Nanoprobes used in conjunction with surface-enhanced Raman scattering (SERS) can be used to reveal a specific molecular marker's optical fingerprint. The work is a proof-of-principle approach to using light to detect infections before patients show symptoms. Duke University biomedical engineers and genome researchers developed the approach, demonstrated in human samples, and are now developing the technique for placement on a chip. Such a diagnostic device could be portable and provide fast, simple and reliable patient information. The silver-based nanoparticle they developed targets a specific molecular marker that spills into the bloodstream at the first stages of an infection. When light is aimed at the sample, the nanoparticle attached to a molecular marker will reflect a distinct optical fingerprint. Tuan Vo-Dinh. Courtesy of Duke University. "We have demonstrated for the first time that the use of these nanoprobes can detect specific genetic materials taken from human samples," said Tuan Vo-Dinh, the R. Eugene and Susie E. Goodson Distinguished Professor of Biomedical Engineering in Duke's Pratt School of Engineering and director of the university's Fitzpatrick Institute for Photonics. His team collaborated with scientists at the university's Institute for Genome Sciences & Policy (IGSP), who have developed a method of measuring the host's response to infection through RNA profiling. The nanoprobes are used in conjunction with SERS, a phenomenon first described in the 1970s known as surface-enhanced Raman scattering (SERS). Raman scattering occurs when light, usually from a laser, is shined on a sample and the target molecule vibrates and scatters back in its own unique light (Raman scatter). However, this Raman response is extremely weak. "When the target molecule is coupled with a metal nanoparticle or nanostructure, the Raman response is greatly enhanced by the SERS effect - often by more than a million times," said Vo-Dinh, who has been studying the potential applications of SERS for decades. "This important proof-of-concept study now paves the way for the development of devices that measure multiple genome-derived markers that will assist with more accurate and rapid diagnosis of infectious disease at the point of care," said Geoffrey Ginsburg, director of genomic medicine at the IGSP. "This would guide care decisions that will lead to more effective treatment and improved outcomes of antimicrobial therapy." The research, which is supported by the National Institutes of Health, DARPA, the Department of Defense, and the Wallace H. Coulter Foundation, appears online in the journal Analytica Chimica Acta. (DOI 10.1016/j.aca.2013.05.017) For more information, visit: www.pratt.duke.edu