|
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. In microscopy, photobleaching may complicate the observation of fluorescent molecules, since they will eventually be destroyed by the light exposure necessary to stimulate them into fluorescing. This is especially problematic in time-lapse microscopy. However, photobleaching may also be used prior to applying the (primarily antibody-linked) fluorescent molecules, in an attempt to quench autofluorescence. This can help improve the signal-to-noise ratio. Photobleaching may also be exploited to st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence Loss In Photobleaching
Fluorescence Loss in Photobleaching (FLIP) is a fluorescence microscopy technique used to examine movement of molecules inside cells and membranes. A cell membrane is typically labeled with a fluorescent dye to allow for observation. A specific area of this labeled section is then bleached several times using the beam of a confocal laser scanning microscope. After each imaging scan, bleaching occurs again. This occurs several times, to ensure that all accessible fluorophores are bleached since unbleached fluorophores are exchanged for bleached fluorophores, causing movement through the cell membrane. The amount of fluorescence from that region is then measured over a period of time to determine the results of the photobleaching on the cell as a whole. Experimental Setup Before photobleaching can occur, cells must be injected with a fluorescent protein, often a green fluorescent protein (GFP), which will allow the targeted proteins to fluoresce and therefore be followed througho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. In microscopy, photobleaching may complicate the observation of fluorescent molecules, since they will eventually be destroyed by the light exposure necessary to stimulate them into fluorescing. This is especially problematic in time-lapse microscopy. However, photobleaching may also be used prior to applying the (primarily antibody-linked) fluorescent molecules, in an attempt to quench autofluorescence. This can help improve the signal-to-noise ratio. Photobleaching may also be exploited to st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence Recovery After Photobleaching
Fluorescence recovery after photobleaching (FRAP) is a method for determining the kinetics of diffusion through tissue or cells. It is capable of quantifying the two dimensional lateral diffusion of a molecularly thin film containing fluorescently labeled probes, or to examine single cells. This technique is very useful in biological studies of cell membrane diffusion and protein binding. In addition, surface deposition of a fluorescing phospholipid bilayer (or monolayer) allows the characterization of hydrophilic (or hydrophobic) surfaces in terms of surface structure and free energy. Similar, though less well known, techniques have been developed to investigate the 3-dimensional diffusion and binding of molecules inside the cell; they are also referred to as FRAP. Experimental setup The basic apparatus comprises an optical microscope, a light source and some fluorescent probe. Fluorescent emission is contingent upon absorption of a specific optical wavelength or color which re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexa (fluor)
The Alexa Fluor family of fluorescent dyes is a series of dyes invented by Molecular Probes, now a part of Thermo Fisher Scientific, and sold under the Invitrogen brand name. Alexa Fluor dyes are frequently used as cell and tissue labels in fluorescence microscopy and cell biology. Alexa Fluor dyes can be conjugated directly to primary antibodies or to secondary antibodies to amplify signal and sensitivity or other biomolecules. The excitation and emission spectra of the Alexa Fluor series cover the visible spectrum and extend into the infrared. The individual members of the family are numbered according roughly to their excitation maxima in nanometers. History Richard and Rosaria Haugland, the founders of Molecular Probes, are well known in biology and chemistry for their research into fluorescent dyes useful in biological research applications. At the time that Molecular Probes was founded, such products were largely unavailable commercially. A number of fluorescent dyes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorophore
A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with several π bonds. Fluorophores are sometimes used alone, as a tracer in fluids, as a dye for staining of certain structures, as a substrate of enzymes, or as a probe or indicator (when its fluorescence is affected by environmental aspects such as polarity or ions). More generally they are covalently bonded to a macromolecule, serving as a marker (or dye, or tag, or reporter) for affine or bioactive reagents ( antibodies, peptides, nucleic acids). Fluorophores are notably used to stain tissues, cells, or materials in a variety of analytical methods, i.e., fluorescent imaging and spectroscopy. Fluorescein, via its amine-reactive isothiocyanate derivative fluorescein isothiocyanate (FITC), has been one of the most popular fluorophor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Fluorescent Protein
