Development and Application of L-band ESR system for in vivo analysis

L波段的电子自旋共振系统是本研究的最新成果，它使生物样品的在体测量成为可能。制作了具有电屏蔽环间隙谐振器(谐振频率为0.7~1 GHz)，并在环路中加入了电屏蔽环间隙谐振器，通过插入盐水溶液检测了该谐振腔的特性。结果表明，电屏蔽法对大批量湿样品的测量是有效的。计算机在线系统通过将计算机与L频段电子自旋共振波谱仪相连，实现了磁场扫描、信号处理和谐振频率的自动控制。信号的累积和平滑使灵敏度提高了约10倍。自动频率控制器可以提供良好的ESR谱，而不会出现基线波动。应用于生物样品和物质样品的测定可在活体状态下检测新鲜芹菜和大鼠体内外源氮氧自由基的行为。观察了芹菜茎中自由基含量的变化及叶中的腐烂行为。对大鼠头部注射氮氧自由基进行了动态研究。此外，对锰干电池进行了现场测试，结果表明，阴极混合物中含有的碳自由基与干电池的放电反应密切相关。ESR成像为了得到样品中自由基团的分布，用凝胶渗透色谱对不同样品进行了二维ESR成像。

L-band ESR system which makes it possible to perform in vivo measurements of biological samples has been newly developed in this study.1. Loop-gap resonator having an electric shieldLoop-gap resonator (resonant frequency = 0.7 to 1 GHz) having an electric shield in the loop was made, the characteristics of this resonator were examined by insertion of saline salt solution. The results indicated that electric shield was effective to measurements of wet samples of large quantities.2. On-line system by computerBy connecting computer to L-band ESR spectrometer, scanning of magnetic field, proccessing of ESR signals, and auto control of resonant frequency were carried out. Accumulation and smoothing of signals increased the sensitivity by about 10 times. Auto controller of frequency could afford good ESR spectra without fluctuation of baseline.3. Application to measurements of biological and material samplesBehaviors of exogenous nitroxide radicals in fresh celery and rat could be examined at in vivo state. The change of radical content passing through celery stalk and the decay behavior in the leaves were observed. Attempts of dynamic studies of nitroxide radicals injected in rat were made at the head of rat. Furthermore, in situ measurements of manganese dry cell were performed, and the results suggested that the carbon radical contained in cathode mix was strongly related to the discharge reactions of dry cell.4. ESR imagingIn order to get the distribution of radicals in sample, two-dimensional ESR imaging of various samples was carried out by Zeugmatography.