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Fluorescent Molecules (fluorescent + molecule)
Selected AbstractsMolecular Engineering of Blue Fluorescent Molecules Based on Silicon End-Capped Diphenylaminofluorene Derivatives for Efficient Organic Light-Emitting MaterialsADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Kum Hee Lee Abstract Blue fluorescent materials based on silicone end-capped 2-diphenylaminofluorene derivatives are synthesized and characterized. These materials are doped into a 2-methyl-9,10- di -[2-naphthyl]anthracene host as blue dopant materials in the emitting layer of organic light-emitting diode devices bearing a structure of ITO/DNTPD (60,nm)/NPB (30,nm)/emitting layer (30,nm)/Alq3 (20,nm)/LiF (1.0,nm)/Al (200,nm). All devices exhibit highly efficient blue electroluminescence with high external quantum efficiencies (3.47%,7.34% at 20,mA,cm,2). The best luminous efficiency of 11.2,cd,A,1 and highest quantum efficiency of 7.34% at 20,mA,cm,2 are obtained in a device with CIE coordinates (0.15, 0.25). A deep-blue OLED with CIE coordinates (0.15, 0.14) exhibits a luminous efficiency of 3.70,cd,A,1 and quantum efficiency of 3.47% at 20,mA,cm,2. [source] Single-molecule near-field optical energy transfer microscopy with dielectric tipsJOURNAL OF MICROSCOPY, Issue 3 2003W. Trabesinger Summary The fluorescence lifetime and the fluorescence rate of single molecules are recorded as a function of the position of a Si3N4 atomic force microscopy tip with respect to the molecule. We observe a decrease of the excited state lifetime and the fluorescence rate when the tip apex is in close proximity to the molecule. These effects are attributed to the fact that the dielectric tip converts non-propagating near-fields to propagating fields within the dielectric tip effectively quenching the fluorescence. The spatial extension of the quenching area is of subwavelength dimensions. The results are discussed in terms of molecular fluorescence in a system of stratified media. The experiment provides surprising new insights into the interactions between a fluorescent molecule and a dielectric tip. The methodology holds promise for applications in ultra high-resolution near-field optical imaging at the level of single fluorophores. [source] Design and synthesis of a solid-phase fluorescent mass tagJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2005Yang Shi Abstract In this study, we demonstrate the design of a new solid-phase fluorescent mass tag (FMT) that contains the following features: (1) the FMT is synthesized using Fmoc chemistry which is simple, rapid, and cost-effective; (2) lysine is used as a uniformly labeled amino acid (using stable isotopes) to allow 8 Da difference between "heavy" and "light" tags; (3) a fluorescent molecule is coupled to the isotope tag that allows a tagged peptide to be detected by online fluorescence; and (4) an iodoacetyl reactive group provides cysteine reactivity. Using MALDI-TOF MS and HPLC, we show that the FMT reagent can be used to label standard cysteine-containing peptides as well as cysteine-containing peptides from a BSA tryptic digest. [source] Kaolin,epoxy-based nanocomposites: A complementary study of the epoxy curing by FTIR and fluorescencePOLYMER COMPOSITES, Issue 5 2010P.D. Castrillo This work is focused on the study of the effect exerted by the presence of kaolin on the cure reaction of an epoxy-based polymer, discussing the influence of different kaolin pretreatments. During the last few years, the interest on polymer matrix nanocomposite materials has sharply increased because generally they show improved properties when compared with those of the neat polymer (without filler). Among this sort of materials, polymer clay nanocomposites have been widely studied. However, there are not many works about kaolin-based composites. Although several techniques have been used to monitor the cure process in epoxy-based composites such as Fourier transform infrared spectroscopy (FTIR) or differential scanning calorimetry, only the use of the fluorescent response from a fluorophore seems to be adequate to monitor the reaction exactly at the interfaces at a molecular scale. In this work, FTIR and fluorimetry were used to monitor the cure reaction of the different composite systems at different curing temperatures. The analysis of FTIR experiments revealed that the presence of the reinforcement clay affects the extent of the cure reaction depending on the nature of its surface. On the other hand, the use of a fluorescent molecule chemically bonded to the reinforcement allows studying the curing exactly at the interface. Finally, with the collected data, a kinetic analysis was done and the results obtained were compared in terms of the