The study of the sterilization effect of gamma ray irradiation of immobilized collagen polypropylene nonwoven fabric surfaces

Abstract Exposure to gamma ray irradiation is a frequent, clean, and superior method used to prevent bacterial contamination of sterilized biomedical end products. However, the potential damage induced by gamma ray irradiation of collagen is of concern because of the decay of bioactivity, which correlates with considerable structural alterations. In this experiment, antenna‐coupling microwave plasma was utilized to activate nonwoven polypropylene (PP) fabric, and then the sample was grafted to acrylic acid (AAc). Type III collagen was immobilized by using water‐soluble 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide as a coupling agent. The collagen‐immobilized samples, with temperatures of under 4°C, were exposed to gamma ray irradiation at different dose intervals. Gamma ray irradiation was applied to evaluate the bioactivity on the collagen‐immobilized nonwoven polypropylene and to determine the results of sterilization. Five kinds of sterilization index bacteria, all subject to Good Manufacturing Practice (GMP) criteria, were applied as a standard plate‐count sterilization test. Our experimental results demonstrate that in human plasma incubated with various intervals of gamma ray irradiation, fibrinogen concentration decreases while platelet and red blood cell adhesion increase. However, the dose required for thrombination demonstrated a significant change in gamma ray irradiation exposure of fewer than 10 KGy (p = 0.05). The decay of bioactivity of the gamma‐ray‐irradiated collagen‐bonded surfaces was evaluated and indicated that the decrease of R‐CONHR′, the degradation of amides (broken CN bonds of collagen and formation of the ROCNH₂ and OCR′ bonds), and the increase of CO, CO bonds gradually may damage collagen by increasing the intervals of gamma ray irradiation. These effects considerably influence the bioactivity of the collagen‐bonded fabric. It is clear that gamma ray irradiation exposure of ≈10 KGy has the potential of moderating the bioactivities of collagen and therefore likely is a vital factor in the acceleration of biodegradation. The dose required for thrombination and sterilization reaches significance at 7.5 KGy. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1033–1043, 2003