Waterborne Pathogen Detection Using a Magnetoresistive Immuno-Chip

Magnetoresistive bioassays, in which the traditional optical labels are replaced by magnetic labels, hold the promise of increased response speed, sensitivity, and portability in the detection system. These properties make these systems ideal for the monitoring of microbiological quality of drinking water or hydric resources. In this chapter, we demonstrate the applicability of magnetoresistive biosensors for the detection of the environmental pathogen Salmonella typhimurium . The approach comprises the coating of magnetic nanoparticles with polyclonal antibodies to Salmonella spp. in order to specifically capture and concentrate the Salmonella cells from solution. Once captured, the magnetically labeled cells are recognized by a second immuno-recognition on top of the sensor’s surface through the use of specific monoclonal antibodies. Quantitative data are then obtained using an electronic platform to measure the resistance change of the sensor due to presence of the magnetic particles.