The probe's green fluorescent burst lasts little more than a billionth of a second - a nanosecond - but just long enough to separate it from surrounding signals, according to co-author Nicholas Turro, Ph.D., the William P. Schweitzer professor of chemistry at Columbia University. He also holds professorships in the department of chemical engineering and the department of earth and environmental engineering.
"A cell contains a lot of material that absorbs and emits light when it's excited," Turro said. "That's been the problem. However, if you wait 10 nanoseconds, the signals from the native fluorescence go away. What's left is the signal from the probe, which is engineered to be more long-lived at about 50 nanoseconds."
The result is a clear indication of the presence of PDGF.
"The problem of background signals is a major obstacle in many of these biodetection methods," said Paras N. Prasad, Ph.D., a distinguished professor of chemistry and executive director of the Institute for Lasers, Photonics and Biophotonics at the University of Buffalo. "Dr. Tan and his colleagues were able to address that with their light-switching method. This is a significant advancement in minimizing a frequent problem."
Much work remains to be done, but the technique potentially could be a diagnostic tool for cancer and other diseases. It could also be used to detect illicit drugs, such as cocaine, in the body, researchers say.
"Eventually we would like to see this assay become as convenient as a pregnancy test," said Chaoyong James Yang, a chemistry doctoral student in the Tan group and the first author of th
Source:University of Florida