Sandra Galmarini

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.

Beyond Unpredictability: The Importance of Reproducibility in Understanding the Protein Corona of Nanoparticles

While it is well established that the surface of a nanoparticle plays a pivotal role for the protein corona, the vast number of proteins present in biological media render general conclusions about affinities between nanoparticle surfaces and proteins nontrivial. Recently published articles increasingly reveal differences between systems and an ever increasing number of influencing factors for the protein corona. In contrast, the present study posits that the reported differences may, at least in part, be due to poor experimental design, which leads to biased results. The present study investigates protein adsorption onto silica nanoparticles with different chemical groups on the surface by the statistical analysis of triplicate measurements as well as control measurements. We demonstrate that 60% of the identified protein types did not have any significant affinities for the nanoparticles. Of the remaining 40%, 60% were driven by surface charges and only 40% preferentially adsorbed onto specific surface groups. Furthermore, we found that of the 20 most abundant proteins in the serum, only five bound to the nanoparticles studied here. We illustrate the importance of control replicate experiments to avoid exaggerated differences between systems and to properly quantify the differences and similarities between comparable systems.