458427 Covalent Surface Modification of Carbon Coated Nanomagnets Allow Stable Dispersions in Aqueous Solutions and Specific Post-Modification

Thursday, November 17, 2016: 8:30 AM
Peninsula (Hotel Nikko San Francisco)
Corinne Hofer1, Elia Schneider2, Robert N. Grass3, Martin Zeltner4 and Wendelin J. Stark3, (1)ETH Zurich, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland, (2)ETH Zurich Institute for Chemical and Bioengineering, ETH Zurich, Zurich, (3)Institute for Chemical and Bioengineering, ETH-Zürich, Zürich, Switzerland, (4)ETH Zurich, 8093 Zurich, Switzerland

For many applications of magnetic nanoparticles such as for medical diagnostics, biotechnology, biomedical applications and magnetic biosensors, stable dispersions of magnetic nanoparticles in aqueous solutions are crucial1. Ferromagnetic pure metallic nanoparticles possess a very high saturation magnetization but also show a considerable tendency to agglomerate. Thus, it is highly desirable to create a material which combines the high saturation magnetization but still forms stable dispersions in aqueous solutions.

Here, we describe how specific covalent surface coating can lead to the formation of a metal cobalt nanoparticle based ferromagnetic fluid with unprecedented dispersion stability and chemical functionality 2. More detailed, graphene-like carbon protected metallic nanomagnets, prepared by flame spray synthesis3, which are covalently functionalized on the particle surface via diazonium chemistry are shown. A block-copolymer is grown directly from the particle surface by SI-ATRP. This block-copolymer consists of a negatively charged polymer block that is responsible for the colloidal stability of the particles and a second polymer block, which allows post-modification of the particles. The length of both polymer blocks is crucial for the colloidal stability of the particles and is studied in this work. Post-modification of this material by introduction of azide-functionality followed by the well-known “click”-reaction, allows the attachment of various desired target molecules.  These nanoparticles form stable dispersions in various aqueous solutions, including biological relevant buffer systems.

1              A. H. Lu, E. L. Salabas and F. Schuth, Angew. Chem.-Int. Edit., 2007, 46, 1222.

2              C. J. Hofer, V. Zlateski, P. R. Stoessel, D. Paunescu, E. M. Schneider, R. N. Grass, M. Zeltner and W. J. Stark, Chem. Commun., 2015, 51, 1826.

3              R. N. Grass, E. K. Athanassiou and W. J. Stark, Angew. Chem.-Int. Edit., 2007, 46, 4909.

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