The dream presented in “Fantastic Voyage”, a movie nearly fifty years old, is that of being able to miniaturize a vehicle and its occupants to travel through the body’s vascular network and tissues to treat disease. This dream is morphing into an expectation that modern technologies should be able to do what seemed like a distant future to a previous generation. Of course we won’t be putting doctors through a miniaturization machine. Instead, hopefully, self-propelled robots will be doing the hard work. Researchers at Technion-Israel Institute of Technology, the Max Planck Institute for Intelligent Systems, and University of Stuttgart, Germany, have developed tiny propellers that can move through biological tissue with ease.
Only 70 nanometers in diameter and 400 nanometers long, compared to about 7000 nanometer diameter of red blood cells, the new propellers can penetrate through tissues that larger devices would have to injure to be able to pass through. Consisting of silica and a nickel head, they are powered by an external magnetic field that rotates to make the devices spin along. The team tested the technology inside hyaluronan, a high-molecular-mass polysaccharide commonly found within connective and other tissues. Though the hyaluronan gel contains long polymers, the propellers managed to travel through while being navigated using an external control system.
From the announcement:
The team expected that they would have trouble 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, exceeding the highest speeds measured in glycerin as compared with micro-propellers, which show very low or negligible propulsion,” said study co-author Associate Professor Alex Leshanksy of the Technion Faculty of Chemical Engineering.
While the nanopropellers are astonishing for their technical complexity, the real significance is how they might affect medicine. “One can now think about targeted applications, for instance in the eye where they 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 applications seem wide, varied, and exciting.
Study in ACS Nano: Nanopropellers and Their Actuation in Complex Viscoelastic Media…