Triple-modified PEEK surface via plasma treatment, polydopamine coating and chlorhexidine: Assessment of biocompatibility and antibacterial properties.

OBJECTIVE: To develop and evaluate a novel surface modification strategy for polyetheretherketone (PEEK) that combines cold plasma treatment with dopamine-crosslinked chlorhexidine (CHX) to enhance both soft tissue integration and antimicrobial properties for potential dental applications.

METHODS: PEEK surfaces were modified through cold plasma treatment followed by polydopamine (PDA) coating and CHX functionalization. Surface characterization was performed by SEM, FTIR, XPS, profilometer and contact angle measurements. A 15-day CHX in vitro release test was conducted to evaluate the drug delivery profile of the modified surfaces. Biological response was evaluated through human gingival fibroblasts (HGFs) cultures, examining cell adhesion and proliferation capacity. Antimicrobial efficacy was systematically evaluated through bacterial viability, colony enumeration, biofilm formation, and adhesion analysis.

RESULTS: The P-PDA-CHX modification significantly improved surface hydrophilicity, reducing contact angles from 83.6 ± 3.1° to 24.2 ± 4.2°. Surface roughness of P-PDA-CHX (0.38 ± 0.029 μm) was significantly higher than that of the P-PDA (0.28 ± 0.048 μm) and P-CHX (0.33 ± 0.033 μm) groups (p < 0.05). Compared to unmodified surfaces, the modified surfaces demonstrated enhanced HGFs proliferation and adhesion, with cells showing improved spreading and cytoskeletal organization. The P-PDA-CHX coating exhibited sustained chlorhexidine release over 15 days and demonstrated superior antibacterial properties, significantly reducing bacterial adhesion and biofilm formation while maintaining excellent biocompatibility with HGFs.

SIGNIFICANCE: This surface modification strategy offers a promising approach for improving PEEK's biological and antibacterial properties. The combination of cold plasma treatment, PDA coating, and CHX functionalization provides a solution to enhance both cellular response and bacterial resistance, which could benefit various dental applications of PEEK materials, including customized abutments, where tissue integration and bacterial control are essential.