'Smart Bandage' Detects Bacteria With Silicon Sensor
Peter Singer, Editor-in-Chief -- Semiconductor International, 12/1/2001
Imagine placing an adhesive bandage on a cut and having the bandage tell you immediately that dangerous bacteria have gotten into the wound and that you need to seek a doctor's help. Researchers at the University of Rochester (Rochester, N.Y.) have taken the first major step toward a bandage that will change color depending on what kind of bacteria may be present. It can instantly diagnose whether the wound may require special care or what kind of antibiotics may work best in treating it.
Benjamin Miller, assistant professor of chemistry, and Philippe Fauchet, professor and chair of electrical and computer engineering, have devised a sand-grain-sized wafer that can differentiate between two classes of bacteria, called Gram-positive and Gram-negative. The sensor — the first substantial improvement in identifying Gram-positive and -negative bacteria since Hans Christian Joachim Gram developed the original staining technique in 1884 — is reported in an upcoming issue of the Journal of the American Chemical Society. The accomplishment is evidence that it's indeed possible to accurately identify bacteria with a silicon sensor, spurring Miller's team to expand the research to several other types of bacteria, including salmonella, listeria and enteropathogenic E. coli, all of which can cause serious disease in humans.
Today, if a doctor needs to identify whether a bacterial infection is Gram-positive or -negative, the bacteria need to be stained and examined under a microscope. "The Gram stain has been an important tool in analyzing bacteria for more than a century, but it's amazing to me that we're still using a procedure that's effectively out of the Stone Age," Miller said. "We can now get the same information immediately, at home or in the doctor's office."
The technique currently used by doctors uses a stain that interacts with the cell walls of bacteria, changing the color of the bacteria depending on their Gram type. The drawback to this method is that it is prone to human error, since a person has to judge whether the bacteria have changed color under the microscope. The "smart bandage" zeroes in on a type of molecule called lipid A on the surface of Gram-negative bacteria. In an earlier publication, Miller showed how he was able to create a complementary molecule that binds to lipid A, while his newest research shows that it's possible to link that molecule to a silicon sensor that will change when the detector molecule binds to the lipid. Currently, the color change is subtle and could be missed by the human eye. However, the bandage is part of a "smart medical home" — designed by several researchers at the university to monitor health at home — so a simple device could read the bandage, confer with other instruments throughout the house to determine if the kind of bacteria in the wound is something of particular danger to you, and make a recommendation.
"This is an important step in changing the way preventive medicine is perceived and practiced," said Alice Pentland, chair of the department of dermatology at the University of Rochester. "This kind of research can put a very simple and accurate tool into the hands of anyone, giving them more control over their own health than ever before."
The team has lined up a dozen more types of pathogenic bacteria and already mapped out all the targets for which they will need to devise a binding molecule. Among those in the team's sights are antibiotic-resistant strains. "We're working on a way to detect whether or not a certain strain of bacteria is antibiotic-resistant, and which antibiotic that may be," Miller said. "That will be extremely challenging, but we think we can do it."
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