AVS 46th International Symposium
    Biomaterial Interfaces Group Monday Sessions
       Session BI-MoM

Paper BI-MoM10
Detection of Immobilized Superparamagnetic Nanosphere Assay Labels using Giant Magnetoresistive Sensors

Monday, October 25, 1999, 11:20 am, Room 613/614

Session: Biosensor-Biology Interface
Presenter: M.C. Tondra, Nonvolatile Electronics
Authors: M.C. Tondra, Nonvolatile Electronics
M. Porter, Iowa State University
Correspondent: Click to Email
Commercially available superparamagnetic nanospheres are commonly used in a wide range of biological applications, particularly in magnetically assisted separations. A new and potentially significant technology involves the use of these particles as labels in nanomagnetic assay applications. This labeling is analogous to that of flourescent beads: the beads are excited and detected with magnetic fields rather than with photons. A major advantage of this technique is that the means for label excitation and detection are easily integrable on a silicon circuit. A preliminary study of this technique demonstrated its basic feasibility, and projected a sensitivity of better than 10@super -12@ Mole.@footnote 1@ This paper presents detailed magnetic and geometric design considerations for this type of assay, and addresses the range of applications over which the technique is appropriate. It is shown that, with proper sensor design and immobilization techniques, integrated magnetoresistive sensors can be used to easily detect the presence or absence of single 1000 nm magnetic microspheres immobilized on the surface of a giant magnetoresistive sensor. Detection of microsphere labels in the 10 to 100 nm range may also be possible if other sensing parameters are compatible. @FootnoteText@ @Footnote 1@ David R. Baselt, Gil U. Lee, Mohan Natesan, Steven W. Metzger, Paul E. Sheehan, and Richard J. Colton, "A Biosensor Based on Magnetoresistance Technology," Biosensors and Bioelectronics, Vol. 13, pp. 731-739 (1998).