一种溶酶体靶向双光子亚硝酰氢荧光探针的合成及细胞成像研究

亚硝酰氢(HNO)是一氧化氮单电子还原并质子化的产物,具有重要的生物学意义.以4-(2-氨基乙基)-吗啉作为溶酶体靶向基团,1,8-萘二甲酰亚胺作为双光子荧光团,三苯基膦作为HNO识别基团,构建了一个能够特异性定位于溶酶体的打开型双光子荧光探针Lyso-HNO.研究结果表明,该探针响应迅速,对HNO表现出良好的选择性,较高的灵敏性,检测极限可达202 nmol·L-1.该探针可对HeLa细胞溶酶体外源HNO进行双光子荧光成像研究.     

溶酶体荧光探针研究新进展

溶酶体在细胞各种生命活动,如物质代谢、细胞膜循环、细胞凋亡中发挥着重要作用.将溶酶体可视化,并对其活性物种、特定微环境及关键生理过程进行检测,不仅有助于理解溶酶体参与生命活动的分子机制,而且对疾病的治疗具有重要的指导意义.近年来,许多靶向溶酶体的荧光探针被相继报道,其检测对象包括还原性物种、活性氧、活性氮、氢离子、金属离子、阴离子以及生物酶等,还包括对温度、粘度、极性、p H等微环境的检测.溶酶体的荧光探针的定位机制分为三类:利用溶酶体的酸性生理环境、利用溶酶体的物质代谢功能以及利用溶酶体特殊的膜蛋白或水解酶.对近年来出现的主要溶酶体荧光探针进行了总结与评述,展望了溶酶体荧光探针应用于探究重要细胞生理过程的分子机制,以及相关疾病诊断方面的发展趋势.     

一个基于NBD-NH2荧光团的增强型pH荧光探针及其细胞造影研究

本文以NBD-NH₂荧光团偶联N-(4-吡啶甲基)乙二胺质子受体构建了基于光致电子转移(PET)机制的pH探针NBD-Py。探针在pH5.0~8.5范围内显示pH降低导致的荧光增强响应,pK_a为6.48。响应不受胞内常见金属离子干扰且有良好的可逆性。研究表明质子受体中引入4-甲基吡啶修饰乙二胺是探针实现对弱酸/近中性pH响应的关键。HeLa细胞中的造影证实了探针的pHi造影能力和溶酶体靶向性能,为溶酶体pH相关的生理过程研究提供了新的可靠手段。     

一个基于NBD-NH2荧光团的增强型pH荧光探针及其细胞造影研究

本文以NBD-NH₂荧光团偶联N-(4-吡啶甲基)乙二胺质子受体构建了基于光致电子转移(PET)机制的pH探针NBD-Py。探针在pH 5.0~8.5范围内显示pH降低导致的荧光增强响应,pK_a为6.48。该响应不受胞内常见金属离子干扰且有良好的可逆性。研究表明质子受体中引入4-甲基吡啶修饰乙二胺是探针实现对弱酸/近中性pH响应的关键。HeLa细胞中的造影证实了探针的pH_i造影能力和溶酶体靶向性能,为溶酶体pH相关的生理过程研究提供了新的可靠手段。     

溶酶体靶向的生物硫醇荧光探针的合成及应用研究

生物硫醇是一类非常重要的活性物质,在细胞的生长或凋亡过程中发挥着重要的作用.本文以香豆素为荧光团,吗啉为溶酶体靶向基团,成功设计并合成了生物硫醇的荧光识别探针Lyso-thiol.该探针可在磷酸盐缓冲溶液(PBS)体系中(pH 7.40)特异性地对生物硫醇产生"off-on"的荧光信号变化,具有高选择性与灵敏度,并可在较大浓度范围内对生物硫醇进行线性检测.在生物硫醇的饱和浓度下,探针最高可实现745倍的荧光强度增强.该探针还具有良好的生物相容性、溶酶体靶向能力及细胞成像能力.     

一种基于罗丹明类似物的Cys近红外荧光探针

基于罗丹明类似物作为荧光团合成了一例新型半胱氨酸(Cys)近红外荧光探针CS-Cys.该探针能特异性识别Cys,其他含巯基氨基酸不与探针响应,响应机理为:Cys与CS-Cys分子中的丙烯酸酯发生共轭加成-环化反应,进而羟基裸露并释放出荧光.通过对CS-Cys与Cys在不同pH环境中反应后的荧光变化进行研究,发现通过改变溶液pH值可调节给电子基的供电子能力和荧光团ICT过程,从而使荧光激发波长和发射波长达到近红外区域.     

