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Magnetic immunostaining is a technique used to accelerate the antigen-antibody immunoreaction by increasing the local density of antibody on the surface of a tissue specimen using a magnetic field. The high density of antibody is achieved by applying a magnetic force to antibody-labeled ferrite beads toward the specimen. A technical challenge of using conventional magnets for this technique has been the inhomogeneous accumulation of magnetic beads on the specimen in accordance with the distribution of the magnetic field. Thus, in this study, a dome-shaped magnet that generated a strong and uniform magnetic force distribution was proposed and demonstrated. Numerical analysis was used to optimize the shape of the magnet. Analysis of the motion of magnetic beads showed that the accumulation of beads on the sample was complete within one minute and that the resulting homogeneity was sufficient for rapid and accurate immunostaining. Finally, experiments showed that the homogeneity of the bead distribution was improved by the use of a prototype dome-shaped magnet compared to conventional cylindrical magnets.Magnetic immunostaining is a technique used to accelerate the antigen-antibody immunoreaction by increasing the local density of antibody on the surface of a tissue specimen using a magnetic field. The high density of antibody is achieved by applying a magnetic force to antibody-labeled ferrite beads toward the specimen. A technical challenge of using conventional magnets for this technique has been the inhomogeneous accumulation of magnetic beads on the specimen in accordance with the distribution of the magnetic field. Thus, in this study, a dome-shaped magnet that generated a strong and uniform magnetic force distribution was proposed and demonstrated. Numerical analysis was used to optimize the shape of the magnet. Analysis of the motion of magnetic beads showed that the accumulation of beads on the sample was complete within one minute and that the resulting homogeneity was sufficient for rapid and accurate immunostaining. Finally, experiments showed that the homogeneity of the bead distribution was ...

Magnetic immunostaining provides a novel technique for rapid intraoperative diagnosis of cancer metastasis and its characteristics in lymph nodes. Previous studies have shown the effectiveness of this technique using the manual staining process. However, to make this technique feasible for use in hospitals, establishing an automatic process is important. Thus, the objective of this study is to realize a device for immunostaining using magnetic fields that could not only automatically stain the samples, but also wash the specimen and change experimental solutions as well. The specifications for our prototype device were determined based on the manually performed experiments. We successfully fabricated a prototype device and demonstrated automatic immunostaining using it. The device completed, within 10 minutes, processes of blocking the specimen, injection of the magnetic beads, antigen-antibody reaction, and washing out the beads. The reaction took 1 minute, which was significantly shorter than that of conventional immunostaining. The device is expected to provide improved reproducibility of staining because of its automated processes.