Biofunctionalizing Magnetic Nanowires Toward Targeting and Killing Leukemia Cancer Cells

The objective of targeting technologies in the field of nanomedicine is to specifically focus therapies on diseased cells in order to deliver the treatment to these cells without harming healthy ones. The use of magnetic materials in such biomedical applications offers many advantages. They can be functionalized with an agent that enhances the biocompatibility and the targeting while, at the same time, they can be controlled and monitored remotely. Iron nanowires (Fe NWs), which usually have a native oxide shell, are specifically attractive, since they are highly biocompatible, strongly magnetic, and can be coated with different biological agents. Shape anisotropy makes these NWs permanently magnetic and, therefore, can be exploited for multifaceted remote manipulations, rendering them versatile nano-robots. As such, they have been used before in combination with a magnetic field to induce cancer cell death. In order to minimize the side effects of this method, this paper aims to enhance the targeting ability of these NWs toward particular cells. Specifically, leukemic cells are targeted by functionalizing Fe NWs with anti-CD44 antibodies, a cell surface marker, which is overexpressed in leukemic cells compared to healthy blood cells. Fe NWs were electrochemically fabricated with an average diameter of 35 nm and a length around
$3~\mu \text{m}$
. They were coated with bovine serum albumin to facilitate their conjugation covalently with an anti-CD44 antibody by using 3-(3-dimethyl-aminopropyl) carbodiimide and of N-hydroxysuccinimide. In order to confirm the presence of anti-CD44 antibodies on the surface of the NWs, immunostaining and Fourier transform infrared spectroscopy were used. In addition, cytotoxicity effects of bare Fe NWs and coated and functionalized NWs were studied by using cell proliferation assays. These studies illustrated that the NWs have a high level of biocompatibility.