January 2017 Meeting Announcement, Delaware Valley Mass Spectrometry Discussion Group
- Topic: "Chemical Imaging Mass Spectrometry: A Universal, Quantitative, Rapid Tool for Discovery of Biomarkers, IED Classification and Brain Mapping
- Speaker:Robert J. Levis, Temple University
- Date: Monday, January 9, 2017. 6:00 PM
- Please RSVP to email@example.com by Thursday January 5.
- Time: Social Hour: 6:00 PM.
Talk: 7:00 PM.
- Place: Department of Chemistry, Villanova University (Mendel Hall 154)
While electrospray ionization mass spectrometry (ESI-MS) has revolutionized the analysis of biological macromolecules, there are limitations to the method. ESI is not universal in the sense that solvent systems must be optimized for a given hydrophobic or hydrophilic sample. This leads to a lack of quantitative measurement for mixtures of molecules. ESI MS is not a rapid method, requiring many minutes to perform a measurement. This presentation will focus on an approach that overcomes these limitations by separating the sample introduction and ionization steps of ESI using laser vaporization of sample directly into the ESI droplet stream.
The interaction of ultraintense, ultrafast radiation with van der Waals bound condensed phase systems results in a useful approach for sample introduction to an electrospray source, namely transfer of molecules into the gas phase without decomposition. We have explored laser vaporization as a means to deliver sample directly into an electrospray source for subsequent mass spectral analysis. We have found that molecules as large as tobacco mosaic virus may be transferred from the solution phase into the gas phase not only without decomposition, but also maintaining biological activity after interacting with a laser pulse of duration 50 femtoseconds and intensity 10^13 W cm^-2.
This talk will introduce the method of laser electrospray mass spectrometry (LEMS) and will explore the use of LEMS to measure condensed phase tertiary structure of protein, measurement of enzyme substrate dissociation constant, and classification materials including improvised explosive devices (IED), black powder manufacturer, and gunshot residue manufacturer from the quantitative, direct analysis of complex mixtures. The universal detection of molecules using a single electrospray solvent composition, either polar or nonpolar, for either hydrophilic or hydrophobic samples will be presented. The ability to perform an ESI measurement approximately every second will be discussed, and this provides the ability to perform many thousands of ESI measurements per day. Finally, we will discuss the use of LEMS as a means to chemically image mouse brain to identify new biomarkers for traumatic brain injury.
Traumatic brain injury (TBI) is a complex injury involving multiple physiological and biochemical alterations to tissue. The potentially thousands of relevant biomarkers spread over a volume of thousands of mm3 inherently makes the spatially-resolved chemical analysis of brain a big data problem. LEMS was employed to image TBI mouse brain sample and assess the spatial distribution of biomarkers after trauma. The imaging experiment was performed using a 100 µm laser spot size rastered over a 4 x 4 mm area of a mild TBI brain tissue section to generate 100 Gbytes of data. Species identified by mass spectra were spatially mapped and compared to corresponding optical images of the brain sample. A present challenge for the method is the development of data mining techniques to identify relevant biomarkers for TBI.
Robert J. Levis, PhD. is Professor of Chemistry at Temple University and Director of the Center for Advanced Photonics Research, a consortium of 40 faculty, postdocs and students. His research interests focus on the exploration of the chemistry and physics of molecules interacting with ultrafast (~10 fs) and ultra-intense (10^13 W cm^-2) laser fields. Levis' research focuses on new ways to diagnose disease, spatially map cellular components, classify tissue and phenotype, detect improvised explosive devices, classify explosives for forensics analysis, synthesize novel, narrowly-dispersed nanomaterials, discover and understand new extreme nonlinear phenomena, and to discover new chemistry using quantum control. Current research areas in the Center include: chemical imaging mass spectrometry, laser-based synthesis and processing of nanomaterials, laser vaporization of condensed phase systems, laser filamentation in air, control of chemical reactions using shaped laser pulses, elucidation of the evolution of laser-generated plasmas and control of strong-field chemistry. His research has been described in over 160 peer-reviewed publications. The methods developed in the Levis laboratory over the last 26 years are used worldwide to explore strong field chemistry and physics.
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