Foodborne pathogens are infectious biological agents such as bacteria or viruses present in food or water that cause mild to severe diseases, that could lead to hospitalization, or even death. Food borne diseases have a significant impact on public health, nation’s healthcare infrastructure and the economy. It is important to diagnose and detect these pathogens early in the food distribution and supply chain in order to avoid expensive recalls and major outbreaks. Among these pathogens, Listeria monocytogenes is the cause of 23 % of all foodborne pathogen outbreaks in the United States since 2019 and caused hospitalization of 93 % in confirmed cases. At present, culture-based microbiological or molecular diagnostic methods are used that require laboratory tests and take anywhere from two to five days for results. Biosensors could present an alternative to conventional laboratory-based methods for rapid and early detection of the pathogens. The dissertation focuses on the development of an electrochemical biosensor on a portable diagnostic platform that is capable of detecting Listeria monocytogenes in both buffer and in simple food-matrix such as chicken broth. The detection approach was an electrochemical biosensor, with bacteriophage as recognition molecule immobilized on a carbon nanotube modified glassy carbon (GC) and a portable screen printed (SP) electrodes. The detection signal was generated through an electrochemical impedance spectroscopy (EIS) and was done under stationary and flow conditions with sample volumes of up to 100 µL. The biosensors showed very high sensitivity and selectivity with a limit of detection below 10 CFU/mL in pure samples. The dissertation research demonstrates the feasibility of this biosensor for use in food diagnostics as well as provide a scientific foundation for development of similar electrochemical sensing platform for detection of other bacterial cells.
