CHEMICAL INACTIVATORS AS STERILIZATION AGENTS FOR BOVINE COLLAGEN MATERIALS

The use of collagen as a biomedical implant raises safety issues with regard to viruses and prions. Specific chemical agents that inactivate prion infectivity could be applied to collagen implants. The physicoc hemical changes and the in vitro and in vivo biocompatibility of colla gen treated by formic acid (FA), trifluoroacetic acid (TFA), tetrafluo roethanol (TFE), and hexafluoroisopropanol (HFIP) were investigated. I n addition, the effects of these treatments on nucleic acids incorpora ted in collagen were analyzed. The molecules of FA and, more important , of TFA remained within collagen. FA, TFA and HFIP treatments modify the secondary structure of collagen, as shown by Fourier transform inf rared spectroscopy, while TFE does not. Differential scanning calorime try measurements showed a decrease in the denaturation temperature com pared to untreated collagen. However, resistance to collagenase was mo dified only after HFIP treatment. In vitro, cell growth was not impair ed; in vivo, implants induced a temporary inflammatory reaction that w as prolonged with TFA and HFIP treatments. TFE and FA-treated collagen were thoroughly infiltrated by fibroblasts. On the other hand, FA and TFA resulted in extensive depurination of nucleic acids while HFIP an d TFE did so to a lesser degree. Among the investigated chemical scrap ie inactivators, FA treatment could offer a safe and biocompatible col lagen-derived material for biomedical use. (C) 1997 John Wiley & Sons, Inc.