Using Magnetostrictive Biosensors for Salmonella typhimurium and Campylobacter jejuni Detection
Type of Degreethesis
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Salmonella and Campylobacter are two of the most common genera of foodborne pathogens. Contaminated foods, water, undercooked foods or contact with infected animals could cause salmonellosis and campylobacteriosis. Magnetostrictive materials are highly sensitive to the mass loaded on the surface. This property has been used for fabricating biosensors for pathogen detection. In this study, a magnetostrictive paticle (MSP) in size of 1.0 × 0.2 × 0.25 mm or 2 × 2 × 0.25 mm was fabricated and coated with three layers of silica and 100 nm of gold. The coatings are highly stable according to the resonance frequency response in water. Anti-Campylobacter and anti-Salmonella antibodies were well immobilized on silica and gold coated sensors by covalent bonding and adsorption, respectively. The immobilization efficiencies were tested by ELISA. Scanning electron microscope (SEM) images and resonance frequencies showed that the MSP based biosensors can capture Salmonella typhimurium and Camplylobacter jejuni in water. Comparing the SEM images and the frequency data of silica and gold coated biosensors, the performances of these two biosensors were similar and both biosensors are feasible for pathogen detection with the sensitivity of 102 CFU/mL in foods.