Researchers at Oregon State Univ. have found a way to use
magnetic "nanobeads" to help detect chemical and biological agents, with
possible applications in everything from bioterrorism to medical diagnostics,
environmental monitoring, or even water and food safety.
When fully developed as a hand-held, portable sensor, like
something you might see in a science fiction movie, it will provide a whole
diagnostic laboratory on a single chip.
The research could revolutionize the size, speed, and
accuracy of chemical detection systems around the world.
New findings on this "microfluidic sensor" were reported in Sensors and Actuators, and the
university is pursuing a patent on related technologies. The collaborative
studies were led by Vincent Remcho, an OSU professor of chemistry, and Pallavi
Dhagat, an assistant professor in the OSU School of Electrical Engineering and
The key, scientists say, is tapping into the capability of
ferromagnetic iron oxide nanoparticles—extraordinarily tiny pieces of rust. The
use of such particles in the new system can not only detect chemicals with
sensitivity and selectivity, but they can be incorporated into a system of
integrated circuits to instantly display the findings.
"The particles we're using are 1,000 times smaller than
those now being used in common diagnostic tests, allowing a device to be
portable and used in the field," said Remcho, who is also associate dean for
research and graduate programs in the OSU College of Science.
"Just as important, however, is that these nanoparticles are
made of iron," he said. "Because of that, we can use magnetism and electronics
to make them also function as a signaling device, to give us immediate access
to the information available."
According to Dhagat, this should result in a powerful
sensing technology that is fast, accurate, inexpensive, mass-producible, and
small enough to hold in your hand.
"This could completely change the world of chemical assays,"
Existing assays are often cumbersome and time consuming,
using biochemical probes that require expensive equipment, expert personnel, or
a complex laboratory to detect or interpret.
In the new approach, tiny nanoparticles could be attached to
these biochemical probes, tagging along to see what they find. When a chemical
of interest is detected, a "ferromagnetic resonance" is used to relay the
information electronically to a tiny computer and the information immediately
displayed to the user. No special thin films or complex processing is required,
but the detection capability is still extremely sensitive and accurate.
Essentially, the system might be used to detect almost
anything of interest in air or water. And the use of what is ordinary, rusty
iron should help address issues of safety in the resulting nanotechnology
Rapid detection of chemical toxins used in bioterrorism
would be possible, including such concerns as anthrax, ricin, or smallpox,
where immediate, accurate and highly sensitive tests would be needed. Partly
for that reason, the work has been supported by a four-year grant from the Army
Research Laboratory, in collaboration with the Oregon Nanoscience and
However, routine and improved monitoring of commercial water
treatment and supplies could be pursued, along with other needs in
environmental monitoring, cargo inspections, biomedical applications in
research or medical care, pharmaceutical drug testing, or even more common uses
in food safety.
Other OSU researchers working on this project include Tim
Marr, a graduate student in electrical engineering, and Esha Chatterjee, a
graduate chemistry student.
The concept has been proven in the latest study, scientists
say, and work is continuing with microfluidics research to make the technology
robust and durable for extended use in the field.