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Biomedical applications of superparamagnetic iron oxide nanoparticles (NPs) for therapeutic and diagnostic purposes require NPs to be stable under physiologic conditions. This can only be achieved if NPs are sterically stabilized with appropriate dispersants that bind irreversibly to the iron oxide surface. Tight control over the dispersant layer not only prevents NP agglomeration but additionally paves the way to tailor NP size, charge, the type and density of functionalities presented at the NP surface. These factors are especially important for the in vivo performance of NPs. One possibility to sterically stabilize NPs is to graft low molecular weight dispersants to these surfaces. Stabilization of NPs with low molecular weight dispersants relies on high affinity anchors that firmly bind spacers and functionalities to the NP surface at high density. This thesis compares the ability of different anchors to firmly bind low molecular weight dispersants to Fe3O4 NP surfaces and investigates the stability of NPs sterically stabilized with different dispersants. Furthermore, the performance of these sterically stabilized iron oxide NPs in selected biomedical applications is addressed.

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Esther Amstad hails from Beckenried (NW), Switzerland. She received her BSc and MSc in material science from ETH Zurich, Switzerland. Under the supervision of Prof. Marcus Textor and Dr. Erik Reimhult she carried out her PhD thesis at the same university. She is currently a Postdoctoral fellow in the group of David A. Weitz at Harvard University.

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