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.