Synthetic Crosslinker Based on Amino–yne Click to Enhance the Suture Tension of Collagen-Based Corneal Repair Materials

Collagen can self-assemble to form fibers with a unique structure and retain a reticular fibrous structure after membrane formation. However, collagen membranes without further modification are easy to tear. In this study, two crosslinkers (linear di-alkynyl poly­(ethylene glycol) (DA-PEG) and branched tetra-alkynyl poly­(ethylene glycol) (4arm-DA-PEG)) were synthesized, and exogenous crosslinking between collagen fiber bundles through the amino–yne click reaction was studied. Fourier-transform infrared spectroscopy (FT-IR) was performed to confirm the successful synthesis of crosslinkers and the construction of the crosslinked network. Scanning electron microscopy (SEM) showed that the crosslinked collagen membranes (Col/DA-PEG; Col/4arm-DA-PEG) had dense fibrous structures, which was expected to provide a structural foundation for surgical suturing. The denser structures and higher crosslinking degree of Col/4arm-DA-PEG provided good mechanical, optical, and antienzymatic properties. Col/4arm-DA-PEG could withstand 4.6 N/mm suture strength, which enabled it for suturing. Compared with glutaraldehyde-crosslinked membranes, Col/DA-PEG and Col/4arm-DA-PEG showed low cytotoxicity and better biocompatibility, as observed by CCK-8 assay and confocal laser scanning microscopy. These results indicate that alkynyl-terminated PEG systems can be used as ideal collagen crosslinkers to enhance the suture tension of collagen-based materials, especially in corneal repair materials.