Diameter-dependent effects of nanopillar arrays on PEEK bioactivity and soft tissue integration

Poly-Ether-Ether-Ketone (PEEK) is a promising material for bony structure defects reconstruction due to its favorable mechanical properties and radiolucency. However, its clinical application is limited by poor soft tissue integration resulting from surface bio-inertness. In this study, a highly uniform Nanopillar Array PEEK (NAP) was fabricated using an anodic aluminum oxide (AAO) template-based melt-casting method. The resulting nanostructures exhibited precise control over nanopillar diameter (100-300 nm) without detectable chemical alterations. In vitro experiments demonstrated that NAP significantly enhanced fibroblast adhesion, proliferation, and collagen secretion, with efficacy positively correlating to nanopillar diameters. In the in vivo chest wall implantation model, NAP promoted superior soft tissue integration, as evidenced by increased collagen deposition and elevated expression of integrinβ1, fibronectin, COL-1, VEGF, and CTGF. Transcriptome analysis revealed that NAP upregulated Areg and Farp1 genes, which are associated with cytoskeletal reorganization and adhesion signaling, in a diameter-dependent manner. In conclusion, this study establishes a reproducible strategy for tailoring PEEK surface topography to enhance bioactivity and provides insights into the design of advanced implants for soft tissue integration.