Bifunctional Electrospun PAN/ε-Polylysine Composite Membranes for High-Efficiency PM _2.5 and PM ₁₀ Filtration with Antimicrobial Protection

Airborne particulate matter (PM_2.5 and PM₁₀) and bioaerosols pose synergistic threats to respiratory health, necessitating advanced filtration technologies that simultaneously address particulate and microbial contamination. We report a bifunctional multilayer composite air filter membrane fabricated by electrospinning polyacrylonitrile (PAN) nanofibers (average diameter 609 ± 88 nm) onto nonwoven substrates integrated with ε-poly-l-lysine (ε-PL) antimicrobial coating. Optimized electrospinning conditions (10 wt % PAN, 15 min deposition) yielded uniform, bead-free nanofibers achieving exceptional filtration efficiencies of 99.39 ± 0.09% for PM_2.5 and 99.50 ± 0.16% for PM₁₀, while maintaining low pressure drop (175 ± 5 Pa) suitable for respiratory applications. The ε-PL coating, immobilized via PVA-mediated adhesion, transformed the hydrophobic spunbond surface to hydrophilic (contact angle reduced from 108° to 48°) and conferred potent antimicrobial activity. Time-kill assays demonstrated concentration-dependent bactericidal effects, with 10 mg/mL ε-PL achieving complete bacterial eradication (>6-log reduction) within 24 h against both Gram-positive and Gram-negative pathogens. Comparative analysis revealed superior performance over commercial multilayer masks (66-98% efficiency for PM_2.5; 66-98% efficiency for PM₁₀), despite lower basis weight (94.01 ± 1.95 g/m²). The quality factor analysis confirmed optimal balance between high filtration efficiency and breathability at 15 min electrospinning time. These dual-functional membranes demonstrate the synergistic integration of high-efficiency particulate filtration across multiple size fractions with antimicrobial protection, offering a promising platform for personal protective equipment, HVAC systems, and healthcare air purification applications where simultaneous removal of coarse and fine airborne particles and pathogen inactivation is critical.