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

说明(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有利于血管扩张和免疫活动，如防止肿瘤生长。然而，细胞内NO的过量生产可以导致反应性NO物种的增殖，这些物种与癌症和几种退行性神经疾病有关，包括阿尔茨海默病、帕金森氏病、亨廷顿病和多发性硬化症。尽管目前存在几个NO传感器，但它们都有局限性，降低了在体内使用的便利性。虽然NO的检测已经在体内完成，但NO的可逆感觉仍然是量化不同细胞位置的NO浓度和对外部刺激做出反应的重要因素。这一建议包括设计一个与光诱导电子转移(PET)耦合的NO的可逆结合部位，以允许进行荧光成像。本研究的最终目的是开发一种细胞水平的可逆的NO荧光探针，可以在体内用于对NO的时空检测。所提出的荧光传感器家族使用顺磁性Fe(111)(S=1/2)中心，兼具荧光猝灭和NO结合位点的双重作用。NO与Fe(111)中心的配位将形成抗磁性的{Fe-NO}6络合物，从而使悬挂的荧光团上的荧光得以恢复。配体支架提供了一个独特的平台，在这里配体电子和疏水口袋都可以进行微调。将研究各种配体取代和荧光团，以调整Fe(111)中心的NO结合性质，以有利于可逆的NO结合；将官能团掺入配体可以允许细胞靶向。公共卫生相关性细胞一氧化氮(NO)的过量产生可导致反应性NO物种(RNO)的增殖，RNO与癌症和几种神经系统疾病有关，包括阿尔茨海默病、帕金森氏病、亨廷顿病和多发性硬化症。对NO在生物系统中作为化学信使的作用的详细理解具有跨越许多医学领域的意义。在这一应用中，我们提出了NO荧光探针的设计，这将允许检测和定量细胞组件中的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.