NSTI Nanotech 2009

Bio-functionalized Ferromagnetic Microdisks for Targeted Tumor Therapy

E. Rozhkova, D.-H. Kim, I. Ilasov, S.D. Bader, M.S. Lesniak, T. Rajh, V. Novosad
Argonne National Laboratory, US

Keywords: novel magnetic nanoparticles, bio-nano materials, spin vortices, magneto-mecanical cancer cell destruction


We report the fabrication process, magnetic behavior as well as the surface modification of ferromagnetic microdisks suspended in aqueous solution. They posses unique properties such as high Ms, zero remanence due to spin vortex formation, intrinsic spin resonance at low frequencies, and capability of delivering more than one type of bio-substance at once. Furthermore, because of their anisotropic shape, our magnetic particles rotate under alternative magnetic field of small amplitude. We find that just ~10-50 millisecond long field pulse of only few Gauss in amplitude is enough to achieve complete rotation (allignement) of suspended 1micron, 50nm think Fe20Ni80 disks. This can be used for promoting the idea of advanced therapies that include combined drug delivery and magneto-mechanical cell destruction when targeting tumor cell. The approach enables us to fabricate suitable magnetic carriers with excellent size tolerances, and then release them from the wafer into solution, ready for therapeutic use. The particles have a magnetic core, and are covered with few nm of gold on each side to provide protective, bio-compatibility and selective adhesion functions. Gold is chosen since its surface may be functionalized by a broad range of biomolecules including targeting leader sequences such as proteins (eg antibodies), polypeptides, and nucleic acid vectors. To demonstrate the later, an attempt to bind cysteine-containing polypeptides or F(ab`)2 fragments of IL13 to the disks surface was undertaken. The binding properties were tested via the reaction with a fluorescent marker 5-((2-(and-3)- S- (acetylmercapto) -succinoyl) amino) fluorescein (SAMSA) followed by conjugation of antibody fragments F(ab`)2, and subsequent conjugate-cells receptors (antibody-antigene) binding experiments. Employed technology (optical lithography) allows us to fabricating disks with sizes down to 800nm. With nanoimprint tools one should be able to achieve low-cost production of even smaller disks (50-100 nm) with magnetic vortex state suitable for biomedical application. Cell culture experiments are in progress as will be discussed as well.
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