title: Keeping Nanoparticles Fully Functional: Long-Term Storage and Alteration of Magnetite.
abstract: Magnetite is an iron oxide found in rocks. Its magnetic properties are used for paleoclimatic reconstructions. It can also be synthesized in the laboratory to exploit its magnetic properties for bio- and nanotechnological applications. However, although the magnetic properties depend on particle size in a well-understood manner, they also depend on the structure of the oxide, because magnetite oxidizes to maghemite under environmental conditions. The dynamics of this process have not been well described. Here, a study of the alteration of magnetite particles of different sizes as a function of their storage conditions is presented. Smaller nanoparticles are shown to oxidize more rapidly than larger ones, and that the lower the storage temperature, the lower the measured oxidation. In addition, the magnetic properties of the altered particles are not decreased dramatically, thus suggesting that this alteration will not impact the use of such nanoparticles as medical carriers.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm 14424 Potsdam (Germany), /567-9402 E-mail: damien.faivre@mpikg.mpg.de.
authors.forename: Marc
authors.initials: M
authors.lastname: Widdrat
authors.affiliation: Institute of Geophysics, ETH-Zürich Sonneggstrasse 5, CH-8092 Zürich (Switzerland).
authors.forename: Monika
authors.initials: M
authors.lastname: Kumari
authors.affiliation: Department of Earth and Environmental Sciences, University of Pannonia Egyetem u. 10, H8200 Veszprém (Hungary).
authors.forename: Éva
authors.initials: É
authors.lastname: Tompa
authors.affiliation: Department of Earth and Environmental Sciences, University of Pannonia Egyetem u. 10, H8200 Veszprém (Hungary).
authors.forename: Mihály
authors.initials: M
authors.lastname: Pósfai
authors.affiliation: Institute of Geophysics, ETH-Zürich Sonneggstrasse 5, CH-8092 Zürich (Switzerland).
authors.forename: Ann M
authors.initials: AM
authors.lastname: Hirt
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm 14424 Potsdam (Germany), /567-9402 E-mail: damien.faivre@mpikg.mpg.de.
authors.forename: Damien
authors.initials: D
authors.lastname: Faivre
keywords: hematite; iron; magnetic properties; magnetite; nanoparticles