The in-flow capture of superparamagnetic nanoparticles for targeting therapeutics.

Superparamagnetic nanoparticles have been synthesized that could potentially be used to magnetically target therapeutics within the body. The magnetic targeting and successful in-flow capture of 330-nm and 580-nm agglomerates of these magnetite nanoparticles was performed using a 0.5-T magnet. Optical observation of magnetic nanoparticle capture in microcapillary flow provides a useful preliminary way of establishing conditions for the magnetic capture of nanoparticles with direct relevance to blood vessels for magnetically directed therapy. A stable nanoparticle layer of 580-nm agglomerates could be formed at mean capillary flow velocities of up to 2.5 cm s(-1) and for the 330-nm agglomerates at velocities up to 4.4 cm s(-1). These data show that smaller nanoparticle agglomerates form a layer that is impervious to erosion by fluid shear. Capillary blocking by nanoparticles, analogous to an embolism, was not detected in these experiments.