In Fantastic Voyage, a cheesy science fiction movie from the 1960s, a submarine and crew are miniaturized and injected into a person's blood stream to remove a brain clot. While researchers have yet to develop the shrink ray, one group of scientists has created a tiny propeller, not unlike the device that propels submarines, except that it is 100 times smaller than a human blood cell.
Measuring 70 nm in diameter and 400 nm long, the nanopropeller could move through the human body, and even inside cells, to perform medical procedures and deliver drugs.
For the nanopropeller's maiden voyage, a team of German and Israeli researchers used a gel made of hyaluronan, a material that occurs in the human body, containing a polymer mesh. Openings in the mesh are large enough for nanometer-sized objects to pass through. A fairly weak rotating magnetic field was used to control motion.
The team expected to encounter some difficulties controlling the motion of the nanopropellers, since at their size they start to be governed by diffusion, just as if they were molecules. But because the nanopropellers are the same size as the mesh in the gel, they "actually display significantly enhanced propulsion velocities," says study co-author Associate Professor Alex Leshanksy of the Technion Faculty of Chemical Engineering in a press release describing the research published by the American Technion Society.
This breakthrough could have an astonishing impact on medical technology. "One can now think about targeted applications, for instance in the eye where [propeller-driven devices] may be moved to a precise location at the retina," says Peer Fischer, a member of the research team and head of the Micro, Nano, and Molecular Systems Lab at the Max Planck Institute for Intelligent Systems. Scientists could also attach active molecules to the tips of the propellers, or use the propellers to deliver tiny doses of radiation.
The team is composed of researchers from the Technion-Israel Institute of Technology's Russell Berrie Nanotechnology Institute (Haifa), the Max Planck Institute for Intelligent Systems (Stuttgart, Germany), and the Institute for Physical Chemistry at the University of Stuttgart. A paper describing the research was published in the June 2014 issue of ACS Nano.
|This schematic shows micro- and nanopropellers in hyaluronan gel. The polymeric mesh structure hinders the larger helices, whereas smaller propellers with a diameter close to the mesh size can pass through the network without being affected by the macroscopic viscoelasticity caused by the entangled polymer chains.|