Web Release Date: June 14,
Bio-functionalization of Monodisperse Magnetic Nanoparticles and Their Use as Biomolecular Labels in a Magnetic Tunnel Junction Based Sensor
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IBM T.J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, Department of Applied Physics & Applied Mathematics, Columbia University, New York, New York 10027, and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305
Received: March 3, 2005
In Final Form: April 25, 2005
Abstract:
Monodisperse magnetic nanoparticles (NPs) could enable the ultra-sensitive magnetic detection of biological analytes. However, rendering these particles biocompatible has remained a challenge. We report the bio-functionalization and detection of 12-nm manganese ferrite NPs. We have achieved the site-specific binding of biotin-functionalized NPs onto avidin-patterned silicon oxide substrates and DNA-functionalized NPs onto complementary DNA-patterned silicon oxide substrates. Utilizing scanning SQUID microscopy, we show that these substrate-bound NPs retain their magnetic properties. Finally, we demonstrate a novel method of detecting either protein binding or DNA hybridization at room temperature using the NPs and a magnetic tunnel-junction-based biosensor situated in orthogonal magnetic fields.
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