ABSTRACT GYLYUK, ALEXEY. Properties of Gallium Nitride-Microorganism Interfaces. (Under the direction of Dr. Albena Ivanisevic). A wide portfolio of advanced programmable materials and structures has been developed for biological applications in the last two decades. In particular, due to their unique properties, semiconducting materials have been utilized in areas of biocomputing, implantable electronics, and healthcare. As a new concept of such programmable material design, biointerfaces based on inorganic semiconducting materials as substrates introduce unconventional paths for bioinformatics and biosensing. In particular, understanding how the properties of a substrate can alter microbial biofilm behavior enables researchers to better characterize and thus create programmable biointerfaces with necessary characteristics on-demand. During the preliminary research stage, the most promising semiconductor material types along with target microorganisms were identified and subsequently utilized for further studies. Gallium-based surfaces (particularly, GaN with different doping levels) were chosen as the most promising semiconducting materials to be used in inorganic substrate-microorganism biointerfaces. The work was based on the hypothesis that they can be tailored to induce controllable microorganism behavior under specific user defined external conditions. At this stage of the work Pseudomonas aeruginosa was the test organism in the first two experimental parts of the dissertation work. As a the typical in-hospital infection, P.aeruginosa possesses high survivability and enhanced abilities to form resilient biofilms on various surfaces. These factors allowed us to perform a set of studies that enable to create GaN-P.aeruginosa biointerfaces, characterize them and identify factors triggering the morphological and physiological reactions of formulated structures. The final stage of the dissertation project involved utilization of the yeast culture Saccharomyces cerevisiae which expanded the class of microorganisms used in the dissertation work. Comparing several characterization techniques and applying modern approaches permitted the confirmation and further validated the results obtained previously. Additionally, identification of instruments and techniques possessing the most advantages for this type of research made it possible to improve the data gathering and analysis as well as define the future research directions. © Copyright 2020 by Alexey Gulyuk All Rights Reserved Properties of Gallium Nitride-Microorganism Interfaces by Alexey Gulyuk 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 Materials Science and Engineering Raleigh, North Carolina 2020 APPROVED BY: _______________________________ _______________________________ Dr. Albena Ivanisevic Dr. Ramon Collazo Committee Chair _______________________________ _______________________________ Dr. Nelson Vinueza Benitez Dr. Yaroslava Yingling DEDICATION To my Mom and Dad. ii BIOGRAPHY Alexey V. Gulyuk received his B.S. in Engineering Physics from Belarusian State University in 2014. He moved on to graduate studies in physics at North Carolina Central University. Alexey successfully completed his research project under guidance of Prof. Igor Bondarev and earned an M.S. degree in Physics in 2016. The same year, he started the PhD program in Materials Science and Engineering at North Carolina State University and worked under the direction of Prof. Albena Ivanisevic. While being part of undergraduate and graduate community, Alexey expressed interest in natural sciences and engineering, teaching, mentoring, and establishing scientific communications in interdisciplinary groups. His previous research was primarily focused on signal generation and analysis, development of theoretical physical models involving advanced simulation techniques. Current research interests lie in characterizing the inorganic semiconducting materials and development of new bioelectronic modalities by interfacing inorganic substrates with various microorganisms and organic tissue. After receiving his PhD in Materials Science and Engineering, Alexey hopes to continue participating in research activities and serving as an active contributor to innovative development and progress in scientific community and industry. iii ACKNOWLEDGMENTS First, I would love to express special gratitude to my advisor, Dr. Albena Ivanisevic, for her dedicated work, mentorship, guidance, support, and understanding through my years at NC State. Thank you to my committee members, Dr. Yaroslava Yingling, Dr. Ramon Collazo, and Dr. Nelson Vinueza Benitez for their valuable input and continual feedback. Furthermore, I would like to acknowledge our collaborators and people I had pleasure to work with: Dr. Dennis LaJeunesse from UNCG who became a source of continuous inspiration and wisdom, Dr. Susan Bernacki from BME department who is always willing to help or provide some advice, Dr. Ronny Kirste from MSE, Dr. Mark Walters from SMIF at Duke University, Chuck Mooney from AIF. I am very thankful to: Dr. Bernacki, Dr. Mozdziak and Dr. Petitte, Dr. Mackenzie and Valerie Lapham, Steve Barr and Lisa Chang, and especially to Dr. Yingling for being excellent professors and mentors through the course of my interdisciplinary studies at NC State. Many thanks to people at MSE who always provided so much needed assistance: Dr. Elizabeth Dickey, Dr. Lewis Reynolds, George Martell, and Edna Deas. Best wishes and many thanks to my group members: Sara Gleco, Patrick Snyder and Taylor Adams for being inspiring peers and simply good friends. I am also thankful to Dr. Igor V. Bondarev who was my mentor since I first came to the US, whose guidance I relied on, and who always served as an example of academic excellence. On a personal level, I would like to thank people who made everything possible and without whom I would never be here – my parents, Alla and Vasiliy – a source of everlasting love and continuous support in my life. Furthermore, I am sincerely thankful to Tanya who believed in me, for always being there for me. To my aunt Olga, Alex, Julia for their so much appreciated help, encouragement, and a lot of fun time spent together. Lastly, to my friends: Mitch, Chris, Ming, Silvestr, Katya, and Ira for being a valued part of my life. iv TABLE OF CONTENTS LIST OF TABLES ........................................................................................................................ vi LIST OF FIGURES ..................................................................................................................... vii Chapter 1: Tuning Microbial Activity via Programmatic Alteration of Cell/Substrate Interfaces .................................................................................................................. 1 1.1 Introduction ..................................................................................................................... 1 1.2 Microorganisms and Interactions with Planar Inorganic Matter and Their Importance for a Programmable Materials ........................................................................................ 3 1.2.1 Advanced Programmable Materials ....................................................................... 4 1.2.2 Current Trends in Programmable Materials .......................................................... 4 1.3 Interactions of Microorganisms with Planar Inorganic Matter and Their Importance for a Programmable Biointerface Conception ................................................................ 7 1.3.1 Biointerface as a Novel Type of Material .............................................................. 7 1.3.2 Inorganic Materials Interacting with Microorganisms .......................................... 9 1.3.3 Physiological Responses Within Biointerfacial Structures.................................. 12 1.3.4 Genetic Responses in Biological Systems ........................................................... 17 1.4 Conclusions ................................................................................................................... 23 Chapter 2: Characterization of Pseudomonas Aeruginosa Films on Different Inorganic Surfaces Before and After UV Light Exposure ................................................... 29 2.1 Introduction ................................................................................................................... 29 2.2 Results and Discussion ................................................................................................. 30 2.2.1 Characterization Prior To Bacterial Film Formation ........................................... 30 2.2.2 P.aeruginosa Film Characterization .................................................................... 36 2.3 Experimental section ..................................................................................................... 41 2.4 Conclusions ................................................................................................................... 43 Chapter 3: The Interfacial Properties of Doped Semiconductor Materials Can Alter the Behavior of Pseudomonas Aeruginosa Films ....................................................... 44 3.1 Introduction ................................................................................................................... 44 3.2 Results and Discussion ................................................................................................