Development of Low-temperature Sterilization Technique Using Microwave Plasma and Its Medical Application

在这项研究中，我们旨在开发一种新的利用大容量微波等离子体的低温灭菌技术，并将其结果应用于医疗领域。在2004财政年度，我们进行了实验，以阐明等离子体灭菌的机理，并研究改善低温快速灭菌特性的可能性。为了确认导管等特定医疗设备的灭菌效果，我们在2005和2006两个会计年度，对包装的医疗器械进行了体波等离子体低温内灭菌的实验验证。本文的主要研究成果如下：(1)氧等离子体杀菌机理的阐明：实验证实氧等离子体中氧自由基的刻蚀作用是主要的杀菌因素。而在氧…中没有观察到强的紫外光发射在较多的等离子体中，由于在290~400 nm范围内有几个较强的紫外光发射，表明紫外光发射是氮等离子体中的主要因素。(2)通过控制微波等离子体的开关来降低热效应：对于塑料医疗器械，由于非耐热材料，要求避免热效应。通过引入微波等离子体的时间调制操作，成功地将样品的温度降低到70℃以下。(3)体波等离子体生产实验：利用体波等离子体对包裹物品内部进行杀菌实验。我们确认血浆是在塑料瓶里产生的。利用脉冲微波等离子体对玻璃纸包裹的生物指示剂(芽孢杆菌)在20min内杀菌效果进行了验证。(4)·OH自由基的影响：考察了水蒸气的加入对微波等离子体灭菌性能的影响。结果表明，水蒸气对提高杀菌速度起着重要作用。孢子细胞的崩解可能与胞质中产生的羟基自由基有关。(5)结果综述：共发表期刊论文16篇，著作2部，国际会议论文集38篇，国内会议发表论文132篇。我们还申请了7项与目前的等离子灭菌相关的国内外专利，并获得了1项等离子灭菌方法的专利。较少

In this research, we aimed at developing a novel low-temperature sterilization technique using large-volume microwave plasma and finally applying the results to the medical field. In the fiscal year 2004, we have carried out the experiments to clarify the mechanism of plasma sterilization and to study the possibility of improving the characteristics of rapid sterilization at low temperature. In the fiscal years 2005 and 2006, we have performed the experimental verification of low-temperature internal sterilization for the wrapped medical instruments using the volume-wave plasma in order to confirm the sterilization of specific medical equipments such as catheter. In the following, we listed the main results of the present research.(1) Clarification of the sterilization mechanism of oxygen plasma: It was experimentally confirmed that the etching effect due to the oxygen radicals was the main sterilizing factor in the oxygen plasma. While no strong UV emission was observed in the oxygen … More plasma, it was shown that the UV emissions were main factor in the nitrogen plasma, since there were several strong UV emissions in the range of 290〜400 nm.(2) Reduction of thermal effect by means of on-off control of microwave plasma: It is required to avoid thermal effect in the case of plastic medical instruments, because of non-heat resist materials. By introducing the time-modulated operation of microwave plasma, we succeeded to reduce the temperature of the samples less than 70 ℃.(3) Experiment of volume-wave plasma production: To sterilize inside the wrapped articles, we have carried out the sterilization experiment using the volume-wave plasma. We confirmed that the plasma was produced inside the plastic bottle. By using the pulsed-microwave plasma, we confirmed the sterilization of biological indicators (Bacillus Atrophaous) wrapped by glassine paper within 20 min.(4) Effect of OH radicals: We have investigated the effect of water vapor addition on the sterilization performance using the microwave plasma with air-simulated nitrogen-oxygen gas mixture. From the results, it was deduced that the water vapor played an important role on the improvement of sterilization speed. The collapse of spore cells might be attributed to the OH radicals generated in the plasma.(5) Summary of results: We reported 16 journal papers, 2 books, 38 proceeding of international conferences, and 132 presentations in the domestic meetings. We also applied 7 domestic and foreign patents relating with the present plasma sterilization, and we have taken one patent on the plasma sterilization method. Less