ABSTRACT BOKHART, MARK THOMAS. Development and Application of Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging for Drug Distribution Studies. (Under the direction of Dr. David C. Muddiman.) Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a hybrid ionization technique combining resonant laser ablation and electrospray ionization. Analysis in a spatially resolved manner permits mass spectrometry imaging (MSI) analyses to be performed by displaying ion intensities in a 2-dimension array. IR-MALDESI has several unique advantages over conventional MSI techniques, for example matrix-assisted laser desorption/ionization (MALDI), such as operation at ambient conditions and the use of a biologically-compatible ice matrix. Additionally, the mid-infrared (IR) laser used for ablation has much greater ablation depth compared to ultraviolet lasers used in MALDI, usually completely ablating the sampled material at each rastered position. This attribute provides quantitative sampling of material at each position, giving high quality MSI data. The IR-MALDESI MSI source was optimized through a systematic investigation of factors effecting desorption of analytes including IR laser wavelength, geometric considerations and the inclusion of ice as a matrix. Additional optimization was performed by investigating trends in analyte response as the mass spectrometer C-trap injection time was varied. The shorter C-trap injection times lead to increases in ion abundance and identification of more species in untargeted analyses. A quantitative mass spectrometry imaging method was developed for use with IR- MALDESI, where a normalization compound is uniformly incorporated beneath the tissue to be quantified along with a spatial calibration curve incorporated on top of the same tissue. Normalization to the normalization compound reduced per-voxel variability, producing high quality MS images and accurate quantification from MSI data. This quantitative method was then applied to the analysis of 11 organs from a dosed, non-human primate study. IR- MALDESI MSI provided absolute quantification of an antiretroviral drug while displaying the heterogeneous distribution within sections of organs. IR-MALDESI MSI was also used to show drug incorporation into patient’s hair for monitoring drug regimen adherence. A method of normalization to hair melanin content was used to compare drug incorporation among several patients based on hair color. The spatial resolution of IR-MALDESI MSI was improved to 50-micron voxel size through the incorporation of a multi-element optical system. An adjustable iris, 3.75x beam expander and aspheric focusing lens were used to shrink the laser focal point compared to a single focusing lens. Important laser parameters were defined to characterize the laser beam caustic of both designs for comparison. The open-source MSI software, MSiReader, had several new tools added to facilitate the analysis of drug distribution studies. The software has the capability to load multiple files at once, allowing facile comparison of multiple data sets. An image overlay tool has been developed to allow comparison of the MSI data to any image file by displaying both concurrently. The quantification procedure has been streamlined into the MSiQuantification tool, where the user can define calibration and quantification parameters directly in MSiReader. Finally, MSiReader can now display mass measurement accuracy (MMA) heatmaps depicting the MMA for individual voxels in MSI data. © Copyright 2017 Mark Thomas Bokhart All Rights Reserved Development and Application of Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging for Drug Distribution Studies by Mark Thomas Bokhart A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Chemistry Raleigh, North Carolina 2017 APPROVED BY: _______________________________ _______________________________ David C. Muddiman Edmond Bowden Committee Chair _______________________________ _______________________________ Gufeng Wang Balaji Rao BIOGRAPHY Mark Bokhart was born on June 6, 1990 in Bay City, Michigan to Dan and Rebecca Bokhart. His passion for science was evident early on in his education, taking a great interest in science and mathematics courses. He attended Garber High School in Essexville, Michigan where he took every science and math course available by the time he graduated in May 2008. Not quite sure what he wanted to do as a career after graduation from high school, Mark attended Delta Community College in University Center, Michigan beginning in August 2008. After 2 years of community college, Mark’s interest and success in chemistry courses led him to purse a bachelor’s degree in chemistry at Michigan State University starting in August 2010. While at MSU, he worked as an undergraduate researcher at MSU’s Diagnostic Center for Population and Animal Health in the toxicology section under the supervision of Drs. John Buchweitz and Andreas Lehner. While there, he developed an appreciation for analytical methodology and realized the great need to further development of analytical technologies to solve real-world problems. In May 2013, Mark graduated from MSU with a Bachelor’s of Science in Chemistry. He then went on to pursue a Ph.D. degree in Analytical Chemistry at North Carolina State University under the direction of Dr. David Muddiman. ii ACKNOWLEDGMENTS I would like to formally acknowledge the unwavering support and mentorship of Dr. David C. Muddiman throughout my Ph.D. studies. I am extremely grateful for the extensive resources and great opportunities provided by the Muddiman laboratory and North Carolina State University. My work was highly collaborative, spanning across departments and institutions, and my projects would not have been as successful without the guidance of everyone involved. In particular, thanks to Dr. Eli Rosen for always listening to my experimental ideas and Ken Garrard for helping me with a wide variety of data analysis and visualization techniques. My experiences in graduate school would not have been as enjoyable and productive without the support and companionship of the former and current Muddiman lab members. And finally, I would not have succeeded without the support of the friends I made while at NCSU, especially Rosa Castrejon Garcia. iii TABLE OF CONTENTS List of Tables ……………………………...………………………………………........................... xi List of Figures ……………………………….......…………………………………………...……. xii List of Publications ........................................................................................................................... xv 1 Introduction ....................................................................................................................... 1 1.1 Soft Ionization Methods ............................................................................................. 1 1.1.1 Electrospray Ionization ....................................................................................... 1 1.1.2 Matrix Assisted Laser Desorption Ionization (MALDI) .................................... 3 1.1.3 Matrix Assisted Laser Desorption Electrospray Ionization (MALDESI) ........... 4 1.2 Fourier Transform Mass Spectrometry ...................................................................... 5 1.3 Mass Spectrometry Imaging (MSI) ............................................................................ 7 1.4 Human Immunodeficiency Virus (HIV) Treatment with Antiretroviral Drugs ......... 9 1.5 Synopsis of Completed Work .................................................................................. 10 1.6 References ................................................................................................................ 12 2 Influence of Desorption Conditions on Analyte Sensitivity and Internal Energy in Discrete Tissue or Whole Body Imaging by IR-MALDESI ................................................................. 20 2.1 Introduction .............................................................................................................. 20 2.2 Experimental ............................................................................................................ 24 2.2.1 Chemicals and Materials ................................................................................... 24 2.2.2 Sample Preparation ........................................................................................... 24 2.2.3 Instrumentation ................................................................................................. 25 2.2.4 Data Analysis .................................................................................................... 26 iv 2.3 Results and Discussion ............................................................................................. 27 2.3.1 Optimization of Desorption Conditions using an Ice Matrix ............................ 27 2.3.2 Whole Body Imaging ........................................................................................ 32 2.3.3 Response Factors and Internal Energy Distribution across Whole Body ......... 38 2.4 Conclusions .............................................................................................................. 42 2.5 Acknowledgments .................................................................................................... 42 2.6 References ...............................................................................................................