Category
Fluorescence imaging
Related concepts (28)
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light.
Keggin structure
Keggin structure is the best known structural form for heteropoly acids. It is the structural form of α-Keggin anions, which have a general formula of , where X is the heteroatom (most commonly are pentavalent phosphorus PV, tetravalent silicon SiIV, or trivalent boron BIII), M is the addendum atom (most common are molybdenum Mo and tungsten W), and O represents oxygen. The structure self-assembles in acidic aqueous solution and is the most stable structure of polyoxometalate catalysts.
Heteropolymetalate
In chemistry, the heteropolymetalates are a subset of the polyoxometalates, which consist of three or more transition metal oxyanions linked together by shared oxygen atoms to form a closed 3-dimensional molecular framework. In contrast to isopolymetalates, which contain only one kind of metal atom, the heteropolymetalates contain differing main group oxyanions. The metal atoms are usually group 6 (Mo, W) or less commonly group 5 (V, Nb, Ta) transition metals in their highest oxidation states.
Hexamethylenetetramine
Hexamethylenetetramine, also known as methenamine, hexamine, or urotropin, is a heterocyclic organic compound with the formula (CH2)6N4. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like structure similar to adamantane. It is useful in the synthesis of other organic compounds, including plastics, pharmaceuticals, and rubber additives. It sublimes in vacuum at 280 °C. Hexamethylenetetramine was discovered by Aleksandr Butlerov in 1859.
Malachite green
Malachite green is an organic compound that is used as a dyestuff and controversially as an antimicrobial in aquaculture. Malachite green is traditionally used as a dye for materials such as silk, leather, and paper. Despite its name the dye is not prepared from the mineral malachite; the name just comes from the similarity of color. Malachite green is classified in the dyestuff industry as a triarylmethane dye and also using in pigment industry.
Propidium iodide
Propidium iodide (or PI) is a fluorescent intercalating agent that can be used to stain cells and nucleic acids. PI binds to DNA by intercalating between the bases with little or no sequence preference. When in an aqueous solution, PI has a fluorescent excitation maximum of 493 nm (blue-green), and an emission maximum of 636 nm (red). After binding DNA, the quantum yield of PI is enhanced 20-30 fold, and the excitation/emission maximum of PI is shifted to 535 nm (green) / 617 nm (orange-red).
Methylene blue
Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. As a medication, it is mainly used to treat methemoglobinemia by converting/chemically reducing the ferric iron in hemoglobin to ferrous iron. Specifically, it is used to treat methemoglobin levels that are greater than 30% or in which there are symptoms despite oxygen therapy. It has previously been used for treating cyanide poisoning and urinary tract infections, but this use is no longer recommended.
Photobleaching
In optics, photobleaching (sometimes termed fading) is the photochemical alteration of a dye or a fluorophore molecule such that it is permanently unable to fluoresce. This is caused by cleaving of covalent bonds or non-specific reactions between the fluorophore and surrounding molecules. Such irreversible modifications in covalent bonds are caused by transition from a singlet state to the triplet state of the fluorophores. The number of excitation cycles to achieve full bleaching varies.
Quenching (fluorescence)
In chemistry, quenching refers to any process which decreases the fluorescent intensity of a given substance. A variety of processes can result in quenching, such as excited state reactions, energy transfer, complex-formation and collisions. As a consequence, quenching is often heavily dependent on pressure and temperature. Molecular oxygen, iodine ions and acrylamide are common chemical quenchers. The chloride ion is a well known quencher for quinine fluorescence.
Methylene (compound)
Methylene (IUPAC name: Methylidene, also called carbene or methene) is an organic compound with the chemical formula CH2 (also written [CH2]). It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct. Methylene is the simplest carbene. It is usually detected only at very low temperatures, or as a short-lived intermediate in chemical reactions. The trivial name carbene is the preferred IUPAC name.