Looking deep into the eyes
The quest to use nanorobots in our bodies as tools has reached a milestone. Scientists have developed nanopropellers and were able to direct them through the vitreous body of the eye. Such nanorobots could improve the targeted delivery of drugs.
Scientists from the Micro, Nano and Molecular Systems Group at the Max-Planck-Institute for Intelligent Systems in Stuttgart have developed nanorobots shaped like propellers. The devices are capable of penetrating through the dense tissue of the vitreous body of the eye. This is a novel development, because the current micro- or nanorobots were only capable of moving through model liquids. The vitreous body is particularly hard to move through because it is composed of a molecule matrix, created to prevent larger particles or objects to enter. Furthermore, the chemical properties of the molecule matrix cause particles to get stuck within its “web”.
Technology inspired by nature
A non-adhesive coating and helicoidal form provides the discovered solution. The 500 nanometer wide propellers allow the nanorobots to move through the narrow molecular matrix of the gel-like vitreous body.
The reduced adhesive properties were achieved with two layers of coating. The first layer consists of molecules which attach to the surface of the nanorobot. The second layer is a liquid coating that serves to reduce the adhesive forces between the nanorobot and the surrounding tissue. “We took inspiration from nature”, explains Zhiguang Wu, author of the study. “We applied a liquid that can be found on pitcher plants on the nanopropellers. The pitcher plant (Nepenthes) has an omniphobous liquid on it, so that insects slip on it and fall into the plant from its leaves. This liquid is as slippery as a Teflon surface in a frying pan. It would be impossible for the nanorobot to move through the eye without this liquid, because it minimizes the adhesion between the molecular network of the vitreous body and our nanorobot.”
Magnetic guidance
The guiding of the nanorobots is possible because the scientist integrated iron into the nanopropellers. Thanks to this, they can direct the nanorobot to the desired target from the outside via magnetic fields. First, more than ten thousand of the helicoidal nanorobots are injected into the vitreous body from a syringe. Surrounding magnetic coils turn the propellers and move them in a targeted manner towards the retina, where the nanorobot swarm docks onto.
With nanorobots, medication can be delivered in a more targeted manner in the field of ophthalmology, whereas current delivery methods rely on passive diffusion. This way, rapid delivery to a defined region is simply not possible.
The findings were published in Science.
Video: https://www.youtube.com/watch?v=XCTPWW7XSS0
Image source: Schematic of the three-step targeted delivery procedure used for the slippery micropropellers. Copyright: MPI for intelligent systems
Source (German): https://www.springerprofessional.de/nanotechnologie/materialentwicklung/nanoroboter--die-sich-im-auge-fortbewegen/16251934
Original article: http://advances.sciencemag.org/content/4/11/eaat4388