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Abstract
Bacteria are ubiquitous; some are pathogenic to plants, animals, or humans. Due to their potential to cause major disease outbreaks, the need for rapid and reliable methods of bacterial detection is highly significant to food safety, public health, and environmental safety. Conventional methods of bacteria detection usually take a few hours to days for identification and often need skilled experts and specialized equipment. On the other hand, biosensors can offer a simpler alternative to conventional methods with several advantages, including ease to use, low detection limits, high sensitivity, desirable selectivity, and faster detection, for real-time monitoring. This dissertation mainly focuses on the development of an electrochemical biosensor architecture based on bacteriophage and bacteriophage protein-based recognition molecules to detect specific bacteria that are highly significant to healthcare and food safety. The first approach involves developing charge-directed, aligned immobilization of bacteriophage on a nanostructured electrode for selective detection of bacterial cells using electrochemical impedance spectroscopy (EIS) as the detection technique. As a proof of concept, Listeria monocytogenes was used as a model target (analyte), and commercially available P100 LISTEX phage was used as a recognition molecule to develop a phage-based impedimetric biosensor architecture. The architecture showed high sensitivity towards L. monocytogenes in select food samples.
The second approach involves developing a phage-protein-based biosensor by immobilizing a genetically engineered phage protein onto a nanostructured electrode for selective detection of bacterial cells using the EIS technique. As proof of concept, Campylobacter jejuni was used as the model analyte, and the genetically engineered phage protein CC-FlaGrab served as the recognition (bioreceptor) molecule. This architecture showed high sensitivity and specificity toward C. jejuni in select samples.
These two architectures could be the foundation for developing more electrochemical biosensing architectures for bacterial cell detection using a combination of recognition molecules and nanostructured electrodes that could be integrated into lab-on-chip devices for commercial development.