Structures and physical properties of cross-linked gelatin fibers

This study aims to prepare a practical gelatin fiber suitable for use as a cross-linked suture. Various gelatin fibers were created in different ways: by cross-linking using heat (H); by cross-linking with carbonic acid (CA), namely citric acid; and by cross-linking with either of two epoxy compounds: ethylene glycol diglycidyl ether (E) and diglycerol triglycidyl ether (D). For each fiber type was produced at several different pH levels (7, 8, 10, and 12) in order to measure changes in the rate at which the amino group reacted with the epoxy group. E and D swelled more than H and CA did, and D swelled more than E and at every pH, D swelled more than E did. The cross-linking densities of E and D fibers reached a minimum at pH 8, corresponding to the degree of swelling. The stresses at a strain of 50% for E and D reached a minimum at pH 8. The toughest fiber, which has the largest surrounded area between stress and strain, was the cross-linked E at pH12.