Researchers at the University of Rochester came up with a laser-based technique that tests urine and blood serum for multiple chemicals in under 60 seconds. The ability to detect some of these chemical markers is thought to have a major implications for diagnosis and treatment of diabetes, cardiovascular, kidney and other diseases :
Co-researchers Andrew J. Berger, associate professor of optics, and Dahu Qi, doctoral candidate, used low-refractive-index tubes instead of cuvettes or other bulky containers for holding biological specimens. And, to get more information from the fluids, they used white light–like that from an ordinary light bulb–along with the laser. The tubes and light bulbs made all the difference.
In the laser technique called Raman spectroscopy, scientists shine laser light onto molecules and the light scatters off, gaining or losing energy. A spectrograph translates the changed energies into spectra. Each chemical presents a Raman spectrum that scientists recognize. The Raman approach is a favorite for finding chemicals that overlap and mix in fluid, much like musical instruments in an orchestra. But Raman spectroscopy comes with a problem.
Raman signal is notoriously weak. Using it to test biofluids, with their lighter chemical concentrations than in many fluids, is not a natural choice. Berger and Qi injected fluid samples into a thin transparent tube specially made to contain the light, and the tube’s long path length of interaction let the scientists collect more Raman scattering. “The tubes have a refractive index lower than water, so the light bounces along inside the liquid core, just as in solid optical fibers for telecommunications,” said Berger. “Other groups had used these fibers to strengthen their Raman signals, so we wanted to see if we could translate that advantage to use with biofluids.”
Press release: Laser Goes Tubing for Faster Body-Fluid Tests …
