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You searched for +publisher:"Temple University" +contributor:("McEwen, Charles N.;"). Showing records 1 – 2 of 2 total matches.

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Temple University

1. Karki, Santosh. Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules.

Degree: PhD, 2017, Temple University

Chemistry

This dissertation elucidates a greater understanding of protein folding and unfolding processes during the lifetimes of electrospray and nano-spray droplets in laser electrospray mass spectrometry (LEMS) and nano-laser electrospray mass spectrometry (nano-LEMS) measurements, respectively. The similarity in mass spectral features obtained from conventional electrospray measurements for supercharged proteins with those of LEMS measurements suggested that supercharging phenomena occurs in the electrospray droplets during the droplet desolvation process. It was observed that the laser vaporization of protein from condensed phase into the electrospray droplets containing denaturing electrospray solution and a supercharging reagent resulted in the increase in ion abundance of higher charge states in comparison with electrospray measurements. Conversely, the addition of solution additives with varying gas phase basicity in the electrospray solvent resulted in charge reduction for unfolded protein upon laser vaporization from condensed phase into the charged electrospray droplets. The extent of charge reduction and the fraction of folded protein within the electrospray droplets was found to be dependent upon both the extent of protein denaturation in the solution prior to laser vaporization and the gas phase basicity of solution additives. The ability of the LEMS technique to analyze molecules from solution with high matrix effects was established by the successful detection of protein molecules from solution with high salt concentration. Experiments with LEMS enabled the detection of a protonated protein feature as the dominating peak in the mass spectra for up to 250 mM sodium chloride while conventional electrospray resulted in predominantly salt-adducted features, with suppression of the protonated protein ions for the salt concentration of 5 mM. This dissertation also expanded upon the use of a reaction system to measure the lifetimes of laser vaporized liquid droplets coupled with electrospray and nano-spray postionization mass spectrometry. Electrospray and nanospray droplet lifetimes were measured to be 4.5±0.6 ms and 1.4±0.3 ms using LEMS and nano-LEMS measurements, respectively. Time dependent protein folding measurements using LEMS revealed intermediate states during protein folding processes which are often limited in conventional electrospray measurements where bulk solution in manipulated (change in pH) to achieve protein folding.

Temple University – Theses

Advisors/Committee Members: Levis, Robert J.;, Levis, Robert J., Valentine, Ann M., Zdilla, Michael J., McEwen, Charles N.;.

Subjects/Keywords: Chemistry;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Karki, S. (2017). Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,434619

Chicago Manual of Style (16th Edition):

Karki, Santosh. “Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules.” 2017. Doctoral Dissertation, Temple University. Accessed August 18, 2019. http://digital.library.temple.edu/u?/p245801coll10,434619.

MLA Handbook (7th Edition):

Karki, Santosh. “Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules.” 2017. Web. 18 Aug 2019.

Vancouver:

Karki S. Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules. [Internet] [Doctoral dissertation]. Temple University; 2017. [cited 2019 Aug 18]. Available from: http://digital.library.temple.edu/u?/p245801coll10,434619.

Council of Science Editors:

Karki S. Laser Electrospray Mass Spectrometry for Structural Analysis of Biomolecules. [Doctoral Dissertation]. Temple University; 2017. Available from: http://digital.library.temple.edu/u?/p245801coll10,434619


Temple University

2. Shi, Fengjian. LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE.

Degree: PhD, 2017, Temple University

Chemistry

This dissertation elucidates the instrumentation and application of a hybrid ambient ionization source, laser electrospray mass spectrometry (LEMS), for the direct analysis and molecular imaging of biological tissue without matrix deposition. In LEMS, laser pulses from a Ti:Sapphire laser amplifier (60 fs, 800 nm, and 1 mJ) interact with surface analytes and transfer them from the condensed phase into the gas phase without the requirement of either exogenous matrix or endogenous water in the sample. The laser vaporized analytes are captured and ionized by an electrospray source, and finally detected by a mass analyzer. It was found that a turn-key, robust femtosecond fiber laser with longer wavelength, longer duration, and lower pulse energy at 1042 nm, 425 fs, and 50 µJ, respectively, provided comparable results with the Ti:Sapphire laser. Vaporization of intact, dried or aqueous cytochrome c and lysozyme samples was demonstrated by the fiber laser. A charge states distribution at lower charge states indicating folded conformation of proteins and the hemoglobin α subunit-heme complex from whole blood was observed. Endogenous anthocyanins, sugars, and other metabolites were detected and revealed the anticipated metabolite profile for the flower petal and leaf samples by the fiber laser. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample. These lipid features were suppressed in both the fiber laser and Ti:Sapphire LEMS measurement in the presence of optimal cutting temperature compounds which are commonly used in animal tissue cryosectioning. This dissertation also details the design of an automated mass spectrometry imaging source based on the Ti:Sapphire LEMS. The laser, translation stage, and mass analyzer are synchronized and controlled using a customized user interface to enable step-by-step scanning of the area of interest on a given tissue sample. The imaging source is coupled with a high resolution accurate mass quadrupole time-of-flight (QTOF) mass analyzer with tandem mass analysis capability. A lateral resolution of 60 µm was demonstrated on a patterned ink film by LEMS imaging. Plant metabolites including sugar and anthocyanins were directly imaged from a leaf sample. Small metabolites, lipids and proteins were simultaneously imaged from a single tissue section of a pig liver sample. Biomarkers of blood-brain barrier damage and traumatic brain injury (TBI) that occurred during the injury were detected and imaged from a TBI mouse brain. The loading values from principal component analysis (PCA) were shown to be useful for identification of features of interest from the large LEMS imaging dataset.

Temple University – Theses

Advisors/Committee Members: Levis, Robert J.;, Levis, Robert J., Valentine, Ann M., Strongin, Daniel R., McEwen, Charles N.;.

Subjects/Keywords: Analytical chemistry; Physical chemistry; Medical imaging;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Shi, F. (2017). LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,445496

Chicago Manual of Style (16th Edition):

Shi, Fengjian. “LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE.” 2017. Doctoral Dissertation, Temple University. Accessed August 18, 2019. http://digital.library.temple.edu/u?/p245801coll10,445496.

MLA Handbook (7th Edition):

Shi, Fengjian. “LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE.” 2017. Web. 18 Aug 2019.

Vancouver:

Shi F. LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE. [Internet] [Doctoral dissertation]. Temple University; 2017. [cited 2019 Aug 18]. Available from: http://digital.library.temple.edu/u?/p245801coll10,445496.

Council of Science Editors:

Shi F. LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE. [Doctoral Dissertation]. Temple University; 2017. Available from: http://digital.library.temple.edu/u?/p245801coll10,445496

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