GLUTARALDEHYDE AS A CROSS-LINKING AGENT FOR COLLAGEN-BASED BIOMATERIALS

The formation of Schiff bases during crosslinking of dermal sheep coll agen (DSC) with glutaraldehyde (GA), their stability and their reactiv ity towards GA was studied. All available free amine groups had reacte d with GA to form a Schiff base within 5 min after the start of the re action under the conditions studied (0.5% (w/w) GA). Before crosslinks are formed the hydrolysable Schiff bases initially present were stabi lized by further reaction with GA molecules. An increase in shrinkage temperature (T-s) from 56 degrees C for non-crosslinked DSC (N-DSC) to 78 degrees C for GA crosslinked DSC (G-DSC) was achieved after crossl inking for 1 h. From the relationship between the free amine group con tent and the T-s during crosslinking it was concluded that higher GA c oncentrations and longer reaction times will result in the introductio n of pendant-GA-related molecules rather than crosslinks. After 24 h c rosslinking an average uptake of 3 GA molecules per reacted amine grou p was found. No increase in the tensile strength of the materials was observed after crosslinking, which may be a result of formation of cro sslinks within the fibres rather than in between fibres. Aligning of t he fibres by applying a pre-strain to the samples and subsequent cross linking yielded materials with an increased tensile strength.