Quantitative biomolecular sensing station based on magnetoresistive patterned arrays

• DOI: 10.1016/j.bios.2012.02.048
• Publication Date: 2012-03-01T05:01:35Z
• Authors: D. Serrate; J.M. De Teresa; C. Marquina; J. Marzo; D. Saurel; F.A. Cardoso; S. Cardoso; P.P. Freitas; M.R. Ibarra
• Keywords: STRIPS; SIGNAL (programming language); Magnetic particle inspection

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 (5.5 ng/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.