Inactivation of bacterial spores and viruses in biological material using supercritical carbon dioxide with sterilant.

The purpose of this study was to validate supercritical carbon dioxide (SC-CO(2)) as a terminal sterilization method for biological materials, specifically acellular dermal matrix. In this study, bacterial spores, Bacillus atrophaeus, were inoculated onto porcine acellular dermal matrix to serve as a "worst case" challenge device. The inactivation of the spores by SC-CO(2) with peracetic acid (PAA) sterilant was analyzed as a function of exposure times ranging from 1 to 30 min. A linear inactivation profile for the Bacillus atrophaeus spores was observed, and a SC-CO(2) exposure time of 27 min was determined to achieve a sterility assurance level of 10(-6). The inactivation of viruses was also studied using Encephalomyocarditis (EMC) viruses. After 15 min of exposure to SC-CO(2) with PAA sterilant, more than a 6 log(10) reduction was observed for EMC viruses. Biochemical and biomechanical evaluations showed that the SC-CO(2) treatment with PAA sterilant did not cause significant changes in porcine acellular matrix's susceptibility to collagenase digestion, tensile or tear strength, indicating limited alteration of the tissue structure following SC-CO(2) sterilization.