Skip to main content

Event Details

  • Wednesday, February 27, 2019
  • 13:30 - 14:00

Magnetic Nanowires - Wireless Bio Transducers

Unique features of magnetic nanowires render them attractive materials for biomedical transducer applications. Due to the high aspect ratio, they are characterized by single magnetic domain properties, which can be exploited by electromagnetic interrogation. This allows utilizing such nanowires as remotely operated nanorobots, i.e. induce motion, produce heat or sense their location. Their versatility is further enhanced by surface functionalization, making them cell-specific targeting agents or drug delivery vehicles.
Magnetic nanowires are fabricated by a facile and efficient method using electrodeposition into nanoporous membranes. Iron nanowires are highly biocompatible, and they can be further optimized by annealing, resulting in nanowires with an iron core, an iron oxide shell and tailored magnetization. In combination with polymer matrices, nanowires are employed as ultra-low power flow sensors, for realizing bioinspired artificial skins with tactile sensing capabilities, or to trigger remotely controlled drug delivery particles. Magnetic nanowires are readily internalized by cells via phagocytosis. When applying an alternating magnetic field, they kill cancer cells by a magnetomechanical effect. When further functionalizing the nanowires with drugs, they deliver these drugs into cells, and a combined treatment effect can be obtained together with a magnetic field and/or laser irradiation. The later exploits a photo-thermal effect, that utilizes the near infrared light absorption of iron oxide. Surface coating with antibodies give nanowires specific targeting capabilities, as will be shown for the case of anti-CD44 antibodies to target leukemic cells. The nanowires also have excellent properties as magnetic resonance imaging contrast agents, providing high transverse magnetic relaxivities. This enables high-resolution cell tracking in combination with their manipulation.
Nanostructured substrates for cell growth can be produced, when partially releasing the nanowires from the nanoporous membranes. Due to mimicking the mechanical properties of cellular environments, stem cells growing on top of such substrates show alterations in their differentiation behavior. Thereby, nanowire dimensions modify the stiffness of the cellular environment, affecting the cells’ behavior. A mechanical stimulus can be applied via activating the substrate by an electromagnetic field, providing means for additional manipulations of the cell faith. Differentiation of mesenchymal stem cells into osteoblasts can be achieved on such substrates by electromagnetically induced mechanical stimuli within a few days. With the growing relevance of nanomaterials in biomedical applications, multi-functionality of nanoprobes is being discovered and exploited. Combining a high capacity for functionalization, with diagnostic capabilities and therapeutic functions, iron nanowires are ideal candidates for these theranostics approaches.

Speaker: Jurgen Kosel