Department of Chemistry, RCSI, 123 St Stephen's Green, Dublin 2, Ireland.
Department of Pharmaceutical Science & Technology, College of Chemistry and Biology, Donghua University, Shanghai 201620, China.
Biochim Biophys Acta Biomembr. 2018 Nov;1860(11):2272-2280. doi: 10.1016/j.bbamem.2018.09.006. Epub 2018 Sep 8.
It is challenging to achieve selective off to on modulation of the emissive state of a fluorophore within a complex and heterogeneous cellular environment. Herein we show that the dis-assembly of a non-fluorescent aggregate to produce individual fluorescent molecules, termed disaggregation induced emission (DIE), can be utilised to achieve this goal with an amphiphilic BF-azadipyrromethene (NIR-AZA) probe. Optical near-infrared properties of the NIR-AZA probe used in this study include absorption and emission maxima at 700 and 726 nm respectively when in the emissive non-aggregated state. Key to the success of the probe is the bis-sulfonic acid substitution of the NIR-AZA fluorophore, which is atypical for membrane probes as it does not contain zwitterionic lipid substituents. The aggregation/disaggregation properties of the NIR-fluorophore have been investigated in model surfactant and synthetic liposomal systems and shown to be emissive responsive to both. Real-time live cell imaging experiments in HeLa Kyoto and MC3T3 cells showed a rapid switch on of emission specific to the plasma membrane of viable and apoptotic cells attributable to a disaggregation-induced emission of the probe. Image analysis software confirmed localisation of fluorescence to the plasma membrane. Cell membrane staining was also effective for formaldehyde fixed cells, with staining possible either before or after fixation. This study adds new and important findings to recent developments of DIE responsive probes and further applications of this controllable emission-switching event are anticipated.
在复杂且异质的细胞环境中，实现荧光团发射状态的选择性关闭到开启调制具有挑战性。在此，我们展示了通过将非荧光聚集物解组装以产生称为解组装诱导发射（DIE）的单个荧光分子，可以利用具有两亲性 BF-偶氮二吡咯甲川（NIR-AZA）探针来实现这一目标。本研究中使用的 NIR-AZA 探针的光学近红外性质包括在发射非聚集状态下分别为 700nm 和 726nm 的吸收和发射最大值。探针成功的关键是 NIR-AZA 荧光团的双磺酸取代，这对于膜探针来说是不典型的，因为它不包含两性离子脂质取代基。NIR-荧光团的聚集/解聚集性质已经在模型表面活性剂和合成脂质体系统中进行了研究，并显示出对两者都具有发射响应性。在 HeLa Kyoto 和 MC3T3 细胞中的实时活细胞成像实验表明，发射的快速开启是由于探针的解组装诱导发射，这归因于活细胞和凋亡细胞的质膜特异性。图像分析软件证实了荧光的局部化到质膜。对于甲醛固定的细胞，细胞膜染色也很有效，固定前或固定后都可以进行染色。这项研究为 DIE 响应探针的最新发展增加了新的和重要的发现，并预计这种可控的发射切换事件将有更多的应用。
