Aqueous stabilisation of carbon-encapsulated superparamagnetic α-iron nanoparticles for biomedical applications.

Carbon-based nanomaterials, such as carbon-encapsulated magnetic nanoparticles (CEMNP, core@shell), show a wide range of desirable properties for applications in the biomedical field (clinical MRI, hyperthermia), for energy production and storage (hydrogen storage), for the improvement of electronic components and for environmental applications (water-treatment). However, this kind of nanoparticle tends to aggregate in water suspensions. This often hampers the processability of the suspensions and presents an obstacle to their application in many fields. Here the stabilisation of core-shell Fe-C nanoparticles by surface adsorbed polyvinyl-alcohol (PVA) is presented. Different PVA/CEMNP mass ratios (9, 36, 144 and 576 w/w) were studied. Several characterisation techniques were used in order to determine the size distribution of the particles and to optimize the PVA/CEMNP ratio. A good colloidal stability was obtained for spherical nanoparticles about 50 nm in diameter containing several superparamagnetic Fe cores. The nanoparticles were found to be isolated and well dispersed in solution. The use of PVA for coating carbon-encapsulated Fe nanoparticles does not only result in a good colloidal stability in aqueous suspensions, but the resulting particles also show low cytotoxicity and an interesting cell internalization behaviour. The simple stabilization method developed here can likely be extended to other core@shell nanoparticle systems as well as other carbon-based nanomaterials in the future.

Ex situ evaluation of the composition of protein corona of intravenously injected superparamagnetic nanoparticles in rats.

It is now well recognized that the surfaces of nanoparticles (NPs) are coated with biomolecules (e.g., proteins) in a biological medium. Although extensive reports have been published on the protein corona at the surface of NPs in vitro, there are very few on the in vivo protein corona. The main reason for having very poor information regarding the protein corona in vivo is that separation of NPs from the in vivo environment has not been possible by using available techniques. Knowledge of the in vivo protein corona could lead to better understanding and prediction of the fate of NPs in vivo. Here, by using the unique magnetic properties of superparamagnetic iron oxide NPs (SPIONs), NPs were extracted from rat sera after in vivo interaction with the rat's physiological system. More specifically, the in vivo protein coronas of polyvinyl-alcohol-coated SPIONs with various surface charges are defined. The compositions of the corona at the surface of various SPIONs and their effects on the biodistribution of SPIONs were examined and compared with the corona composition of particles incubated for the same time in rat serum.