The effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures

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Abstract
The purpose of the study was to examine the effect of γ irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures. The sutures of size 2–0 were irradiated at dosage levels of 0–20 mrad. The three enzymes chosen for this study, were esterase, α‐chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions, their corresponding buffer controls, and implanted in inbred black‐and‐white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH = 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the con‐figuration and chemical structure of the PGA sutures.