A new technique for better detection of infectious disease biomarkers has scientists looking at ordinary shrink wrap in a whole new way. Developed by a team at the University of California, Irvine, the method uses shrink wrap coated with a combination of metals to boost the signal of fluorescent markers used in biosensing a thousandfold. The technique could enable earlier detection of infectious diseases and more effective treatment. In their study, the researchers deposited thin layers of gold and nickel onto a thermoplastic polymer. When heated, the shrink wrap contracts and causes the stiffer metal layers to buckle and wrinkle into flowerlike structures that are much smaller than those previously demonstrated. Shrink wrap nanostructures under a scanning electron microscope show different thicknesses of nickel and gold in the metal coating. Courtesy of Optical Materials Express. When researchers shined a light on the wrinkled creation, the electromagnetic field was amplified within the nanoscale gaps between the shrink wrap’s folds. Samples of biomarkers — in this case, immunoglobulin G (IgG) — were added to the top of the wrinkled metal layer. The biomarkers were then tagged with fluorescent probes to allow their detection under NIR light. “IgG is one of the most common circulating antibodies in the immune system, making up about 80 percent of the all antibodies in the body, and is found in most bodily fluids,” said UC Irvine graduate student Himanshu Sharma. The research also found that shrink wrap wrinkles significantly enhanced the intensity of the signals the biomarkers produced, which, according to co-author Michelle Khine, a biomedical engineering professor at UC Irvine, is the result of excitation of localized surface plasmons. “If you have a solution with very few molecules that you are trying to detect, as in the case of infectious diseases, this platform will help amplify the signal so that a single molecule can be detected,” she said. This nanotechnology paves the way for the creation of a lower-cost, highly-sensitive diagnostic device, the researchers say. Currently, such detection methods and devices are quite expensive. Additional antibodies, such as immunoglobulin A (IgA) and immunoglobulin M (IgM), could detect other agents in the future, including cytomegalovirus and the pathogen that causes typhoid fever. However, additional research and testing are needed. “The technique should work with measuring fluorescent markers in biological samples, but we have not yet tested bodily fluids,” Khine said. The research is published in Optical Materials Express. For more information, visit: www.uci.edu.