β-半乳糖苷酶荧光探针的研究进展

β-半乳糖苷酶是细胞溶酶体中的水解酶,其重要的生理功能是催化水解糖苷键,将乳糖转化成半乳糖.在遗传学领域中对人类β-半乳糖苷酶缺陷病的诊断和基础研究也是重要的指征,故β-半乳糖苷酶活性的检测在生命医学领域具有重要意义.近年来,荧光探针因具有选择性好、灵敏度高及高时空分辨率成像等优点,深受研究者的青睐,已发展了大量的可用于生物体系内β-半乳糖苷酶识别与可视化成像的荧光探针.本文对识别β-半乳糖苷酶的荧光探针的设计策略以及研究进展进行了综述,对未来β-半乳糖苷酶识别荧光探针的研究方向进行了展望.     

羧酸酯酶比率型双光子荧光探针的构建及生物成像研究

羧酸酯酶(CaE)水平的异常与脂肪肝、高血脂等多种疾病的发生密切相关,发展用于快速、准确地检测CaE含量的荧光探针对上述疾病的早期诊断具有重要意义.本文基于分子内电荷转移原理,设计合成了一种对CaE具有高选择性识别的红光比率型双光子荧光探针DCM-CE.CaE催化水解断裂探针分子的酯键,导致酶促反应前后探针的荧光光谱性能发生显著的改变,以此实现对CaE的比率荧光检测.该探针具有较好的选择性、较低的检测下限以及较宽的pH响应范围.此外,我们成功地将DCM-CE应用于活细胞中对内源性CaE的双光子荧光成像.     

稀土-荧光素双重荧光响应pH探针分子的合成与荧光性质研究

将含有8-氨基喹啉与荧光素衍生物缩合的席夫碱QZ1与铕髥的TTA(噻吩基三氟乙酰丙酮)化合物作为基本原料合成了新的铕髥-荧光素化合物Eu-QZ1,并对其进行了光谱表征。化合物Eu-QZ1在470 nm光的激发下产生荧光素的特征绿色荧光(530 nm)。在从碱到酸(pH从9.0到6.0)滴定过程中该荧光的强度增强了接近5倍,其pKa值计算为7.30。在370 nm光的激发下,Eu-QZ1发射稀土铕髥离子的特征红色荧光(主峰位于612 nm)。在从酸到碱(pH从5.5到8.5)滴定过程中,该荧光的强度增强了接近10倍,其pKa值计算为7.39。这些结果表明Eu-QZ1是1个高灵敏度双荧光响应的pH探针。细胞试验表明Eu-QZ1具有良好的细胞通透性,能够在红光和绿光两个位置标记海拉细胞中的pH范围。     

一种基于苯并噻唑的新型过氧亚硝酸盐荧光探针的合成及应用

作为一种典型的活性氮物质,过氧亚硝酸盐(ONOO-)在生理和病理过程中发挥着重要作用。但目前已有的用于检测ONOO-的荧光探针大多存在对ONOO-响应时间长、选择性不足、灵敏性差等缺点,极大地限制了生物体内ONOO-的实时、原位检测。此外,一些探针合成复杂和纯化困难,不利于探针推广使用。该文以2-(2′-羟基-3′-醛基-5′-甲基苯基)苯并噻唑和1,1-二甲基肼为原料,通过一步缩合,简单过滤处理得到一种基于苯并噻唑的新型ONOO-荧光探针BD。但由于N—N单键旋转产生非辐射能量损失,探针BD荧光较弱。在引入ONOO-后,探针BD上的腙水解成醛基,N—N单键脱落,荧光增强,同时可观察到明显的颜色变化。在PBS缓冲溶液(DMSO∶H2O=2∶8,体积比,pH 7.4)中,探针BD对ONOO-具有快速响应(25 s)、高灵敏度(7 nmol/L)和高选择性的特点,可在较宽pH值范围内工作。此外,探针BD还成功地用于肝癌细胞中ONOO-的荧光成像,因此,可作为揭示ONOO-在细胞中作用的一个很有潜力的分析工具。     

Developing a novel ratiometric fluorescent probe based on ESIPT for the detection of pH changes in living cells

As an important parameter of intracellular metabolism, pH plays important roles in maintaining normal physiological processes. The abnormal pH could cause disorder of cell function which may cause neurological diseases. Herein, we present two novel ratiometric fluorescent probes to detect pH changes. The probes employed 2-(2′-hydroxyphenyl)benzothiazole as fluorescent platform, and displayed desirable fluorescence response to pH on the basis of excited state intramolecular proton transfer (ESIPT) process. The probe BtyC-1 showed green fluorescence at 546 nm under acidic conditions, while it displayed strong blue fluorescence at 473 nm and weak green fluorescence at 546 nm under alkaline conditions. Biological experiments demonstrated that the probe BtyC-1 could be successfully applied for the ratiometric imaging of cellular pH and the NH₄Cl-induced pH changes in living cells.     

