April 28, 2011 — Researchers at Oregon State University 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, and water and food safety.

The sensor tech will be developed into a handheld, portable sensor that provides a whole diagnostic laboratory on a single chip. The research could revolutionize the size, speed and accuracy of chemical detection systems around the world.

Figure 1. Immunoassay based sensor: How the new sensor technology developed at Oregon State University might work using magnetic beads. (Graphic courtesy of Oregon State University).

New findings on this microfluidic sensor were recently 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 associate dean for research and graduate programs in the OSU College of Science, and Pallavi Dhagat, an assistant professor in the OSU School of Electrical Engineering and Computer Science. Other OSU researchers working on this project include Tim Marr, a graduate student in electrical engineering, and Esha Chatterjee, a graduate chemistry student.

The scientists tap into the capability of ferromagnetic iron oxide nanoparticles to detect chemicals with sensitivity and selectivity. These ferromagnetic iron oxide nanoparticles can be incorporated into a system of integrated circuits (ICs) to instantly display the findings.

Because the nanoparticles are made of iron, they can be used as a signaling device with support of magnetism and electronics, providing immediate access to the information, said Remcho.

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. 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.

Figure 2. The technology developed at Oregon State University uses ferromagnetic "nanobeads" to develop a powerful, small new type of sensor. (Graphic courtesy of Oregon State University)

In the new approach, tiny nanoparticles could be attached to these biochemical probes. 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.

Rapid detection of chemical toxins used in bioterrorism would be possible, including such concerns as anthrax, ricin or smallpox. The work has been supported by a four-year grant from the Army Research Laboratory, in collaboration with the Oregon Nanoscience and Microtechnologies Institute.

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.

The concept has been proven in the latest study, the scientists say, and work is continuing with microfluidics research to make the technology robust and durable for extended use in the field.

Courtesy of David Stauth, http://hdl.handle.net/1957/20494

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