Magnetic Nanorobotics—Fabrication, Materials and Forces

Micro-/nano-robotics holds great potential for biomedical applications. Structures that are smaller than the macromolecular mesh size in gel-like media and tissues may be propelled relatively more easily compared to larger structures, even though the strength of the magnetic moment reduces with size. We have shown that magnetic nanopropellers can penetrate real biological tissues. If functionalized with enzymes they can soften mucine so that they can be propelled with weak magnetic fields. If coated with an anti-adhesion layer, they can propel over cm distances through the vitreous of the eye and steered to a small region at the optic disc of the retina. Our work indicates that transport into and inside tissues requires careful design, but is possible such that micro and nanopropellers can overcome biological barriers. This is an important first step to realize targeted delivery in dense tissues. An important aspect is the choice of magnetic material that is used to penetrate tissues and/or for the delivery of genetic material into cells. Magnetic nanopropellers and nanorobotic systems benefit from hard magnets. Fully biocompatible magnetic nanocarriers, that are not cytotoxic and that ideally also degradable over time, are promising tools for biomedical applications, but call for careful material choices. In this talk, we discuss the material selection, fabrication, and the resultant forces that are necessary for magnetic actuation and penetration of tissues.