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.

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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

New nanotech technique for lower-cost materials repair

In the super-small world of nanostructures, a team of polymer scientists and engineers at the University of Massachusetts Amherst have discovered how to make nano-scale repairs to a damaged surface equivalent to spot-filling a scratched car fender rather than re-surfacing the entire part. The work builds on a theoretical prediction by chemical engineer and co-author Anna Balazs at the University of Pittsburgh.

Their discovery is reported this week in the current issue of Nature Nanotechnology. The new technique has many practical implications, especially that repairing a damaged surface with this method would require significantly smaller amounts of material, avoiding the need to coat entire surfaces when only a tiny fraction is cracked, says team leader and UMass Amherst polymer scientist Todd Emrick.

"This is particularly important because even small fractures can then lead to structural failure but our technique provides a strong and effective repair. The need for rapid, efficient coating and repair mechanisms is pervasive today in everything from airplane wings to microelectronic materials to biological implant devices," he adds.

At nano-scale, damaged areas typically possess characteristics quite distinct from their undamaged surrounding surface, including different topography, wetting characteristics, roughness and even chemical functionality, Emrick explains. He adds, "Anna Balazs predicted, using computer simulation, that if nanoparticles were held in a certain type of microcapsule, they would probe a surface and release nanoparticles into certain specific regions of that surface," effectively allowing a spot-repair.

This vision of capsules probing and releasing their contents in a smart, triggered fashion, known as "repair-and-go," is characteristic of biological process, such as in white blood cells, Emrick adds.

He says the experimental work to support the concept required insight into the chemistry, physics and mechanical aspects of materials encapsulation and controlled release, and was achieved by collaboration among three polymer materials laboratories at UMass Amherst, led by Alfred Crosby, Thomas Russell and himself.

The researchers show how using a polymer surfactant stabilizes oil droplets in water (in emulsion droplets or capsules), encapsulating nanoparticles efficiently, but in a manner where they can be released when desired, since the capsule wall is very thin.

"We then found that the nanoparticle-containing capsules roll or glide over damaged substrates, and very selectively deposit their nanoparticle contents into the damaged (cracked) regions. Because the nanoparticles we use are fluorescent, their localization in the cracked regions is clearly evident, as is the selectivity of their localization."

Using rapid and selective deposition of sensor material in damaged regions, their innovative work also provides a precise method for detecting damaged substrates, he stresses. Finally, the new encapsulation techniques allow delivery of hydrophobic objects in a water-based system, further precluding the need for organic solvents in industrial processes that are dis-advantageous from an environmental standpoint.

Emrick says, "Having realized the concept experimentally, looking forward we now hope to demonstrate recovery of mechanical properties of coated objects by adjusting the composition of the nanoparticles being delivered."

The work was supported by the National Science Foundations' (NSF) Materials Research Science and Engineering Center on Polymers at UMass Amherst, an NSF Integrative Graduate Education and Research Traineeship (IGERT) award, the NSF Center for Hierarchical Manufacturing, the U.S. Department of Energy and its Office of Basic Energy Science.

Story Source:

The above story is reprinted from materials provided by University of Massachusetts Amherst.

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

Journal Reference:

Katrina Kratz, Amrit Narasimhan, Ravisubhash Tangirala, SungCheal Moon, Ravindra Revanur, Santanu Kundu, Hyun Suk Kim, Alfred J. Crosby, Thomas P. Russell, Todd Emrick, German Kolmakov, Anna C. Balazs. Probing and repairing damaged surfaces with nanoparticle-containing microcapsules. Nature Nanotechnology, 2012; DOI: 10.1038/nnano.2011.235

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