Adhesion-Resistant, Sandwich-Structured Zein Nanofiber Membrane for Air Filtration

To address the adhesion problem of curcumin-containing zein fibers, sandwich-structured zein/poly(vinyl alcohol) (PVA) membranes with a curcumin-functionalized core layer were fabricated via sequential electrospinning (outer-core-outer). The core layer exhibited flattened and adhesive fibers, whereas encapsulation within protective outer layers yielded cylindrical, non-adhesive fibers with tunable diameters (0.43–1.0 μm). The sandwich membranes exhibited enhanced mechanical properties (tensile strength up to 4.67 MPa) and stable hydrophobicity. Filtration tests demonstrated > 95% efficiency for 0.3 μm particles and > 97% for particles ≥ 0.5 μm, with pressure drop values ranging from 7.03 to 7.56 mbar. Post-filtration imaging revealed that curcumin-containing membranes displayed dispersed particle deposition on individual fibers, while the curcumin-free outer layer showed extensive particle aggregation, indicating curcumin-induced particle anchoring. FTIR analysis confirmed curcumin-mediated hydrogen bonding and increased β-sheet content. The sandwich design resolves core layer adhesion while preserving filtration functionality, offering a sustainable strategy for bio-based air filtration materials.