The BioCascade-David: An Integrated Cascade Impactor for Inhalation Toxicology and Bioaerosol Collection

SRIPRIYA NANNU SHANKAR, Yuetong Zhang, Yuqiao Chen, Eric Le, William Vass, John Lednicky, Tracey Logan, Rebeccah Messcher, Gregory S. Lewis, Arantzazu Eiguren-Fernandez, Stavros Amanatidis, Tara Sabo-Attwood, Chang-Yu Wu, University of Florida

     Abstract Number: 83
     Working Group: Instrumentation and Methods

Abstract
Particle size is one of the main factors governing the transport, deposition, and fate of particles in the atmosphere as well as in the respiratory system. Existing aerosol collection and exposure systems are capable of either depositing size-fractionated particles onto a dry surface or exposing cells maintained in liquid medium to all airborne particles without size-fractionation. While the former leads to loss of particles during extraction or loss in viability of bioaerosols collected, the latter does not provide information on size-dependent properties. The BioCascade paired with the Dosimetric Aerosol in Vitro Inhalation Device (DAVID) collects airborne particles into liquid in 4 stages (>8.5, 3.9-8.5, 1.3-3.9 and <1.3 μm) when operated at 4.5 L/min. The performance of the BioCascade-DAVID when challenged with aerosols generated during combustion was demonstrated using smoke particles from burning incense. Samples collected in stage 3 (1.3-3.9 μm) contained the highest concentration of redox compounds (48±7 μg/mL) and antioxidant potential (4.0±1 μM ascorbic acid equivalents), as assessed by Dithiothreitol and ascorbic acid assays respectively. In vitro anti-inflammatory activity, evaluated by inhibition of bovine serum albumin denaturation assay, showed compounds present in stage 2 inhibited the protein denaturation by ~27%, followed by stage 3 (~22%). From the samples collected in liquid medium using the BioCascade-DAVID, 32 and 71 organic compounds were detected by Gas Chromatography and Liquid Chromatography, respectively. The BioCascade-DAVID was further evaluated for collecting and delivering viable Human Coronavirus-OC43 to Vero E6 cells, as exemplified by the initiation of virus-induced cytopathic effects 3 days post inoculation, in stages 3 and 4. The results demonstrate the applicability of the BioCascade-DAVID in collecting size-fractionated aerosols and delivering them to a liquid medium for ease of analyses or to deliver particles directly to cells, without compromising the viability of the virus or host cells.