Inge K. Herrmann

The rapidly growing applications of nanomagnets require acid/base stable, oxidation-resistant shells with chemically controlled surface structure. An ideal core should be metallic and highly magnetic. We demonstrate the production of iron-based nanoparticles, ranging from iron oxide to iron and iron carbide, by systematically modifying the degree of reduction during flame spray synthesis under a controlled atmosphere. At a laboratory scale, continuous production yields iron-based particles of 20−50 nm at a production rate of >10 g h−1. Carbon-encapsulated iron carbide (C/Fe3C) combines exceptionally high saturation magnetization (140 emu g−1), air stability (up to 200 °C), and resistance against acidic dissolution (1 week in 24% HCl). The top graphene-like carbon layer could be covalently functionalized with various linkers, thus allowing us to chemically design the particle surface. Activity was demonstrated by reacting 2-phenyl ethyl amine functionalized nanomagnets with carboxylic acid chlorides as a model reaction. The present nanomagnets consist of biologically well-accepted constituents. They combine the required chemical reliability, improved magnetization if compared to magnetite with the potential for technical scale manufacturing, and therefore open stable nanomagnets to a broad range of fascinating separation problems (extraction/water treatment) and biomedical research.

Injection of functional nanomagnets in human blood enables selective removal of disease-causing metals, overdosed drugs, and proteins at the (sub-)nanomolar level. This direct in vivo extraction provides a powerful alternative to classical pharmaceutical treatments as disease-causing agents are removed from the organism rather than treating symptoms from exposure. A number of clinically relevant assays demonstrate blood compatibility of the functional nanomagnets.

nanoparticle radioenhancers and highlight the importance of catalytic activity. This review provides a concise overview on the knowledge of nanoparticle radioenhancement mechanisms and their quantification. It critically discusses potential radioenhancer candidate materials and general design criteria for different radiation therapy modalities, and concludes with research priorities in order to advance the development of nanomaterials, to enhance the efficacy of radiotherapy and to increase at the same time the therapeutic window.