technique used and the information source (interface or bulk). At the interface, the activation energy for the epoxy reaction is lower than that carried out in the bulk indicating that the reaction at the interface proceeds via a particular mechanism for which the reaction is favored. It seems that a higher amount of hydroxyl groups is capable of catalyzing the cure reaction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Study of binding stoichiometries of the human immunodeficiency virus type,1 reverse transcriptase by capillary electrophoresis and laser-induced fluorescence polarization using aptamers as probesELECTROPHORESIS, Issue 2 2006Hao Fu Abstract Binding stoichiometries between four DNA aptamers (RT12, RT26, RTlt49, and ODN93) and the reverse transcriptase (RT) of the type,1 human immunodeficiency virus (HIV-1) were studied using affinity CE (ACE) coupled with LIF polarization and fluorescence polarization (FP). The ACE/LIF study showed evidence of two binding stoichiometries between the HIV-1,RT protein and aptamers RT12, RT26, and ODN93, suggesting that these aptamers can bind to both the p66 and p51 subunits of the HIV-1,RT. Only one binding stoichiometry for aptamer RTlt49 was found. The affinity complexes were easily separated from the unbound aptamers; however, the different stoichiometries were not well resolved. A complementary technique, FP, was able to provide additional information about the binding and supporting evidence for the ACE/LIF results. The ACE/LIFP study also revealed that the FP values of the 1:1 complexes of the HIV-1,RT protein with aptamers RT12, RT26, and ODN93 were always much greater than those of the 1:2 complexes. This was initially surprising because the larger molecular size of the 1:2 complexes was expected to result in higher FP values than the corresponding 1:1 complexes. This phenomenon was probably a result of fluorescence resonance energy transfer between the two fluorescent molecules bound to the HIV-1,RT protein. [source] Development of New Pyrrolocoumarin Derivatives with Satisfactory Fluorescent Properties and Notably Large Stokes ShiftsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 36 2008Lei Chen Abstract Small, organic, fluorescent molecules with large Stokes shifts and long emission wavelengths are ideal dyes for various modern fluorescent imaging technologies such as FRET. In this study, we designed and synthesized a number of new fluorescent molecules on the basic structures of two pyrrolocoumarin skeletons where Fischer's indole synthesis and the Suzuki coupling successfully served as the efficient molecular editing protocols. The examination of the fluorescent properties and further structural optimization of these compounds afforded three new pyrrolocoumarin dyes with notably large Stokes shifts and satisfactory fluorescent properties. Among these, 30 showed a large Stokes shift (113 nm) and intense fluorescence (, = 0.55, ,em = 523 nm), and thus showed great potential in biological imaging studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Mohammed Ibrahim Shukoor Abstract Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced into the polymer chain to trace the nanoparticles in Caki-1 (human kidney cancer) cells. The ssDNA coupled nanoparticles are used to target Toll-like receptors 9 (TLR9) receptors inside the cells and to activate the classical TLR cascade. The presence of TLR9 is demonstrated independently in the Caki-1 cell line by western blotting and immunostaining techniques. The magnetic properties of the MnO core make functionalized MnO nanoparticles potential diagnostic agents for magnetic resonance imaging (MRI) thereby enabling multimodal detection by a combination of MR and optical imaging methods. The trimodal nanoparticles allow the imaging of cellular trafficking by different means and simultaneously are an effective drug carrier system. [source] One-Pot Synthesis of Functional Helicoidal Hybrid Organic,Inorganic Nanofibers with Periodically Organized MesoporosityADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Frédéric Rambaud Abstract The one-pot synthesis and properties of multifunctional hybrid mesoporous organosilica fibers with helical shapes are described. These hybrid mesoporous fibers are prepared without chiral elements and functionalized with a large variety of organic R functions (R,=,alkylthiols, phenylsulfonates, alkylphosphonates, dansyl, aminopropyl, fluoroalkyl, etc.). The resulting nanomaterials are thoroughly characterized by a variety of techniques. The use of a synergetic combination of achiral molecules as co-directing structuring agents, a surfactant, and an organofunctional silica precursor R-Si(OR)3 allows, via carefully tuning of the main synthesis parameters