Nonaldehyde sterilization of biologic tissue for use in implantable medical devices

Biologic tissue stabilized by dye-mediated photooxidation has found application in implantable devices. The desire to avoid aldehydes in the processing of photooxidized tissues led to the development of a nonaldehyde, iodine based sterilant. The interaction of tissue with iodine was indicated by a change in tissue shrinkage temperature, dependent upon solution and incubation parameters. The amino acid tyrosine also was altered, presumably because of aromatic ring iodination. Transmission electron microscopic study indicated no change in the quarter staggered array structure of collagen under controlled iodine treatment conditions. The D-10 values for iodine kill of several organisms, in the absence of tissue, were determined in 0.1% iodine (pH 6.5) at 37 degrees C for Bacillus subtilis (12 min), Aspergillus niger, Escherichia coli, Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa (all <1 min). In a separate experiment, samples of 0.1% iodine (pH 6.5) containing photooxidized pericardial tissue were inoculated with 1.6 x 10(7) Bacillus subtilis, 4.6 x 10(6) Pseudomonas aeruginosa, or 7.2 x 10(6) Staphylococcus aureus and incubated at 37degrees>C. No survivors were detected on the tissue samples after exposure of 48 hr. Photooxidized pericardial tissue samples inoculated with either 3.2 x 10(5) porcine parvovirus or 1 x 10(9) infectious bovine rhinotracheitis were exposed to 0.1% iodine (pH 6.5) at 36 degrees C for 12 hr. No viral particles were detected after exposure, yielding minimum viral log reduction factors of 3.0 and 6.5, respectively. The results presented indicate the potential for a nonaldehyde, iodine based solution to sterilize implantable devices containing biologic tissue.