Detection and Imaging of Nitric Oxide with Novel Fluorescent Indicators: Diaminofluoresceins
作者:Hirotatsu Kojima、Naoki Nakatsubo、Kazuya Kikuchi、Shigenori Kawahara、Yutaka Kirino、Hiroshi Nagoshi、Yasunobu Hirata、Tetsuo Nagano
DOI:10.1021/ac9801723
日期:1998.7.1
Nitric oxide is a gaseous, free radical which plays a role as an intracellular second messenger and a diffusable intercellular messenger. To obtain direct evidence for NO functions in vivo, we have designed and synthesized diaminofluoresceins (DAFs) as novel fluorescent indicators for NO. The fluorescent chemical transformation of DAFs is based on the reactivity of the aromatic vicinal diamines with NO in the presence of dioxygen. The N-nitrosation of DAFs, yielding the highly green-fluorescent triazole form, offers the advantages of specificity, sensitivity, and a simple protocol for the direct detection of NO (detection limit 5 nM). The fluorescence quantum efficiencies are increased more than 100 times after the transformation of DAFs by NO. Fluorescence detection with visible light excitation and high sensitivity enabled the practical assay of NO production in living cells. Membrane-permeable DAF-2 diacetate (DAF-2 DA) can be used for real-time bioimaging of NO with fine temporal and spatial resolution. The dye was loaded into activated rat aortic smooth muscle cells, where the ester bonds are hydrolyzed by intracellular esterase, generating DAF-2. The fluorescence in the cells increased in a NO concentration-dependent manner.
一氧化氮是一种气态自由基,它既是细胞内的第二信使,也是可扩散的细胞间信使。为了直接证明一氧化氮在体内的功能,我们设计并合成了二氨基荧光素(DAFs),作为一氧化氮的新型荧光指示剂。DAFs 的荧光化学变化是基于芳香族环状二胺在二氧存在下与 NO 的反应性。DAFs 的 N-亚硝基化反应生成了高绿色荧光的三唑形式,具有特异性、灵敏度高、操作简单等优点,可直接检测 NO(检测限为 5 nM)。DAF 被 NO 转化后,荧光量子效率提高了 100 多倍。利用可见光激发的荧光检测和高灵敏度,可以对活细胞中的 NO 生成进行实际检测。膜渗透性 DAF-2 diacetate(DAF-2 DA)可用于对 NO 进行实时生物成像,并具有较高的时间和空间分辨率。将染料装入活化的大鼠主动脉平滑肌细胞,细胞内酯酶水解酯键,生成 DAF-2。细胞内的荧光增加与 NO 浓度有关。