Abstract
Protein-coated magnetic nanoparticles are promising candidates for various medical applications. Prior to their application into a biological system, one has to guarantee that the particle dispersions are free from pathogens or any other microbiologic contamination. Furthermore, to find entrance into clinical routine, the nanoparticle dispersions have to be storable for several months. In this study, we tested several procedures for sterilization and preservation of nanoparticle containing liquids on their influence on the integrity of the protein coating on the surface of these particles. For this, samples were treated by freezing, autoclaving, lyophilization, and ultraviolet (UV) irradiation, and characterized by means of dynamic light scattering, determination of surface potential, and gel electrophoresis afterwards. We found that the UV sterilization followed by lyophilization under the addition of polyethylene glycol are the most promising procedures for the preparation of sterilized long-term durable protein-coated magnetic nanoparticles. Ongoing work is focused on the optimization of used protocols for UV sterilization and lyophilization for further improvement of the storage time.
Highlights
Magnetic nanoparticles (MNP) are interesting tools for a variety of applications for diagnosis and therapy in medicine [1,2]
When injecting MNP into a biological system, a layer made of different proteins present in the biological system is formed on the surface of the MNP—the so-called protein corona [10,11]
In our previous investigations [15,16] we could demonstrate that the formation of the corona occurs within seconds and the corona composition is influenced by the temperature at which corona formation takes place, as well as the duration of particle-protein interaction
Summary
Magnetic nanoparticles (MNP) are interesting tools for a variety of applications for diagnosis and therapy in medicine [1,2]. Prominent examples are magnetic drug targeting [3,4], magnetic particle hyperthermia [5,6] or magnetic particle imaging [7,8] For this purpose, aqueous MNP dispersions (ferrofluids) have to be administered to the body, which requires a reliable sterilization of the ferrofluids to exclude any risk for the patient from pathogens within the fluid. In the recent years it was demonstrated that magnetic multicore nanoparticles show very promising magnetic properties for several medical applications [31] Since these particles show a size above 200 nm, a sterilization by means of filtration is not possible. The aim of the presented study is to establish procedures which allow a reliable sterilization and preservation of larger protein-coated MNP without any damaging effect on the integrity of the corona proteins. Protein-coated MNP were prepared as described before [16,32], treated by different procedures for sterilization and preservation, and characterized afterwards regarding possible damaging effects on the integrity of the protein coating
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