title: Bio-functionalization of monodisperse magnetic nanoparticles and their use as biomolecular labels in a magnetic tunnel junction based sensor.
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.
authors.affiliation: IBM T.J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA.
authors.forename: Stephanie G
authors.initials: SG
authors.lastname: Grancharov
authors.forename: Hao
authors.initials: H
authors.lastname: Zeng
authors.forename: Shouheng
authors.initials: S
authors.lastname: Sun
authors.forename: Shan X
authors.initials: SX
authors.lastname: Wang
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Brien
authors.forename: C B
authors.initials: CB
authors.lastname: Murray
authors.forename: J R
authors.initials: JR
authors.lastname: Kirtley
authors.forename: G A
authors.initials: GA
authors.lastname: Held
mesh_terms: D001360:Avidin / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D053758:Nanoparticles; D009693:Nucleic Acid Hybridization; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D004277:DNA, Single-Stranded; D005290:Ferric Compounds; D001360:Avidin; D008345:Manganese; D001710:Biotin; D012822:Silicon Dioxide