Development of New Atomic-Based EPR Spin Probes

描述（由申请人提供）：新的基于原子的EPR自旋探针的开发概述/摘要电子顺磁共振（EPR）方法在医学中的使用是一个快速发展的领域。在过去的十年中已经取得了重大进展，EPR可能很快被用于指导癌症，中风和对氧合和缺氧进行非侵入性测量至关重要的疾病的治疗。然而，进一步改进以提高其检测活性氧（ROS）产生的自由基的灵敏度将使其适用于更广泛的疾病。生物医学EPR系统的一个关键组成部分是自旋探针，这是检测顺磁自由基所必需的基本化学试剂。然而，目前的自旋探针具有局限性。例如，当前一代的自旋探针不够灵敏，不能直接检测或成像年龄相关的病症或由ROS介导的疾病（例如帕金森病和阿尔茨海默病）中活性氧物质的体内产生。为了克服这些局限性，我们建议研究新的自旋探针的顺磁性原子封装在富勒烯笼的基础上。含有未成对电子的原子，例如钉扎在对称C60笼中心的原子氮，完全不受与外部物质反应的影响，并产生前所未有的窄线宽。例如，N@C60具有已知最宽的EPR线宽之一，使其检测效率比目前的化合物高100至1000倍。除了保护封装的原子，富勒烯笼可以与自由基物种相互作用，并且在N@C60表面上发生的反应在其EPR光谱中产生可测量的位移。这些特性，沿着已被证实的生物相容性，使得富勒烯封装的原子成为理想的自旋探针。N@C60是理想的自旋探针的缩影，但目前对它的研究受到大量生产和纯化困难的阻碍。然而，原子N不是富勒烯封装的唯一可能选择。我们已经研究了具有类似EPR性质的替代原子，但更容易商业化生产。该项目的具体目标是合成和表征这些候选物中最有前途的，并证明它可以形成一种新型EPR自旋探针的基础，与目前的化合物相比具有许多优点。 公共卫生相关性：电子顺磁共振（EPR）是一种类似于磁共振成像（MRI）的新兴技术，有可能帮助诊断和指导疾病的治疗，如癌症，中风和其他涉及活性氧（ROS）稳态破坏的疾病。EPR依赖于称为自旋探针的分子试剂与附近的氧或活性氧自由基相互作用，以产生可检测的信号。然而，需要具有更高灵敏度的新化合物来改进EPR技术并使其用于更多疾病。为了消除现有的自旋探针固有的局限性，我们建议研究基于顺磁性原子封装在C60富勒烯，将有更高的灵敏度，在他们的能力，以检测活性氧物种的新型自旋探针。开发新的自旋探针，允许在体内检测产生的ROS，例如，帕金森氏症和其他ROS疾病将代表生物医学EPR技术的重大进展。

DESCRIPTION (provided by applicant): Development of New Atomic-Based EPR Spin Probes Summary/Abstract The use of electron paramagnetic resonance (EPR) methods in medicine is a rapidly advancing field. There has been significant progress in the past decade, and EPR may soon be used to guide the treatment of cancer, strokes, and conditions where it is crucial to make non-invasive measurements of oxygenation and hypoxia. However, further improvements to increase its sensitivity to detect radicals generated by reactive oxygen species (ROS) would make it applicable to a wider range of diseases. A key component of the biomedical EPR system is the spin probe, the fundamental chemical agent necessary to detect paramagnetic radicals. However, current spin probes have limitations. For example, the current generation of spin probes are not sensitive enough to directly detect or image the in vivo generation of reactive oxygen species in age related disorders or diseases mediated by ROS such as Parkinson's and Alzheimer's disease. To overcome these limitations, we propose to investigate new spin probes based upon paramagnetic atoms encapsulated in fullerene cages. Atoms containing unpaired electrons, such as atomic nitrogen pinned at the center of the symmetric C60 cage, are completely protected from reaction with external species and produce unprecedented narrow line widths. For example, N@C60 has one of the narrowest known EPR line widths, giving it a detection efficiency 100 to 1000 times better than the current compounds. In addition to protecting the encapsulated atom, the fullerene cage can interact with radical species, and reactions occurring on the surface of N@C60 produce measurable shifts in its EPR spectrum. Such features, along with proven biological compatibility, make fullerene-encapsulated atoms ideal spin probes. N@C60 epitomizes the ideal spin probe, but research on it is currently hindered by difficulties in producing and purifying it in bulk. However, atomic N is not the only possible choice for fullerene encapsulation. We have examined alternative atoms that will have similar EPR properties, but will be far easier to produce commercially. The specific aim of this project is to synthesize and characterize the most promising of these candidates and demonstrate that it can form the basis for a new type of EPR spin probe with many advantages over the current compounds. PUBLIC HEALTH RELEVANCE: Electron paramagnetic resonance (EPR) is an emerging technique similar to magnetic resonance imaging (MRI) that has the potential to help diagnose and guide the treatment of diseases such as cancer, stroke, and other conditions involving disruption of reactive oxygen species (ROS) homeostasis. EPR relies upon molecular agents called spin probes to interact with nearby oxygen or reactive oxygen radicals to generate a detectable signal. However, new compounds with higher sensitivity are needed to improve EPR technology and allow it to be used for more diseases. To remove the limitations inherent to current spin probes, we propose to investigate new types of spin probes based upon paramagnetic atoms encapsulated in C60 fullerenes that will have higher sensitivity in their ability to detect reactive oxygen species. The development of new spin probes that allow in vivo detection of ROS produced, for example, by Parkinson's and other ROS diseases would represent a significant advance in biomedical EPR technology.