Chemical sensors made from polymers are playing a key role in detecting terrorists' explosives, from Iraq to the National Mall in Washington, an expert in the field told a group of polymer scientists and students at the University of Akron.
Timothy Swager, a chemistry professor at Massachusetts Institute of Technology in Cambridge, said the polymer sensors can pick up chemical signals from TNT. He described the painstaking research that led to electrically conductive, or ``conjugated,'' polymers. The specially designed polymers carry a charge along the backbone of the chain of molecules, which he dubbed ``molecular wire sensors.''
Swager's Aug. 10 speech kicked off a celebration of 50 years of UA's doctorate program in polymer chemistry.
Other speakers addressed polymers in medical implants, drug delivery and nanocomposites. But the technical presentation on bomb-sniffing polymers was especially timely - coming just hours after British authorities announced they had broken up a major terrorist plot.
Swager is a consultant for Nomadics Inc., an Oklahoma City-based company that makes explosives-detection devices.
``I've spent most of my career on polymer sensors,'' he said.
Swager showed a slide of a sensors used by the U.S. military in Iraq. Soldiers protected in fortified areas run the sensor, which is mounted on a robotic platform. The sensor is used to inspect cars at traffic checkpoints.
He said the U.S. Park Service used hand-held sensors to check people on the National Mall for the July 4 celebration this year.
Swager said experts also are working on molecular structures to detect DMNB, an additive required in commercial explosives.
Attendees of the University of Akron event also heard about advances in medical polymers from Buddy Ratner, director of the University of Washington's Engineered Biomaterials center in Seattle, and Joseph DeSimone, a professor of chemistry and chemical engineering at the University of North Carolina at Chapel Hill.
Ratner detailed the 50-year history of polymeric biomaterials - materials implanted in the body - that began after World War II, when doctors learned about plastics developed for the war, such as nylon, Teflon, silicones and high-density polyethylene. Today, 70 percent of all biomaterials are made with polymers, he said, in products such as interocular lenses, hip and knee replacements and artificial hearts.
``Millions of lives are saved by these devices, and the quality of life improved for millions more. This is quite an admirable success for any field in 50 years,'' Ratner said.
The market will only grow as the population ages in the United States and Europe, and as China and other developing nations become more prosperous and their citizens demand modern medical technology, Ratner said.
He called the next step ``biomaterials that heal.'' Polymer-based materials can rebuild or repair body tissue, bones and even internal organs, he said. Another new area is the controlled release of medicine to treat cancer and other diseases.
The body naturally walls off foreign objects to protect itself. Researchers are working on compatible materials and developing coatings that the body will accept - materials with which to cover medical implants and control the release of medicine.
Ratner also described research that can make sheets of living cells and a new way to make porous scaffolding to build body tissue. In another promising technology, a person could use an ultrasound device to activate the release of chronic-pain medication from an implanted device.
DeSimone moved into the world of nanomedicine by describing a process for molding nanosize particles that can deliver drugs inside the body using molds made from liquid Teflon. By pouring the fluorocarbons, researchers can create patterned structures over a large area - the mold. He called polytetrafluoroethylene, or Teflon, ``one of the forgotten areas of polymer science.''
DeSimone explained how medical researchers are using imprint lithography - a method developed to make etched silicon chips for computers - to produce the drug-delivery particles. First, the liquid PTFE is poured onto a surface, to make a mold of a large number of the particles.
The polymer is photo-chemically cured in seconds. Then the mold is peeled off the surface.
DeSimone said the resulting particles can be customized to release their medical cargo exactly where needed, and designed for the individual patient.
In 2004, DeSimone founded a company called Liquidia Technologies to develop the new molding method. Liquidia's technology is the main focus of a new cancer nanotechnology research center at UNC-Chapel Hill.