Publications

Transcutaneous devices such as dental implants frequently fail due to infections at their interfaces with epithelial tissues. These infections are facilitated by the lack of integration between the devices and the surrounding soft tissues. This study aims to improve epithelial integration through surface modification of a transcutaneous implant material (polyetheretherketone (PEEK)). The modification involved covalent bonding of collagen via two distinct methods: (1) nonselective binding through any primary amines present on collagen using carbodiimide-based coupling and (2) site-specific binding to the free amine on the N-terminus of collagen molecules. The second approach preserves active sites responsible for interacting with integrins, crucial for epithelial cell adhesion, located near the C terminus. Both conjugation methods resulted in similar amounts of immobilized collagen; yet, surfaces with 2-PCA-based collagen conjugation exhibited 4 times more free amines. This indicates that fewer amines were used for conjugation in these samples, confirming that 2-PCA selectively binds collagen only through the N-terminus amines. Collagen-conjugated surfaces significantly enhanced HaCaT epithelial cell viability and adhesion compared to unmodified PEEK. Furthermore, 2-PCA-based conjugation resulted in a 2-fold increase in beta 4 subunit gene expression of integrin alpha 6 beta 4 (a key epithelial cell adhesion marker), higher integrin beta 4 immunofluorescence (IF) intensity, and over a 30% improvement in cell retention following mechanical detachment, compared to nonselective conjugation. These findings suggest that selective collagen conjugation on PEEK surfaces increases the accessibility of collagen domains responsible for binding with integrin receptors, which in turn improves epithelial cell attachment, offering a promising strategy for reducing infections and enhancing the longevity of transcutaneous devices.

JTD Keywords: Cell-adhesion, Conjugation, Domains, Fibroblasts, Fibronectin, Integrin, Matrix, Protein, Selective protein conjugation, Soft tissue integration, Strategies, Titanium surfaces, Transcutaneous implants