Detection of Bioaerosol by Measuring Single Particle Differential Circular Polarization Scattering (CIDS)
YONG-LE PAN, Aimable Kalume, Chuji Wang, Joshua L. Santarpia,
U.S. Army Research Laboratory Abstract Number: 57
Working Group: Instrumentation and Methods
AbstractRapid detection and characterization of bioaerosol has been an important research topic for health and environment sciences. Currently real-time bioaerosol detection is mainly based on fluorescence, elastic scattering etc. optical methods, their effectiveness are often limited by the prevalence of interferents and significant costs. These inadequacies led to new exploration.
It was reported that DNA helical structures in biological molecules produce non-zero circular intensity differential scattering (CIDS, normalized Mueller scattering-matrix element S14/S11) as compared to other particles with non-helical structures. To date CIDS measurements have only been carried out for a group of particles using a polarization modulator, lock-in amplifier, and rotating detector due to its ultra-weak signals (10-3-10-6). Such complex instrumentation is not suitable outside a laboratory setting for use as a biosensor.
We report an advanced design, improved from our previous work (Optics Express 30 (2), 1442 (2022)), for measuring CIDS from single individual flowing through particles without any moving parts or modulator. An elliptical reflector is used to project scattering light at different angles onto a 32-anode PMT for phase function recording with two illuminating laser beams in left- and right-circular polarizations, which are 80 mm separation around the focus of the reflector as a particle moving through them with 8 ms time interval. This innovative setup, significantly, shortens a complete measurement from tens of minutes to 17 ms. CIDS phase functions from single particles of B. subtilis, E. coli spores, MS2 bacteriophage, Yersinia rohdei, DNA-tagged polystyrene (PSL) microsphere, tryptophan, PSL microsphere, atmospheric aerosol particles are carried out using this system. The results showed all bioaerosol particles have at least 3 times stronger CIDS signals than non-bioaerosol particles. This newly developed system gives promise to a rapid bioaerosol monitoring system with low cost and reduced risk for potential interferents.