The fluorescent nanoprobes for reduced thiol compounds (represented by glutathione, GSH) are constructed based on the aggregation-induced emission (AIE) luminescence mechanism and endosome escape technology. First, a DNA sequence was designed with the decoration of biotin at the 5'-end, disulfide bound in the internal portion, and amino at the 3'-end. The aptamer of the MCF-7 cell was also one of the most important structures in our DNA sequence for the selectivity of MCF-7 cells. We modified streptavidin-modified magnetic beads (MB) with biotin-modified influenza virus hemagglutinin peptide (HA) and biotin-DNA-amino to form MB/DNA/HA. Carboxyl-modified tetraphenylethylene (TPE), an iconic AIE fluorogen, was bonded with amino-modified DNA by covalent interactions (TPE/DNA). Then, the TPE molecule was attached on the outer layer of MB via biotin-modified TPE/DNA to form MB/DNA/HA/TPE. Compared with traditional AIE/biomolecule conjugates, the nanoprobe had an enhanced endosome escape function, due to the assembly of HA. This construction made the intracellular fluorescence response more accurate. In the presence of reduced thiol compounds (take GSH, for example), the disulfide bond on the DNA was reduced by thiol-disulfide exchange reactions and the TPE molecule was released into the solution. The shedding TPE molecule was more hydrophobic than TPE/DNA and the conversion of TPE/DNA to shedding TPE could lead to the aggregation of the TPE fluorogen. Thus, its fluorescence was enhanced. Under the optimized condition, the fluorescence intensity increased with the increase in concentration of GSH' ranging from 1.0 × 10-9 M to 1.0 × 10-5 M' and the detection limit was 1.0 × 10-9 M. The relative standard deviation (RSD) was calculated to be 3.6%. The recovery in cell homogenate was from 94.5 to 102.7%. The nanoprobe provided a way for the detection of reduced thiol compounds in MCF-7 cells. We envision that, in the near future, our strategy of DNA-instructed AIE could be widely applied for biosensing and bioimaging in vitro and even in vivo with dramatically enhanced sensitivity. Graphical Abstract.

中文翻译：

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聚集诱导的发射氟/ DNA探针，带有内体逃逸通道，用于跟踪细胞中还原的硫醇化合物。

基于聚集诱导发射（AIE）发光机理和内体逃逸技术构建了用于还原硫醇化合物的荧光纳米探针（以谷胱甘肽，GSH表示）。首先，设计一个DNA序列，在5'末端修饰生物素，在内部结合二硫键，在3'末端修饰氨基。MCF-7细胞的适体也是我们DNA序列中对MCF-7细胞选择性最重要的结构之一。我们用生物素修饰的流感病毒血凝素肽（HA）和生物素-DNA-氨基修饰链霉亲和素修饰的磁珠（MB），形成MB / DNA / HA。羧基修饰的四苯基乙烯（TPE），一种标志性的AIE氟，通过共价相互作用（TPE / DNA）与氨基修饰的DNA结合。然后，TPE分子通过生物素修饰的TPE / DNA连接到MB的外层，形成MB / DNA / HA / TPE。与传统的AIE /生物分子缀合物相比，由于HA的组装，纳米探针具有增强的内体逃逸功能。这种结构使细胞内荧光反应更准确。在还原的硫醇化合物（例如GSH）存在下，DNA上的二硫键通过硫醇-二硫键交换反应被还原，TPE分子被释放到溶液中。脱落的TPE分子比TPE / DNA更具疏水性，并且TPE / DNA转化为脱落的TPE可能导致TPE氟的聚集。因此，其荧光增强。在优化的条件下，荧光强度随着GSH'浓度的增加从1开始增加。0×10-9 M至1.0×10-5 M'，检出限为1.0×10-9M。相对标准偏差（RSD）计算为3.6％。细胞匀浆的回收率为94.5至102.7％。纳米探针为检测MCF-7细胞中还原的硫醇化合物提供了一种方法。我们设想，在不久的将来，我们的DNA指导的AIE策略可以显着提高灵敏度，从而广泛应用于体外甚至是体内的生物传感和生物成像。图形概要。我们的DNA指导的AIE策略可以显着提高灵敏度，从而可以广泛应用于体外甚至体内的生物传感和生物成像。图形概要。我们的DNA指导的AIE策略可以显着提高灵敏度，从而可以在体外甚至在体内广泛应用于生物传感和生物成像。图形概要。