Super-paramagnetic magnetite nanoparticles obtained by different synthesis and separation methods stabilized by biocompatible coatings

Abstract

Magnetite nanoparticles were chemically synthesized by co-precipitation method, using gelatine added in-situ and ex-situ and also using two different separation techniques for the magnetite particles (magnet or centrifuge). The product was analysed by different techniques, such as SEM, DLS, FTIR and XRD. From the comparison of the results it was concluded that the added gelatine can be preserved in the final product with a higher probability if it is added ex-situ. This is because a larger and more uncertain part of gelatine is lost during the washing – separation steps when it is added in-situ. Thus, the ex-situ addition of gelatine is more efficient to stabilize nano-magnetite particles. Also, it was concluded that particle separation by centrifuge was more efficient to separate larger and mostly paramagnetic magnetite particles, while separation by a magnet was more efficient for smaller superparamagnetic magnetite particles. This is explained by different mechanism behind these two separation techniques. Thus, for the production of suspensions with superparamagnetic nano-magnetite particles the separation method using a strong magnet is preferred vs a centrifuge. It was further shown that when sucrose was applied together with gelatine, the stabilization of magnetite particles was improved compared to the case when only gelatine was used.