Single-particle optical-trapping Raman spectroscopy for the detection and identification of aerosolized airborne biological particles

The detection and identification of bioaerosol particles, especially a potential threat from aerosolized biowarfare agents (BWAs), has become increasingly important. Here, we report on single-particle optical-trapping Raman spectroscopy (OT-RS) for the detection and identification of airborne biological particles. OT enables the capture of single particles in air for several minutes or longer, more than sufficient to capture the Raman spectra and minimize the interference from background aerosol particles. Simultaneously, the embedded imaging system can provide real-time information on the shape and size of the trapped particles. Several kinds of bioaerosol particles were analyzed using OT-RS including four BWA surrogates: Bacillus globigii, Yersinia rhodei, MS2, and Bacillus subtilis, along with some interfering bioaerosol particles commonly presented in the atmosphere. Similarities and differences of the Raman spectra of these biological particles are discussed. In addition, the BWA surrogates are well classified by using the principal component analysis. The results demonstrate that single-particle OT-RS can be used not only for the potential detection of BWAs but also for the identification of BWAs. (paper)