CROSS-LINKING OF DERMAL SHEEP COLLAGEN USING A WATER-SOLUBLE CARBODIIMIDE

A cross-linking method for collagen-based biomaterials was developed u sing the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC). Cross-linking using EDC involves the activation of carboxylic acid groups to give O-acylisourea groups, wh ich form cross-links after reaction with free amine groups. Treatment of dermal sheep collagen (DSC) with EDC (E-DSC) resulted in materials with an increased shrinkage temperature (T-s) and a decreased free ami ne group content, showing that cross-linking occurred. Addition of N-h ydroxysuccinimide to the EDC-containing cross-linking solution (E/N-DS C) increased the rate of cross-linking. Cross-linking increased the T- s of non-cross-linked DSC samples from 56 to 73 degrees C for E-DSC an d to 86 degrees C for E/N-DSC samples, respectively. For both cross-li nking methods a linear relation between the decrease in free amine gro up content and the increase in T-s was observed. The tensile strength and the high strain modulus of E/N-DSC samples decreased upon cross-li nking from 18 to 15 MPa and from 26 to 16 MPa, respectively. The elong ation at break of E/N-DSC increased upon cross-linking from 142 to 180 %.