Magnetic Nanoparticle Synthesis Strategies for Biosensor Development Oscar M. Suarez, University of Puerto Rico at Mayag

1. Magnetic Nanoparticle Synthesis Strategies for Biosensor DevelopmentOscar M. Suarez, University of Puerto Rico at Mayaguez, DMR 0351449 Partnership for Research and Education on Functional and Nanostructured Materials Magnetic nanoparticles have attracted great interest for applications beyond magnetic data storage. For example, these particles are being investigated for use in biosensors, in which attachment of an analyte results in an increase in particle size with concomitant changes in the magnetic relaxation properties of the particles. Though this application has been demonstrated in principle, the performance of such sensors has not been addressed quantitatively and in relation to theories of nanoparticle rotational Brownian motion. One obstacle in making such quantitative comparisons has been the use of inadequate particle formulations. Magnetic nanoparticles synthesized through thermal decomposition of organo-metallic precursors We have compared three different particle synthesis strategies with respect to obtaining particles of controllable size, narrow size distribution, and easily modifiable surfaces. Reverse micelles yielded monodisperse ~3 nm particles, but the strongly adsorbed surfactant precluded further modification. Aqueous precipitation resulted in nanoparticles that were easy to modify but with broad particle size distributions. Thermal decomposition of organometallic precursors resulted in monodisperse nanoparticles of controllable size, with surfaces which could be easily modified by replacement of the adsorbed surfactant, however the particle yield is low. These results underscore the need for new synthesis techniques capable of yielding large quantities of monodisperse nanoparticles.