Multilayer Electrospun Poly(L-Lactic Acid)/Polyacrylonitrile (PLLA/PAN) Mesoporous Matrices: Structural Design and Properties

This study developed hierarchical mesoporous electrospun scaffolds using a five-layer, sequence-controlled architecture combining poly(L-lactic acid) (PLLA) and polyacrylonitrile (PAN) to tune porosity/transport and mechanical performance for biomedical fibrous matrices. Two multilayer stacks (PLLA/PAN/PLLA/PAN/PLLA and PAN/PLLA/PAN/PLLA/PAN) were compared to neat PLLA and neat PAN controls. Nitrogen adsorption–desorption confirmed mesoporosity (≈9.3–13.7 nm) and multilayers increased BET surface area to ≈15.9–16.9 m²/g versus neat PLLA (≈4.6 m²/g). Surface chemistry of the outermost layer governed wettability and vapor transport: PLLA-faced laminates remained highly hydrophobic (contact angle ≈114°), while PAN-faced laminates exhibited increased wettability (contact angle ≈38°) and higher water vapor permeability. Uniaxial tensile testing showed that multilayer structuring increased stiffness and strength while maintaining ductility, yielding Young’s moduli of ≈18.74 MPa (PLLA/PAN-ML) and ≈28.08 MPa (PAN/PLLA-ML) compared with ≈8.76 MPa (PLLA) and ≈37.70 MPa (PAN); stress–strain behavior was well captured by a Yeoh hyperelastic model (reported R² > 0.99). After PBS immersion, multilayers retained mechanical integrity with sequence-dependent degradation and mechanical retention, and HaCaT keratinocyte assays showed improved viability for multilayers compared with neat PLLA, supporting use in wound-healing/skin-regeneration scaffolds.