The green fluorescent protein (GFP) is a protein that exhibits bright green fluorescence when exposed to light in the blue to ultraviolet range. The label ''GFP'' traditionally refers to the protein first isolated from the jellyfish '' Aequorea victoria'' and is sometimes called ''avGFP''. However, GFPs have been found in other organisms including corals, sea anemones, zoanithids, copepods and lancelets. The GFP from ''A. victoria'' has a major excitation peak at a wavelength of 395 nm and a minor one at 475 nm. Its emission peak is at 509 nm, which is in the lower green portion of the visible spectrum. The fluorescence quantum yield (QY) of GFP is 0.79. The GFP from the sea pansy (''Renilla reniformis'') has a single major excitation peak at 498 nm. GFP makes for an excellent tool in many forms of biology due to its ability to form an internal chromophore without requiring any accessory cofactors, gene products, or enzymes / substrates other tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DyLight Fluor
The DyLight Fluor family of fluorescent dyes are produced by Dyomics in collaboration with Thermo Fisher Scientific. DyLight dyes are typically used in biotechnology and research applications as biomolecule, cell and tissue labels for fluorescence microscopy, cell biology or molecular biology. Historically, fluorophores such as fluorescein, rhodamine, Cy3 and Cy5 have been used in a wide variety of applications. These dyes have limitations for use in microscopy and other applications that require exposure to an intense light source such as a laser, because they photobleach quickly (however, bleaching can be reduced at least 10 fold using oxygen scavenging). DyLight Fluors have comparable excitation and emission spectra and are claimed to be more photostable, brighter, and less pH-sensitive. The excitation and emission spectra of the DyLight Fluor series cover much of the visible spectrum and extend into the infrared region, allowing detection using most fluorescence micros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Dot
Quantum dots (QDs) are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band. The excited electron can drop back into the valence band releasing its energy as light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the conductance band and the valence band, or the transition between discrete energy states when band structure is no longer a good definition in QDs. In the language of materials science, nanoscale semiconductor materials tightly confine either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-lapse Microscopy
Time-lapse microscopy is time-lapse photography applied to microscopy. Microscope image sequences are recorded and then viewed at a greater speed to give an accelerated view of the microscopic process. Before the introduction of the video tape recorder in the 1960s, time-lapse microscopy recordings were made on photographic film. During this period, time-lapse microscopy was referred to as microcinematography. With the increasing use of video recorders, the term time-lapse video microscopy was gradually adopted. Today, the term video is increasingly dropped, reflecting that a digital still camera is used to record the individual image frames, instead of a video recorder. Applications Time-lapse microscopy can be used to observe any microscopic object over time. However, its main use is within cell biology to observe artificially cultured cells. Depending on the cell culture, different microscopy techniques can be applied to enhance characteristics of the cells as most cells ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Imaging
Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery with only a few monks or nuns * Prison cell, a room used to hold people in prisons Groups of people * Cell, a group of people in a cell group, a form of Christian church organization * Cell, a unit of a clandestine cell system, a penetration-resistant form of a secret or outlawed organization * Cellular organizational structure, such as in business management Science, mathematics, and technology Computing and telecommunications * Cell (EDA), a term used in an electronic circuit design schematics * Cell (microprocessor), a microprocessor architecture developed by Sony, Toshiba, and IBM * Memory cell (computing), the basic unit of (volatile or non-volatile) computer memory * Cell, a unit in a database table or spreadsheet, formed by the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors ( fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microscopy
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy. Optical microscopy and electron microscopy involve the diffraction, reflection, or refraction of electromagnetic radiation/electron beams interacting with the specimen, and the collection of the scattered radiation or another signal in order to create an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscopy) or by scanning a fine beam over the sample (for example confocal laser scanning microscopy and scanning electron microscopy). Scanning probe microscopy involves the interaction of a scanning probe with the surface of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
