Magnetoresistance Characteristics of Magnetic Nanoparticles for Binding with Antibodies in Solution

Magnetic nanoparticles with an average diameter of less than 50 nm with an amine-group surface coated with silica or dextran are being used as immunotherapeutic antibody conjugates. The magnetoresistance (MR) characteristics of magnetic nanoparticles (MNPs) are investigated according to the strength of the external magnetic field that changed the distribution of the nanoparticle solution at a 1 mm interval between two copper electrodes having a diameter of 1 mm. In the case of the silica amine group MNP solution, which is rapidly separated by an external magnetic field, the magnetoresistance curve is non-uniform. In the case of MNPs with an antibody attached to an amine group, the initial MR value, MR ratio, and solution coercivity are 0.74M Omega, 1.6%, and 200 Oe, respectively, depending on the external magnetic field. In addition, it took more than 10 hours under a powerful magnetic field to completely separate the magnetic dextran nanoparticles from which the dispersant is sufficiently added to a MNP solution of 2 mg/mL. The dextran MNP solution, which maintained the concentration, shows a symmetric butterfly-shaped magnetoresistance curve with MR, MR ratio, and solution coercive force of 1.43M Omega, 0.2%, and 260 Oe, respectively, depending on the external magnetic field. These results show that it is possible to control the induction of MNPs for the development of antibodies for immunotherapy to a target with a magnetic field.