Crosslinking and modification of dermal sheep collagen using 1,4-butanediol diglycidyl ether

Crosslinking of dermal sheep collagen (DSC) was accomplished using 1,4-buta nediol diglycidyl ether (BDDGE). At pH values > 8.0, epoxide groups of BDDG E will react with amine groups of collagen. The effects of BDDGE concentrat ion, pH, time, and temperature were studied. Utilization of a 4-wt % BDDGE instead of 1-wt % resulted in a faster reaction. Whereas similar values of shrinkage temperature were obtained, fewer primary amine groups bad reacted at a lower BDDGE concentration, which implies that the crosslinking reacti on had a higher efficacy. An:increase in pH from 8.5 to 10.5 resulted in a faster reaction but reduced crosslink efficacy. Furthermore, an increase in reaction temperature accelerated the reaction without changing the crossli nk efficacy. Crosslinking under acidic conditions (pH < 6.0) evoked a react ion between epoxide groups and carboxylic acid groups of collagen. Addition al studies showed that no oligomeric crosslinks could be formed. However, h ydrolysis of the epoxide groups played a role in the crosslink mechanism es pecially under acidic reaction conditions. The macroscopic properties of th ese materials were dependent on the crosslinking method. Whereas a flexible and soft tissue was found if crosslinking was performed at pH < 6.0, a sti ff sponge was obtained under alkaline conditions. Reaction of DSC with a mo nofunctional compound (glycidyl isopropyl ether) led to comparable trends i n reaction rate and in similar macroscopical differences in materials as ob served with BDDGE. (C) 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 46, 424-433, 1999.