HIGH FREQUENCY EPR OF VIABLE BIOLOGICAL SYSTEMS

在过去的十年里，已经表明，非常高的频率 (VHF)EPR在许多类型的实验中提供了很大的优势。 然而，迄今为止，我们还没有看到任何有记录的尝试应用这一点， 技术，以可行的生物系统。 原因有两个 技术和心理：W波段（95 GHz）的采样量 可以比传统的X波段小1000倍， 损失略高。 在目前的工作中，我们证明了 甚高频电子顺磁共振在细胞研究中的前景。 VHF EPR具有更好的 绝对点灵敏度，这是研究中必不可少的 小物体（如单个细胞）或表面，包括细胞 膜。 VHF EPR提供了更好的g值分辨率， 一种是用光谱分离不同种类的氮氧化合物 同一体系中的自由基，或不同分子中的自由基 环境（例如，更清楚地区分氮氧化物 溶解在脂质、膜和水相中的分子， 细胞）。 VHF EPR光谱学的另一种可能的应用， 成像是在低温生物学中，氮氧自旋探针可以用于 以跟踪冷冻过程中细胞的再分配过程。

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.