Comparative Antibacterial Performance of Solution‐Cast vs. Electrospun PLA/Lignin Membranes: Impact of Fabrication Technique

This study demonstrates how material architecture dictates the antibacterial performance of bio‐based polylactic acid (PLA) and lignin membranes. While solution casting encapsulates active components, electrospinning (ES) yields microstructured networks (1.1 ≤ R a ≤ 4.04 µm) of fiber diameter (d) (0.2 ≤ d ≤ 6.2 µm) that maximize surface exposure of antimicrobial phenolic groups. In direct contact assays, electrospun PLA+Lignin membranes exhibit a slight selective effect, achieving a statistically significant ( p < 0.001)–13.09% growth inhibition exclusively against Micrococcus luteus (M. luteus) . Conversely, no significant antimicrobial activity is observed against Escherichia coli (E. coli) , Staphylococcus aureus (S. aureus) , or Staphylococcus epidermidis (S. epidermidis) , nor through agar diffusion assays. These findings reveal that integrating technical lignin into electrospun matrices does not provide broad‐spectrum surface protection, but offers localized, contact‐dependent activity. This structural constraint highlights the necessity of precise architectural control over leaching mechanisms when engineering active, bio‐based surfaces.