Synergistic bioactive and antibacterial surface engineering of polyetheretherketone via silver/calcium phosphate composite coatings.

Abstract

This study developed a silver/calcium phosphate (Ag/CaP) composite coating on polyetheretherketone (PEEK) to enhance its bioactivity and antibacterial performance. PEEK surfaces were first nanostructured via low-temperature argon plasma treatment, followed by polydopamine polymerization as a bioadhesive platform. Ag nanoparticles were subsequently deposited through redox reactions, and a CaP layer was chemically mineralized. Surface characterization by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy and surface roughness (Ra) measurements confirmed nanoscale grooves, hierarchical topography, uniform nanoparticle distribution and markedly improved hydrophilicity. Ion release studies demonstrated that Ag/PEEK exhibited a burst release of Ag⁺, whereas the CaP/Ag/PEEK coating achieved a sustained, controlled release of Ag⁺ together with Ca²⁺ and PO₄³⁻, maintaining concentrations within the cytocompatible range. Biological assays using mouse MC3T3-E1 pre-osteoblasts showed that the CaP/Ag/PEEK coating significantly promoted cell adhesion, proliferation and osteogenic differentiation, with enhanced alkaline phosphatase activity and markedly increased extracellular matrix mineralization. Antibacterial testing against Staphylococcus aureus and Escherichia coli revealed over 90% inhibition for Ag-containing coatings, with CaP/Ag/PEEK maintaining strong antibacterial efficacy while reducing Ag-associated cytotoxicity. The results suggest that the synergistic effects of Ag and CaP coatings promote bone regeneration and infection resistance, highlighting the potential of this surface modification strategy for orthopaedic implant applications.