Absorption and fluorescence properties of fluorescein
01 Jun 1995-Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (Elsevier)-Vol. 51, Iss: 6
TL;DR: In this article, the authors characterized the protolytic equilibria of fluorescein and determined the spectroscopic properties of its proclivity to fluorescence, and derived the equilibrium constants relating the chemical activities of the cation, neutral form, anion and dianion.
About: This article is published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.The article was published on 1995-06-01. It has received 951 citations till now. The article focuses on the topics: Quantum yield.
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TL;DR: The scientific, medical, and diagnostic communities have been presented the most powerful tool for quantitative nucleic acids analysis: real-time PCR, a refinement of the original Polymerase Chain Reaction (PCR) developed by Kary Mullis and coworkers in the mid 80:ies.
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TL;DR: In this article, the progress made in the past decade or so, focusing on sensor design strategy based on molecular structure and fluorescent mechanism is reviewed, and the results show that fluorescent imaging has proven to be the most suitable technique for its in vivo monitoring.
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TL;DR: The application of a water-soluble fluorogenic dye, Thioflavin T (ThT), in a dual role of exclusively inducing quadruplex folding in the 22AG human telomeric DNA, both in the presence and absence of Tris buffer/salt, is demonstrated.
Abstract: The quest for a G-quadruplex specific fluorescent sensor among other DNA forms under physiological salt conditions has been addressed in this article We demonstrate for the first time the application of a water-soluble fluorogenic dye, Thioflavin T (ThT), in a dual role of exclusively inducing quadruplex folding in the 22AG human telomeric DNA, both in the presence and absence of Tris buffer/salt, and sensing the same through its fluorescence light-up having emission enhancement of the order of 2100-fold in the visible region Appropriate conditions allow an apparent switch over of the parallel quadruplex structure in 22AG–ThT (50 mM Tris, pH 72) solution to the antiparallel form just by the addition of K+ ions in the range 10–50 mM Moreover, addition of ThT cooperatively stabilizes the K+ induced antiparallel quadruplexes by a ΔTm ∼11 °C The distinction of ThT as a quadruplex inducer has been contrasted with the erstwhile used structurally related dye, Thiazole Orange (TO), which did not induce any q
503 citations
TL;DR: It is shown that polyelectrolyte-multilayer capsules containing metallic nanoparticles in their walls can be remotely activated to release encapsulated materials inside living cells and this approach is ideally suited to applications where precise control is necessary.
Abstract: Drug delivery into biological cells is an important and growing area of application. Among other systems, such as gels, polymeric micelles, liposomes, and colloids, nanoengineered polyelectrolyte multilayer microcapsules offer a unique opportunity to combine surface multifunctionality with design flexibility for the delivery of encapsulated materials into designated compartments and cells. Furthermore, microcapsules can be arranged in arrays for imaging, could be appropriate candidates for a cell-sorting system, and serve as fluorescence markers for the characterization of cells by fluorescence-activated cell sorting (FACS). The capsules are fabricated using the layer-bylayer (LbL) method by alternately adsorbing oppositely charged polymers on colloidal templates followed by core dissolution. In this regard, proteins and biocompatible polymers have also received increased interest. The main advantage of such a method is the precise control over the chemical composition of the surfaces. In the area of biomedical applications, polyelectrolytemultilayer capsules are envisioned for the delivery of encapsulated materials into biological cells. Recently, we have presented the real-time monitoring and remote release of encapsulated materials from polyelectrolyte-multilayer capsules on the single-capsule level. Such an approach is different from the studies reported by other research groups in that it is performed on a single-capsule level, which is the method ideally suited to applications where precise control is necessary. In addition, the distinctive feature reported in reference [10b] is the measurement of the temperature rise induced locally by absorption of laser light by nanoparticles. In general, nanoparticles are becoming ubiquitous components that link chemistry and physics with biology and biochemistry. They can be embedded in the walls of capsules to provide functionality, and they are also finding increasing interest for biological imaging. Herein, we show that polyelectrolyte-multilayer