Detecting Chemical and Biological Agents on the Nanoscale

Kyle Osberg is a fourth-year student working towards a PhD in Materials Science and Engineering. He is originally from Houston, TX.

Researchers and students at Northwestern University have developed a new way to look for chemical and biological agents using miniaturized detectors that work at nanoscale dimensions. The research is being done in the laboratory of Dr. Chad Mirkin, a National Security Science and Engineering Faculty Fellow (NSSEFF) funded by the Department of Defense. NSSEFF supports world-class faculty members and their development of the next generation of leading scientists.

Among Dr. Mirkin’s students is Kyle Osberg, a fourth year Ph.D. candidate from Houston, Texas, who is studying materials science and engineering. Kyle and a team of four students work on nanometer-sized gold and silver disks that are stacked and spaced at different intervals. They can be used to detect chemical and biological agents, encrypt and authenticate information, and track materials or people of interest, all while being highly covert and invisible to the naked eye.

One vision is that these disks can be embedded into fibers within lightweight, wearable fabrics worn by soldiers to monitor for possible biological and chemical threats.

The disks are arranged like bar codes and are termed nanodisk codes. Using a microscope, Kyle can detect the light scattered from molecules that are attached to the metal disks. These molecules can act as reporters, providing a way for the codes to be read or be used to target specific chemical and biological agents.

Each disk location in the array gives a signal that is individually resolved, allowing the pattern of disks to be observed as signal from the molecules in the microscope (see graphic). Moving the disks around and varying the sequence of gold and silver can produce unique codes and detection results. With five encoding locations, for example, 98 unique codes can be fabricated based on different combinations of the three possibilities (no disks, silver, and gold) at each of the five locations.

Kyle and his colleagues are also demonstrating how this system can be used to detect chemical and biological molecules such as DNA.