Electrospinning as a method for preparation of redispersible dry product with high content of magnetic nanoparticles.

One of the key technological challenges in the development of iron-oxide-based magnetic nanoparticles (MNPs) is their long-term physical stability in colloidal dispersions. This can be improved by their transformation into a dry form. Here, we introduce electrospinning as a drying method for ethanol-based and water-based MNP dispersions, which enables the preparation of high-loaded dry MNP products. The obtained easily dispersible electrospun product contained up to 50 % (w/w) of MNPs, homogeneously distributed in the fibrillar structure, which is much more compared to the products of currently available methods for drying MNP dispersions. The polymers used as building blocks of nanofibers, namely poloxamer 188 and polyethylene oxide, improved the tolerance of MNPs to high ionic strength dispersion medium and thus enhanced the short-term physical stability of MNP dispersions after reconstitution. The dry product was stable for up to 1 month at room temperature and relative humidity up to 70 %. It was in the form of a nanofiber mat, which prevented the aerosolization of MNPs and their unintentional ambient exposure. Therefore, the electrospun product with MNPs is expected to be a safer dry formulation of MNPs than the nanoparticulate powders, which are usually the final products of the conventional drying methods.