New type of biosensor based on magnetic nanoparticle detection

A new type of biosensor has been developed based on detection of nanosized superparamagnetic particles that serve as labels in bioreactions. The method is based on non-linear magnetic material detection by a magnetic field having components at two frequencie f(1), and f(2). The response is measured at the combinatorial frequencies f(i) = mf(1) + nf(2), where m and n are integers, e.g., f(i) = f(1) +/- 2f(2). Several highly sensitive readers of superparamagnetic particles have been designed and used for development of various formats of immunoassays, including those compatible with immunoconcentration and magnetic enrichment of antigens. (C) 2006 Elsevier B.V. All rights reserved.