Fluorescence Sensing of NO: Development of Reversible Sensors Using Fe(III)

描述（由申请人提供）：一氧化氮（NO）历来被视为环境污染物和大气健康危害，但最近已显示其在心血管、免疫和神经系统的生物信号事件中发挥积极作用。NO产生的调节是非常重要的，因为低细胞浓度的NO有益于血管舒张和免疫活性，如防止肿瘤生长。然而，细胞NO的过度产生可导致反应性NO种类的增殖，其与致癌作用和几种退行性神经障碍（包括阿尔茨海默病、帕金森病、亨廷顿病和多发性硬化症）有关。尽管目前存在几种NO传感器，但它们都具有限制，这降低了体内使用的便利性。虽然NO检测已在体内完成，NO的可逆传感仍然是一个重要因素，在定量NO浓度在不同的细胞区域和响应于外部刺激。该建议涉及一个可逆的结合位点的设计，再加上光诱导电子转移（PET），允许荧光成像的NO。本研究的最终目标是开发一种用于细胞水平的NO的可逆荧光探针，其可用于在体内对NO的时间和空间检测。所提出的荧光传感器家族使用顺磁性Fe（III）（S = 1/2）中心，其充当荧光猝灭剂和NO的结合位点的双重作用。6复合物，允许在悬垂荧光团上恢复荧光。配体支架提供了一个独特的平台，其中配体电子器件和用于NO结合的疏水口袋都可以进行微调。将研究各种配体取代和荧光团以调节Fe（III）中心的NO结合性质以有利于可逆的NO结合;官能团掺入配体中可以允许细胞靶向。细胞一氧化氮（NO）的过度产生可导致活性NO物质（RNOS）的增殖，其与致癌作用和几种神经系统疾病（包括阿尔茨海默病、帕金森病、亨廷顿病和多发性硬化症）有关。详细了解NO作为生物系统中的化学信使的作用，其影响跨越许多医学领域。在此应用中，我们提出了一氧化氮荧光探针的设计，这将允许检测和定量NO细胞成分。

DESCRIPTION (provided by applicant): Nitric oxide (NO) has historically been viewed as an environmental pollutant and as an atmospheric health hazard, but recently it has been shown to play an active role in biological signaling events in the cardiovascular, immune, and nervous systems. Regulation of NO production is of immense importance because low cellular concentrations of NO are beneficial for vasodilation and immune activity such as preventing tumor growth. Overproduction of cellular NO, however, can lead to the proliferation of reactive NO species which have been implicated in carcinogenesis and several degenerative neurological disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. Although several NO sensors currently exist, they all have limitations which diminish the facility of in vivo use. While NO detection has been accomplished in vivo, the reversible sensing of NO remains an important factor in quantifying NO concentrations in different cellular locales and in response to external stimuli. This proposal involves the design of a reversible binding site for NO coupled with photoinduced electron transfer (PET) to allow for fluorescent imaging. The ultimate goal of this research is to develop a reversible fluorescent probe for cellular levels of NO which can be used in vivo for the temporal and spatial detection of NO. The proposed family of fluorescent sensors use paramagnetic Fe(lll) (S = 1/2) centers serving a dual role as both fluorescence quencher and binding site for NO. Coordination of NO to the Fe(lll) center will afford a diamagnetic {Fe-NO}6 complex, allowing for the restoration of fluorescence on the pendant fluorophore. The ligand scaffold provides a unique platform where both the ligand electronics and the hydrophobic pocket for NO binding can be finely tuned. Various ligand substitutions and fluorophores will be investigated to tune the NO binding properties of the Fe(lll) center to favor reversible NO binding; functional group incorporation into the ligand can allow for cellular targeting. PUBLIC HEALTH RELEVANCE Overproduction of cellular nitric oxide (NO) can lead to the proliferation of reactive NO species (RNOS) which have been implicated in carcinogenesis and several neurological disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. A detailed understanding of the role of NO as a chemical messenger in biological systems has implications that span across many fields of medicine. In this application, we propose the design of fluorescent probes for NO which will allow for the detection and quantification of NO in cellular components.