Design and fabrication of non-superparamagnetic high moment magnetic nanoparticles for bioapplications

We present a new type of magnetic nanoparticles for bioapplications. Multilayered nanodisks consisting of two magnetic layers separated by a non-magnetic layer with two capping layers were designed and fabricated. Two key magnetic requirements for bioapplications, a high saturation magnetic moment and a near-zero remanence, were achieved through the magnetostatic interlayer coupling between two magnetic layers. Capping layers provide functionalization sites for biomolecule attachment. A pillar-template-based synthesis method was employed for fabrication. Nanodisks with a diameter of 70 nm and a thickness of 60 nm were produced in large quantity. The magnetic characterization shows that each nanodisk possesses a magnetic moment equivalent to 100 10-nm Co nanoparticles and a near-zero remanent moment.