Conformal polypyrrole biointerfaces on porous PHA monoliths via oxidative chemical vapor deposition

Abstract

Chronic wounds require dressings that manage exudate, conform to soft tissue, provide mechanical support, and deliver intrinsic bioactivity. Here, we report conductive, hydrogel-like porous polyhydroxyalkanoate (PHA) monoliths dressings coated with polypyrrole (PPy) using oxidative chemical vapor deposition (oCVD). Porous PHA substrates were prepared from polyhydroxybutyrate (PHB) and a P4HB-containing copolymer by thermally induced phase separation and were uniformly functionalized throughout their three-dimensional architecture by this solvent-free process. The resulting PHA/PPy porous monoliths combine high water uptake with electrical conductivity and biological activity. They exhibit a swelling ratio of ∼250 %, maintaining a moist environment while preserving viscoelastic integrity. Sheet resistance ranges from 26 to 86 kΩ/sq, enabling platforms for electrical sensing in tissue repair. The composites do not induce cytotoxicity and exhibit intrinsic radical-scavenging capacity and antibacterial activity against both Gram-positive and Gram-negative bacteria. These properties are achieved without chemical derivatization of the PHA matrix. The hydrophobic PHA core provides mechanical robustness, while the conformal PPy layer imparts conductivity and bioactivity. Overall, this oCVD route provides a scalable, solvent-free strategy to engineer multifunctional, hydrogel-like porous monolith dressings that integrate moisture management, mechanical resilience, electrical conduction, and inherent antioxidant and antimicrobial activity. These features position the developed materials as promising bioactive and bioelectronic wound dressings and soft tissue interfaces.