London, Nov 5 (IANS): An international team of scientists have developed a propeller-shaped nanorobots that, for the first time, can drill through dense tissue as is prevalent in an eye.

The scientists, including from Max Planck Institute in Germany, applied a non-stick coating to the nanopropellers, which are only 500 nm wide -- exactly small enough to fit through the tight molecular matrix of the gel-like substance in the vitreous of the eye.

The molecule-matrix is like a tight mesh of double-sided adhesive tape.

The drills are 200 times smaller than the diameter of a human hair, even smaller than a bacterium's width.

Their shape and their slippery coating enable the nanopropellers to move relatively unhindered through an eye, without damaging the sensitive biological tissue around them.

"We applied a liquid layer found on the carnivorous pitcher plant, which has a slippery surface on the peristome to catch insects," said lead author Zhiguang Wu, a post-doctoral student at the California Institute of Technology.

"It is like the Teflon coating of a frying pan. This slippery coating is crucial for the efficient propulsion of our robots inside the eye, as it minimises the adhesion between the biological protein network in the vitreous and the surface of our nanorobots."

This is the first time scientists were able to steer nanorobots through dense tissue, as so far, it has only been demonstrated in model systems or biological fluids.

These nanopropellers can be one day loaded with drugs or other therapeutic agents and steer them to a targeted area, where they can deliver the medication to where it is needed.

"The principle of the propulsion of the nanorobots, their small size, as well as the slippery coating, will be useful, not only in the eye, but for the penetration of a variety of tissues in the human body," said Tian Qiu, from the "Micro, Nano and Molecular Systems" Lab at the Max Planck Institute for Intelligent Systems.