Journal of Magnetism and Magnetic Materials, 423, p. 436-440 (2017); doi:10.1016/j.jmmm.2016.09.106
Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-ofcare testing of biochemical substances and nanoparticle capillarity flow studies.
This work was partly supported by the Spanish Government Projects MINECO-13-MAT2012-33405 and MINECO-13-CTQ2013-47396-R, and Principality of Asturias Project GRUPIN14-037. M. Oliveira-Rodríguez thanks FICYT (Asturias, Spain) for grant BP14-005, and D. Lago-Cachón thanks Instituto Universitario de Tecnología Industrial de Asturias and the Council of Gijón for grant SV-14-GIJÓN- 1.10.