Band-aid-like patch boosts fluorescence brightness in diagnostic tests



[Image from Washington University in St. Louis]

Researchers at Washington University in St. Louis have created a high-tech metal nanostructure patch that increases fluorescence intensity by 100 times in medical diagnostic tests.

Fluorescence-based biosensing and bioimaging technologies have been used to detect and image different biological species. It is convenient to use, but they have poor sensitivity. For example, the fluorescent signal can be weak when a patient has low levels of antigens in the blood or urine which means it can be more difficult to get a diagnosis.

The Washington University in St. Louis researchers collaborated with the Air Force Research Laboratory at Wright-Patterson Air Force Base to develop a high-tech fix that uses metal nanostructures to increase fluorescence intensity. The solution is cheap and easy, according to the researchers.

“Using fluorescence for bio detection is very convenient and easy, but the problem is it’s not that sensitive, and that’s why researchers don’t want to rely on it,” Srikanth Singamaneni, professor of mechanical engineering and material science, said in a press release.

Other techniques that boost fluorescence signals rely on enzyme-based amplification and need extra steps to prolong operation time, as well as specialized and expensive read-out systems.

The patch developed by the researchers, called the plasmic patch, doesn’t need a change in testing protocol to work. Instead, the flexible piece of film is about a centimeter square the features embedded nanomaterials. The only thing researchers need to do to image with it is to prepare the sample as they would normally do and then apply the patch over the top and scan the sample.

“It’s a thin layer of elastic, transparent material with gold nano rods or other plasmonic nanostructure absorbed on the top,” Jingyi Luan, one of the lead authors on the study, said. “These nanostructures act as antennae: they concentrate light into a tiny volume around the molecules emitting fluorescence. The fluorescence is dramatic, making it easier to visualize. The patch can be imagined to be a magnifying glass for the light.”

The researchers suggest that the patch is a cheap alternative because it costs about a nickel per applications. They also suggest that it could be used in microarray in addition to research applications and diagnostics.

“The plasmonic patch will enable the detection of low abundance analyses in combination with conventional detection methodologies, which is the beauty of our approach,” Rajesh Naik, chief scientist at the Air Force Research Lab’s 711th Human Performance Wing, said.

“It’s a last step, just like a Band-Aid,” Singamaneni said. “You apply it, and the dimness problem in these fluorescence-based detection methods is solved.”

The research was published in the journal Light:Science and Applications and was supported by the National Science Foundation, National Institutes of Health and the Barnes-Jewish Hospital Research Foundation.

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