Differential Magnetic Catch and Release: Analysis and Separation of Magnetic Nanoparticles

摘要

This article reports the purification and separation of magnetic nanoparticle mixtures using differential magnetic catch and release (DMCR). This method applies a variable magnetic flux orthogonal to the flow direction in an open tubular capillary to trap and controllably release magnetic nanoparticles. Magnetic moments of 8, 12, and 17 nm diameter CoFe_(2)O_(4) nanoparticles are calculated using the applied magnetic flux and experimentally determined force required to trap 50percent of the particle sample. Balancing the relative strengths of the drag and magnetic forces enables separation and purification of magnetic CoFe_(2)O_(4) nanoparticle samples with <20 nm diameters. Samples were characterized by transmission electron microscopy to determine the average size and size dispersity of the sample population. DMCR is further demonstrated to be useful for separation of a magnetic nanoparticle mixture, resulting in samples with narrowed size distributions.