Kanjickal Deenu, Lopina Stephanie, Evancho-Chapman Mary Michelle, Schmidt Steven, Inbaraj Johnson J, Cardon Thomas B, Lorigan Gary A
Department of Chemical Engineering, University of Akron, Akron, Ohio 44325, USA.
J Biomed Mater Res A. 2009 Feb;88(2):409-18. doi: 10.1002/jbm.a.31717.
The effects of several sterilization procedures on a poly(ethylene glycol) (PEG) hydrogel have been examined by electron spin resonance (ESR) spectroscopy. The crosslinked polyurethanes were synthesized by reacting PEG with a tri-functional isocyanate. The free radical concentration of unsterilized, ethylene oxide (EtO), hydrogen peroxide (H(2)O(2)), and gamma sterilized hydrogels were monitored over time. Free radical presence was observed for all the treatments, unsterilized and sterilized PEG hydrogels. The unsterilized and the EtO sterilized samples elicited similar levels of free radical intensity whereas, the H(2)O(2) and gamma sterilized samples had a significantly higher free radical concentration. The spectra reveal overlapping resonances of a peroxy and a triphenylmethyl radical. The concentration of the free radicals increase for all the treatments over time except for the gamma sterilized sample. The increase is significantly higher in the H(2)O(2) sterilized sample. A tentative model is proposed to explain the reaction pathway leading to the production of the free radicals. The observed increases in the free radical concentrations of the EtO and hydrogen peroxide sterilized hydrogels over a five-month-period make it difficult to predict properties that are affected by free radical concentrations. In that light, gamma sterilization, that does not induce a change in free radical concentrations over a five month period, could be the sterilization method of choice for PEG hydrogels that could potentially be stored for undetermined periods of time prior to application.
通过电子自旋共振（ESR）光谱研究了几种灭菌程序对聚乙二醇（PEG）水凝胶的影响。交联聚氨酯是通过使PEG与三官能异氰酸酯反应合成的。对未灭菌、环氧乙烷（EtO）、过氧化氢（H₂O₂）和γ射线灭菌水凝胶的自由基浓度随时间进行了监测。在所有处理中，包括未灭菌和已灭菌的PEG水凝胶，均观察到自由基的存在。未灭菌和EtO灭菌的样品引发的自由基强度水平相似，而H₂O₂和γ射线灭菌的样品具有明显更高的自由基浓度。光谱显示了过氧自由基和三苯甲基自由基的重叠共振。除γ射线灭菌样品外，所有处理的自由基浓度均随时间增加。在H₂O₂灭菌样品中，这种增加明显更高。提出了一个初步模型来解释导致自由基产生的反应途径。在五个月的时间里，观察到EtO和过氧化氢灭菌水凝胶的自由基浓度增加，这使得难以预测受自由基浓度影响的性能。鉴于此，γ射线灭菌在五个月的时间内不会引起自由基浓度的变化，对于可能在应用前储存不确定时间的PEG水凝胶来说，可能是首选的灭菌方法。
