ◽  
Si-Wei Zhang ◽  
Meng Zhang ◽  
Chengcheng Wu ◽  
Wansi Li ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Blue Emission ◽  
Bidentate Ligand ◽  
Monodentate Ligand ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
High Quantum ◽  
Molecular Stability ◽  
Blue Emitters ◽  
The Stability

Cyclometalated iridium (III) complexes are indispensable in the field of phosphorescent organic light-emitting diodes (PhOLEDs), while the improvement of blue iridium (III) complexes is as yet limited and challenging. More diversified blue emitters are needed to break through the bottleneck of the industry. Hence, a novel [3+2+1] coordinated iridium (III) complex (noted as Ir-dfpMepy-CN) bearing tridentate bis-N-heterocyclic carbene (NHC) chelate (2,6-bisimidazolylidene benzene), bidentate chelates 2-(2,4-difluorophenyl)-4-methylpyridine (dfpMepy), and monodentate ligand (-CN) has been designed and synthesized. The tridentate bis-NHC ligand enhances molecular stability by forming strong bonds with the center iridium atom. The electron-withdrawing groups in the bidentate ligand (dfpMepy) and monodentate ligand (-CN) ameliorate the stability of the HOMO levels. Ir-dfpMepy-CN shows photoluminescence peaks of 440 and 466 nm with a high quantum efficiency of 84 ± 5%. Additionally, the HATCN (10 nm)/TAPC (40 nm)/TcTa (10 nm)/10 wt% Ir-dfpMepy-CN in DPEPO (10 nm)/TmPyPB (40 nm)/Liq (2.5 nm)/Al (100 nm) OLED device employing the complex shows a CIE coordinate of (0.16, 0.17), reaching a deeper blue emission. The high quantum efficiency is attributed to rapid singlet to triplet charge transfer transition of 0.9–1.2 ps. The successful synthesis of Ir-dfpMepy-CN has opened a new window to develop advanced blue emitters and dopant alternatives for future efficient blue PhOLEDs.

scholarly journals Spatio-temporal selection of reference genes in the two congeneric species of Glycyrrhiza

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuping Li ◽  
Xiaoju Liang ◽  
Xuguo Zhou ◽  
Yu An ◽  
Ming Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Developmental Stage ◽  
Reference Genes ◽  
Developmental Stages ◽  
Individual Factors ◽  
Congeneric Species ◽  
Spatio Temporal ◽  
The Stability ◽  
Different Tissues ◽  
Selection Of

AbstractGlycyrrhiza, a genus of perennial medicinal herbs, has been traditionally used to treat human diseases, including respiratory disorders. Functional analysis of genes involved in the synthesis, accumulation, and degradation of bioactive compounds in these medicinal plants requires accurate measurement of their expression profiles. Reverse transcription quantitative real-time PCR (RT-qPCR) is a primary tool, which requires stably expressed reference genes to serve as the internal references to normalize the target gene expression. In this study, the stability of 14 candidate reference genes from the two congeneric species G. uralensis and G. inflata, including ACT, CAC, CYP, DNAJ, DREB, EF1, RAN, TIF1, TUB, UBC2, ABCC2, COPS3, CS, R3HDM2, were evaluated across different tissues and throughout various developmental stages. More importantly, we investigated the impact of interactions between tissue and developmental stage on the performance of candidate reference genes. Four algorithms, including geNorm, NormFinder, BestKeeper, and Delta Ct, were used to analyze the expression stability and RefFinder, a comprehensive software, provided the final recommendation. Based on previous research and our preliminary data, we hypothesized that internal references for spatio-temporal gene expression are different from the reference genes suited for individual factors. In G. uralensis, the top three most stable reference genes across different tissues were R3HDM2, CAC and TUB, while CAC, CYP and ABCC2 were most suited for different developmental stages. CAC is the only candidate recommended for both biotic factors, which is reflected in the stability ranking for the spatio (tissue)-temporal (developmental stage) interactions (CAC, R3HDM2 and DNAJ). Similarly, in G. inflata, COPS3, R3HDM2 and DREB were selected for tissues, while RAN, COPS3 and CS were recommended for developmental stages. For the tissue-developmental stage interactions, COPS3, DREB and ABCC2 were the most suited reference genes. In both species, only one of the top three candidates was shared between the individual factors and their interactions, specifically, CAC in G. uralensis and COPS3 in G. inflata, which supports our overarching hypothesis. In summary, spatio-temporal selection of reference genes not only lays the foundation for functional genomics research in Glycyrrhiza, but also facilitates these traditional medicinal herbs to reach/maximize their pharmaceutical potential.

Modulation of optical properties of ZnS QDs embedded glasses through aluminum and manganese doping

2021 ◽  
Author(s):  
Kai Li ◽  
Ying Ye ◽  
Wenchao Zhang ◽  
Yuzhou Hu ◽  
Ying Yang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Efficiency ◽  
High Quantum Efficiency ◽  
Information Display ◽  
Manganese Doping ◽  
High Quantum

Nontoxic cadmium-free ZnS and ZnSe QDs QDs with high quantum efficiency have drawn considerable attention for information display. Applications of ZnS and ZnSe QDs are limited by their short emission...

Stabilization of networked switched affine systems with event-triggered strategy

2021 ◽  
pp. 014233122110213
Author(s):  
Dandan Li ◽  
Zhiqiang Zuo ◽  
Yijing Wang
Keyword(s):  
Affine Systems ◽  
Switching Law ◽  
Event Time ◽  
Sliding Motion ◽  
State Dependent ◽  
Event Triggering ◽  
Stability Issue ◽  
The Stability ◽  
Event Based ◽  
Selection Of

Using an event-based switching law, we address the stability issue for continuous-time switched affine systems in the network environment. The state-dependent switching law in terms of the region function is firstly developed. We combine the region function with the event-triggering mechanism to construct the switching law. This can provide more candidates for the selection of the next activated subsystem at each switching instant. As a result, it is possible for us to activate the appropriate subsystem to avoid the sliding motion. The Zeno behavior for the switched affine system can be naturally ruled out by guaranteeing a positive minimum inter-event time between two consecutive executions of the event-triggering threshold. Finally, two numerical examples are given to demonstrate the effectiveness of the proposed method.

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