capsules containing metallic nanoparticles in their walls can be remotely activated to release encapsulatedmaterial inside living cells. Fluorescently labeled polymers were chosen as a model system for encapsulated materials. The remote-release experiments were conducted according to the following scheme. The polyelectrolyte-multilayer shells were doped with metal nanoparticles, which served as absorption centers for energy supplied by a laser beam. These absorption centers cause local heating that disrupts the local polymer matrix and allows the encapsulated material to leave the interior of the capsule. When using lasers with biological objects, it is important to minimize the absorption of laser light by cells and tissue. This can be accomplished by choosing the laser wavelength in the biologically “friendly” window—the near-infrared (NIR) part of the spectrum. Usually the spectral properties of water serve as a good criterion, as it constitutes 80–85% of eukaryotic cells. Indeed, in water the temperature rise in the focus of a laser diode with wavelength 850 nm and operating at optical powers up to 100 mW during less than 1 s exposure time was reported to be under 1 K. Other important parameters that control the interaction of laser light with the absorption centers are the size of the nanoparticles and their concentration on the microcapsules. The concentration of metal nanoparticles plays an important role for two reasons: 1) when the distance between the two adjacent nanoparticles is of the order of their size, the thermal effects produced by [*] Dr. A. G. Skirtach, Dr. O. Kreft, K. K hler, Prof. Dr. H. M hwald, Prof. Dr. G. B. Sukhorukov Institut f+r Grenzfl-chen Max-Planck-Institut f+r Kolloidund Grenzfl-chenforschung Am M+hlenberg 1, 14424 Golm/Potsdam (Germany) Fax: (+49)331-567-9202 E-mail: andre.skirtach@mpikg-golm.mpg.de
498 citations
TL;DR: Fluorescence lifetimes of five representative xanthene dye species were measured in HzO, D20 and in a series of alcohol solvents ranging from methanol to octanol as discussed by the authors.
Abstract: Fluorescence lifetimes of five representative xanthene dye species-the rhodamine B zwitterion (RB'), the rhodamine B cation (RB+), the rhodamine 66 cation (R6G+), the rhodamine 101 zwitterion (R101') and the fluorescein dianion (F2-)-were measured in HzO, D20 and in a series of alcohol solvents ranging from methanol to octanol The lietimes of both RB* and RB+ increased markedly as the solvent was varied from water to actanol In contrast, the lifetimes of R6G+ and R101' decreased slightly over the alcohol series and that of F2- increased only slightly in the same series For all the dyes studied the fluorescence lifetimes observed in DzO were slightly longer than those in H20 Possible causes for the variations observed are discussed
490 citations
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2,199 citations
TL;DR: A method for the partial automation of DNA sequence analysis by means of a fluorophore covalently attached to the oligonucleotide primer used in enzymaticDNA sequence analysis.
Abstract: We have developed a method for the partial automation of DNA sequence analysis. Fluorescence detection of the DNA fragments is accomplished by means of a fluorophore covalently attached to the oligonucleotide primer used in enzymatic DNA sequence analysis. A different coloured fluorophore is used for each of the reactions specific for the bases A, C, G and T. The reaction mixtures are combined and co-electrophoresed down a single polyacrylamide gel tube, the separated fluorescent bands of DNA are detected near the bottom of the tube, and the sequence information is acquired directly by computer.
1,796 citations
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TL;DR: The alanine detection limit corresponds to fewer than 6000 molecules injected onto the column and represents an improvement of four orders of magnitude in the state of the art for fluorescent detection of amino acids and an improvement for the detection limit for isothiocyanate derivatives of amino amino acids.
Abstract: Subattomole analysis of fluorescein isothiocyanate (FITC) derivatives of amino acids is accomplished by combining capillary zone electrophoresis for high-efficiency separation with laser-induced fluorescence for high-sensitivity detection. Concentration detection limits range from 5 x 10(-12) molar for alanine to 9 x 10(-11) molar for lysine, injected in the column; 9 x 10(-21) mole of alanine is contained within the approximately 1-nanoliter injection volume at the detection limit. The alanine detection limit corresponds to fewer than 6000 molecules injected onto the column and represents an improvement of four orders of magnitude in the state of the art for fluorescent detection of amino acids and an improvement of six orders of magnitude in the state of the art for the detection limit for isothiocyanate derivatives of amino acids.
470 citations