Surface-Engineered Filters for Wettability-Driven Collection of Airborne Fungal Spores

Environmental sampling of fungal spores is critical for assessing exposure risks, but current methods often miss low-abundance or spatially dispersed spores, highlighting the need for more sensitive sampling methods. This study explores the use of plasma polymerization to chemically modify air filters for enhanced fungal spore capture. Polyethylene terephthalate (PET) filters are coated with nanothin films from four monomers -acrylic acid, 2-methyl-2-oxazoline (POX), 1,7-octadiene, and perfluorooctane (PFO)- and characterized using ellipsometry, X-ray photoelectron spectroscopy, and contact angle measurements to evaluate film thickness, chemistry, and wettability. A custom aerosolization chamber was used to test the capture efficiency of plasma-modified filters for airborne spores from four species: Aspergillus niger, Cladosporium sp., Penicillium roqueforti, and Rhodotorula glutinis. Quantitative analysis using hemocytometry and dry biomass measurement reveals species-specific adhesion patterns that are predominantly driven by surface chemistry. Hydrophobic PFO-coated filters achieved the highest capture of filamentous fungi, while hydrophilic POX coatings best captured the tested yeast. Coating thickness had no significant effect, highlighting the primacy of surface chemistry over film depth. These findings establish plasma polymerization as an effective strategy to tailor filter surfaces for selective fungal spore capture, providing a proof-of-concept for functionalized air filters that support improved bioaerosol monitoring in built environments.