Single viable fungal aerosol particle discerning using naked eye assisted with laser trapping and microwaving

Abstract

Viable microbial aerosol detection remains a grand challenge. Here, we pioneered a new system that integrates laser trapping and microwave irradiation for online discerning of single viable microbial aerosol particle through naked eye. To test the system, three fungal species Aspergillus niger, Aspergillus oryzae, and Trichoderma harzianum and three non-biological particles such as MnO2, active carbon, and Fe3O4 were suspended and laser trapped in the air inside a house-made glass cube. When microwave irradiated, some fungal spores were observed to rapidly escape from the trapping and even burst with abrupt morphology changes under a longer irradiation. In contrast, others similar to those non-biological particles were shown to behave differently with little morphology change without the cell burst. For all particles tested, microwave irradiation resulted in particle movement within the trapping region, and a particle trapping was then re-established in a new location. Depending on particle type and irradiation time, light scattering properties also differed between biological and non-biological particles when irradiated. Terminating the microwave irradiation was observed to render the non-biological particles to return where they were being laser trapped. Using the developed system, we have demonstrated the viable microbial aerosol detection using naked eye by simply observing the morphology changes and cell burst upon the laser trapping and microwave irradiation. A portable version of the system was further developed and successfully tested for discerning viable aerosol cells from non-biological ones. Further efforts on this development could lead to a new generation of bioaerosol detection strategy.