Ultrasensitive Near-Infrared Fluorescence-Enhanced Probe for in Vivo Nitroreductase Imaging
Ultrasensitive Near-Infrared Fluorescence-Enhanced Probe for in Vivo Nitroreductase Imaging
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用于体内硝基还原酶成像的超灵敏近红外荧光增强探针
DOI：
10.1021/jacs.5b04097
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发表时间：
2015-05-20
影响因子：
15
通讯作者：
Li, Fuyou
中科院分区：
文献类型：
--
作者：
Li, Yuhao;Sun, Yun;Li, Fuyou
缺氧肿瘤中硝基还原酶（NTR）会过表达，因此选择性、高效地检测NTR具有重要意义。迄今为止，虽然已经报道了一些光学方法用于检测溶液中的NTR，但仍然缺乏用于体内NTR监测的有效光学探针。因此，有必要开发一种近红外荧光检测探针。在这项研究中，五个近红外菁染料的荧光报告结构修饰不同的硝基芳香基团，Cy 7 -1-5，已被设计和探索可能的快速检测NTR。我们的实验结果表明，只有对硝基苯甲酸基团修饰的菁探针（Cy 7 -1）可以作为一个快速的近红外荧光增强探针监测和生物成像的NTR。理论研究揭示了其结构功能关系。连接检测基团和荧光报告基团以及硝基位置的接头是形成氢键和空间结构匹配的关键因素，诱导NTR催化能力增强。通过动力学光学等方法研究了Cy 7 -1酶催化还原的体外反应和机理。结果表明，当Cy 7 -1被NTR催化还原为Cy 7-NH 2时，吸电子基团诱导的电子转移过程被阻断，这表现在检测过程中荧光强度增强。缺氧A549细胞的共聚焦荧光成像证实了Cy 7 -1在细胞水平上的NTR检测能力。重要的是，Cy 7 -1可以检测小鼠缺氧肿瘤模型中的肿瘤缺氧，显示出其NIR荧光特性的快速和显著增强，适用于荧光生物成像。该方法有可能用于肿瘤缺氧诊断。
Nitroreductase (NTR) can be overexpressed in hypoxic tumors, thus the selective and efficient detection of NTR is of great importance. To date, although a few optical methods have been reported for the detection of NTR in solution, an effective optical probe for NTR monitoring in vivo is still lacking. Therefore, it is necessary to develop a near-infrared (NIR) fluorescent detection probe for NTR. In this study, five NIR cyanine dyes with fluorescence reporting structure decorated with different nitro aromatic groups, Cy7-1-5, have been designed and explored for possible rapid detection of NTR. Our experimental results presented that only a para-nitro benzoate group modified cyanine probe (Cy7-1) could serve as a rapid NIR fluorescence-enhanced probe for monitoring and bioimaging of NTR. The structure function relationship has been revealed by theoretical study. The linker connecting the detecting and fluorescence reporting groups and the nitro group position is a key factor for the formation of hydrogen bonds and spatial structure match, inducing the NTR catalytic ability enhancement. The in vitro response and mechanism of the enzyme-catalyzed reduction of Cy7-1 have been investigated through kinetic optical studies and other methods. The results have indicated that an electro-withdrawing group induced electron-transfer process becomes blocked when Cy7-1 is catalytically reduced to Cy7-NH2 by NTR, which is manifested in enhanced fluorescence intensity during the detection process. Confocal fluorescence imaging of hypoxic A549 cells has confirmed the NTR detection ability of Cy7-1 at the cellular level. Importantly, Cy7-1 can detect tumor hypoxia in a murine hypoxic tumor model, showing a rapid and significant enhancement of its NIR fluorescence characteristics suitable for fluorescence bioimaging. This method may potentially be used for tumor hypoxia diagnosis.