(369c) Biocompatible and Biodegradable Nanoparticle Labels

The focus of this research is to produce a magnetic label for magnetic cell separation that is biocompatible and degrades harmlessly in the body. These are achieved with the natural polysaccharide alginic acid and magnetite (Fe3O4), both benign and approved for implantation. A method has been developed for the production of 5 (+/- 5) µm magnetic alginate spheres, using only FDA ?safe? materials. The magnetophoretic mobility of the resulting microspheres is controlled by the uptake of magnetite, a function of the experimental parameters. The first application of these biodegradable microspheres will be for the magnetic purification of porcine islets of Langerhans (see 2005 AIChE Abstract 17656). Magnetic isolation of porcine islets was previously demonstrated on several occasions using 4.5 µm Dynal Dynabeads®. Following enzymatic digestion of the infused pancreas, 95% of labeled islets were recovered at ~15% purity. Customized alginate particles would be sufficiently magnetic to retain labeled tissue but not magnetic enough to draft unlabeled tissue. In parallel colloidal Fe3O4 will be employed in a magnetic field-flow fractionation (Mag FFF) device. FFF is a separation technique in which a sample is introduced into the laminar flow profile within a thin, elongated channel. As the sample travels through the FFF channel a magnetic field applied perpendicularly to the flow profile drives sample toward the channel walls where the axial velocity is lower. Components thus elute by the order of distance from the centerline of the channel. In order to optimize the power of a magnetic field, it is necessary to maximize the particle magnetic susceptibility and minimize the channel depth. A femtosecond cutting laser permits non-cleanroom fabrication of microscale features. A micrometer-scale channel will be quickly and cheaply etched onto glass microscope cover slips and mated to a syringe pump and UV detector. The Mag FFF device will be used initially to fractionate colloidal magnetic nanoparticles and eventually to fractionate labeled subcellular biological components.