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

描述（由申请人提供）：一氧化氮（NO）历来被视为一种环境污染物和大气健康危害，但最近已被证明在心血管、免疫和神经系统的生物信号事件中发挥积极作用。调节NO的产生是非常重要的，因为低细胞浓度的NO有利于血管舒张和免疫活性，如防止肿瘤生长。然而，细胞一氧化氮的过量产生可导致活性一氧化氮的增殖，这与致癌和几种退行性神经系统疾病有关，包括阿尔茨海默病、帕金森病、亨廷顿病和多发性硬化症。虽然目前存在几种一氧化氮传感器，但它们都有局限性，从而降低了在体内使用的方便性。虽然一氧化氮检测已经在体内完成，但一氧化氮的可逆感知仍然是量化不同细胞区域和外部刺激反应中一氧化氮浓度的重要因素。这个建议涉及到设计一个可逆的结合位点的NO与光诱导电子转移（PET）偶联，以允许荧光成像。本研究的最终目标是开发一种可逆的细胞水平NO荧光探针，可用于体内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(ll) （S = 1/2）中心作为荧光猝灭剂和NO结合位点的双重作用。NO与Fe（ll）中心的配位将产生抗磁性{Fe-NO}6配合物，从而允许在垂坠的荧光团上恢复荧光。配体支架提供了一个独特的平台，在这个平台上，配体电子学和NO结合的疏水口袋都可以被精细地调节。将研究各种配体取代和荧光团，以调整Fe（ll）中心的NO结合特性，使其有利于可逆的NO结合；将官能团结合到配体中可以实现细胞靶向。细胞一氧化氮（NO）的过量产生可导致反应性NO物种（RNOS）的增殖，这与致癌和几种神经系统疾病有关，包括阿尔茨海默病、帕金森病、亨廷顿病和多发性硬化症。详细了解一氧化氮在生物系统中作为化学信使的作用，对医学的许多领域都有影响。在这个应用中，我们提出了NO荧光探针的设计，这将允许检测和定量细胞成分中的NO。

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.