|Carbon Nanotubes Increase Biological Sensor Speed|
|SciMed - Horizons|
|TS-Si News Service|
|Wednesday, 14 March 2012 08:00|
Corvallis, OR, USA. Carbon nanotubes can markedly increase the speed of biological sensors, a technology that could reduce the time needed for lab tests to minutes, speeding diagnosis and treatment while reducing the costs of production and operation.
The speed of prototype nano-biosensors have nearly tripled, suggesting applications not only in medicine but also in the development of new drugs, toxicology, environmental monitoring, and other fields.
"With these types of sensors, it should be possible to do many medical lab tests in minutes, allowing the doctor to make a diagnosis during a single office visit," said Ethan Minot, an assistant professor of physics at Oregon State University (OSU). "Many existing tests take days, cost quite a bit and require trained laboratory technicians. This approach should accomplish the same thing with a hand-held sensor, and might cut the cost of an existing $50 lab test to about $1," he said. The research was reported in the journal Lab on a Chip, which deals with miniaturisation for chemistry, physics, biology and bioengineering .
More refinements are necessary before the systems are ready for commercial production, scientists say, but they hold great potential. The key to the new technology, the researchers say, is the unusual capability of carbon nanotubes. An outgrowth of nanotechnology, which deals with extraordinarily small particles near the molecular level, these nanotubes are long, hollow structures that have unique mechanical, optical and electronic properties, and are finding many applications.
In this case, carbon nanotubes can be used to detect a protein on the surface of a sensor. The nanotubes change their electrical resistance when a protein lands on them, and the extent of this change can be measured to determine the presence of a particular protein such as serum and ductal protein biomarkers that may be indicators of breast cancer.
The newest advance was the creation of a way to keep proteins from sticking to other surfaces, like fluid sticking to the wall of a pipe. By finding a way to essentially "grease the pipe," OSU researchers were able to speed the sensing process by 2.5 times.
Further work is needed to improve the selective binding of proteins, the scientists said, before it is ready to develop into commercial biosensors. "Electronic detection of blood-borne biomarker proteins offers the exciting possibility of point-of-care medical diagnostics," the researchers wrote in their study.
"Ideally such electronic biosensor devices would be low-cost and would quantify multiple biomarkers within a few minutes."
FundingThe research was supported by the U.S. Army Research Laboratory (ARL) through the Oregon Nanoscience and Microtechnologies Institute (ONAMI).
ParticipationThis work was a collaboration of researchers in the OSU Department of Physics, Department of Chemistry, and the University of California, Santa Barbara. A co-author was Vincent Remcho, professor and interim dean of the OSU College of Science, and a national expert in new biosensing technology.
CitationIncreasing the detection speed of an all-electronic real-time biosensor. Matthew R. Leyden, Robert J. Messinger, Canan Schuman, Tal Sharf, Vincent T. Remcho, Todd M. Squires, Ethan D. Minot. Lab on a Chip 2012; 12(5): 954-959. doi:10.1039/C2LC21020G
Biosensor response time, which depends sensitively on the transport of biomolecules to the sensor surface, is a critical concern for future biosensor applications. We have fabricated carbon nanotube field-effect transistor biosensors and quantified protein binding rates onto these nanoelectronic sensors. Using this experimental platform we test the effectiveness of a protein repellent coating designed to enhance protein flux to the all-electronic real-time biosensor. We observe a 2.5-fold increase in the initial protein flux to the sensor when upstream binding sites are blocked. Mass transport modelling is used to calculate the maximal flux enhancement that is possible with this strategy. Our results demonstrate a new methodology for characterizing nanoelectronic biosensor performance, and demonstrate a mass transport optimization strategy that is applicable to a wide range of microfluidic based biosensors.
|Last Updated on Wednesday, 14 March 2012 08:12|