Biomedical engineers are developing a hand-held device called a SpectroPen that could help surgeons see the edges of tumors in human patients in real time during surgery.

Scientists at Emory University School of Medicine, Georgia Institute of Technology, and the University of Pennsylvania described the device in an article published this week in the journal Analytical Chemistry.

What a patient with a tumor wants to know after surgery can be expressed succinctly: “Did you get everything?” Statistics indicate that complete removal, or resection, is the single most important predictor of patient survival for most solid tumors.

“This technology could allow a surgeon to directly visualize where the tumors are, in real time. In addition, a post-surgery scan could check tumor margins,” said Shuming Nie, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “A major challenge is to completely remove the tumor as well as identify lymph nodes that may be involved.”

The SpectroPen can be used to detect fluorescent dyes, and also scattered light from tiny gold particles, a technology that Nie and his colleagues have been refining.

The particles consist of polymer-coated gold, coupled to a reporter dye and an antibody that sticks to molecules on the outsides of tumor cells more than it sticks to normal cells. Through an effect called surface-enhanced Raman scattering, the gold in the particle greatly amplifies the signal from the reporter dye. Nie and his team have been able to show that the particles can detect tumors smaller than one millimeter grafted into rodents.