and processing conditions, to control the shape, which is the anisotropic factor, of the hybrid nanofibers. The functionalization of the hybrid materials with fluorescent molecules (dansyl) and gold nanoparticles opens possibilities for sensor and catalytic applications, respectively. Moreover, these hybrid nanofibers can be easily transferred in organic solvents or in a "green" solvent such as water to make stable colloidal dispersions. This tunable functionality of nanofibers also allows their transferability into a variety of polymeric hosts (PVDF, PVBu, and PVP) allowing the formation of functional homogeneous nanocomposite hybrid membranes. [source] Zeolite Nanocrystals: Quantum Yield Measurement of Fluorescent Zeolite Nanopigments (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Mater. Organic fluorescent molecules are infiltrated in the channels of zeolite L nanocrystals, thus obtaining organic-inorganic fluorescent nanoparticles. O. Nicolet et al. present the optical measurement of the quantum yield of fluorescent zeolites by means of a precise and reliable diffuse reflectance technique. Several possible factors that may affect the fluorescence quantum yield are also investigated. [source] Quantum Yield Measurement of Fluorescent Zeolite NanopigmentsADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Olivier Nicolet Abstract Organic fluorescent molecules are infiltrated in the channels of zeolite L nanocrystals, thus creating organic,inorganic fluorescent nanoparticles. Combined with dielectric matrices, these fluorescent nanopigments open the way to the realization of novel optical devices. In this paper, the optical measurement of the quantum yield of fluorescent zeolites by means of a precise and reliable diffuse reflectance technique is presented. Several possible factors that may affect the fluorescence quantum yield are also investigated. [source] Imaging the fluorescence of marine invertebrates and their associated floraJOURNAL OF MICROSCOPY, Issue 2 2008T.D. AINSWORTH Summary The cells and tissues of many marine invertebrates and their associated flora contain fluorescent pigments and proteins, many of which have been utilized commercially and provide marker molecules in other systems for fluorescence imaging technology. However, in the study of marine invertebrates and their symbioses these naturally occurring molecules have been seen to limit or confound fluorescence microscopy analyses. Here we demonstrate the endogenous fluorescence associated with two marine invertebrates (coral and foraminifera) and describe how these qualities can be utilized in fluorescence microanalyses. Understanding and imaging the diversity of fluorescent molecules provide insight into how fluorescence microscopy techniques can now be applied to these complex systems. [source] Optimized protocol of a frequency domain fluorescence lifetime imaging microscope for FRET measurementsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2009Aymeric Leray Abstract Frequency-domain fluorescence lifetime imaging microscopy (FLIM) has become a commonly used technique to measure lifetimes in biological systems. However, lifetime measurements are strongly dependent on numerous experimental parameters. Here, we describe a complete calibration and characterization of a FLIM system and suggest parameter optimization for minimizing measurement errors during acquisition. We used standard fluorescent molecules and reference biological samples, exhibiting both single and multiple lifetime components, to calibrate and evaluate our frequency domain FLIM system. We identify several sources of lifetime precision degradation that may occur in FLIM measurements. Following a rigorous calibration of the system and a careful optimization of the acquisition parameters, we demonstrate fluorescence lifetime measurements accuracy and reliability. In addition, we show its potential on living cells by visualizing FRET in CHO cells. The proposed calibration and optimization protocol is suitable for the measurement of multiple lifetime components sample and is applicable to any frequency domain FLIM system. Using this method on our FLIM microscope enabled us to obtain the best fluorescence lifetime precision accessible with such a system. Microsc. Res. Tech., 2009. © 2008 Wiley-Liss, Inc. [source] Latent Blue and Red Fluorophores Based on the Trimethyl LockCHEMBIOCHEM, Issue 8 2006Luke D. Lavis Unlocking fluorescence. The "trimethyl lock" is an effective way to mask structurally diverse fluorescent molecules for the preparation of fluorogenic enzyme substrates. These novel probes exhibit remarkable stability in water, and this makes them useful for a variety of biochemical and biological applications. [source] | ||||||||||||||||