Bio-functionalization of monodisperse magnetic nanoparticles and their use as biomolecular labels in a magnetic tunnel junction based sensor

J Phys Chem B. 2005 Jul 7;109(26):13030-5. doi: 10.1021/jp051098c.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Avidin / chemistry
  • Biosensing Techniques / methods*
  • Biotin / chemistry
  • DNA, Single-Stranded / chemistry
  • Ferric Compounds / chemistry*
  • Magnetics*
  • Manganese / chemistry*
  • Nanoparticles
  • Nucleic Acid Hybridization
  • Silicon Dioxide / chemistry


  • DNA, Single-Stranded
  • Ferric Compounds
  • Avidin
  • Manganese
  • Biotin
  • Silicon Dioxide