A new understanding of the structure of nano particles proves the old adage that "good things come in small packages." Researchers at Kettering University and Wayne State University have found that the size and magnetic properties of nanoparticles can be controlled, allowing improved magnetic storage devices and control during catalysis, a process used in chemical engineering for manufacturing various chemicals.
Dr.s Prem Vaishnava, professor of Applied Physics of Kettering University, and R. Naik, of Wayne State University, presented their findings at the annual American Physical Society meeting in Austin, Texas, March 3 to 7. Their research was funded by a National Science Foundation grant.
At a billionth of a meter, nanometer-sized particles are as small as something can get (as far as scientists know), and still be visible (just barely) with an electron microscope. They are so small, in fact, about one hundred thousand of them would fit on the period at the end of this sentence.
Vaishnava and Naik discovered that magnetic nano particles have a physical structure that includes a shell of iron oxide and a core of iron that are different from one another. This is breaking news in the nanotechnology arena, because it translates into expanded uses for the tiny titans in computer, biomedical and chemical engineering applications.
"We found when you can control the size of the nano particle, you can control the magnetic properties as well," Vaishnava said. "Thus far, such control of magnetic properties has been observed only in multi-layer thin-films that are used in detecting magnetic fields in a computer's Dynamic Random Access Memory (DRAM), where a computer retains memory even after it is turned off," Vaishnava said. Nano particles can replace the multi-layer thin-films, which are difficult and expensive to make, he said.
"One of our questions was 'When you put one billion nano particles together, how are they going to behave?'" he said. "Without the magnetic field they go in every direction. When you apply a magnetic field their spins are oriented in one direction and their electrical resistance decreases several hundred times ( a process called magnetoresistance) so you can control them easily. So, if you can put this many nano particles in a very, very small space, and maneuver them the way you want, then you can create all kinds of exciting applications," he said.
Exactly what advocates of NBIC convergence want to hear, according to a Feb. 10 "New York Times" article. NBIC stands for nanotechnology, biotechnology, information technology and cognitive science. An informal group of government, academic and industry researchers is working toward a convergence of these disciplines to create a new field of science. Such a convergence would facilitate nanoscale innovations for new applications in all four disciplines.
One of those applications is the delivery of medicine, such as chemotherapy, to specific parts of the body. Vaishnava said research in this area is still in the experimental stages, but that the use of nano particles in medicine is promising. "The smaller the particle the more effectively you can deliver the medication," he said.
How it works involves attaching medication, say for the kidney, to nano particles. Then the medication is delivered either orally or is injected into the patient and a large magnet is placed at the location of the kidney. The nano particles are attracted to the magnet and the medication is delivered to the place where it is most effective.
Another medical application is to use nano particles as contrast material in Magnetic Resonance Imaging (MRI). "They are going to produce very good contrast on MRI pictures," said Vaishnava, "enabling doctors to better see what is going on inside the human body."
An equally exciting improvement to nano particle applications is in the field of magnetic memory storage. There is considerable pressure on the computer industry to increase the density of storage. Vaishnava feels this issue can be easily addressed by reducing the size of the particles.
In chemical engineering nano particles are used in catalysis to accelerate the speed of chemical reactions in the manufacture of various materials. "Since their surface area is large, they can accelerate the speed of the reaction without participating in the reaction," Vaishnava said.
Vaishnava introduces his undergraduate students at Kettering to nano particles by having them make their own. "In our lab session they will synthesize nano particles from a liquid solution and then characterize them," he said. "Because you are not always sure that what you have made is what you intended to make, they have to characterize it by identifying its properties," Vaishnava said. "It's a good experience for undergraduate students."
About his enthusiasm for researching the tiny but mighty nano particle, Vaishnava said "the more we know about them, the more effectively they can be used." The irony is almost overwhelming when he describes the field of nano particle research as "vast."
Written by: Dawn Hibbard