EFFECTS OF VARIOUS CHEMICAL STERILIZATION METHODS ON THE CROSS-LINKING AND ENZYMATIC DEGRADATION CHARACTERISTICS OF AN EPOXY-FIXED BIOLOGICAL TISSUE

Due to the nature of bioprostheses, which are mainly biological tissue s that cannot be sterilized with heat or irradiation, the sterilizatio n method by choice is generally liquid chemicals. It is known that a n umber of liquid chemicals can have rapid germicidal effect and can be used to sterilize bioprostheses. The study was to evaluate the effects of various chemical sterilization methods on the crosslinking and enz ymatic degradation characteristics of an epoxy-fixed biological tissue . The chemical sterilants employed were: a 70% ethanol solution (EtOH) , a 2% epoxy compound + 20% ethanol solution (EX-810), a 2% propylene oxide + 20% ethanol solution (PO), and a 0.625% glutaraldehyde + 20% e thanol + 0.2% polysorbate solution (GA). Both masking and crosslinking of the free amino groups within the epoxy-fixed tissue were observed subsequent to sterilization with GA or EX-810. This improved the resis tance of the GA or EX-810 sterilized tissues against collagenase degra dation as compared to its nonsterilized counterpart. However, subseque nt to sterilization with PO, only masking of the free amino groups wit hin the epoxy-fixed tissue was noted. The inhibition of the collagenas e degradation by masking of the free amino groups was traded off by th e more random molecular packing of the PO sterilized sample due to the introduction of the side branches. Sterilization of the epoxy-fixed t issue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place. The resistance to degradation of the EtO H sterilized tissue, however, did not improve as compared to its nonst erilized counterpart. (C) 1997 John Wiley & Sons, Inc.