Fluorescent Probes for Manganese(II)

描述(申请人提供)：钙离子等金属离子的荧光探针已被证明是非常有价值的生物研究工具，特别是在神经科学中，金属扮演着化学信使的角色。“开荧光”，即探针发光或变色，远比“关荧光”好，后者的荧光被分析物猝灭。理想的探针应该是比例式的，在一个波长上显示不荧光，在另一个波长上按比例增加荧光。许多生物感兴趣的顺磁性金属离子，包括铜(11)、铁(11)、锰(11)、镍(11)、钴(11)等，只能用已知的探针进行非荧光研究，因为它们的未配对电子提供了一种猝灭荧光的机制。该项目的目标是开发一种新的方法，允许对顺磁性金属离子进行在线荧光检测。在初步实验中，在与生理条件相似的溶液条件下，观察到了比率荧光滴定。金属Mn(11)被广泛用于小鼠脑功能的锰增强磁共振成像(MEMRI)研究中。锰(11)通过钙通道而不阻断钙通道，使其成为神经学研究的独特而有价值的工具。然而，由于没有足够的工具可用来将Mn(11)浓度与观察到的对比度直接关联起来，目前还不可能这样做。因此，本提案中描述的探测将为MEMRI研究中所作的假设提供必要的确认。开发一种荧光分析来补充MEMRI技术，将允许测试大脑中Mn(11)的摄取和释放，测试大脑中的区域定位，并允许识别组织特异性摄取。因此，这一R21应用的总体目标是通过荧光观察Mn(11)在小鼠脑内的分布，为神经学研究提供一个强有力的新工具，并展示一种可广泛应用于生物医学研究的有用的新策略。

DESCRIPTION (provided by applicant): Fluorescent probes for metal ions such as Ca(ll) have proven to be tremendously valuable tools for biological research, particularly in neuroscience where metals play roles as chemical messengers. "On- fluorescence," where the probe lights up or changes color, is greatly preferred to "off-fluorescence", where fluorescence is quenched by the analyte. The ideal probe would be ratiometric, showing off-fluorescence at one wavelength and proportionate increase in fluorescence at another wavelength. Many biologically interesting metal ions that are paramagnetic including Cu(ll), Fe(ll), Mn(ll), Ni(ll), Co(ll) and others can only be studied by off-fluorescence using known probes because their unpaired electrons provide a mechanism to quench fluorescence. The goal of this project is to develop a new approach that allows on-fluorescence detection of paramagnetic metal ions. In preliminary experiments, ratiometric fluorescence titration of Mn(ll) was observed under solution conditions similar to physiological. The metal Mn(ll) is used widely as a tool in manganese-enhanced magnetic resonance imaging (MEMRI) studies of brain function in mice. Mn(ll) passes calcium channels without blocking them, making it a unique and valuable tool for neurological research. However, it has not yet been possible to correlate Mn(ll) concentrations directly with observed contrast as no adequate tool is available to do so. The probes described in this proposal would thus provide needed confirmation of assumptions made in MEMRI research. Development of a fluorescence assay to complement MEMRI techniques would allow the test Mn(ll) uptake and release in the brain, test for regional localization within the brain, and allow identification of tissue-specific uptake. Thus, the overall goal of this R21 application is to observe Mn(ll) distribution in mouse brain by fluorescence, providing a powerful new tool for neurological research, and demonstrating a useful new strategy that can be applied broadly in biomedical research.