A facile approach to prepare water-soluble magnetic metal (oxide) frameworks based on Na,Ca alginate and maghemite

A one-step ultrasonication technique for the preparation of magnetic metal (oxide) organic frameworks (MOFs) with a size of >135nm based on sodium alginate crosslinked with Ca2+ ions and maghemite (γ-Fe2O3) nanoparticles with sizes from 7 to 20nm was proposed. The MOFs were characterized by Mössbauer spectroscopy, TEM, magnetometry, and UV-VIS and IR spectroscopy. The grid (crosslinks) preliminarily formed by Ca2+ ions plays an important role in the stabilization of maghemite nanoparticles, and the resulting MOFs can be used as magnetic carriers in systems for hyperthermia and drug delivery.