PULSE WAVE EPR SPECTROSCOPY AND IMAGING

电子顺磁共振(EPR)提供了一种灵敏的方法 检测和定量自由基物种。常规常量 自由基反应，最近越来越多地被用来探索 错综复杂的生物中间体。在这个时候，虽然EPR 比核磁共振敏感得多，它被用作 大于1 MHz--以及可检测信号的稀缺性。因为辐射 诱导出电子的级联并最终导致 自由基物种，ROB已经发展成一种脉搏波(PW) EPR光谱仪和电子顺磁成像(EPI)。自兴奋以来 电子弛豫在微秒和更少，使用纳秒PW-EPR 迄今为止无法实现的快速信号平均和处理是 检测瞬变、短暂的自由径向信号所需。 同样，CW-EPR以前施加的技术限制 采用脉冲技术进行EPT时，微波频率不是僵局 和梯度剖面图以及复杂的电子学和计算 所使用的技术。该项目的目标是创建一个 为PW-EPI体内成像奠定基础。第一要务 在无线电频率上演示一维和二维的项目 电子的图像完成了。开发的第二个里程碑 第一低频脉冲EPR信号的自旋标记(氮氧化物； T1/2=90纳秒)。初步的成功确保了可行性。现在 概念、电子学和计算的局限性正在被 重做了。

Electron Paramagnetic Resonance (EPR) provides a sensitive means of detecting and quantitating free radical species. Conventional constant wave (CW) EPR has provided insight into the basic chemistry of free radical reactions and has most recently been increasingly used to probe the intricacies of biological intermediates. At this time, although EPR is vastly more sensitive than nuclear magnetic resonance, its use as a biological tool has been limited by both the frequency used--routinely greater 1 MHz--and the paucity of detectable signal. Because radiation induces a cascade of electrons and ultimately results in formation of free radical species, the ROB has been developing both a pulse wave (PW) EPR spectrometer and Electron Paramagnetic Imaging (EPI). Since excited electron relax in microseconds and less, the use of nanosecond PW-EPR with heretofore unachievable rapid signal averaging and processing is required for detection of transient, short-lived free radial signals. Likewise, the previous technologic limitations imposed by CW-EPR microwave frequencies are not an impasse when EPT with pulsing techniques and gradient profiling and sophisticated electronics and computational techniques are employed. The goals of this project are to create a prototypical PW-EPR instrument for in vitro biologic studies and to establish the foundation of PW-EPI in vivo imaging. The first priority of the project to demonstrate at radio frequencies one and two dimension images of electrons is completed. The second milestone of developing an intermediately fast averager has been completed and has allowed detection of the first low frequency, pulsed EPR signal of a spin label (nitroxide; T1/2 = 90 nanoseconds). The initial successes assure feasibility. Now the limitations of the concepts and electronics and computation are being reworked.