Magnetic force-based immunoassay using superparamagnetic nanoparticles in microfluidic channel

This paper presents immunoassay based on the magnetic force in the poly(dimethylsiloxane) (PDMS) microfluidic device using superparamagnetic 50-nm nanoparticles as a label and fluorescent 1 μm polystyrene beads as a solid support. The superparamagnetic nanoparticles and polystyrene beads are immobilized with specific antibodies. When target analytes react with the polystyrene beads and superparamagnetic nanoparticles simultaneously, the superparamagnetic nanoparticles can be attached onto the microbeads by the antigen-antibody complex. Only the microbeads conjugated with superparamagnetic nanoparticles by analytes consequently move to the high gradient magnetic fields under the specific applied magnetic field.