HIGH FREQUENCY EPR OF VIABLE BIOLOGICAL SYSTEMS

在过去的十年里，已经证明了非常高的频率 (甚高频)电子顺磁共振在许多类型的实验中具有很大的优势。 然而，到目前为止，我们还没有看到有记录的尝试应用这一点 从技术到可行的生物系统。这样做的原因既有 技术和心理：W频段(95 GHz)的样本量 可能比传统X波段小1000倍，而且微波 损失要高一些。在目前的工作中，我们演示了 甚高频电子顺磁共振在细胞研究中的应用前景。VHF EPR有一个更好的 绝对点敏感度，这是研究 小对象(如单个细胞)或表面，包括细胞 膜。VHF EPR提供的更好的g值分辨率使 一种以光谱方式分离不同种类的氮氧化物 同一体系中的自由基，或不同分子中的自由基 环境(例如，为了更清楚地区分氮氧化物 溶解在脂类、膜和水相中的分子 细胞)。甚高频电子顺磁共振波谱的另一个可能的应用 成像是在低温生物学中，可以使用氮氧化物自旋探针 在冷冻过程中跟踪细胞内的再分布过程。

Over the past decade it has been shown that very high frequency (VHF) EPR offers great advantages in many types of experiments. However, to date we have seen no documented attempts to apply this technique to viable biological systems. The reasons for this are both technical and psychological: the sample volume at W-band (95 GHz) could be 1000-fold smaller than at conventional X-band, and microwave losses are somewhat higher. In the present work we demonstrate the prospects for VHF EPR in cellular studies. The VHF EPR has a better absolute point sensitivity, which is essentially needed in studies of small objects (like a single cell) or surfaces, including cellular membranes. The better g-value resolution offered by VHF EPR enables one to separate spectroscopically different kinds of nitroxide radicals within the same system, or radicals in different molecular environments (e.g. to distinguish more clearly between nitroxide molecules dissolved in lipids, membranes, and aqueous phase of the cell). Another possible application of VHF EPR spectroscopy and imaging is in cryobiology, where nitroxide spin probes could be used to follow redistribution processes in cells during freezing.