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Laser Ablation Electrospray Ionization
Laser ablation electrospray ionization (LAESI) is an ambient ionization method for mass spectrometry that combines laser ablation from a mid-infrared (mid-IR) laser with a secondary electrospray ionization (ESI) process. The mid-IR laser is used to generate gas phase particles which are then ionized through interactions with charged droplets from the ESI source. LAESI was developed in Professor Akos Vertes lab by Dr. Peter Nemes in 2007 and it was marketed commercially by Protea Biosciences, Inc until 2017. Fiber-LAESI for single-cell analysis approach was developed by Dr. Bindesh Shrestha in Professor Vertes lab in 2009. LAESI is a novel ionization source for mass spectrometry (MS) that has been used to perform MS imaging of plants, tissues, cell pellets, and even single cells. In addition, LAESI has been used to analyze historic documents and untreated biofluids such as urine and blood. The technique of LAESI is performed at atmospheric pressure and therefore overcomes many of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schematic Representation Of Laser Ablation Electrospray Ionization (LAESI)
A schematic, or schematic diagram, is a designed representation of the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the key information the schematic is intended to convey, and may include oversimplified elements in order to make this essential meaning easier to grasp, as well as additional organization of the information. For example, a subway map intended for passengers may represent a subway station with a dot. The dot is not intended to resemble the actual station at all but aims to give the viewer information without unnecessary visual clutter. A schematic diagram of a chemical process uses symbols in place of detailed representations of the vessels, piping, valves, pumps, and other equipment that compose the system, thus emphasizing the functions of the individual elements and the interconnections among them and suppresses their physical details. In an electronic circuit d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambient Ionization
Ambient ionization is a form of ionization in which ions are formed in an ion source outside the mass spectrometer without sample preparation or separation. Ions can be formed by extraction into charged electrospray droplets, thermally desorbed and ionized by chemical ionization, or laser desorbed or ablated and post-ionized before they enter the mass spectrometer. Solid-liquid extraction Solid-liquid extraction based ambient ionization is based on the use of a charged spray, for example electrospray to create a liquid film on the sample surface. Molecules on the surface are extracted into the solvent. The action of the primary droplets hitting the surface produces secondary droplets that are the source of ions for the mass spectrometer. Desorption electrospray ionization (DESI) is one of the original ambient ionization sources and uses an electrospray source to create charged droplets that are directed at a solid sample. The charged droplets pick up the sample through interacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Ablation
Laser ablation or photoablation (also called laser blasting) is the process of removing material from a solid (or occasionally liquid) surface by irradiating it with a laser beam. At low laser flux, the material is heated by the absorbed laser energy and evaporates or sublimates. At high laser flux, the material is typically converted to a plasma. Usually, laser ablation refers to removing material with a pulsed laser, but it is possible to ablate material with a continuous wave laser beam if the laser intensity is high enough. While relatively long laser pulses (e.g. nanosecond pulses) can heat and thermally alter or damage the processed material, ultrashort laser pulses (e.g. femtoseconds) cause only minimal material damage during processing due to the ultrashort light-matter interaction and are therefore also suitable for micromaterial processing. Excimer lasers of deep ultra-violet light are mainly used in photoablation; the wavelength of laser used in photoablation is ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mid-infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discovered tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrospray Ionization
Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized. ESI is different from other ionization processes (e.g. matrix-assisted laser desorption/ionization (MALDI)) since it may produce multiple-charged ions, effectively extending the mass range of the analyser to accommodate the kDa-MDa orders of magnitude observed in proteins and their associated polypeptide fragments. Mass spectrometry using ESI is called electrospray ionization mass spectrometry (ESI-MS) or, less commonly, electrospray mass spectrometry (ES-MS). ESI is a so-called 'soft ionization' technique, since there is very little fragmentation. This can be advantageous in the sense that the molecular ion (or more accurately a pseudo molecular ion) is almost alw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akos Vertes
Akos Vertes is a Hungarian-American professor of chemistry, biochemistry and molecular biology at the George Washington University and a Doctor of the Hungarian Academy of Sciences. Early life and career Vertes was born in Budapest, Hungary. He graduated from the Veres Pálné Gimnázium in 1971 and then got his B.S. and Ph.D. in chemistry from the Eötvös Loránd University in 1974 and 1979 respectively. In 1979 he was appointed research associate at the Hungarian Central Research Institute for Physics and in 1987 was promoted to senior research associate; from 1986 to 1989 he served as its Deputy Head. Until 1991 was an assistant professor at the University of Antwerp in Belgium. In 1991 he immigrated to the United States and was hired by the George Washington University as an associate professor of Analytical chemistry. and was promoted to professor in 2000 and to Professor of Biochemistry and Molecular Biology in 2003. In 1997 he became Deputy Chair of its Department of Ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Nemes
