Quantitative biomolecular sensing station based on magnetoresistive patterned arrays

▸ GMR based magnetoresistive biosensor with sensibility below the visual limit in lateral flow assays and quantitative response in four signal decades. ▸ Large spatial resolution of the test line enabling multianalyte test and reference test lines. ▸ Proved sensibility to model human chorionic gonadotropin hormone down to 5ng/ml. ▸ Versatile, unexpensive and quick performance, featuring controlled contact pressure between sensor array and nitrocellulose strip sample surface. The combination of magnetoresistive sensors and magnetic labeling of bioanalytes, which are selectively captured by their complementary antibody in the proximity of the sensor is a powerful method in order to attain truly quantitative immunological assays. In this paper we present a technical solution to exploit the existing spin valve technology to readout magnetic signals of bio-functionalized magnetic nanoparticles. The method is simple and reliable, and it is based on a discrete scan of lateral flow strips with a precise control of the contact force between sensor and sample. It is shown that the signal of the sensor is proportional to the local magnetization produced by the nanoparticles in a wide range of concentrations, and the sensitivity thresholds in both calibration samples and real immunorecognition assays of human chorionic gonadotropin hormone are well below the visual inspection limit (5.5ng/ml). Furthermore the sample scanning approach and the reduced dimensions of the sensors provide unprecedented spatial resolution of the nanoparticle distribution across the supporting nitrocellulose strip, therefore enabling on-stick control references and multi-analyte capability.