Resumen:
An immunomagnetic method for the selective and quantitative detection of biological species by means of a magnetoresistive biosensor and superparamagnetic particles has been optimized. In order to achieve this, a giant magnetoresistive [Co (5.10 nm)/Cu (2.47 nm)](20) multilayer structure has been chosen as the sensitive material, showing a magnetoresistance of 3.60% at 215 Oe and a sensitivity up to 0.19 Omega/Oe between 145 Oe and 350 Oe. The outward gold surface of the sensor is biofunctionalized with a Self-Assembled Monolayer (SAM). In addition, three different types of magnetic labels have been tested. 2 mu m diameter magnetic carriers (7.68 pg ferrite/particle) have shown the best response and they have induced a shift in the magnetoresistive hysteresis loops up to 9% at 175 Oe. (C) 2011 Elsevier B.V. All rights reserved.
