CPM Seminar

Biofunctionalization and detection of magnetic nanoparticles

Glenn Held

IBM T.J. Watson Research Center

Methods of synthesizing monodisperse, strongly magnetic ferrite nanoparticles have been well documented. However, encapsulation of these particles within an overlayer of biologically active molecules and their subsequent stabilization in a physiological medium has not yet been reported. Such bio-functionalized magnetic nanoparticles would provide the crucial component in ultra-sensitive magnetic detection of both proteins and nucleic acids. In addition, such particles could be used to bind and transport proteins. Following introduction into a living organism, they could also provide a means of monitoring and influencing cellular processes. In this letter, we report the successful bio-funtionalization of 12 nm manganese ferrite (MnFe₂O₄) nanoparticles. We demonstrate the site-specific binding of both biotin and DNA functionalized nanoparticles onto protein patterned silicon oxide substrates. Imaging these substrates with scanning squid microscopy, we show that these particles retain their magnetic properties. Finally, we demonstrate a novel method of detecting the hybridization of these magnetic nanoparticles to a substrate at room temperature using a biosensor comprised of a protein patterned magnetic tunnel junction situated in orthogonal magnetic fields.