Near-Infrared Fluorescence Lifetime pH-Sensitive Probes
Near-Infrared Fluorescence Lifetime pH-Sensitive Probes
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DOI：
10.1016/j.bpj.2011.02.050
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发表时间：
2011-04-20
影响因子：
3.4
通讯作者：
Achilefu, Samuel
中科院分区：
文献类型：
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作者：
Berezin, Mikhail Y.;Guo, Kevin;Achilefu, Samuel
我们报告我们认为是第一个近红外pH敏感的荧光寿命的分子探针，适用于生理范围内的生物应用。具体而言，我们修改了一个已知的荧光团骨架，六甲基吲哚三碳菁，与叔胺功能，电子耦合到荧光团，以产生pH敏感的探针。探针的pK（a）主要取决于胺的位置。在吲哚环的5-位处的外围取代产生具有如通过发射光谱测定的类似于4.9的pK（a）的化合物。相比之下，在中间位的取代使pK（a）移动至5.5。所得化合物LS 482表现出稳态和荧光寿命pH敏感性。这种敏感性源于质子化（类似于酸性DMSO中的1.16 ns）和去质子化（类似于碱性DMSO中的1.4 ns）组分的不同寿命。荧光染料的生物应用的适用性证明了荧光寿命断层扫描系统。询问细胞过程并随后在活生物体中翻译结果的能力进一步增强了这些基于寿命的pH探针的潜力。
We report what we believe to be the first near-infrared pH-sensitive fluorescence lifetime molecular probe suitable for biological applications in physiological range. Specifically, we modified a known fluorophore skeleton, hexamethylindotricarbocyanine, with a tertiary amine functionality that was electronically coupled to the fluorophore, to generate a pH-sensitive probe. The pK(a) of the probe depended critically on the location of the amine. Peripheral substitution at the 5-position of the indole ring resulted in a compound with pK(a) similar to 4.9 as determined by emission spectroscopy. In contrast, substitution at the meso-position shifted the pK(a) to 5.5. The resulting compound, LS482, demonstrated steady-state and fluorescence-lifetime pH-sensitivity. This sensitivity stemmed from distinct lifetimes for protonated (similar to 1.16 ns in acidic DMSO) and deprotonated (similar to 1.4 ns in basic DMSO) components. The suitability of the fluorescent dyes for biological applications was demonstrated with a fluorescence-lifetime tomography system. The ability to interrogate cellular processes and subsequently translate the findings in living organisms further augments the potential of these lifetime-based pH probes.