Enhanced Tissue Compatibility of Polyetheretherketone Disks by Dopamine-Mediated Protein Immobilization

Polyetheretherketone (PEEK) disks with hydrophilic and bioactive surface properties were prepared by covalent immobilization of collagen (Col) or insulin (In) on poly-dopamine (D)-coated PEEK samples using WSC (water soluble carbodiimide) as an activating agent. The poly-dopamine on the PEEK disk was coated by carrying out self-assembled polymerization of the dopamine neurotransmitter in a basic medium at pH 8.5. The poly-dopamine coating of the PEEK surface facilitated the deposition of a uniform layer of aligned molecules of collagen, which increased the bioactivity of the PEEK surfaces allowing for adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells in a minimum essential medium in the presence of 5% CO2 at 37 °C. The collagen-modified PEEK surface had higher bioactivity for MC3T3-E1 cells, compared to the self-assembled poly-dopamine coated PEEK surface or pristine PEEK alone. Alkaline phosphatase, von Kossa, and Alizarin red staining of MC3T3-E1 cells cultured on a collagen-modified PEEK surface, were all found to be increased compared to staining of cells cultured on other PEEK surfaces. The self-assembled polymerization of dopamine on a PEEK surface was found to be useful for the immobilization of proteins such as collagen and insulin. Thus, collagen-and insulinimmobilized PEEK provide an opportunity to enhance the bioactivity of the PEEK samples allowing for better cells adhesion and tissue integration for potential use in tissue implants.