MAGNETIC BEAD-ROLLING FOR ULTRASENSITIVE SURFACE-BASED IMMUNOASSAYS

We describe an active protein transport strategy based on the specific interaction between surface-bound “small” magnetic beads and “large” magnetic beads that carry antigens (Ags) and are simultaneously used as detection labels. When placed in an external magnetic field, the combination of magnetic dipolar forces and microfluidic viscous forces acting on a large bead results in an intense contact between the two types of beads. Specifically, a “rolling” behavior of the large bead over the small bead pattern is induced. This magnetic bead-rolling mechanism allows increasing the probability of immunocomplex formation by more than one order of magnitude.