AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Advanced Exhaled Breath Aerosol (EBA) Collection Using Cryogenic Impaction
SOMAYEH YOUSSEFI, Gregory Lewis, Susanne Hering, Sheryl Ehrman, Donald Milton, University of Maryland School of Public Health
Abstract Number: 379 Working Group: Bioaerosols
Abstract Exhaled breath condensate (EBC) is a popular, non-invasive method to study biomarkers present in exhaled breath. Conventional EBC collects large amounts of water vapor resulting in sample dilution without efficient impaction of fine and submicron particles that are the dominant modes in EBA. In this study we developed a novel bioaerosol collector than can collect EBA effectively and in a significantly small volume.
Because exhaled breath is saturated with water at body temperature (~37°C), it contains enough moisture to grow EBAs without input of additional water vapor. Therefore, decreasing exhaled breath temperature in a laminar flow regime establishes an environment with adequate super saturation. A major innovation here is impaction on a layer of ice maintained at ~-12˚C. With a starting volume of 0.25 ml of water, the final sample volume is approximately 0.4 ml after 30 min of breath collection.
Collecting EBAs on ice has 3 key advantages: 1) Impacting particles on a solid surface is more efficient compared with liquid impingement; 2) Impacting on ice eliminates sample extraction and associated losses that result when particles are impacted on solid dry surfaces – recovery from ice merely requires melting the ice; 3) Collecting EBA on ice preserves labile biomarkers, especially proteins and free nucleic acids susceptible to enzymatic degradation when collected in aqueous media at room temperature.
We collected individual EBA samples from 18 volunteers to study their respiratory proteome. While wearing a nose clip, participants inhaled particle-free air and exhaled into the system. On average 23µg total protein was recovered from 30-min samples, 350x higher yield than previously reported for solid state impaction. It is also 4x higher total protein and 28x more concentrated than for the highest reported protein recovery from exhaled breath concentrate.