Abstract

This study reports the development and characterization of hierarchical mesoporous electrospun scaffolds based on poly(l-lactic acid) (PLLA) and polyacrylonitrile (PAN) fabricated through a multilayer (five-layer) design. Two multilayer configurations, PLLA/PAN-ML and PAN/PLLA-ML, were compared with single-polymer controls to assess how the deposition sequence affects structure, transport, and mechanical performance. Nitrogen adsorption confirmed mesoporosity in the 9.3-13.7 nm range, and multilayers exhibited higher specific surface areas (15.9-16.9 m(2)/g) than neat PLLA (4.6 m(2)/g), indicating an improved fluid-matrix interaction. Water absorption values for PLLA/PAN-ML (500%) and PAN/PLLA-ML (430%) were intermediate between PLLA (60%) and PAN (1130%), revealing sequence-dependent hydrophilicity. Water vapor permeability measurements further showed that mass transport is governed by the outermost layer, with PAN/PLLA-ML displaying higher WVP than PLLA/PAN-ML. Tensile tests demonstrated that the multilayer design enhanced stiffness while preserving ductility, yielding Young's moduli of 18.74 +/- 0.98 and 28.08 +/- 2.19 MPa for PLLA/PAN-ML and PAN/PLLA-ML, respectively, and the stress-strain response was accurately described by the Yeoh hyperelastic model (R-2 > 0.99). After PBS immersion, multilayer scaffolds retained mechanical integrity and exhibited sequence-dependent degradation. In vitro assays with human cells showed higher viability for multilayers than for neat PLLA, supporting their use in tissue-engineering and wound-healing applications. Overall, multilayer electrospinning provides a simple and versatile strategy to simultaneously optimize porosity, wettability/permeability, and mechanical balance in biomedical fibrous scaffolds.