Magnetic nanorods on cruise control.Chemists have created miniature engines out of nanoscale metallic rods that propel themselves using chemical energy. The technology might one day yield new kinds of sensors or even tiny machinery for assembling nanodevices.
Each rod, about 1.5 micrometers long and 400 nanometers wide, consists of multiple segments of platinum, nickel, and gold. When the filaments' makers at Pennsylvania State University Pennsylvania State University, main campus at University Park, State College; land-grant and state supported; coeducational; chartered 1855, opened 1859 as Farmers' High School. in State College added them to an aqueous aqueous /aque·ous/ (a´kwe-us)
1. watery; prepared with water.
2. see under humor.
adj. solution of hydrogen peroxide hydrogen peroxide, chemical compound, H2O2, a colorless, syrupy liquid that is a strong oxidizing agent and, in water solution, a weak acid. It is miscible with cold water and is soluble in alcohol and ether. , the platinum segment, located at one end of the rod, broke down the hydrogen peroxide, releasing oxygen. The oxygen, in turn, weakened the attraction between the water molecules at that end of the nanorod. That opened the way for the rod to advance through the water, platinum end first.
For objects this small, water is highly viscous viscous /vis·cous/ (vis´kus) sticky or gummy; having a high degree of viscosity.
1. Having relatively high resistance to flow.
2. Viscid. , explains Ayusman Sen of Penn State. Without a break in surface tension, "it would be like swimming through molasses molasses, sugar byproduct, the brownish liquid residue left after heat crystallization of sucrose (commercial sugar) in the process of refining. Molasses contains chiefly the uncrystallizable sugars as well as some remnant sucrose. ," he says.
The rods move through the water at a rate of 10 [micro]m per second, says Sen. That's about as fast as a bacterium that propels itself forward with a tiny, whiplike tail. "We raced the nanorods against the bacteria," says Sen. It was a tie.
The two nickel segments within each rod are magnetic, and that enabled the researchers to control the rods' direction of movement. When exposed to a magnetic field, the rods moved perpendicular to it.
The next step will be to attach a nanorod to a device, such as a biosensor A device that detects and analyzes body movement, temperature or fluids and turns it into an electronic signal. See lab on a chip and data glove.
Biosensor searching for viruses, to speed up detection. The researchers describe the roving nanorods in an upcoming Angewandte Chemie.--A.G.