电子顺磁共振（EPR）是组织细胞内定量检测一氧化氮（NO）的可靠手段，但其生物医药应用仍受限于现有NO自旋捕获剂的低灵敏性及潜在毒性。申请人前期工作证实，四硫取代三苯甲基（TAM）自由基拥有优越EPR波谱性质及高度生物稳定性，已成功用于超氧自由基及生物巯基等生理参数的定量检测，极具在体精准检测与成像NO潜质，但目前尚无相关报道。本项目拟将TAM自由基与二价铜离子（Cu2+）配合物相偶联，构建高灵敏、高特异NO自旋捕获剂；通过TAM自由基、Cu2+配体、连接链的结构修饰优化捕获剂的灵敏性、特异性及稳定性，并改善其生物相容性和药代动力学，阐明调节分子性能的结构基础；在细胞和活体层面评估捕获剂应用潜质，以心肌缺血-再灌注为模型，研究NO供体在体释放行为，揭示NO与活性氧及缺血-再灌注损伤的相关性。本项目的有效实施将为NO在体精准检测与成像提供技术平台，推动NO供体类药物研发。

Electron paramagnetic resonance (EPR) has been established as a reliable technique for quantitative detection of cellular and tissue nitric oxide (NO) levels, but its biomedical applications have been greatly limited by the low sensitivity and potential toxicity of the currently available NO probes. Our recent studies have demonstrated that owing to excellent EPR properties and high biostability, tetrathiatriarylmethyl (TAM) radicals have been successfully used for quantitative detection of various physiological parameters including superoxide radical and biothiols. It can be anticipated that TAM radicals show great potential in highly sensitive and quantitative detection and mapping of NO in vivo systems. However, no related study has been reported so far. Therefore, this project will focus on development of the complexes of TAM radicals with copper (II) as highly sensitive and selective NO probes. Chemical modifications to various parts including TAM, linker and copper (II) complex will be used to improve the biostability, sensitivity, selectivity, biocompatibility, and pharmacokinetics of these probes. Based on these results, the structure-activity relationship will be interpreted. Then, these probes will be used to measure NO levels in cellular and in vivo systems using myocardial ischemia-reperfusion (I/R) injury model and explore the release of NO donors in these systems. The NO levels measured in these systems will be correlated with the ROS levels as well as the myocardial I/R injury and detailed mechanisms regarding their interactions will be interpreted. This project would provide a new and reliable tool for precise detection and imaging of NO in vivo systems and thus expedite the research and development of new NO donor-based drugs.