World's smallest propeller could be used for microscopic medicine

July 30, 2014

If you thought that the most impressive news in shrinking technology these days was smart watches, think again. Scientists are quietly toiling in their laboratories to create robots that are only nanometers—billionths of a meter—in length, small enough to maneuver inside the human body and possibly inside human cells. The impact of these miraculous microscopic machines on medicine can only be imagined, but there is no doubt that it will be significant.

One of the first steps in creating these robots is figuring out how to make them move. In a paper published in the June 2014 issue of ACS Nano, an Israeli and German team announced that they had succeeded in creating a tiny screw-shaped propeller that can move in a gel-like fluid, mimicking the environment inside a living organism. The team is comprised of researchers from the Technion-Israel Institute of Technology's Russell Berrie Nanotechnology Institute, the Max Planck Institute for Intelligent Systems, and the Institute for Physical Chemistry at the University of Stuttgart, Germany.

The filament that makes up the propeller, made of silica and nickel, is only 70 nm in diameter; the entire propeller is 400 nm long. (A nanometer is one billionth of a meter.) "If you compare the diameter of the [nanopropellers] with a human blood cell, then the [propellers] are 100 times smaller," said 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. They are so small, in fact, that their motion can be affected by the motion of nearby molecules (known as Brownian motion).

The team already knew that tiny propellers moved well through water, but to test if they could move through living organisms, they chose hyaluronan, a material that occurs throughout the , including the synovial fluids in joints and the vitreous humor in your eyeball. The hyaluronan gel contains a mesh of long proteins called polymers; the polymers are large enough to prevent micrometer-sized propellers from moving much at all. But the openings are large enough for nanometer-sized objects to pass through. The scientists were able to control the motion of the propellers using a relatively weak rotating magnetic field.

The findings were somewhat surprising. 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 Fischer. 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.

Explore further: Detecting material defects in ship propellers

More information: ACS Nano, 2014; DOI: 10.1021/nn502360t

Related Stories

Detecting material defects in ship propellers

April 2, 2012

Ship propellers are as large as a single-family home – and manufacturing them is quite a challenge. During the casting process, pores and miniscule cracks can form that in the worst case may cause a blade to break. Now ...

New algorithm makes quadrocopters safer

December 4, 2013

Drones like quadrocopters have become very popular with hobbyists due to their simplicity and agility. But they are also increasingly being used for commercial applications such as aerial photography and cinematography, inspection ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 30, 2014
Propellers are blades. What are they doing to the objects in the medium through which they propel themselves? Will we acquire a lot of free radicals and protein fragments in our bloodstream for having let these devices propel themselves through it, only to have them aggregate around vital ion channels and ultimately predisposing cells to apoptosis?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.