Hunan Provincial Key Laboratory of Cytochemistry, School of Chemistry and Food Engineering, Changsha University of Science and Technology, Changsha, Hunan 410114, P. R. China.
State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P. R. China.
Anal Chem. 2020 Apr 21;92(8):5787-5794. doi: 10.1021/acs.analchem.9b05278. Epub 2020 Mar 31.
Accurate and sensitive imaging of hypoxia associated with inflammatory bowel disease (IBD) is significant for the precise diagnosis and treatment of this disease, but it remains a challenge for traditional hypoxia-activatable fluorescence probes because of a more moderate hypoxic state during IBD than under other pathological conditions. To address this issue, herein, we designed a hypoxia-activatable and cytoplasmic protein-powered fluorescence cascade amplifier, named HCFA, to image hypoxia associated with IBD . In our design, a 4-aminobenzoic acid (azo)-modified mesoporous silica nanoparticle (MSN) was used as a container to load black hole quencher 2 (BHQ2) and cytoplasmic protein-binding squarylium dye (SQ); then, the β-cyclodextrin polymer (β-CDP) combined with azo through a host-guest interaction to form HCFA. Upon passive stagnation in the inflamed tissue of IBD, the azo band would be cleaved under a hypoxic microenvironment, and SQ was released to activate the fluorescence of HCFA. Moreover, the unconstrained SQ can bind with cytoplasmic protein to exhibit drastic fluorescence intensity enhancement, realizing the fluorescence signal amplification for imaging of hypoxia. When one takes advantage of the large load capacity of MSN and the unique property of SQ, HCFA can sense oxygen levels in the range of 0% to 10%. Meanwhile, the fluorescence imaging results demonstrate that HCFA can sensitively distinguish different levels of cellular hypoxia and monitor the variations of hypoxia , highlighting HCFA as a promising tool for the detection of hypoxia associated with IBD.
准确且敏感地对与炎症性肠病（IBD）相关的缺氧进行成像，对于该疾病的精确诊断和治疗具有重要意义，但由于 IBD 期间的缺氧状态比其他病理条件下更为温和，因此传统的缺氧激活荧光探针仍然具有挑战性。为了解决这个问题，我们设计了一种缺氧激活和细胞质蛋白驱动的荧光级联放大器，命名为 HCFA，用于对与 IBD 相关的缺氧进行成像。在我们的设计中，使用 4-氨基苯甲酸（偶氮）修饰的介孔硅纳米颗粒（MSN）作为容器来装载黑洞猝灭剂 2（BHQ2）和细胞质蛋白结合的 squarylium 染料（SQ）；然后，β-环糊精聚合物（β-CDP）通过主客体相互作用与偶氮结合形成 HCFA。在 IBD 的炎症组织中被动停滞时，偶氮带会在缺氧微环境下被切割，SQ 被释放以激活 HCFA 的荧光。此外，无约束的 SQ 可以与细胞质蛋白结合，表现出剧烈的荧光强度增强，实现了缺氧成像的荧光信号放大。当利用 MSN 的大容量负载能力和 SQ 的独特性质时，HCFA 可以在 0%到 10%的氧水平范围内感知氧气水平。同时，荧光成像结果表明，HCFA 可以敏感地区分不同水平的细胞缺氧，并监测缺氧的变化，突出了 HCFA 作为检测与 IBD 相关的缺氧的有前途的工具。
