AVS 52nd International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+BI-FrM

Invited Paper MI+BI-FrM7
Shaken Not Stirred, A New Approach to Biomagnetic Sensing

Friday, November 4, 2005, 10:20 am, Room 204

Session: Biosensors and Biomagnetism
Presenter: A. Hoffmann, Argonne National Laboratory
Authors: A. Hoffmann, Argonne National Laboratory
S.-H. Chung, Argonne National Laboratory
K. Guslienko, Argonne National Laboratory
S.D. Bader, Argonne National Laboratory
C. Liu, Argonne National Laboratory
B.D. Kay, Argonne National Laboratory
L. Makowski, Argonne National Laboratory
L. Chen, Argonne National Laboratory
Correspondent: Click to Email
Micron and nanosized magnetic particles coated with biochemical surfactants have emerged recently as an important component for enabling many biological and medical applications. Among these biomagnetic sensors have received a lot of attention lately, due to their potential advantages of simplicity and rapidity. The most common approach to biomagnetic sensors utilizes magnetic beads, whose magnetic moment is detected by a magnetic field sensor, such as a giant magnetoresistive spin valve. In contrast we demonstrated a new substrate-free approach to biomagnetic sensing which uses the magnetic ac-susceptibility of ferromagnetic nanoparticles suspended in a liquid for the signal transduction.@footnote 1@ The magnetic relaxation of these nanoparticles is due to their Brownian rotational diffusion, which is easily modified by binding the target of interest to the particles. This scheme has several distinct advantages; (i) it requires only one binding event for successful sensing; (ii) since there is a useful signal both in the absence and presence of the target it has an inherent check for integrity; and (iii) the signal contains information about the size of the target besides the biochemical affinity, which may be used to further distinguish between several different potential targets. We are developing novel magnetic viruses for application in our sensing scheme. They provide a well-defined, mono-dispersed size distribution of the ferromagnetic particles and offer the possibility to readily engineer the desired biological recognition functionality. This work was supported by DOE, BES under contract W-31-109-ENG-38 and DARPA under contract 8C67400. @FootnoteText@ @footnote 1@ S.-H. Chung, et al., Appl. Phys. Lett. vol. 85, 2971 (2004).