“DEVELOPMENT AND OPTIMIZATION OF ELECTROCHEMICAL SENSORS TO DETECT BACTERIAL PATHOGENS FOR POINT-OF-CARE APPLICATIONS”
ABSTRACT This dissertation focuses on the development and optimization of electrochemical sensors to detect bacterial pathogens for point-of-care applications. Recent spikes in hospital-acquired infections have resurfaced fears of antibiotic-resistant bacteria and their adverse effects on human health. Presenting new challenges in pathogenesis and resistance, infections caused by these microorganisms are becoming increasingly difficult to treat, with prompt administration of targeted therapies providing the best chances for patient recovery. To address this emerging threat, this dissertation aims to develop and improve biosensors that will allow for early and rapid detection of these bacterial pathogens.
Pseudomonas aeruginosa is a commonly isolated nosocomial pathogen frequently associated with infections in patients with cystic fibrosis and chronic wounds. P. aeruginosa secretes pyocyanin, a unique quorum sensing molecule that can be monitored electrochemically due to its redox-active nature. Detection of pyocyanin has been demonstrated to be a relatively simple, inexpensive way to screen for P. aeruginosa infections, but there remain significant challenges in the development of this sensing strategy before it can be used as a viable diagnostic technique.
Several enhancements were investigated for sensor improvement. One focus of this work was to use amino acids to up-regulate pyocyanin production to expedite identification methods at the onset of infection. The second focus of this work was to electrochemically screen additional pathogens for unique redox-active molecules. As no other redox-active molecules could be directly measured or identified, a secondary electrochemical detection method was developed using aptamers as highly selective recognition elements. The third focus of this work was to microfabricate an electrochemical sensor to detect pH, a general marker of infection, and pyocyanin to detect the presence of P. aeruginosa for applications toward a smart bandage. Finally, the P. aeruginosa sensor was clinically validated with human and animal patient samples.
Future work and recommendations include continued clinical data collection and further optimization of the aptamer biosensor to detect other clinical pathogens. These sensors will lead to faster detection methods for P. aeruginosa and other clinically-relevant bacteria, allowing clinicians to promptly switch from broad-spectrum antibiotics to targeted therapies, lowering hospital expenditures, minimizing drug resistance, and improving patient care outcomes.
BIOGRAPHY Hunter Sismaet is originally from Seattle, WA where he graduated from the University of Washington in 2012 with ACS-certified degrees in Chemistry and Biochemistry. After graduating, his passion for research took him to Northeastern University in Boston, MA where he is currently pursuing a Ph.D. in Chemical Engineering under the advisement of Prof. Edgar Goluch. Hunter’s research focuses on the development and optimization of electrochemical sensors for detecting bacterial pathogens found in the hospital setting, specifically Pseudomonas aeruginosa. Hunter has 6 peer-reviewed publications, 2 patent applications, and research presented at 38 conferences. His research has directly led to the development of a startup company, QSM Diagnostics, which was recently recognized as a top 26 startup by MassChallenge.
Advisor: Prof. Edgar Goluch
Prof. Elizabeth Podlaha-Murphy
Prof. Thomas Webster
Prof. Yunrong Chai