Flow Spectroscopy For Tagged Nanoparticles

Nanoparticles are often studied in bulk, but sometimes they need personal attention. An instrument built by researchers at the nonprofit La Jolla Bioengineering Institute can now give it to them. David S. Sebba, Dakota A. Watson, and John P. Nolan have constructed a device capable of swiftly snapping high-resolution Raman scattering spectra of individual nanoparticles (ACS Nano, DOI: 10.1021/nn9003346). The instrument can characterize 100 nanoparticles per second as they channel one-by-one through a laser beam. The team needed a way to troubleshoot the synthesis of nanoparticles coated with a dye. These nanomaterials have narrow Raman spectral peaks, which make them ideal labels for cells in biological measurements, such as flow cytometry. But making uniform batches of the modified nanoparticles is difficult: Some of the particles shine brightly and others are duds. Nolan says that the instrument has been crucial in optimizing the team's tag recipe, providing quality-control information, such as the fraction of bright and dull nanoparticles, which no bulk characterization technique can offer. The researchers are planning to use the perfected nanoparticles in a Raman flow cytometer they are developing that will allow immunologists to measure 50 different antigens simultaneously.