IN VIVO EPR SPECTROMETRY VIA 200 MHZ FIELD SWITCHING

由于其非侵入性/非破坏性的性质，磁共振 技术代表了一系列基础和临床 生物医学研究问题。 核磁共振（NMR） 特别是在体内系统的应用中出现了爆炸式增长 从小动物模型到人类。然而， 受到极差的信噪比灵敏度的严重限制。 对于许多应用，电子顺磁共振（EPR）提供了 大大改善SIN，如果与大型 可以解决导电样品。 例如，体内EPR实验 在标准微波频率下遭受极端微波采样-- 穿透限制和天线灵敏度阻尼。 在此我们 提出了一种利用快场的非正统EPR谱仪设计 切换（FFS），如果成功，将启用常规低场（70 Gauss/200 MHz）EPR实验。 无线电频率操作 大大降低了导电样品相关的技术难度。 这 设计，通过避免微波询问脉冲， 谱仪死区时间小于10 ns的快速接收机恢复 预期 这将允许广泛的电子自旋标签， 采用 电子自旋的短自旋晶格弛豫时间将 允许非常有效的时间平均，进一步增加S/N。 FFS-EPR 设计仅利用最近可用的大电流快速开关 晶体管。 据我们所知，目前还没有其他实验室在从事这项工作。 设计策略 如果成功的话，这种体内EPR的方法将使 利用磁共振技术， 生物医学研究问题。

Because of its non-invasive/non-destructive nature, magnetic resonance techniques represent powerful approaches to a host of basic and clinical biomedical research problems. Nuclear magnetic resonance (NMR) in particular has seen an explosion in applications to in vivo systems ranging from small animal models to man. Nevertheless, NMR applications are severely restricted by extremely poor signal-to-noise sensitivity. For many applications, electron paramagnetic resonance (EPR) offers greatly improved SIN if major technical problems associated with large conductive samples can be solved. For example, in vivo EPR experiments at standard microwave frequencies suffer extreme microwave sample-- penetration limitations and antenna sensitivity damping. Herein we propose an unorthodox EPR spectrometer design utilizing fast field switching (FFS) that if successful will enable routine low field (70 Gauss/200 MHz) EPR experiments in vivo. Operation at radio frequencies greatly reduces conductive sample related technical difficulties. This design, by avoiding microwave interrogation pulses, allows for extremely fast receiver recovery with spectrometer dead times less than 10 ns expected. This will allow a wide range of electron spin labels to be used. The short spin lattice relaxation times of electron spins will allow very efficient time averaging further increasing S/N. The FFS-EPR design makes use of only recently available high current fast switching transistors. We know of no other laboratory currently pursuing this design strategy. If successful this approach to in vivo EPR will make accessible to magnetic resonance techniques an entirely new regime of biomedical research problems.