Nanotube technology leading to new era of fast, lower-cost medical diagnostics

 Researchers at Oregon State University have tapped into the extraordinary power of carbon "nanotubes" to increase the speed of biological sensors, a technology that might one day allow a doctor to routinely perform lab tests in minutes, speeding diagnosis and treatment while reducing costs.

The new findings have almost tripled the speed of prototype nano-biosensors, and should find applications not only in medicine but in toxicology, environmental monitoring, new drug development and other fields.

The research was just reported in Lab on a Chip, a professional journal. More refinements are necessary before the systems are ready for commercial production, scientists say, but they hold great potential.

"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 OSU assistant professor of physics. "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 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."

This work was a collaboration of researchers in the OSU Department of Physics, Department of Chemistry, and the University of California at 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.

The research was supported by the U.S. Army Research Laboratory through the Oregon Nanoscience and Microtechnologies Institute.

Story Source:

The above story is reprinted from materials provided by Oregon State University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Matthew R. Leyden, Robert J. Messinger, Canan Schuman, Tal Sharf, Vincent T. Remcho, Todd M. Squires, Ethan D. Minot. Increasing the detection speed of an all-electronic real-time biosensor. Lab on a Chip, 2012; 12 (5): 954 DOI: 10.1039/C2LC21020G

Swedish invention simplifies home diagnostics

Advances in medical diagnostic technology will likely allow individuals to perform preliminary medical diagnoses themselves, in their own home, in the future.

"The idea is to make complex diagnostic processes as simple to perform as modern-day pregnancy tests," says Nathaniel Robinson, who leads the Transport and Separations Group at Linköping University in Sweden

Dr. Robinson and PhD student Per Erlandsson have invented an improved pump, called an electroosmotic pump, which can be placed in a "microfluidic chip." Such chips, sometimes called "lab-on-a-chip" devices, contain miniaturized versions of the beakers and test tubes found in chemistry laboratories interconnected by tiny pipes. Rather than using moving parts, the new pump moves fluids in these pipes via an electric current. The fluids to be pumped can be biological samples such as blood, urine or saliva for medical devices.

"The trick is to generate the ionic current that moves the fluid to be pumped without disturbing the cells, proteins, and other molecules in the sample," according to Dr. Robinson.

To do this, the researchers have employed a type of electronically conducting plastic in the pump's electrodes. The plastic can be electrochemically oxidized or reduced, acting as a transducer between the ions, the charge carriers in fluids, and electrons, which carry charge in metal wires. Traditional electroosmotic pumps use metal electrodes and the electrochemical reactions required are performed on the water in the sample itself. By-products of this electrochemistry included oxygen and hydrogen gas bubbles, and the production of acid or base. Each of these by-products disturbs the microfluidic device and the fluid sample.

"This is primarily why electroosmotic pumps have not been more widely used in the development of medical devices," says Robinson.

The researchers have shown that the pump can be operated repeatedly for extended periods of time, and can operate at relatively low voltages, so that small, portable diagnostic devices can be driven by batteries.

"Several microfluidics articles describe ways to work around the complications associated with integrated metal-electrodes. Here, the alternative reactions of electrochemically active electrodes give us the chance to remove the core problem, the electrolysis of solvent," according to Per Erlandsson, who constructed the pumps.

The researchers have applied for a patent for the new invention and are currently looking for partners who have a need for such pumps in their lab-on-a-chip devices. The research is also described in an article appearing in the latest issue of the scientific journal Electrophoresis.

Simple-to-operate medical devices, that will ultimately enable preliminary self-diagnosis via automated testing kits, will likely become an important part of our healthcare system. Otherwise, we will have a difficult time financing healthcare for an aging population at current or expanded levels of service. For example, by automating and simplifying screening for diseases, such as cancer, a greater portion of the population can be screened, more cases will be caught early, and hospital resources can focus on treatment of individuals who are truly ill. This pump is a significant step towards realizing the devices that will make this possible.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Expertanswer (Expertsvar in Swedish), via AlphaGalileo.

Journal Reference:

Per G. Erlandsson, Nathaniel D. Robinson. Electrolysis-reducing electrodes for electrokinetic devices. Electrophoresis, 2011; 32 (6-7): 784 DOI: 10.1002/elps.201000617