Magnetophoretic velocities of superparamagnetic particles, agglomerates and complexes

• Analysis of the magnetically induced drift velocity of superparamagnetic particles.
• Zeta potential of superparamagnetic particles and non-magnetic particles found.
• Drift velocity of single particles, chains and complexes determined experimentally.
• Magnetic drift velocities of chains and complexes predicted by simple models.

A study into the magnetically induced mobility of four types of superparamagnetic particles (SMPs) was conducted using a video camera, an inverted light microscope and ImageJ tracking software. The objective is to improve the understanding of how SMP-capture assays perform by measuring mobilities of SMPs, when aggregated together or attached to non-magnetic beads (NMB). The magnetically induced velocities of self-assembled SMP chains were measured and found to meet the proposed models. A study into the zeta potential of the SMPs was completed to determine a scenario for maximal electrostatic interactions and efficient capture of the SMPs to a target. SMPs were bound to biotinylated NMBs, representing attachment to a disease biomarker. The drift velocity of SMP chains and SMP–NMB complexes in a gradient magnetic field was compared. It is expected that the observable changes to the magnetophoretic mobility of SMPs attached to a disease biomarker will lead to new biosensor technology.