Rapid DNA multi-analyte immunoassay on a magneto-resistance biosensor

We present the rapid and sensitive detection of amplified DNA on a giant magneto-resistance sensor using superparamagnetic particles as a detection label. The one-step assay is performed on an integrated and miniaturized detection platform suitable for application into point-of-care devices. A double-tagged PCR amplification product of the LamB gene of the Escherichia coli bacterium was used to investigate binding kinetics of the assay. We applied magnetic actuation to concentrate the target–particle complexes at the sensor surface and to remove unbound particles from the sensor surface. We achieved biological dose-response curves detecting 4–250 pM amplicon concentrations in a one-step format in total assay times of less than 3 min. Using various tag-antibody combinations specific for one of the individual genes, multi-analyte detection is shown of several antibiotic resistance genes of the food pathogen Salmonella.