A novel radiotracer method for filter testing

Abstract

Pollen allergens pose a significant health burden, affecting up to 30 % of the population in industrialized countries (Pablos, I.; Wildner, S.; Asam, C.; Wallner, M.; Gadermaier, G. Pollen Allergens for Molecular Diagnosis. Curr. Allergy Asthma Rep. 2016, 16, 1–12). With sizes typically ranging from 15 to 150 μ mm (Wafaa, K.T. Pollen Allergens of some Road Trees, Shrubs and Herbs in Alexandria, Egypt. OAJBS.ID.000143, 2020), they can be filtered out of the air. However, recent studies have revealed that many pollen allergens are transported in free vesicles called pollensomes (Prado, N.; de Linares, C.; Sanz, M.L.; Gamboa, P.; Villalba, M.; Rodríguez, R.; Batanero, E. Pollensomes as Natural Vehicles for Pollen Allergens. J. Immun. (Balt., Md. : 1950) 2015, 195, 445–449, Rutter, B.D.; Innes, R.W. Extracellular Vesicles as Key Mediators of Plant-Microbe Interactions. Curr. Opin. Plant Biol. 2018, 44, 16–22). These vesicles, which have a much smaller size of approximately 28–60 nm (Prado, N.; de Linares, C.; Sanz, M.L.; Gamboa, P.; Villalba, M.; Rodríguez, R.; Batanero, E. Pollensomes as Natural Vehicles for Pollen Allergens. J. Immun. (Balt., Md. : 1950) 2015, 195, 445–449), cannot be retained by conventional filters. However, novel filter materials have been developed (Gotschall, K. Personal Communication; KLAVEGO GmbH & Co KG, 2022) which are capable of binding even such small protein structures selectively. Standard test methods exist for determining the retention efficiency for common filter technologies. However, these methods cannot be directly applied to the aforementioned nanoparticles. This limitation arises from the fact that the particle concentration of the filtered gas is often too low for conventional aerosol measurement devices to yield meaningful results. In this study, a novel test procedure using a solution of bovine serum albumin (BSA) labeled with radioactive iodine (I-131) is developed to determine the retention efficiency of filters by a highly sensitive radiotracer technique.