Assessment of Cytocompatibility and Magnetic Properties of Nanostructured Silicon Loaded with Superparamagnetic Iron Oxide Nanoparticles

The aim of this work is to create a biocompatible superparamagnetic nanocomposite applicable as vehicle for magnetically guided drug delivery. Therefore Fe₃O₄-nanoparticles have been infiltrated or chemically grown within nanostructured silicon. Both materials, the nanostructured silicon as well as the iron oxide nanoparticles, offer low toxicity and investigations concerning the cell-viability have been carried out. The magnetic properties of the system have been optimized concerning the blocking temperature T_B and the magnetic moment M which means that T_B has to be far below room temperature and M should be as high as possible, whereas these both properties are counteracting. T_B indicates the transition between superparamagnetic behavior and blocked state of the composite. Due to the fact that T_B is not only dependent on the particle size (diameters between 4 and 10 nm have been investigated) but also on the magnetic interactions between the particles there are two main routes to fabricate such a composite with desired T_B - first a modification of the pore-loading with a concomitant variation of the distance between the particles within one pore and second a variation of the porous silicon morphology influencing the distance between particles within adjacent pores. To ensure that there is no remanence after the external field has been switched off, magnetic coupling between the particles has to be kept sufficiently low. A particle-size/distance and template dependent assessment of the magnetic properties and the cytotoxicity of the nanocomposite will be presented. Furthermore the differences between infiltrated Fe₃O₄-nanoparticles and chemically grown particles inside the pores will be figured out.