Surface-Engineered Polyacrylonitrile Nanofiber Membranes: Synergistic Enhancement of Conductivity and Antibacterial Activity via Layer-by-Layer Assembly

Flexible conductive materials with high electrical conductivity, mechanical flexibility, and biocompatibility are critical for applications in wearable electronics, flexible sensors, and neural tissue engineering. Here, we present an approach to design poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) modified polyacrylonitrile (PAN) based nanofiber membranes with enhanced properties using three key strategies: (I) blending electrospinning followed by organic solvent post-treatment (PAN/PEDOT/PSS); (II) alkaline hydrolysis of electrospun PAN fibers to introduce surface amide groups, followed by layer-by-layer (LbL) assembly of PEDOT/PSS and organic solvent treatment (HPAN@PEDOT/PSS); (III) in situ reduction of silver nanoparticles (Ag NPs) on hydrolyzed PAN fibers, followed by PEDOT/PSS LbL assembly and organic solvent treatment (HPAN@Ag@PEDOT/PSS). The systematic optimization of the organic solvent post-treatment (ethylene glycol (EG), 50 °C, 20 min) improves the conductivity of the blend fibers from near-insulating to 2.17 × 10–2 S/cm. The hydrolysis-induced amide groups significantly enhance the loading of PEDOT/PSS through hydrogen bonding, increasing conductivity by 33 times to 7.14 × 10–1 S/cm. The subsequent integration of Ag NPs creates a conductive network, achieving a remarkable conductivity of 8.26 × 10–1 S/cm, a 38-fold improvement. X-ray photoelectron spectroscopy (XPS) confirms that Ag NPs act not only as conductive fillers but also promote EG-induced phase separation of PEDOT/PSS, facilitating the transition of PEDOT chains from a benzoid to a quinoid conformation, which enriches the conductive PEDOT phase at the fiber surface. The optimized HPAN@Ag@PEDOT/PSS membrane demonstrates excellent antibacterial activity (99.86% against Staphylococcus aureus, 99.24% against Escherichia coli). This work demonstrates the potential of surface chemical engineering, LbL assembly, and metallic nanoparticle integration as effective strategies to develop multifunctional, high-performance flexible materials for bioelectronics and antimicrobial applications.