Monitoring the pH fluctuation of lysosome under cell stress using a near-infrared ratiometric fluorescent probe

Cell stress responses are associated with numerous diseases including diabetes, neurodegenerative diseases, and cancer. Several events occur under cell stress, in which, are protein expression and organelle-specific pH fluctuation. To understand the lysosomal pH variation under cell stress, a novel NIR ratiometric pH-responsive fluorescent probe (BLT) with lysosomes localization capability was developed. The quinoline ring of BLT combined with hydrogen ion which triggered the rearrangement of π electrons conjugated at low pH medium, meanwhile, the absorption and fluorescent spectra of BLT showed a red-shifts, which gived a ratiometric signal. Moreover, the probe BLT with a suitable pK_a value has the potential to discern changes in lysosomal pH, either induced by heat stress or oxidative stress or acetaminophen-induced (APAP) injury stress. Importantly, this ratiometric fluorescent probe innovatively tracks pH changes in lysosome in APAP-induced liver injury in live cells, mice, and zebrafish. The probe BLT as a novel fluorescent probe possesses important value for exploring lysosomal-associated physiological varieties of drug-induced hepatotoxicity.     

Super-resolution imaging and real-time tracking lysosome in living cells by a fluorescent probe

Lysosomes function as important organelles within cells and their movement associates with diverse biological events, hence the real-time tracking of lysosomal movement is of great significance. However, since most lysosome fluorescent probes suffer from relatively unsatisfactory photostability, tracking lysosomal movement in real-time remains challenging. Here, we report that a naphthalimide-based fluorescent compound, namely NIMS, is a quite promising probe for lysosome imaging. The visualizing mechanism lies in the selective accumulation of NIMS in lysosomes via a protonation reaction, followed by the fluorescence enhancement due to the interactions of NIMS with proteins. Owing to its high selectivity and good photostability, NIMS was successfully applied to capture super-resolution fluorescence images of lysosomes. More importantly, real-time tracking of lysosome movement in a single living cell by NIMS was realized with a confocal laser scanning microscope. Surprisingly, even in normal culture conditions, around 2/3 of the captured lysosomes were observed to move within 5 min, indicative of the highly dynamic features of lysosomes. Thus, this probe may facilitate the understanding of the lysosome dynamics in physiological or pathological conditions.     

A selective coumarin-based “turn-on” fluorescent sensor for the detection of cysteine and its applications for bioimaging

A coumarin-based compound (1) was designed and synthesized as a new turn-on fluorescent probe for the detection of cysteine. The in vivo imaging of Hi5 cell and Caenorhabditis elegans had further confirmed the cysteine detection by compound 1.     

A Lysosome‐Compatible Near‐Infrared Fluorescent Probe for Targeted Monitoring of Nitric Oxide

The requirement for nitric oxide (NO) of lysosomes has motivated the development of a sophisticated fluorescent probe to monitor the distribution of this important biomolecule at the subcellular level in living cells. A near‐infrared (NIR) fluorescent Si‐rhodamine (SiRB)‐NO probe was designed based on the NO‐induced ring‐opening process of Si‐rhodamine. The probe exhibits fast chromogenic and fluorogenic responses, and high sensitivity and selectivity toward trace amounts of NO. Significantly, the spirolactam in Si‐rhodamine exhibits very good tolerance to H⁺, which in turn brings extremely low background fluorescence not only in the physiological environment but also under acidic conditions. The stability of the highly fluorescent product in acidic solution provides persistent fluorescence emission for long‐term imaging experiments. To achieve targeted imaging with improved spatial resolution and sensitivity, an efficient lysosome‐targeting moiety was conjugated to a SiRB‐NO probe, affording a tailored lysosome‐targeting NIR fluorescent Lyso‐SiRB‐NO probe. Inheriting the key advantages of its parent SiRB‐NO probe, Lyso‐SiRB‐NO is a functional probe that is suited for monitoring lysosomal NO with excellent lysosome compatibility. Imaging experiments demonstrated the monitoring of both exogenous and endogenous NO in real time by using the Lyso‐SiRB‐NO probe.     