Peter Nemes, Ph.D., is a Hungarian-American chemist, who is active in the fields of bioanalytical chemistry, mass spectrometry, cell/developmental biology, neuroscience, and biochemistry. Biography Nemes has been an associate professor at the University of Maryland, College Park (UMD) since January 2018. Prior to his appointment there, he was an assistant professor at the Department of Chemistry at George Washington University (Washington, DC), where he taught bioanalytical chemistry. Nemes graduated with summa cum laude with a Master's of Science (M.Sc.) from the Eötvös Loránd University in 2004. His original thesis research was conducted in the Department of Mass Spectrometry at the Hungarian Academy of Sciences, Budapest, Hungary. Under mentorship by Vekey Karoly, Nemes studied the formation of amino acid clusters in the gas phase upon electrospray ionization,1 such as the magic serine clusters that preferentially incorporate amino acids and sugars of certain chirality matc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Electrospray Ionization
Secondary electro-spray ionization (SESI) is an ambient ionization technique for the analysis of trace concentrations of vapors, where a nano-electrospray produces charging agents that collide with the analyte molecules directly in gas-phase. In the subsequent reaction, the charge is transferred and vapors get ionized, most molecules get protonated (in positive mode) and deprotonated (in negative mode). SESI works in combination with mass spectrometry or ion-mobility spectrometry. History The fact that trace concentrations of gases in contact with an electrospray plume were efficiently ionized was first observed by Fenn and colleagues when they noted that tiny concentrations of plasticizers produced intense peaks in their mass spectra. However, it was not until 2000 when this problem was reframed as a solution, when Hill and coworkers used an electrospray to ionize molecules in the gas phase, and named the technique Secondary Electrospray Ionization. In 2007, the almost simultaneo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extractive Electrospray Ionization
Extractive electrospray ionization (EESI) is a spray-type, ambient ionization sourceChen, H., G. Gamez, and R. Zenobi, What Can We Learn from Ambient Ionization Techniques? Journal of the American Society for Mass Spectrometry, 2009. 20(11): p. 1947-1963.Cooks, R.G., et al., Ambient Mass Spectrometry. Science, 2006. 311(5767): p. 1566-1570.Harris, G.A., A.S. Galhena, and F.M. Ferna?ndez, Ambient Sampling/Ionization Mass Spectrometry: Applications and Current Trends. Analytical Chemistry, 2011. 83(12): p. 4508-4538.Huang, M.-Z., et al., Ambient Ionization Mass Spectrometry. Annual Review of Analytical Chemistry, 2010. 3(1): p. 43-65.Van Berkel, G.J., S.P. Pasilis, and O. Ovchinnikova, Established and emerging atmospheric pressure surface sampling/ionization techniques for mass spectrometry. Journal of Mass Spectrometry, 2008. 43(9): p. 1161-1180. in mass spectrometry that uses two colliding aerosols, one of which is generated by electrospray. In standard EESI, syringe pumps provide t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrospray Ionization
Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized. ESI is different from other ionization processes (e.g. matrix-assisted laser desorption/ionization (MALDI)) since it may produce multiple-charged ions, effectively extending the mass range of the analyser to accommodate the kDa-MDa orders of magnitude observed in proteins and their associated polypeptide fragments. Mass spectrometry using ESI is called electrospray ionization mass spectrometry (ESI-MS) or, less commonly, electrospray mass spectrometry (ES-MS). ESI is a so-called 'soft ionization' technique, since there is very little fragmentation. This can be advantageous in the sense that the molecular ion (or more accurately a pseudo molecular ion) is almost alw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix-assisted Laser Desorption Electrospray Ionization
Matrix-assisted laser desorption electrospray ionization (MALDESI) was first introduced in 2006 as a novel Ambient ionization, ambient ionization technique which combines the benefits of Electrospray ionization, electrospray ionization (ESI) and Matrix-assisted laser desorption/ionization, matrix-assisted laser desorption/ionization (MALDI). An Infrared, infrared (IR) or Ultraviolet, ultraviolet (UV) laser can be utilized in MALDESI to Excited state, resonantly excite an endogenous or exogenous matrix. The term ‘Matrix (mass spectrometry), matrix’ refers to any molecule that is present in large excess and absorbs the energy of the laser, thus facilitating desorption of analyte molecules. The original MALDESI design was implemented using common Matrix-assisted laser desorption/ionization, organic matrices, similar to those used in MALDI, along with a UV laser. The current MALDESI source employs endogenous water or a thin layer of exogenously deposited ice as the energy-absorbing ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionized, for example by bombarding it with a beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragments) are then separated accordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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