Biofunctionalization of 3D printed PEEK using integrated cathodic arc plasma coating: a one-step solution to antimicrobial and bioactive PEEK Implant

This study introduces a novel hybrid additive manufacturing (AM) approach that integrates a surface coating process directly into the AM workflow. By incorporating a vacuum arc plasma source into a Fused Filament Fabrication (FFF) system, we combine the design freedom and scalability of 3D printing with the ability to biofunctionalize the printed polymer part in a single fabrication step. Polyetheretherketone (PEEK) is widely used in biomedical engineering due to its excellent mechanical properties, biocompatibility, and radiolucency. However, its bioinert nature poses challenges for infection prevention and bone integration. This study aims to evaluate the coatings produced by this integrated process on a PEEK substrate specifically in a biomedical context, focusing on their antimicrobial performance and cytocompatibility. The results show that zinc (Zn) is the most effective antimicrobial agent among the tested coatings (Ag₂O, Cu, and Zn), achieving a reduction in bacterial adhesion of over 4 log. Moreover, TiO₂/Zn composite coatings exhibit strong antimicrobial activity while maintaining good cytocompatibility with fibroblastic cells in vitro. Qualitative imaging also indicates improved osteoblast attachment on surfaces coated with TiO₂ and TiO₂/Zn. This hybrid manufacturing platform enables the production of implants with tailored structural and biological properties in a single step, representing a significant advancement in the development of next-generation medical implants.