用于检测Al3+和pH值的双功能荧光分子探针

利用荧光素(Fluorescein)对罗丹明6G(Rhodamine 6G)进行修饰,得到荧光分子探针R6G-Flu杂化物.此探针可特异性识别Al3+,检出限可低至10-8 mol/L级;向含有探针分子的溶液中加入Al3+后,溶液的颜色由无色变为粉色,并且在紫外灯下发出绿色荧光,可实现肉眼对10 μmol/L Al3+的定性检测.考察了不同pH值下R6G-Flu的荧光性质. 结果表明,此探针还可用于酸性范围(pH 3.00~6.00)和碱性范围(pH 8.00~10.50)内pH值的精确检测.实验结果表明,R6G-Flu是一种可用于Al3+和pH值检测的双功能荧光分子探针.     

A novel resorufin based fluorescent “turn-on” probe for the selective detection of hydrazine and application in living cells

In this study, a resorufin derivative RTP-1, which is a novel fluorescent ‘‘turn-on' probe for sensitive detection of hydrazine within 30 min, is designed and synthesized. The selective deprotection of the ester group of the probe by hydrazine led to a prominent enhancement of fluorescent intensity, as well as a remarkable color change from colorless to pink, which could be distinguished by naked eye. The fluorescence enhancement showed decent linear relationship with hydrazine concentration ranging from 0 to 50 mmol/L, with a detection limit of 0.84 mmol/L. The specificity of RTP-1 for hydrazine to a number of metal ions, anions and amines is satisfactory. The sensing mechanism of RTP-1 and hydrazine was evaluated by HPLC, ESI mass spectrometry and density functional theory(DFT).Moreover, we have utilized this fluorescent probe for imaging hydrazine in living cells, and the fluorescence was clearly observed when the cells were incubated with hydrazine(100 mmol/L) for 30 min.     

A NBD-based simple but effective fluorescent pH probe for imaging of lysosomes in living cells

NBDlyso with lysosome-locating morpholine moiety has been developed as a high selective and sensitive fluorescent pH probe. This probe can respond to acidic pH (2.0–7.0) in a short time (less than 1 min) and not almost change after continuously illuminated for an extended period by ultraviolet light. The fluorescence intensity of NBDlyso enhanced 100-fold in acidic solution, with very good linear relationship (R² = 0.996). The pK_a of probe NBDlyso is 4.10. Therefore, NBDlyso was used to detect lysosomal pH changes successfully. Besides, X-ray crystallography was used to verify the structure of NBDlyso, and the recognition mechanism involving photo-induced electron transfer was interpreted theoretically by means of DFT and TDDFT calculations skillfully when NBDlyso comes into play under the acidic condition. This probe showed good ability to sense pH change in living cell image.     

罗丹明6G衍生物基偏酸性“关开型”pH荧光探针

以罗丹明6G和水合肼为原料,先制备罗丹明6G酰肼,接着在乙醇中滴加少量冰醋酸做催化剂后与2,5-二甲氧基苯甲醛反应,合成了一种新型的pH荧光分子探针(RGSBD),进行了结构表征及荧光性能研究。结果表明,原本在氢离子浓度较低,即体系pH较高时(pH≥4.0),探针RGSBD内酰胺螺环闭环导致不显示荧光并且无色,然而在氢离子浓度较大即体系pH较低时(pH<4.0)时,其内酰胺螺环闭环产生了明显的颜色变化,发出强烈的荧光。pH 1.9时,探针的荧光强度达到最大,最大荧光峰发生显著的红移。进一步研究表明,探针RGSBD的荧光峰强度差值与pH在1.9~3.2范围内呈良好的线性关系,探针RGSBD识别H^+的选择性高,稳定性与可逆性强,可发展用作生物体内pH荧光传感材料。     

缺氧响应荧光探针的成像及治疗应用

由于肿瘤内部细胞远离血管, 其氧气消耗量远远超出血液供应量, 因此容易导致肿瘤缺氧. 肿瘤缺氧会引发肿瘤扩散加速、 诱导某些基因过表达及产生药物抗药性等问题. 基于此, 发展性能优异的缺氧响应荧光探针对肿瘤的诊断和治疗具有重要意义. 本文对缺氧响应荧光探针在成像及治疗方面的应用进展进行了综合评述, 介绍了硝基、 偶氮键和醌3种常用的缺氧响应基团, 并探讨了它们在缺氧微环境下的识别机理; 介绍了缺氧响应荧光探针的构建及其在生物成像方面的最新研究成果; 总结了缺氧响应荧光探针在基因治疗、 光动力学治疗、 化学治疗及协同治疗方面的研究进展; 展望了缺氧响应荧光探针在临床诊断和治疗方面的应用前景.